JP7487010B2 - Reference point forming device, satellite image processing device, and satellite image processing method - Google Patents

Description

The present invention relates to a reference point forming device, a satellite image processing device, and a satellite image processing method.

In recent years, images taken by Synthetic Aperture Radar (SAR) satellites and optical satellites have been used to capture the state and changes of the earth's surface over a wide range and with high resolution. When using SAR satellites, it is possible to capture the target, such as the ground surface, even at night or on cloudy days. For example, Patent Document 1 discloses an anti-aircraft marker that has a pillar section erected on the ground surface and a flat section laid on the ground surface around the pillar section, and is made of a material that reflects radio waves emitted by a SAR satellite. On the other hand, the processing required to make the target intuitively understandable from images taken by SAR satellites (hereinafter referred to as SAR images) is somewhat complicated.

When optical satellites are used, it is easy to intuitively identify the subject from the captured image, but it is difficult to capture images under consistent optical conditions, and it takes time to adjust the conditions. Therefore, in order to utilize the advantages of both capturing images using SAR satellites and capturing images using optical satellites, a method has been proposed that combines SAR images with images captured by optical satellites (hereinafter referred to as optical images). For example, Patent Document 2 discloses a method of combining SAR images with optical images so that objects on the Earth's surface can be easily identified. In the method disclosed in Patent Document 2, the acquired SAR image is approximated based on black-and-white panchromatic image characteristics, and the approximated radar image data is aligned with the optical image.

JP 2014-048163 A JP 2009-047516 A

In general, even if the SAR image and the optical image are taken of the same measurement area, the shooting directions are different. Therefore, in the process after combining the SAR image and the optical image, it is necessary to correct at least one of the images to match them. Conventionally, for example, a method is used in which patterns of a specified area in the SAR image and the optical image are extracted and the positions of these patterns in each image are matched with each other.

However, because there are no anti-aircraft markers on the SAR and optical images, the accuracy of matching the positions in each image is reduced, as mentioned above. Furthermore, if the measurement area includes the Earth's surface, the SAR and optical images are subject to misalignment and distortion due to the effects of the atmosphere and ionosphere, as well as distortion due to the Earth being an uneven ellipsoid. This makes it difficult to accurately match the SAR and optical images.

The present invention provides a reference point formation device, a satellite image processing device, and a satellite image processing method that can accurately match SAR images and optical images.

The reference point forming device of the present invention comprises a radio wave reflecting unit that reflects radio waves emitted from a SAR satellite in a first direction relative to the incident direction, and a pattern forming unit that forms a reference point pattern indicating the position of the reference point when photographed from a second direction by an optical satellite.
According to the above-mentioned reference point forming device, radio waves transmitted from the SAR satellite are reflected in a predetermined direction and finally reach the SAR satellite. The SAR image sent from the SAR satellite includes position information of the reference point. According to the above-mentioned reference point forming device, a reference point pattern is formed in an optical image taken by an optical satellite based on reflected light of irradiated light such as sunlight. The reference point pattern makes it easy to determine the position of the reference point in the optical image that is common to the SAR image. Therefore, the SAR image and the optical image can be accurately matched based on the information of the common reference points.

In the reference point forming device according to the present invention, the reference point pattern may include a plurality of straight reference lines that intersect at the reference points when viewed from the second direction.
In the reference point forming device according to the present invention, the reference point pattern may include one or more polygonal reference lines centered on the reference point when viewed from the second direction.
In the reference point forming device according to the present invention, the reference point pattern may include one or more annular reference lines centered on the reference point when viewed from the second direction.
According to the above-mentioned reference point forming device, the intersection of the linear reference lines becomes the reference point, and the position of the reference point can be easily determined in the image processing of the optical image. Also, according to the above-mentioned reference point forming device, the position of the reference point at the center of the polygonal reference line or the annular reference line can be easily determined.

The reference point forming device according to the present invention may have a plurality of regions adjacent to each other with the reference line as a boundary, the regions differing from each other in the amount of light reflected when a light wave is incident thereon or in the wavelength of the light wave.
According to the above-mentioned reference point forming device, a reference point pattern including reflected images of multiple areas is obtained in the optical image captured by the optical satellite, and the position of the reference point can be easily determined by the reference line that appears in the reference point pattern.

The reference point forming device of the present invention has a base portion having an intersecting plane that intersects with the second direction at the reference point, and a plate-shaped portion erected on the intersecting plane and arranged along the reference line when viewed from the second direction, wherein the radio wave reflecting portion is provided on a plate surface inclined with respect to the intersecting plane and on the intersecting plane in the plate-shaped portion, and the pattern forming portion may be provided on the intersecting plane.
According to the above-mentioned reference point forming device, the SAR image contains the position information of the reference point based on the information of the radio waves reflected by the plate surface and the crossing surface of the plate-shaped part. Also, according to the above-mentioned reference point forming device, the optical image includes a reference point pattern formed from the crossing surface of the imaged base part, and the position of the reference point common to the SAR image can be easily identified.

The reference point forming device of the present invention comprises a base portion having an intersecting plane that intersects with the second direction at the reference point, a radome formed from the outer edge of the base portion so as to move away from the intersecting plane toward a position on the front side of the reference point in the direction of incidence of the radio waves, and which transmits the radio waves, and a plate-shaped portion erected on the intersecting plane and contained in the inner space of the radome, wherein the radio wave reflecting portion is provided on a plate surface inclined with respect to the intersecting plane in the plate-shaped portion and on the intersecting plane, and the pattern forming portion is provided on the outer surface of the radome.
According to the above-mentioned reference point forming device, since the plate-shaped portion is housed in the inner space of the radome, the inclination angle of the plate-shaped portion relative to the base portion is prevented from being changed by external factors such as wind hitting the plate-shaped portion.

The reference point forming device of the present invention may have a base portion having an intersecting surface that intersects in the second direction, and a columnar portion erected on the intersecting surface and whose bottom surface is in contact with the intersecting surface, wherein the radio wave reflection portion is provided on a side surface of the columnar portion and on the intersecting surface that is exposed when viewed from the second direction, and the pattern forming portion is provided on a top surface of the columnar portion when viewed from the second direction, and on the intersecting surface that is exposed when viewed from the second direction.
In addition, the reference point forming device of the present invention may have a base portion having an intersecting surface that intersects with the second direction, and a conical portion erected on the intersecting surface and whose bottom surface is in contact with the intersecting surface, the conical portion having an orthogonal surface that is perpendicular to the intersecting surface and an inclined surface that is inclined with respect to both the intersecting surface and the orthogonal surface, the radio wave reflecting portion being provided on the orthogonal surface and the intersecting surface that is exposed when viewed from the second direction, and the pattern forming portion being provided on the inclined surface and the intersecting surface that is exposed when viewed from the second direction.
According to the above-mentioned reference point forming device, the SAR image includes the position information of the reference point based on the radio waves reflected by the side surface of the columnar portion or the orthogonal surface and the intersection surface of the pyramidal portion. Also, according to the above-mentioned reference point forming device, the optical image includes a reference point pattern formed from the captured top surface of the columnar portion or the inclined surface of the pyramidal upper portion and the intersection surface exposed when viewed from the second direction, and the position of the reference point common to the SAR image can be easily identified.

The reference point forming device of the present invention further includes a positioning signal receiving antenna provided at the top of the cone-shaped portion and configured to receive a positioning signal transmitted from the synthetic aperture radar satellite, and the pattern forming portion may be provided on the surface of the positioning signal receiving antenna and on the inclined surface and the intersection surface exposed when viewed from the second direction.
According to the above-mentioned reference point forming device, the positioning signal receiving antenna is provided on the closer side in the direction of incidence of the radio waves than the radio wave reflecting section, thereby improving the receiving sensitivity of the positioning signal and improving the accuracy of matching the SAR image with the optical image.

In the reference point forming device according to the present invention, a solar cell may be provided on the intersecting surface exposed when viewed from the second direction.
According to the above-mentioned reference point forming device, when sunlight is irradiated onto the intersection surface exposed when viewed from the second direction, electricity is generated, making it possible to supply power to equipment electrically connected to the reference point forming device, and the supplied electricity is utilized.

The satellite image processing device of the present invention comprises the above-mentioned reference point formation device, and an image processing unit that compares the common reference points between a radar image and an optical image created based on radar image information received from the synthetic aperture radar satellite and optical image information received from the optical satellite, and matches the radar image with the optical image.
A satellite image processing method according to the present invention is a satellite image processing method using the above-mentioned satellite image processing device, and includes creating a radar image and an optical image based on radar image information received from the synthetic aperture radar satellite and optical image information received from the optical satellite, and matching the radar image and the optical image by comparing the reference points that are common to both the radar image and the optical image.
According to the above-mentioned satellite image processing device and satellite image processing method, a reference point forming device in which a radio wave reflecting section that reflects radio waves from a SAR satellite and a pattern forming section to which a reference point pattern is applied share a common position is used to compare reference points common to the radar image and the optical image, thereby enabling the SAR image and the optical image to correspond more accurately than in the past.

The present invention provides a satellite image processing device and a satellite image processing method that can accurately match SAR images with optical images.

1 is a schematic diagram of a satellite image processing device according to the present invention; 1 is a perspective view of a reference point forming device according to a first embodiment of the present invention; 3 is a plan view of the reference point forming device shown in FIG. 2 as viewed from a third direction. 2 is a schematic diagram for explaining correspondence between a SAR image and an optical image in the satellite image processing device shown in FIG. 1 . FIG. 11 is a perspective view of a reference point forming device according to a second embodiment of the present invention; 6 is a plan view of the reference point forming device shown in FIG. 5 as viewed from a third direction. FIG. 13 is a perspective view of a reference point forming device according to a third embodiment of the present invention; FIG. 13 is a perspective view of a reference point forming device according to a fourth embodiment of the present invention. 9 is a plan view of the reference point forming device shown in FIG. 8 as viewed from a third direction. FIG. 13 is a perspective view of a reference point forming device according to a fifth embodiment of the present invention. FIG. 13 is a perspective view of a reference point forming device according to a sixth embodiment of the present invention. FIG. 13 is a perspective view of a reference point forming device according to a seventh embodiment of the present invention. FIG. 13 is a perspective view of a reference point forming device according to an eighth embodiment of the present invention. FIG. 13 is a perspective view of a reference point forming device according to a ninth aspect of the present invention. FIG. 15 is a perspective view of a reference point forming device according to a tenth embodiment of the present invention. 16 is a perspective view showing the configuration of the inner space of the radome of the reference point forming device shown in FIG. 15 . FIG. 23 is a perspective view of a reference point forming device according to an eleventh aspect of the present invention. 18 is a perspective view showing the configuration of the inner space of the radome of the reference point forming device shown in FIG. 17 . FIG. 23 is a perspective view of a reference point forming device according to a twelfth aspect of the present invention. FIG. 23 is a perspective view of a reference point forming device according to a thirteenth aspect of the present invention. FIG. 23 is a perspective view of a reference point forming device according to a fourteenth aspect of the present invention. FIG. 23 is a perspective view of a reference point forming device according to a fifteenth aspect of the present invention.

The following describes the reference point forming device, satellite image processing device, and satellite image processing method according to the present invention with reference to the drawings.

As shown in Fig. 1, a satellite image processing device 300 according to the present invention includes GNSS receiving units 160-1, ..., 160-j (j is a natural number of 2 or more) arranged on the Earth's surface GD, and an image processing unit 310. A number of artificial satellites (SAR satellites, optical satellites) 50-1, 50-2, ..., 50-n (n is a natural number of 2 or more, preferably a natural number of 4 or more) orbit above the Earth's surface GD.

In the following, in a description common to GNSS receiving units 160-1, ..., 160-j, these GNSS receiving units may be collectively referred to as GNSS receiving unit 160. Similarly, in a description common to multiple artificial satellites 50-1, ..., 50-n, these artificial satellites may be collectively referred to as artificial satellite 50. Note that natural numbers j and n are each set appropriately and are not limited to specific values. Of the multiple GNSS receiving units 160, FIG. 1 illustrates GNSS receiving units 160-1, 160-2, and 160-3. Of the multiple artificial satellites 50, FIG. 1 illustrates artificial satellites 50-1, 50-2, and 50-n.

Each of the artificial satellites 50 emits radio waves E and creates SAR images and optical images (satellite images) based on the time it takes for the emitted radio waves E to be reflected back to itself and changes in the characteristics of the reflected radio waves E. That is, each of the artificial satellites 50 is a SAR satellite or an optical satellite. If the artificial satellite 50 is a SAR satellite, the radio waves E have a longer wavelength than, for example, visible light. If the artificial satellite 50 is an optical satellite, the radio waves E are, for example, visible light.

The GNSS receiving units 160 are installed at predetermined locations on the earth's surface GD throughout the country. Each GNSS receiving unit 160 is equipped with a reference point forming device 400, a positioning antenna (not shown), a wireless communication device, a battery, and heaters and monitoring devices necessary for the operation of these components.

The reference point forming device 400 is provided at a predetermined position on the ground surface GD. As shown in Figures 2 and 3, the reference point forming device 400 includes a radio wave reflecting section 410 and a pattern forming section 420.

When the satellite 50 is an SAR satellite, the radio wave reflecting unit 410 reflects the radio waves E emitted from the satellite 50 in a direction (first direction) D1 that is parallel and opposite to the direction of incidence. When the satellite 50 is an optical satellite, the pattern forming unit 420 forms a reference point pattern 435 that indicates the reference point 430 when photographed by the satellite 50 from a predetermined direction (second direction) D2.

Hereinafter, the reference point forming device 400 of the first aspect will be referred to as the reference point forming device 400A. The reference point forming device 400A includes a base portion 441 and cone-shaped portions 461 and 462. The base portion 441 is a base formed in a plate shape and has an intersection surface 442. The intersection surface 442 is arranged so that it can be photographed when the earth's surface GD of the subject is imaged from the artificial satellite 50 when the artificial satellite 50 is an optical satellite. That is, the intersection surface 442 intersects with the direction D2 and is, for example, approximately perpendicular to the direction D2. When viewed from the direction D2, the reference point 430 is located at the center of the intersection surface 442. The base portion 441 and the intersection surface 442 are formed in a rectangular shape when viewed from the direction D3 perpendicular to the intersection surface 442.

Each of the pyramids 461 and 462 is a triangular pyramid erected on the intersecting surface 442. The pyramid 461 has a bottom surface 444, two orthogonal surfaces 465 and 466, and one inclined surface 468. The bottom surface 444 is in contact with the intersecting surface 442 and is formed in an isosceles triangle shape with a right apex angle when viewed from the direction D2. The orthogonal surfaces 465 and 466 and the inclined surface 468 constitute the side surfaces of the triangular pyramid. The two orthogonal surfaces 465 and 466 rise from the isosceles that sandwich the apex angle of the bottom surface 444 toward the reference point 430 and are perpendicular to the intersecting surface 442. The inclined surface 468 rises from the base of the bottom surface 444 toward the reference point 430 and is inclined with respect to the intersecting surface 442 and each of the orthogonal surfaces 465 and 466.

The apex of each of the pyramidal portions 461 and 462 overlaps with the reference point 430 when viewed from the direction D3. Furthermore, the pyramidal portions 461 and 462 are point-symmetric with respect to the reference point 430 and face each other. The bases of the inclined surfaces 468 of the pyramidal portions 461 and 462 overlap with the outer edges of the base portion 441 and the intersecting surface 442 that are parallel to each other when viewed from the direction D3.

When the artificial satellite 50 is an optical satellite, the earth's surface GD is imaged from almost directly above, so the direction D2 can be said to be almost the same as the direction D3. In the reference point forming device 400A, the radio wave reflecting unit 410 is provided on the orthogonal surfaces 465, 466 and the crossing surface 443 exposed when viewed from the direction D3 (i.e., the direction D2). The orthogonal surfaces 465, 466 of the pyramidal portions 461, 462 and the crossing surface 443 are configured to be able to reflect radio waves E. The orthogonal surface 465 of the pyramidal portion 461, the orthogonal surface 466 of the pyramidal portion 462, and the crossing surface 443 connecting the bases of these orthogonal surfaces in the directions D2/D3 constitute a corner reflector and function as the radio wave reflecting unit 410. Similarly, the orthogonal surface 466 of the pyramidal portion 461, the orthogonal surface 465 of the pyramidal portion 462, and the intersecting surface 443 connecting the bases of these orthogonal surfaces form a corner reflector and function as the radio wave reflecting portion 410.

In the reference point forming device 400A, the pattern forming section 420 is provided on the inclined surfaces 468 of each of the pyramidal sections 461 and 462 and on the intersecting surface 443 of the base section 441, and is composed of the inclined surfaces 468 and the intersecting surface 443 that are adjacent to each other when viewed from the direction D3 as shown in FIG. 3.

The inclined surfaces 468 of the cone-shaped portions 461 and 462 and the intersecting surface 443 of the base portion 441 reflect different amounts or wavelengths of light when the same light wave L is incident thereon. Therefore, if the inclined surfaces 468 and the intersecting surface 443 are each considered to be regions, the reference point forming device 400A has regions that reflect different amounts or wavelengths of light when the light wave L is incident thereon.

The inclined surface 468 and the intersecting surface 443 form a reference point pattern 435 when viewed from the directions D2 and D3. The reference point pattern 435 is not particularly limited as long as the reference point 430 can be determined by image processing of an image of the reference point pattern 435. For example, a pattern published in a manual on anti-aircraft markers (UAV) issued by the Geospatial Information Authority of Japan, Ministry of Land, Infrastructure, Transport and Tourism, can be referenced. The reference point pattern 435 shown in FIG. 3 is a so-called X-shaped pattern of a UAV. For example, the inclined surface 468 is black when viewed from the directions D2 and D3. In contrast, the intersecting surface 443 is white or yellow, which is highly distinguishable from the black of the inclined surface 468. It is also possible that the inclined surface 468 is white or yellow and the intersecting surface 443 is black.

When the reference point pattern 435 is imaged from the direction D2, the optical image includes the reference point pattern 435, and linear reference lines 481 and 482 appear in the reference point pattern 435. The reference line 481 overlaps with the orthogonal surfaces 465 of the pyramidal parts 461 and 462 when viewed from the direction D3, and appears in the optical image by the inclined surfaces 468 and the intersecting surface 443 adjacent to each other with the orthogonal surface 465 as a boundary. The reference line 482 overlaps with the orthogonal surfaces 466 of the pyramidal parts 461 and 462 when viewed from the direction D3, and appears in the optical image by the inclined surfaces 468 and the intersecting surface 443 adjacent to each other with the orthogonal surface 466 as a boundary. The reference lines 481 and 482 intersect each other at right angles at the reference point 430 when viewed from the direction D3, forming the letter X. In other words, the reference point 430 is indicated by the intersection of the reference lines 481 and 482 identified from the reference point pattern 435.

It is preferable that the size of the reference point pattern 435 when viewed from the directions D2 and D3 is at least twice the ground resolution (GSD) of the optical satellite. This means that it is possible to assign the areas of the reference point pattern 435 to be distinguished from one another to at least one pixel in the optical image captured by the optical satellite. In the reference point pattern 435 illustrated in FIG. 3, it is preferable that the length of the side along the pixel arrangement of the optical image 520 described later among each side of the inclined surface 468 and each side of the crossing surface 443 is equal to or greater than the GSD of the optical satellite. For example, when the GSD of the optical satellite is 25 cm and the reference lines 481 and 482 shown in FIG. 3 are approximately parallel to the arrangement direction of the multiple pixels of the optical image 520, it is preferable that each of the isosceles triangular bottom surface 444 of the pyramidal portion 461 and the isosceles of the crossing surface 443 of the base portion 441 is equal to or greater than 25 cm. That is, the length of the reference lines 481, 482 is preferably 50 cm or more, which is twice 25 cm. When the reference lines 481, 482 shown in FIG. 3 intersect with the arrangement direction of multiple pixels in the optical image 520, it is preferable that the base surface 444 of the pyramidal portion 461 and the base of the intersecting surface 443 of the base portion 441 are 50 cm or more.

The positioning antenna, wireless communication device, battery, heater, monitoring device, etc. in each of the GNSS receiving units 160 shown in FIG. 1 are housed in a support unit provided, for example, below the reference point forming device 400. The peripheral devices including the positioning antenna are positioned so as not to block the reflection of radio waves E in the radio wave reflecting unit 410 of the reference point forming device 400 and the image of the pattern forming unit 420.

The image processing unit 310 receives information on the SAR image (radar image information) and information on the optical image (optical image information) from the artificial satellite 50 via a central station or reference station (not shown), and creates a SAR image (radar image) 510 and an optical image 520 based on each piece of information, as shown in FIG. 4. The SAR image 510 determines the position information, such as the latitude, longitude, and altitude, of the reference point 430-k (k is any natural number), based on the time it takes for the radio waves E emitted from the SAR satellite to be reflected by the SAR satellite itself and the change in the characteristics of the reflected radio waves E.

On the other hand, the optical image 520 reveals the relative position of the reference point 430-k, which is the center position of the reference point pattern 435 photographed by the optical satellite. The image processing unit 310 compares the reference point 430-k common to the SAR image 510 and the optical image 520, associates the SAR image 510 with the optical image 520, and aligns the SAR image 510 with the optical image 520.

The satellite image processing method according to the present invention is a method for matching SAR image 510 and optical image 520 using satellite image processing device 300. The satellite image processing method according to the present invention creates SAR image 510 and optical image 520 based on information about the SAR image received from a SAR satellite and information about the optical image received from an optical satellite, and compares at least common reference points 430-k between SAR image 510 and optical image 520. Each step of the satellite image processing method will be briefly described below.

First, if the artificial satellite 50 is a SAR satellite, radio waves E are emitted from the artificial satellite 50 to a predetermined measurement area of the earth's surface GD including the reference point formation device 400A. The artificial satellite 50 emits information about the SAR image toward the positioning antenna of the reference point formation device 400 based on information about the radio waves E reflected by the radio wave reflecting section 410 of the reference point formation device 400.

When the artificial satellite 50 is an optical satellite, the artificial satellite 50 photographs a predetermined measurement area of the earth's surface GD from the direction D2 in the same manner as when the above-mentioned SAR satellite is used. The artificial satellite 50 transmits the photographed image information as information on an optical image to the positioning antenna of the reference point forming device 400. The information on the SAR image and the optical image is transmitted from the positioning antenna to the image processing unit 310 via a base station or the like.

The image processing unit 310 creates an SAR image 510 from information about the SAR image, and calculates accurate position information for each of the reference points 430-1, ..., 430-k included in the SAR image 510. A database such as a base station is used to calculate the position information for each of the reference points 430-1, ..., 430-k. The image processing unit 310 also creates an optical image 520 from information about the optical image, and calculates the position of each of the reference points 430-1, ..., 430-k from each of the reference point patterns 435-1, ..., 435-k.

Next, a matching process is performed between the SAR image 510 and the optical image 520, and corresponding reference points 430-1, ..., 430-k in the SAR image 510 and the optical image 520 are compared. This causes the SAR image 510 and the optical image 520 to correspond to each other based on the common reference points 430-1, ..., 430-k. Methods for the matching process between the SAR image 510 and the optical image 520 include, but are not limited to, known coordinate conversion methods, earth edge detection methods, and distortion correction information determination processes. Note that it is preferable to perform the above-mentioned matching process after orthorectifying the SAR image 510 and the optical image 520, respectively.

The SAR image 510 and the optical image 520, which are associated with each other, can be synthesized, and the synthesized satellite image can be corrected as necessary. Then, based on the synthesized satellite image, it is possible to detect, for example, a change in the ground surface GD of the measurement area.

The reference point forming device 400A of the first aspect described above includes the radio wave reflecting unit 410 and the pattern forming unit 420. According to the reference point forming device 400A, the radio wave E transmitted from the SAR satellite is reflected in a predetermined direction D1 by the radio wave reflecting unit 410 and finally reaches the SAR satellite. The position information of each of 430-1, ..., 430-k in the SAR image 510 is accurately calculated. Also, according to the reference point forming device 400A, an optical image is taken by an optical satellite based on the reflected light reflected when sunlight is irradiated on the reference point forming device 400A. The reference point patterns 435-1, ..., 435-k appear in the optical image 520. The reference point patterns 435-1, ..., 435-k make it easy to know the position information of the reference points 430-1, ..., 430-k common to the SAR image 510 and the optical image 520. By matching the common reference points 430-1, ..., 430-k with each other, the SAR image 510 and the optical image 520 can be accurately matched based on the information of the reference points 430-1, ..., 430-k.

In addition, in the first aspect of the reference point forming device 400A, a plurality of straight reference lines 481, 482 appear in the reference point pattern 435-1, ..., 435-k, which intersect at the reference points 430-1, ..., 430-k when viewed from the direction D2. With the reference point forming device 400A, the intersection of the reference lines 481, 482 is the reference point 430, so the positions of the reference points 430-1, ..., 430-k can be easily determined using image processing or the like.

The reference point forming device 400A of the first aspect has inclined surfaces 468 of the pyramidal portions 461 and 462 and an intersection surface 443 of the base portion 441 as multiple regions that are adjacent to each other when viewed from directions D2 and D3 with reference lines 481 and 482 as boundaries and that reflect light waves L with different wavelengths when the light waves L are incident on the multiple regions.

With the reference point forming device 400A, the optical image 520 includes images of the inclined surface 468 and the intersection surface 443, which have different colors relative to the light wave L, that is, a reference point pattern 435 including reflected images of multiple regions, and the position of the reference point 430 can be easily determined by the reference lines 481, 482 that appear on the reference point pattern 435.

The reference point forming device 400A of the first aspect also includes the above-mentioned base portion 441 and the pyramidal portions 461 and 462. In the reference point forming device 400A, the radio wave reflecting portion 410 is provided on the orthogonal surfaces 465 and 466 of the pyramidal portions 461 and 462 and on the crossing surface 443 that contacts the orthogonal surfaces 465 and 466 in the base portion 441. The pattern forming portion 420 is provided on the inclined surfaces 468 of the pyramidal portions 461 and 462 and on the crossing surface 443 in the base portion 441. Therefore, according to the reference point forming device 400A, the radio wave E from the SAR satellite is reflected in the direction D1 by the orthogonal surfaces 465 and 466 and the crossing surface 443 that constitute the corner reflector, and reaches the SAR satellite. In the SAR image 510, the position information of the reference point 430 can be known based on the radio wave E reflected by the orthogonal surfaces 465 and 466 and the crossing surface 443. Furthermore, with the reference point forming device 400A, a reference point pattern 435 consisting of an inclined surface 468 and an intersecting surface 443 appears in the optical image 520 captured from the direction D2, so the positions of the reference points 430-1, ..., 430-k that are common to the SAR image 510 can be easily determined.

In addition, in the first aspect of the reference point forming device 400A, the size of the reference point pattern 435 when viewed from directions D2, D3 is more than twice the GSD of the optical satellite. This allows the patterns to be distinguished from each other, that is, the reference point patterns 435-1, ..., 435-k, to be assigned to at least one pixel in the optical image 520 captured by the optical satellite, and the reference point pattern 435 can be correctly identified by image processing, making it possible to accurately detect the positions of the reference points 430-1, ..., 430-k in the optical image 520.

The satellite image processing device 300 according to the present invention comprises the reference point formation device 400A of the first aspect described above, and an image processing unit 310 that matches the SAR image 510 with the optical image 520 by matching common reference points 430-1, ..., 430-k in the SAR image 510 and the optical image 520.

In the satellite image processing method according to the present invention, the measurement area of the earth's surface GD including the above-mentioned satellite image processing device 300 is imaged by an artificial satellite 50, information on the SAR image 510 and information on the optical image 520 are received from the artificial satellite 50, and the SAR image 510 and the optical image 520 are created based on this information. Also, in the satellite image processing method according to the present invention, the SAR image 510 and the optical image 520 are matched by checking reference points 430-1, ..., 430-k common to the SAR image 510 and the optical image 520.

In the above-mentioned satellite image processing device and satellite image processing method, when viewed from the directions D2 and D3, the reference point 430 is located at the connection point of the two radio wave reflecting units 410 in the reference point forming device 400A, and the relative positional relationship between the reference point 430 and the radio wave reflecting unit 410 is clear. This makes it possible to clearly determine the positional information of each of the reference points 430-1, ..., 430-k based on the information of the SAR image 510. Furthermore, the reference point forming device 400A includes a pattern forming unit 420 together with the radio wave reflecting unit 410, and the reference point pattern 435 is applied to the reference point forming device 400A, thereby making the relative positional relationship between the reference point 430 and the pattern forming unit 420 clear. By image processing of the reference point pattern 435, the positional information of each of the reference points 430-1, ..., 430-k in the optical image 520 can be clearly determined. Therefore, according to the above-mentioned satellite image processing device and satellite image processing method, it is possible to more accurately and easily match the SAR image 510 and the optical image 520 than in the past, based on the reference points 430-1, ..., 430-k that are common to the SAR image 510 and the optical image 520.

Next, as a modified example of the reference point forming device 400A of the first embodiment, other embodiments of the reference point forming device 400 will be described. Note that among the components of the reference point forming device 400 of each of the following embodiments, those that are common to the reference point forming device 400 described above are given the same reference numbers as the reference point forming device 400 described above, and their description will be omitted. In addition, a satellite image processing device equipped with the reference point forming device 400 of the following embodiment and a satellite image processing method using the satellite image processing device are similar to the reference point forming device 400 and satellite image processing method described above.

Hereinafter, the reference point forming device 400 of the second aspect will be referred to as the reference point forming device 400B. As shown in FIG. 5, the reference point forming device 400B includes a base portion 441, pyramidal portions 461 and 462, and a positioning signal receiving antenna 470. The positioning signal receiving antenna 470 is provided on the top portion 463 of the pyramidal portions 461 and 462. When the artificial satellite 50 is a SAR satellite, the positioning signal receiving antenna 470 is configured to be able to receive the positioning signal transmitted from the SAR satellite, i.e., the information of the SAR image 510.

The shape of the positioning signal receiving antenna 470 is not particularly limited as long as it can receive the positioning signal as described above, but it is formed, for example, in a cone shape. The bottom surface 471 of the cone-shaped positioning signal receiving antenna 470 is in contact with the apex 463 of the cone-shaped portions 461 and 462. As shown in FIG. 6, the apex 472 of the cone-shaped positioning signal receiving antenna 470 overlaps with the reference point 430 when viewed from the direction D3. When viewed from the direction D3, the size of the bottom surface 471 of the positioning signal receiving antenna 470 is smaller than the base portion 441, and is large enough not to prevent the incidence of radio waves E into the radio wave reflecting portion 410 and the reflection of radio waves E from the radio wave reflecting portion 410.

In the reference point forming device 400B, the pattern forming unit 420 is provided on the surface of the positioning signal receiving antenna 470 when viewed from the directions D2 and D3, i.e., on the side 473 of the conical positioning signal receiving antenna 470, the inclined surfaces 469 of each of the pyramidal portions 461 and 462, and the intersecting surface 445 of the base portion 441. The inclined surface 469 is the exposed portion of the inclined surface 468 that does not overlap with the side surface 473 of the positioning signal receiving antenna 470 when viewed from the directions D2 and D3. The intersecting surface 445 is the exposed portion of the intersecting surface 443 that does not overlap with the side surface 473 when viewed from the directions D2 and D3.

In the side 473 of the positioning signal receiving antenna 470, the side 473-1 that overlaps with the inclined surface 468 when viewed from the directions D2 and D3 is a color different from at least the crossing surface 445, for example the same black as the inclined surface 469. In the side 473 of the positioning signal receiving antenna 470, the side 473-2 that overlaps with the crossing surface 443 when viewed from the directions D2 and D3 is a color different from at least the side 473-1 and the inclined surface 469, for example the same white or yellow as the crossing surface 445. By coloring each of the sides 473-1 and 473-2 in this way, when the reference point forming device 400B is imaged from the directions D2 and D3, the reference point pattern 435 is formed, and reference lines 481 and 482 appear in the reference point pattern 435.

According to the reference point forming device 400B described above, the positioning signal receiving antenna 470 is located in a position that does not block the reflection of the radio waves E at the radio wave reflecting section 410, and is located closer to the radio wave reflecting section 410 in the direction of incidence of the radio waves E than the reference point forming device 400A, so that the receiving sensitivity of the positioning signal is higher than that of the reference point forming device 400A, and the accuracy of the correspondence between the SAR image 510 and the optical image 520 can be improved.

Hereinafter, the third aspect of the reference point forming device 400 will be referred to as the reference point forming device 400C. As shown in FIG. 7, the reference point forming device 400C comprises a base portion 441 and four plate-shaped portions 475, 476, 477, and 478. Each of the plate-shaped portions 475-478 is erected on the intersecting surface 442. Note that directions D1, D2, and D3 are omitted from the drawings of the reference point forming device 400 of each aspect below.

Each of the plate-shaped parts 475-478 is formed in a triangular shape having a first side connecting the center point 448, which overlaps with the reference point 430 when viewed from the direction D3 on the crossing surface 442, and each of the four corners of the crossing surface 442, a second side connecting the center point 448 and the reference point 430 and approximately perpendicular to the crossing surface 442, and a third side connecting the reference point 430 and each of the four corners of the crossing surface 442. When viewed from the directions D2 and D3, the plate-shaped parts 475-478 are arranged radially with the reference point 430 as the center. The triangular plate surface of each of the plate-shaped parts 475-478 is perpendicular to the crossing surface 442 and forms orthogonal surfaces 465 and 466. Each of the plate-shaped parts 475-478 is configured to be able to reflect radio waves E.

In the reference point forming device 400C, when viewed from the directions D2 and D3, the plate-shaped portions 475 and 477 are provided along the reference line 481, and the plate-shaped portions 476 and 478 are provided along the reference line 482. In addition, since almost the entire surface of the intersecting surface 442 is exposed when viewed from the directions D2 and D3, the intersecting surface 443-2 adjacent to the intersecting surface 443-1 on the intersecting surface 442 with the reference lines 481 and 482 as boundaries is exposed when viewed from the directions D2 and D3.

The orthogonal surface 465 of the plate-shaped portion 475, the orthogonal surface 466 of the plate-shaped portion 478, and the intersecting surface 443-1 connecting the first sides of these orthogonal surfaces form a first corner reflector. Similarly, the orthogonal surface 466 of the plate-shaped portion 476, the orthogonal surface 465 of the plate-shaped portion 477, and the intersecting surface 443-1 connecting the first sides of these orthogonal surfaces form a second corner reflector. Also, the orthogonal surface 466 of the plate-shaped portion 475, the orthogonal surface 465 of the plate-shaped portion 476, and the intersecting surface 443-2 connecting the first sides of these orthogonal surfaces form a third corner reflector. Similarly, the orthogonal surface 466 of the plate-shaped portion 477, the orthogonal surface 465 of the plate-shaped portion 478, and the intersecting surface 443-2 connecting the first sides of these orthogonal surfaces form a fourth corner reflector. In other words, the reference point forming device 400C has a radio wave reflecting section 410 that is composed of four corner reflectors.

In the reference point forming device 400C, the reference point pattern 435 is formed by the intersecting planes 443-1 and 443-2. The two intersecting planes 443-1 and the two intersecting planes 443-2 have different light quantities or wavelengths of reflected light when irradiated with light waves L. For example, the intersecting plane 443-1 is white or yellow, and the intersecting plane 443-2 is red or green. By arranging the intersecting planes 443-1 and 443-2 in this way, the reference point pattern 435 is formed when viewed from directions D2 and D3, and when imaged by an optical satellite from direction D2. In the reference point pattern 435 that appears in the optical image 520, the positions of the reference points 430-1, ..., 430-k are indicated by the reference lines 481 and 482 as the boundaries of the intersecting planes 443-1 and 443-2.

According to the reference point forming device 400C described above, the SAR image 510 contains information on the radio wave E reflected by one of the four corner reflectors. Based on this information, the position information of each of the reference points 430-1, ..., 430-k of the SAR image 510 is indicated. Furthermore, in the optical image 520, reference point patterns 435-1, ..., 435-k are formed from the captured intersection planes 443-1, 443-2, and the position information of each of the reference points 430-1, ..., 430-k is indicated. By matching each of the reference points 430-1, ..., 430-k common to the SAR image 510 and the optical image 520, the SAR image 510 and the optical image 520 can be made to correspond more accurately than before.

In addition, in the reference point forming device 400C, a solar cell 550 may be provided on one of the intersecting surfaces 443-1 and 443-2. Considering the known materials of solar cells, a normal solar cell is close to black under visible light, so it is preferable to provide the solar cell 550 on the surface of the intersecting surface 443-1 or 443-2 that is to be black. By providing the solar cell 550 on the intersecting surface 443-1 or 443-2, the reference point forming device 400C can generate electricity by irradiating the solar cell 550 with light waves L or sunlight, and supply electricity to itself and to devices electrically connected to itself.

Hereinafter, the reference point forming device 400 of the fourth aspect will be referred to as the reference point forming device 400D. As shown in FIG. 8, the reference point forming device 400D includes a base portion 441 and four plate-shaped portions 475, 476, 477, and 478. However, in the reference point forming device 400D, the shape of the base portion 441 as viewed from the directions D2 and D3 is polygonal and substantially circular. Each of the plate-shaped portions 475-478 is formed in a fan shape having a first side connecting a center point 448 that overlaps with the reference point 430 on the intersecting surface 442 as viewed from the direction D3 and four positions spaced 90° apart from each other in the circumferential direction on the outer edge of the intersecting surface 442, a second side connecting the center point 448 and the reference point 430 and substantially perpendicular to the intersecting surface 442, and an arc connecting the reference point 430 and each of the four positions on the outer edge of the intersecting surface 442.

As shown in FIG. 9, in the reference point forming device 400D, the intersecting surface 443-2 has a predetermined width in the radial direction centered on the reference point 430 (i.e., the center point 448) when viewed from the directions D2 and D3, and is provided in a ring shape over the entire circumferential direction. The intersecting surface 443-1 is provided in the region from the center point 448 in the radial direction of the intersecting surface 442 to the inner peripheral edge of the intersecting surface 443-2, and in the region from the outer peripheral edge of the intersecting surface 443-2 to the peripheral edge of the intersecting surface 442 in the radial direction. When the intersecting surfaces 443-1 and 443-2 in such a relative arrangement are imaged from the directions D2 and D3, a reference point pattern 435 by the polygonal ring-shaped intersecting surface 443-2 having a predetermined width in the radial direction appears in the optical image 520.

In the reference point pattern 435 illustrated in FIG. 9, the size of the reference point pattern 435 as viewed from the directions D2 and D3 is preferably set appropriately to be at least twice the GSD of the optical satellite. For example, it is preferable that the size of the reference point pattern 435 and the base portion 441 as viewed from the directions D2 and D3 is set so that each side of the reference line 483, which has a polygonal shape with more corners than a square as viewed from the directions D2 and D3, is equal to or greater than the GSD of the optical satellite. As will be described in some aspects later, the area to be detected by the reference point pattern 435 is assigned to at least one pixel in the optical image captured by the optical satellite according to the shape of the reference point pattern 435 as viewed from the directions D2 and D3, and the size of the reference point pattern 435 is set taking into account the GSD of the optical satellite so that the presence or absence of the reference point pattern 435 can be identified by two adjacent pixels.

As described above, in the reference point forming device 400D, two polygonal reference lines 483, 484 appear in the reference point pattern 435 with the reference point 230 as the center when viewed from the directions D2, D3. Although not shown, the image processing unit 310 of the satellite image processing device 300 equipped with the reference point forming device 400D can calculate the position of the reference point 430 by obtaining the center points of the reference lines 483, 484 that appear in the optical image 520 by image processing. According to the reference point forming device 400D, the centers of the reference lines 483, 484 in the optical image 520 are obtained as the reference points 430-1, ..., 430-k, and the reference points 430-1, ..., 430-k common to the SAR image 510 can be calculated. Therefore, according to the reference point forming device 400D, like the reference point forming device 400C, the SAR image 510 and the optical image 520 can be made to correspond more accurately than before.

8 and 9 show an example of the intersecting surface 443-2 and the reference lines 483, 484 that are approximately dodecagonal when viewed from the directions D2 and D3, but the intersecting surface 443-2 and the reference lines 483, 484 may be formed in any polygonal shape with three or more corners, or in a perfect circle or ellipse, and may be formed in any shape as long as the reference point 430 can be calculated by image processing of the reference point pattern 435 in the optical image 520. For example, if the intersecting surface 443-2 and the reference lines 483, 484 are formed in an equilateral triangle or regular pentagon when viewed from the directions D2 and D3, the position information of the reference point 430 can be calculated by finding the center of gravity of the reference point pattern 435.

Also, when viewed from the directions D2 and D3, the reference lines 483 and 484 may be formed in different shapes as long as they have a relative relationship with the common reference point 430. That is, the inner peripheral edge and the outer peripheral edge of the intersecting surface 433-2 may be formed in different shapes with the above-mentioned relative relationship when viewed from the directions D2 and D3. For example, the reference line 483 (i.e., the inner peripheral edge of the intersecting surface 433-2) may be formed in a regular hexagon of a predetermined size centered on the reference point 430, and the reference line 484 (i.e., the outer peripheral edge of the intersecting surface 433-2) may be formed in a regular dodecagon having an inscribed circle larger than the reference line 483 when viewed from the directions D2 and D3. In this case, the same effect as that of the reference point forming device 400D described above can be obtained.

Hereinafter, the fifth aspect of the reference point forming device 400 will be referred to as the reference point forming device 400E. As shown in FIG. 10, the reference point forming device 400E includes a base portion 441 and four plate-shaped portions 475, 476, 477, and 478, and has the same basic configuration as the reference point forming device 400C.

However, in the reference point forming device 400E, each of the plate-like portions 475-478 is formed in a rectangular shape having a first side that connects the center point 448 and the center of each of the four sides of the intersecting surface 442 when viewed from the direction D3 on the rectangular intersecting surface 442, a second side that connects the center point 448 and the reference point 430 and is approximately perpendicular to the intersecting surface 442, a third side that connects the reference point 430 and a position elevated from the center of each of the four sides of the intersecting surface 442 to the same height as the reference point 430, and a fourth side that descends from a position elevated from the center of each of the four sides of the intersecting surface 442 as described above to the center of each of the four sides.

In the reference point forming device 400E, a reference point pattern 435 similar to the so-called + shape of the UAV described with respect to the reference point forming device 400A is formed from the relative arrangement of the intersecting planes 443-1 and 443-2, and reference lines 481 and 482 appear.

In the case of the reference point pattern 435 illustrated in FIG. 10, it is preferable that the size of the reference point pattern 435 when viewed from directions D2 and D3 is at least twice the GSD of the optical satellite. For example, when the reference lines 481 and 482 are approximately parallel to the arrangement direction of the multiple pixels in the optical image 520, it is preferable that the length of each of the four sides of the intersection planes 443-1 and 443-2, which have a rectangular shape when viewed from directions D2 and D3, is at least the GSD. In other words, it is preferable that the length of the reference lines 481 and 482 is at least 50 cm.

The reference point forming device 400E described above provides the same effects as the reference point forming devices 400A, 400C, etc., and since reference point patterns 435-1, ..., 435-k are formed in the optical image 520 from the intersecting planes 443-1, 443-2, the position information of each of the reference points 430-1, ..., 430-k is indicated. By comparing each of the reference points 430-1, ..., 430-k common to the SAR image 510 and the optical image 520, the SAR image 510 and the optical image 520 can be matched more accurately than before.

As a modified example of the reference point forming device 400E, there is a reference point forming device 400F of the sixth aspect shown in FIG. 11. In the reference point forming device 400F, in the crossing surface 442, the crossing surface 442 on the radial center side and the crossing surface 442 on the radial outer side are crossing surfaces 443-1 and 443-2 that reflect different amounts of light or wavelengths when a light wave L is incident on the crossing surface 442 with a reference line 483 of a substantially dodecagonal shape centered on the reference point 430 as viewed from the direction D3. For example, in the crossing surface 442 located between the plate-shaped parts 475 and 478 and the crossing surface 442 located between the plate-shaped parts 476 and 477 as viewed from the direction D3, the area from the reference point 430 to the reference line 483 in the radial direction is the crossing surface 443-2, and the area from the reference line 483 to the periphery of the crossing surface 442 is the crossing surface 443-1. On the other hand, when viewed from direction D3, in the intersecting surface 442 located between plate-shaped portions 475 and 476 and the intersecting surface 442 located between plate-shaped portions 477 and 478, the area from reference point 430 to the reference line 483 in the radial direction is intersecting surface 443-2, and the area from reference line 483 to the periphery of intersecting surface 442 is intersecting surface 443-1.

In the reference point forming device 400F, a reference point pattern 435 is formed that is a combination of the so-called + shape and O shape of the UAV described in relation to the reference point forming device 400A, based on the relative positioning of the intersecting planes 443-1 and 443-2, and a reference line 483 appears in addition to the reference lines 481 and 482.

In the case of the reference point pattern 435 illustrated in FIG. 11, the size of the reference point pattern 435 as viewed from the directions D2 and D3 is preferably set appropriately to be at least twice the GSD of the optical satellite. For example, when the reference lines 481 and 482 are approximately parallel to the arrangement direction of the multiple pixels in the optical image 520, it is preferable that the size of the reference point pattern 435 and the base portion 441 as viewed from the directions D2 and D3 is set so that the length of each side along the reference lines 481 and 482 in each of the intersection planes 443-1 and 443-2, which have an approximately fan shape as viewed from the directions D2 and D3, is equal to or greater than the GSD.

The reference point forming device 400F described above provides the same effects as the reference point forming device 400E. Furthermore, the reference point forming device 400F forms a more complex reference point pattern 435 than the reference point forming device 400E by including reference line 483 in addition to reference lines 481 and 482, but the degree of discrimination of the reference point pattern 435 relative to the surrounding terrain pattern in the optical image 520 is increased. This improves the accuracy of calculation of the position information of the reference point 430.

As another modified example of the reference point forming device 400E from the reference point forming device 400F, there is a reference point forming device 400G of the seventh aspect shown in Fig. 12. In the reference point forming device 400G, in the crossing surface 442, the crossing surface 442 on the radial center side and the crossing surface 442 on the radial outer side are crossing surfaces 443-1, 443-2 that reflect different amounts or wavelengths of light when the light wave L is incident on the crossing surface 442, with each of the reference lines 483, 484, 485 having a substantially circular (annular) shape centered on the reference point 430 as viewed from the direction D3 as boundaries. As an example, in the intersecting surface 442 located between the plate-shaped portions 475 and 478 when viewed from the direction D3, the area from the reference point 430 to the reference line 483 in the radial direction is the intersecting surface 443-2, the area between the reference lines 483 and 484 is 443-1, the area between the reference lines 484 and 485 is 443-2, and the area from the reference line 485 to the periphery of the intersecting surface 442 is the intersecting surface 443-1.

In the case of the reference point pattern 435 illustrated in FIG. 12, it is preferable that the size of the reference point pattern 435 when viewed from the directions D2 and D3 is appropriately set to at least twice the GSD of the optical satellite. For example, it is preferable that the size of the reference point pattern 435 and the base portion 441 when viewed from the directions D2 and D3 is set so that the length of the longest diagonal of the intersecting surface 443-2, which has a polygonal shape with more corners than a square, when viewed from the directions D2 and D3, is at least the GSD, and the distance between the intersecting surfaces 443-2 in the radial direction is at least the GSD.

The reference point forming device 400G described above provides the same effects as the reference point forming device 400E. Furthermore, the reference point forming device 400G forms a more complex reference point pattern 435 than the reference point forming device 400F, as the reference lines 481-485 appear. This increases the degree of discrimination of the reference point pattern 435 against the surrounding topographical patterns in the optical image 520, thereby improving the accuracy of calculation of the position information of the reference point 430.

In addition, in the intersecting surface 442, the annular intersecting surface 443-2 between the reference lines 484, 485 in the radial direction from the reference point 430 (i.e., the center point 448) when viewed from the direction D3 may be partially missing in the circumferential direction to form the intersecting surface 443-1, as shown by the dashed line in FIG. 12.

Hereinafter, the reference point forming device 400 of the eighth aspect will be referred to as the reference point forming device 400H. As shown in FIG. 13, the reference point forming device 400H includes a base portion 441 and a columnar portion 490. The columnar portion 490 is erected on the intersecting surface 442. The columnar portion 490 is formed in a polygonal prism shape close to a cylindrical shape, and includes a top surface 491, a bottom surface 492, and a side surface 493 that connects the top surface 491 and the bottom surface 492 in the direction D3. The center of the top surface 491 of the columnar portion 490 overlaps with the reference point 430 when viewed from the direction D3. The center of the bottom surface 492 of the columnar portion 490 overlaps with the center of the intersecting surface 442 when viewed from the direction D3.

In the reference point forming device 400H, at least the side surface 493 of the columnar portion 490 and the crossing surface 443 of the crossing surface 442 that is exposed when viewed from the direction D3 are configured to be able to reflect radio waves E. The radio wave reflecting portion 410 of the reference point forming device 400H is provided on the side surface 493 and the crossing surface 443. In other words, the side surface 493 and the crossing surface 443 function as an omnidirectional corner reflector when viewed from the directions D2 and D3.

In the reference point forming device 400H, when a light wave L is incident on the top surface 491 of the columnar portion 490 from a predetermined direction, the amount or wavelength of light reflected in the direction D2 is different from that of the intersecting surface 443 of the base portion 441. For example, the intersecting surface 443 is white or yellow, and the top surface 491 is black. By coloring or configuring the intersecting surface 443 and the top surface 491 as described above, when the reference point forming device 400H is imaged from the direction D2, a reference point pattern 435 is formed, and a reference line 483 appears in the reference point pattern 435. In other words, the pattern forming portion 420 is provided on the entire intersecting surface 443 and the top surface 491.

In the reference point forming device 400H, the so-called circle-shaped reference point pattern 435 of the UAV described in relation to the reference point forming device 400A is formed from the relative positioning of the intersection surface 443 and the top surface 491. In the optical image 520, the reference point 430 is calculated by determining the center of the top surface 491 and the reference line 483 identified by image processing or the like with respect to the intersection surface 443 in the formed reference point pattern 435.

In the case of the reference point pattern 435 illustrated in FIG. 13, it is preferable that the size of the reference point pattern 435 when viewed from the directions D2 and D3 is appropriately set to be at least twice the GSD of the optical satellite. For example, it is preferable that the size of the reference point pattern 435 and the columnar portion 490 when viewed from the directions D2 and D3 is set so that the length of the longest diagonal of the intersecting surface 443-2, which has a polygonal shape with more corners than a square when viewed from the directions D2 and D3, is equal to or greater than the GSD.

The reference point forming device 400H described above has a simple configuration with a base portion 441 and a columnar portion 490, and yet provides the same effects as the reference point forming device 400 described above. Since reference point patterns 435-1, ..., 435-k are formed in the SAR image 510 and the optical image 520, the SAR image 510 and the optical image 520 can be matched more accurately than before by matching them with each of the reference points 430-1, ..., 430-k that are common to each image.

A modified example of the reference point forming device 400H is the reference point forming device 400I of the ninth aspect shown in FIG. 14. In the reference point forming device 400I, the intersecting surfaces 442 of the base portion 441 are partitioned at 90° intervals in the circumferential direction from the center point 448. In the four regions including the two intersecting surfaces 443-1, 443-2, the amount or wavelength of light reflected in the direction D2 when a light wave L is incident from a predetermined direction is different between adjacent regions in the circumferential direction. In other words, in the regions of the intersecting surface 442 that are exposed when viewed from the directions D2, D3, the intersecting surfaces 443-1, 443-2 are alternately provided at 90° intervals in the circumferential direction.

In the reference point forming device 400I, the top surface 491 of the columnar portion 490 is divided into sections every 90° in the circumferential direction from the reference point 430. In the four regions including the two top surfaces 491-1, 492-2, the amount or wavelength of light reflected in the direction D2 when a light wave L is incident from a specified direction is different between adjacent regions in the circumferential direction. When viewed from the directions D2 and D3, the boundaries of the four sections of the top surface 491 and the four sections of the intersecting surface 442 overlap each other in the circumferential direction. The intersecting surface 443-1 and the top surface 491-1 are, for example, white or yellow. The intersecting surface 443-2 and the top surface 491-2 are, for example, red or green. As a result, when viewed from direction D2, in the reference point forming device 400I, multiple straight reference lines 481 and 482 that intersect at the reference point 430 appear in the reference point pattern 435 instead of the reference line 483 of the reference point forming device 400I.

In the case of the reference point pattern 435 illustrated in FIG. 14, it is preferable that the size of the reference point pattern 435 when viewed from the directions D2 and D3 is appropriately set to be at least twice the GSD of the optical satellite. For example, it is preferable that the sizes of the reference point pattern 435, base portion 441, and columnar portion 490 when viewed from the directions D2 and D3 are set so that the diameter length of the intersecting planes 443-1 and 443-2, which have a sector shape with a central angle of 90° when viewed from the directions D2 and D3, is equal to or greater than the GSD.

The reference point forming device 400I described above provides the same effects as the reference point forming device 400H.

In FIG. 14, an example is shown in which the intersecting surface 443-1 and the top surface 491-1, and the intersecting surface 443-2 and the top surface 491-2 are the same color, but for example, the intersecting surface 443-1 and the top surface 491-2 may be white or yellow, and the intersecting surface 443-2 and the top surface 491-1 may be red or green. When the intersecting surfaces 443-1, 443-2 and the top surfaces 491-1, 491-2 are colored in this way, the reference point pattern 435 includes the reference lines 481, 482, and the reference point pattern 435. This increases the degree of discrimination of the reference point pattern 435 against the surrounding topographical patterns in the optical image 520, and the calculation accuracy of the position information of the reference point 430 can be improved. In other words, the intersecting surface 443 and the top surface 491 can be divided according to the reference line to be expressed, and each area can be colored.

Hereinafter, the reference point forming device 400 of the tenth aspect will be referred to as the reference point forming device 400J. As shown in FIG. 15 and FIG. 16, the reference point forming device 400J includes a base portion 441, four plate-shaped portions 475-478, and a radome 504. The radome 504 is formed so as to move away from the intersection surface 442 from the outer edge of the base portion 441 toward the apex (position) 431 on the front side of the reference point 430 in the incident direction of the radio wave E. The base portion 441 is formed in a circular shape when viewed from the directions D2 and D3. In other words, the radome 504 is formed of the side of a cone having the apex 431, and the base portion 441 corresponds to the bottom surface of the cone mentioned above. The radome 504 is made of a material that transmits radio waves E and is capable of transmitting radio waves E. The apex 431 overlaps with the reference point 430 when viewed from the directions D2 and D3.

The plate-shaped portions 475-478 of the reference point forming device 400J are formed in a triangular shape, similar to the plate-shaped portions 475-478 of the reference point forming device 400C. However, since the base portion 441 is formed in a circular shape, the first side of each of the plate-shaped portions 475-478 connects the center point 448 to each of four positions on the outer edge of the intersecting surface 442 that are spaced 90° apart in the circumferential direction, as shown in FIG. 16. The third side of each of the plate-shaped portions 475-478 connects the reference point 430 to each of the four positions on the outer edge of the intersecting surface 442.

In the reference point forming device 400J, the entire intersecting surface 442 is configured to be capable of reflecting radio waves E. The plate-shaped parts 475-478 are housed in the inner space 495 of the radome 504. The orthogonal surface 465 of the plate-shaped part 475, the orthogonal surface 466 of the plate-shaped part 478, and the intersecting surface 442 connecting the first sides of these orthogonal surfaces form a first corner reflector. Similarly, in the reference point forming device 400J, second to fourth corner reflectors are formed in which the intersecting surfaces 443-1 and 443-2 in the reference point forming device 400C are replaced with the intersecting surface 442. In other words, in the reference point forming device 400J, the radio wave reflecting part 410 is equipped with the first to fourth corner reflectors described above.

In the reference point forming device 400J, the pattern forming section 420 is provided on the outer surface 507 of the side surface 506 of the radome 504. As shown in FIG. 15, when viewed from the directions D2 and D3, the outer surface 507 is partitioned into a plurality of regions at a predetermined angle in the circumferential direction. In the plurality of regions of the outer surface 507 of the radome 504, the amount or wavelength of light reflected in the direction D2 when a light wave L is incident from a predetermined direction is different between adjacent regions in the circumferential direction. For example, among the plurality of regions of the outer surface 507, for the outer surfaces 507-1 and 507-2 adjacent to each other in the circumferential direction, the outer surface 507-1 is white or yellow, and the outer surface 507-2 is red or green. As a result, in the reference point forming device 400J, when viewed from the direction D2, a plurality of straight reference lines 481, 482, 483, etc. that intersect at the reference point 430 appear in the reference point pattern 435. In addition, in the reference point forming device 400J, when viewed from directions D2 and D3, the reference lines 481, 482, 483, etc. may or may not overlap the plate-shaped portions 475-478.

The reference point forming device 400J described above provides the same effects as the reference point forming device 400C. Furthermore, by providing a radome 504 having a pattern forming section 420 composed of outer surfaces 507-1 and 507-2, the reference point forming device 400J can protect the plate-shaped sections 475-478, since the plate-shaped sections 475-478 are housed in the inner space 495 of the radome 504. It can also prevent the angle and attitude of the plate-shaped sections 475-478 relative to the base section 441 and the intersecting surface 442 from changing due to external factors such as wind hitting the plate-shaped sections 475-478.

As a modified example of the reference point forming device 400J, there is a reference point forming device 400K of an eleventh aspect shown in FIG. 17 and FIG. 18. The base portion 441 of the reference point forming device 400K is formed in a rectangular shape when viewed from the directions D2 and D3. In addition, the radome 504 of the reference point forming device 400K is composed of the part that corresponds to the side of a quadrangular pyramid, since the base portion 441 has a rectangular shape. The reference point forming device 400K is a reference point forming device 400J described above in which the shape of the base portion 441 is changed from a circular shape to a rectangular shape, and it can be said that the reference point forming device 400K is a reference point forming device 400C described above equipped with a radome 504.

In the reference point forming device 400K, the outer surface 507 of the radome 504 is divided into four isosceles triangular regions, which are alternately divided into outer surfaces 507-1, 507-2 in the circumferential direction. In other words, in the four regions, when a light wave L is incident from a predetermined direction, the amount or wavelength of light reflected in direction D2 differs between adjacent regions in the circumferential direction. As a result, in the reference point forming device 400K, similar to the reference point forming devices 400A and 400C, a so-called X-shaped reference point pattern 435 of the UAV is formed when viewed from directions D2 and D3, and when imaged by an optical satellite from direction D2.

The reference point forming device 400K described above provides the same effects as the reference point forming device 400J.

In the reference point forming device 400 described above, the direction D2 is mainly a direction from above the ground surface GD toward the ground surface GD and in all directions or approximately all directions centered on the reference point 430. However, the direction D2 can be freely selected, and the configuration of the above-mentioned reference point forming device 400 can be changed according to the number and orientation of the directions D2 and the directivity of the reference point forming device 400. In addition, the reference point pattern 435 in the reference point forming device 400 can be freely and partially changed as appropriate as long as it can indicate the reference point 430.

For example, the reference point forming device 400 of the twelfth aspect is described as the reference point forming device 400L. As shown in FIG. 19, the reference point forming device 400L has a base portion 441 that is substantially the same as the reference point forming device 400D, and two plate-shaped portions 476 and 478. In reality, the plate-shaped portions 476 and 478 are configured as a single plate-shaped member. The intersecting surface 442 in the reference point forming device 400L is partitioned at 90° intervals in the circumferential direction from the center point 448, similar to the intersecting surface 442 in the reference point forming device 400I. The intersecting surface 442 in the reference point forming device 400L has intersecting surfaces 443-1 and 443-2 alternately provided in the circumferential direction with the reference lines 481 and 482 as boundaries.

In the reference point forming device 400L, the orthogonal surface 465 of the plate-shaped portion 476, the orthogonal surface 466 of the plate-shaped portion 478, and the intersecting surfaces 443-1, 443-2 facing these orthogonal surfaces form a first corner reflector. The orthogonal surface 466 of the plate-shaped portion 476, the orthogonal surface 465 of the plate-shaped portion 478, and the intersecting surfaces 443-1, 443-2 facing these orthogonal surfaces form a second corner reflector. In other words, the reference point forming device 400L has a radio wave reflecting section 410 composed of two corner reflectors.

The above-mentioned reference point forming device 400L provides the same effects as the reference point forming devices 400D, 400I, etc. Furthermore, the reference point forming device 400L can form a so-called X-shaped reference point pattern 435 for the UAV by setting the direction D2 to two directions. The reference point forming device 400L may also be provided with two plate-shaped portions 475, 477 instead of the two plate-shaped portions 476, 478.

A modified example of the reference point forming device 400L is the reference point forming device 400M of the thirteenth aspect shown in Figure 20. When the plate-like parts 475, 478 in the reference point forming device 400D are made into a single plate-like member, the reference point forming device 400M includes a circular base part 441 when viewed from the directions D2, D3, and two plate-like members 479-1, 479-2, as shown in Figure 20.

The two plate-like members 479-1 and 479-2 share one end 530a in the radial direction of the diameter 530 passing through the center point 448 of the intersecting surface 442, and move away from each other in the radial direction from the end 530a toward the other end 530b in the radial direction of the diameter 530. In the reference point forming device 400M, the incident radio wave E is reflected in the direction D1 by the orthogonal surface 465 of the plate-like member 479-1 and the intersecting surface 442 facing the orthogonal surface 465. Similarly, the incident radio wave E is reflected in the direction D1 by the orthogonal surface 466 of the plate-like member 479-2 and the intersecting surface 442 facing the orthogonal surface 466. In other words, the radio wave reflecting section 410 of the reference point forming device 400M is provided at least on the orthogonal surface 465, the intersecting surface 442, and the orthogonal surface 466 of the plate-like member 479-1.

In the reference point forming device 400M, the intersecting surface 442 of the base portion 441 is divided into intersecting surface 443-2, which is an area from the center point 448 to a predetermined radial length, and intersecting surface 443-1, which is an area from the predetermined length to the outer edge. The reference point pattern 435 formed by the reference point forming device 400M is a so-called circle-shaped pattern of a UAV when viewed from directions D2 and D3, although not shown. In the reference point pattern 435, a reference line 483 appears as a boundary line dividing the two areas of the intersecting surface 442.

The above-mentioned reference point forming device 400M provides the same effects as the reference point forming devices 400D, 400I, etc. Furthermore, the reference point forming device 400M can form a so-called O-shaped reference point pattern 435 for a UAV by setting the direction D2 to two directions. Furthermore, the reference point forming device 400M can easily change and adjust the direction D2 by adjusting the distance between the plate-like members 479-1, 479-2 along the outer edge of the intersecting surface 442 with the end 530b of the diameter 530 as the center.

Hereinafter, the reference point forming device 400 of the 14th aspect will be referred to as the reference point forming device 400N. As shown in FIG. 21, the reference point forming device 400J includes a circular base portion 441 as viewed from the directions D2 and D3, and two plate-shaped members 479-3 and 479-4. The plate-shaped members 479-3 and 479-4 are connected to each other at one corner of the base portion 441 as viewed from the direction D3, and are perpendicular to the intersecting surface 442 from the two sides of the base portion 441 that are connected to each other at one corner. In the reference point forming device 400N, the orthogonal surface 466 of the plate-shaped member 479-3, the orthogonal surface 465 of the plate-shaped member 479-4, and the intersecting surface 442 facing these orthogonal surfaces form a corner reflector. The reference point forming device 400N includes a radio wave reflecting section 410 that is composed of one corner reflector.

In the reference point forming device 400N, the intersecting surface 442 of the base portion 441 is divided into four regions by boundary lines from the center point 448 to the center of each of the four sides of the outer edge, similar to the reference point forming device 400E. Intersecting surfaces 443-1, 443-2 are alternately provided in the circumferential direction on the intersecting surface 442, with the aforementioned boundary lines as boundaries. The reference point pattern 435 formed by the reference point forming device 400N is a so-called +-shaped pattern of a UAV. In the reference point pattern 435, reference lines 486, 487 appear as boundary lines between the intersecting surfaces 443-1, 443-2, which are perpendicular to each other at the reference point 430.

The above-mentioned reference point forming device 400N can provide the same effects as the reference point forming device 400E, etc. Furthermore, the reference point forming device 400N can form a so-called +-shaped reference point pattern 435 for the UAV by using direction D2 as one direction.

Hereinafter, the reference point forming device 400 of the fifteenth aspect will be referred to as the reference point forming device 400P. As shown in FIG. 22, the reference point forming device 400P includes a base portion 441 similar to that of the reference point forming device 400C, four plate-shaped portions 475, 476, 477, and 478, and further includes a top plate portion 500 provided on the top portion 463 of the plate-shaped portions 475, 476, 477, and 478. The top plate portion 500 is formed of a plate-shaped member having a circular shape centered on the top portion 463 when viewed from the directions D2 and D3. The plate-shaped member of the top plate portion 500 is formed of a material that can transmit the radio waves E transmitted from the SAR satellite. Examples of the aforementioned material include glass fiber, polytetrafluoroethylene, or the same material as the radome 504 or a known radome.

In the reference point forming device 400P, the entire intersecting surface 442 is configured to be able to reflect radio waves E. The orthogonal surface 465 of the plate-shaped portion 475, the orthogonal surface 466 of the plate-shaped portion 478, and the intersecting surface 442 connecting the first sides of these orthogonal surfaces form a first corner reflector. Similarly, in the reference point forming device 400P, the second to fourth corner reflectors are configured by replacing the intersecting surfaces 443-1 and 443-2 in the reference point forming device 400C with the intersecting surface 442. In other words, the reference point forming device 400P has a radio wave reflecting section 410 composed of four corner reflectors. As described above, the top plate portion 500 is formed of a material that can transmit radio waves E emitted from the SAR satellite, so the radio waves E that enter the top plate portion 500 along the directions D2 and D3 pass through the top plate portion 500 and enter each of the four corner reflectors. Radio waves E reflected by each of the four corner reflectors pass through the top plate 500 and travel along directions D2 and D3 toward the SAR satellite.

In the reference point forming device 400P, the pattern forming unit 420 is provided on the surface 502 of the top plate 500, that is, the surface of the top plate 500 facing the optical satellite when viewed from the directions D2 and D3. When viewed from the directions D2 and D3, the surface 502 is divided into four regions at 90° intervals in the circumferential direction with respect to the center of the top plate 500. In the reference point forming device 400P, the center of the surface 502 of the top plate 500 is the reference point 430, which approximately overlaps with the top 463 from above and below. In the four regions of the surface 502 of the top plate 500, the regions 511 and 512 adjacent to each other in the circumferential direction have different amounts or wavelengths of light reflected in the direction D2 when a light wave L is incident from a predetermined direction. For example, the region 511 is white or yellow, and the region 512 is red or green. As a result, in the reference point forming device 400P, when viewed from the direction D2, multiple straight reference lines 481, 482 that intersect at the reference point 430 appear in the reference point pattern 435. However, the paint or material applied to the areas 511, 512 to differentiate the colors of the areas 511, 512 or to differentiate the reflectance of the light wave L is capable of transmitting the radio wave E.

22, the size of the reference point pattern 435 as viewed from the directions D2 and D3 is preferably set appropriately to be at least twice the GSD of the optical satellite. For example, it is preferable that the size of the reference point pattern 435 and the top plate 500 as viewed from the directions D2 and D3 is set so that the diameter length of the areas 511 and 512 on the surface 502 of the top plate 500 having a sector shape with a central angle of 90° as viewed from the directions D2 and D3 is equal to or greater than the GSD. The size of the top plate 500 as viewed from the directions D2 and D3 may be smaller than the size of the base portion 441 as viewed from the same directions as shown in FIG. 22, or may be approximately equal to the size of the base portion 441 as viewed from the same directions, or may be larger than the size of the base portion 441 as viewed from the same directions. In other words, the size of the top plate 500 when viewed from directions D2 and D3 does not depend on the size of the radio wave reflecting section 410, and can be set appropriately based on the conditions when the GSD of the optical satellite and the optical image 520 are acquired.

The above-mentioned reference point forming device 400P provides the same effects as the reference point forming device 400C. In addition, the reference point forming device 400P allows the pattern forming section 420 to be provided on the top plate section 500 and separated from the radio wave reflecting section 410, which increases the degree of freedom in the shape of the reference point pattern 435, etc.

Note that while FIG. 22 illustrates a disk-shaped top panel 500, the top panel 500 may have a cylindrical shape with a certain thickness as long as it is made of a material that is transparent to radio waves E, and may be formed in a shape other than a circle when viewed from directions D2 and D3 (for example, a polygonal shape including a square, an elliptical shape, etc.). In addition, in the reference point forming device 400P, the shape of the reference point pattern 435 is not limited to the shape illustrated in FIG. 22, and may be any shape that allows the reference point 430 to be detected in the optical image 520 after being photographed by an optical satellite.

The top plate portion 500 of the reference point forming device 400P may be provided on the plate-shaped members 479-3 and 479-4 in another manner, for example, by aligning the center of the surface 502 of the top plate portion 500 with the corners of the plate-shaped members 479-3 and 479-4 of the reference point forming device 400N. In that case, the intersecting surface 442 of the base portion 441 does not need to be divided into a plurality of intersecting surfaces 443-1 and 443-2. In other words, as a modified example of the reference point forming device 400P, the shape of the radio wave reflecting portion 410 disposed below the top plate portion 500 can be freely changed as long as it can retroreflect radio waves E.

Although the preferred embodiment of the present invention and several aspects of the reference point forming device have been described in detail above, the present invention is not limited to the specific embodiment and aspects. The present invention can be modified within the scope of the gist of the present invention described in the claims.

In each of the above-described aspects, an image captured by an optical satellite is exemplified as the optical image 520. However, the optical image 520 in the present invention may be an image captured by an unmanned aerial vehicle (UAV) such as an aircraft or a drone.

Of the multiple aspects of the reference point forming device 400 described above, the configurations of multiple aspects of the reference point forming device 400 may be appropriately combined.

In addition, in the reference point forming device 400 having the above-mentioned several base portions and plate-shaped portions, or the reference point forming device 400 having a radome and a plate-shaped portion, columnar portion, or cone-shaped portion, a so-called star-shaped reference point pattern 435 of the UAV, or any reference point pattern indicating the reference point 430, may be formed.

400, 400A-400N, 400P Reference point forming device 410 Radio wave reflecting section 420 Pattern forming section

Claims (16)

a radio wave reflecting section that reflects radio waves transmitted from a synthetic aperture radar satellite in a first direction relative to the direction of incidence of the radio waves;
a pattern forming unit that forms a reference point pattern that indicates the position of the reference point when photographed from a second direction by an optical satellite;
Equipped with
In the reference point pattern, a plurality of straight reference lines intersecting at the reference points appear when viewed from the second direction,
a base portion having an intersecting plane that intersects with the second direction at the reference point;
A plate-like portion is erected on the intersecting plane and is disposed along the reference line when viewed from the second direction;
having
the radio wave reflection portion is provided on a plate surface inclined with respect to the intersecting surface in the plate-shaped portion and on the intersecting surface,
The pattern forming portion is provided on the intersecting surface.
Reference point forming device. a radio wave reflecting section that reflects radio waves transmitted from a synthetic aperture radar satellite in a first direction relative to the direction of incidence of the radio waves;
a pattern forming unit that forms a reference point pattern that indicates the position of the reference point when photographed from a second direction by an optical satellite;
Equipped with
In the reference point pattern, a plurality of straight reference lines intersecting at the reference points appear when viewed from the second direction,
a base portion having an intersecting plane that intersects with the second direction at the reference point;
a radome that is formed from an outer edge of the base portion toward a position on the front side of the reference point in the incident direction of the radio wave and away from the intersection surface, and that transmits the radio wave;
a plate-like portion erected on the intersecting surface and accommodated in an inner space of the radome;
having
the radio wave reflection portion is provided on a plate surface inclined with respect to the intersecting surface in the plate-shaped portion and on the intersecting surface,
The pattern forming portion is provided on an outer surface of the radome.
Reference point forming device. a radio wave reflecting section that reflects radio waves transmitted from a synthetic aperture radar satellite in a first direction relative to the direction of incidence of the radio waves;
a pattern forming unit that forms a reference point pattern that indicates the position of the reference point when photographed from a second direction by an optical satellite;
Equipped with
In the reference point pattern, a plurality of straight reference lines intersecting at the reference points appear when viewed from the second direction,
A base portion having an intersecting surface that intersects with the second direction;
A columnar portion erected on the intersecting surface and having a bottom surface in contact with the intersecting surface;
having
The radio wave reflecting portion is provided on a side surface of the columnar portion and on the crossing surface exposed when viewed from a second direction,
the pattern forming portion is provided on the top surface of the columnar portion when viewed from the second direction and on the intersecting surface exposed when viewed from the second direction;
Reference point forming device. a radio wave reflecting section that reflects radio waves transmitted from a synthetic aperture radar satellite in a first direction relative to the direction of incidence of the radio waves;
a pattern forming unit that forms a reference point pattern that indicates the position of the reference point when photographed from a second direction by an optical satellite;
Equipped with
In the reference point pattern, a plurality of straight reference lines intersecting at the reference points appear when viewed from the second direction,
a base portion having an intersecting surface that intersects with the second direction;
A cone-shaped portion is provided upright on the intersecting surface, and a bottom surface of the cone-shaped portion is in contact with the intersecting surface;
having
The cone-shaped portion is
An orthogonal plane perpendicular to the intersection plane;
an inclined surface inclined with respect to both the intersecting plane and the orthogonal plane;
having
The radio wave reflecting portion is provided on the orthogonal surface and the intersecting surface exposed when viewed from a second direction,
The pattern forming portion is provided on the inclined surface and the intersecting surface exposed when viewed from a second direction.
Reference point forming device. a radio wave reflecting section that reflects radio waves transmitted from a synthetic aperture radar satellite in a first direction relative to the direction of incidence of the radio waves;
a pattern forming unit that forms a reference point pattern that indicates the position of the reference point when photographed from a second direction by an optical satellite;
Equipped with
In the reference point pattern, a plurality of straight reference lines intersecting at the reference points appear when viewed from the second direction,
a base portion having an intersecting plane that intersects with the second direction at the reference point;
A plate-like portion is erected on the intersecting plane and is disposed along the reference line when viewed from the second direction;
a top plate portion provided on a top of the plate-like portion, having a predetermined size in a radial direction centered on the top when viewed from the second direction, and made of a material that is transparent to the radio waves;
having
the radio wave reflection portion is provided on a plate surface inclined with respect to the intersecting surface in the plate-shaped portion and on the intersecting surface,
The pattern forming portion is provided on the surface of the top plate portion.
Reference point forming device. a radio wave reflecting section that reflects radio waves transmitted from a synthetic aperture radar satellite in a first direction relative to the direction of incidence of the radio waves;
a pattern forming unit that forms a reference point pattern that indicates the position of the reference point when photographed from a second direction by an optical satellite;
Equipped with
In the reference point pattern, one or more polygonal reference lines having the reference point as a center appear when viewed from the second direction,
a base portion having an intersecting plane that intersects with the second direction at the reference point;
A plate-like portion is erected on the intersecting plane and is disposed along the reference line when viewed from the second direction;
having
the radio wave reflection portion is provided on a plate surface inclined with respect to the intersecting surface in the plate-shaped portion and on the intersecting surface,
The pattern forming portion is provided on the intersecting surface.
Reference point forming device. a radio wave reflecting section that reflects radio waves transmitted from a synthetic aperture radar satellite in a first direction relative to the direction of incidence of the radio waves;
a pattern forming unit that forms a reference point pattern that indicates the position of the reference point when photographed from a second direction by an optical satellite;
Equipped with
In the reference point pattern, one or more polygonal reference lines having the reference point as a center appear when viewed from the second direction,
a base portion having an intersecting plane that intersects with the second direction at the reference point;
a radome that is formed from an outer edge of the base portion toward a position on the front side of the reference point in the incident direction of the radio wave and away from the intersection surface, and that transmits the radio wave;
a plate-like portion erected on the intersecting surface and accommodated in an inner space of the radome;
having
the radio wave reflection portion is provided on a plate surface inclined with respect to the intersecting surface in the plate-shaped portion and on the intersecting surface,
The pattern forming portion is provided on an outer surface of the radome.
Reference point forming device. a radio wave reflecting section that reflects radio waves transmitted from a synthetic aperture radar satellite in a first direction relative to the direction of incidence of the radio waves;
a pattern forming unit that forms a reference point pattern that indicates the position of the reference point when photographed from a second direction by an optical satellite;
Equipped with
In the reference point pattern, one or more polygonal reference lines having the reference point as a center appear when viewed from the second direction,
a base portion having an intersecting surface that intersects with the second direction;
A columnar portion erected on the intersecting surface and having a bottom surface in contact with the intersecting surface;
having
The radio wave reflecting portion is provided on a side surface of the columnar portion and on the crossing surface exposed when viewed from a second direction,
the pattern forming portion is provided on the top surface of the columnar portion when viewed from the second direction and on the intersecting surface exposed when viewed from the second direction;
Reference point forming device. a radio wave reflecting section that reflects radio waves transmitted from a synthetic aperture radar satellite in a first direction relative to the direction of incidence of the radio waves;
a pattern forming unit that forms a reference point pattern that indicates the position of the reference point when photographed from a second direction by an optical satellite;
Equipped with
In the reference point pattern, one or more polygonal reference lines having the reference point as a center appear when viewed from the second direction,
a base portion having an intersecting surface that intersects with the second direction;
A cone-shaped portion is provided upright on the intersecting surface, and a bottom surface of the cone-shaped portion is in contact with the intersecting surface;
having
The cone-shaped portion is
An orthogonal plane perpendicular to the intersection plane;
an inclined surface inclined with respect to both the intersecting plane and the orthogonal plane;
having
The radio wave reflecting portion is provided on the orthogonal surface and the intersecting surface exposed when viewed from a second direction,
The pattern forming portion is provided on the inclined surface and the intersecting surface exposed when viewed from a second direction.
Reference point forming device. a radio wave reflecting section that reflects radio waves transmitted from a synthetic aperture radar satellite in a first direction relative to the direction of incidence of the radio waves;
a pattern forming unit that forms a reference point pattern that indicates the position of the reference point when photographed from a second direction by an optical satellite;
Equipped with
In the reference point pattern, one or more polygonal reference lines having the reference point as a center appear when viewed from the second direction,
a base portion having an intersecting plane that intersects with the second direction at the reference point;
A plate-like portion is erected on the intersecting plane and is disposed along the reference line when viewed from the second direction;
a top plate portion provided on a top of the plate-like portion, having a predetermined size in a radial direction centered on the top when viewed from the second direction, and made of a material that is transparent to the radio waves;
having
the radio wave reflection portion is provided on a plate surface inclined with respect to the intersecting surface in the plate-shaped portion and on the intersecting surface,
The pattern forming portion is provided on the surface of the top plate portion.
Reference point forming device. a positioning signal receiving antenna provided on a top of the pyramidal portion and configured to be able to receive a positioning signal transmitted from the synthetic aperture radar satellite;
the pattern forming portion is provided on a surface of the positioning signal receiving antenna, and on the inclined surface and the intersecting surface exposed when viewed from the second direction;
10. The reference point forming device according to claim 4 or 9 . The reference line defines a boundary between adjacent regions, each of which has a different amount of light reflected when a light wave is incident thereon or a different wavelength of the light wave.
The reference point forming device according to any one of claims 1 to 11 . A solar cell is provided on the intersecting surface exposed when viewed from the second direction.
A reference point forming device according to any one of claims 1 to 12 . a size of the reference point pattern when viewed from the second direction is equal to or greater than twice the ground resolution of the optical satellite;
A reference point forming device according to any one of claims 1 to 13 . A reference point forming device according to any one of claims 1 to 14 ,
an image processing unit that compares the common reference points between a radar image and an optical image created based on radar image information received from the synthetic aperture radar satellite and optical image information received from the optical satellite, and matches the radar image with the optical image;
Equipped with
Satellite image processing equipment. A satellite image processing method using the satellite image processing device according to claim 15 ,
creating a radar image and an optical image based on radar image information received from the synthetic aperture radar satellite and optical image information received from the optical satellite;
and matching the radar image with the optical image by matching the common reference points between the radar image and the optical image.
Satellite image processing methods.

Images