JPS5847643B2 - Altitude information extraction method using remote sensing data from satellites - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an altitude information extraction method for determining the altitude difference between two points on the ground using remote sensing data from a satellite.

Traditionally, aerial photography has been used to view the earth's surface from the sky and obtain altitude information.

This method of obtaining altitude information from aerial photographs uses a pair of vertical photographs taken from different points in the sky at the same altitude, and determines altitude information from the coordinate difference between the two photographs of the same object, so-called parallax.

Additionally, remote sensing data from satellites is used in the research stage of resource exploration overseas.

In resource exploration, altitude information on the terrain is of great significance, and new satellites are being launched to obtain this information, such as STEREOSAT1 in the United States and SPOT in Europe in 1984, and ERS-1 in Japan in 1986. It is planned.

By the way, unlike cameras on aircraft, most of the sensors installed on satellites currently face directly below the satellite, and scan perpendicularly to the direction of travel of the satellite, capturing images line by line. Therefore, it is generally not possible to extract altitude information from remote sensing data using traditional methods.

Therefore, an idea is to install two sensors at appropriate angles (stereo angle, θ1 + θ2) before and after the satellite's traveling direction, take images of the same area from different angles in the same orbit, and use these two images. It is being

Figure 1 is a conceptual diagram of this stereo imaging method, assuming that a sensor is attached to a satellite orbiting at an altitude of H/cm above the earth's surface, and the stereo angle is θ1 + θ2. This shows that two images of the same point can be obtained.

Conventionally, the stereo processing method for satellite images is 2.
In order to ensure that the images obtained from the satellite's sensors completely correspond to the map, alignment is performed based on the orbit and attitude of the satellite. Since the deviation between the same points at is the parallax, if this is set as ΔX, the altitude h can be determined by.

However, with this method, it is difficult to correspond with maps, the errors are large, it is difficult to obtain accurate maps in some areas, and there are large errors due to trajectory, attitude, etc. There are problems such as that it is extremely difficult to align the two images.

An object of the present invention is to solve the above-mentioned problems and extract highly accurate altitude information using remote sensing data from a satellite.

The present invention is characterized in that it is possible to calculate the altitude difference between two points by simply determining the distance in the direction of travel between the two points, without the need for correspondence with a map or alignment of two images. It is.

Therefore, the altitude information extraction method using remote sensing data from a satellite according to the present invention uses a first screen using a sensor that scans θ1 ahead in the direction of travel of the satellite;
Using a second screen by a sensor that scans θ2 backward in the traveling direction, find the distance X1tX2 in the traveling direction between the two points P1 and P2 that exist in common on each screen, and calculate the distance between the two points P1 and P2. This feature is characterized in that the altitude difference Δh of is calculated by and used as altitude information.

Hereinafter, the present invention will be explained with reference to the drawings.

FIG. 2 is a diagram showing the scan status of each point P1 and P2, and FIG. 3 is a diagram of FIG. 2 viewed from the side.

In the figure, considering that the satellite is moving in orbit, first the first sensor that scans θ1 in front of the traveling direction detects the height h1.
A first point P1 at a height h2 is scanned, and then a second point P2 at a height h2 is scanned after traveling a distance , the first point P, and then after traveling a distance x2, the second point P2 is scanned.

As a result, in the plan view of FIG. 3 viewed from the side, each distance represents a distance in the traveling direction.

Therefore, if the distance in the traveling direction between the first point P1 and the second point P2 is X, then Xp on the screen of the first sensor becomes and Xp on the screen of the second sensor becomes, so these two equations The altitude difference between these two points is △
h can be expressed as

FIG. 4 is a diagram illustrating a specific procedure for extracting altitude difference information in one embodiment of the present invention.

Set an appropriate angle (stereo angle, θ1 +
A region of interest is cut out from the remote sensing data obtained by two sensors with θ2) and displayed on a display screen.

Then, specify the two points on the screen where you want to find the altitude difference,
The distance x1 in the traveling direction between two points P, , P2 on the display screen by the sensor scanning θ1 ahead in the traveling direction is expressed as p. It is calculated from the number of scan lines between / and P'2.

Furthermore, the distance X2 in the traveling direction between two points P, , P2 on the display screen by the sensor scanning behind θ2 in the traveling direction is expressed as p. It is calculated from the number of scan lines between // and p2//.

Next, the altitude difference between the two points P, , P2 is determined using the above-mentioned equation (4).

As is clear from the above description, according to the present invention, two images are used, but the stereo angle and the distance in the direction of travel between two points are determined separately for each image to extract altitude difference information. , there is no need to correspond or align the two images with a map.

In addition, the stereo angle and the distance in the direction of travel between two points do not depend on factors such as the satellite's position and speed, and there are no altitude errors caused by orbit generation errors or attitude determination errors, so It is possible to extract altitude information more easily and with higher accuracy than with other methods.

[Brief explanation of the drawing]

Fig. 1 is a conceptual diagram of the stereo imaging system, Fig. 2 is a drawing showing the scanning situation of each point P1 and P2, Fig. 3 is a side view of Fig. 2, and Fig. 4 is a diagram of the method of the present invention. FIG. 3 is a diagram illustrating a specific procedure for extracting altitude difference information in an embodiment. θ1+θ2...Stereo angle, H1, H2...
... Orbit altitude from the ground surface, P1, P2 ... Altitude information extraction point, X1 + X2 ... Distance in the traveling direction.

Claims (1)

[Claims] 1. A first screen using a sensor that scans θ1 in front of the satellite's traveling direction, and a second screen using a sensor that scans θ2 backward in the traveling direction, and that exists in common on each screen. remote sensing data from a satellite, characterized in that the distance XI r Advanced information extraction method using.