JP6098975B2 - Marker, object identification device, and object identification method - Google Patents

Description

  The present invention relates to a marker provided on an object in order to distinguish and recognize a plurality of objects. The present invention also relates to an object identification device and method for identifying a plurality of objects from each other based on a plurality of markers provided on the plurality of objects, respectively.

  A method for recognizing an object using a marker is described in Patent Documents 1 and 2 below, for example.

  In Patent Document 1, an object is recognized as follows. The marker is a light emitting diode whose luminance changes in a specific pattern. A range including the object to which the marker is attached is imaged. From the moving image obtained in this way, a pixel whose luminance changes with the light emission pattern of the light emitting diode is specified. Based on the identified pixel, the position and direction of the object are detected.

  In Patent Document 2, an object is recognized as follows. The marker is a geometric pattern such as a straight line, a quadrangle, or an arc. A range including the object to which the marker is attached is imaged. In the obtained image, the position of the geometric pattern of the marker is recognized. Based on this position, the position and direction of the object can be detected.

JP 2009-33366 A JP 2007-3233 A

  In the case of Patent Document 1, if a light emitting diode illuminated by another strong light (for example, sunlight) is imaged, the light from the light emitting diode may not be detected. In this case, the position and direction of the object cannot be detected based on the light from the light emitting diode.

  Therefore, it is desired that the marker can be recognized without being affected by the intensity of light hitting the marker.

In the case of Patent Document 2, in order to recognize a geometric pattern, the vertical or horizontal dimension of the geometric pattern needs to be more than a dozen pixels in the image.
However, when a geometric pattern is imaged from a distance of 100 m or more with a field of view of 60 degrees or more, even if a camera with about 1 million pixels is used, a geometric pattern of about 0.5 m is used in the image. The vertical or horizontal dimension of the geometric pattern is about 5 pixels or less. As a result, the geometric pattern cannot be recognized. Therefore, the position and direction of the object cannot be detected based on the geometric pattern.

  Therefore, it is desirable to be able to recognize the marker even if the size of the marker in the image is small.

  Furthermore, it is desired that a plurality of markers provided respectively on a plurality of objects can be distinguished from each other and recognized.

  Therefore, an object of the present invention is to recognize a marker even when strong light (for example, sunlight) is directly applied to the marker when the marker is recognized from image data obtained by imaging an area including the marker. An object of the present invention is to make it possible to recognize a marker even if the size of the marker in the image data is small, and to distinguish and recognize a plurality of markers respectively provided on a plurality of objects.

In order to achieve the above object, according to the present invention, a marker provided on the surface of an object,
Having a plurality of polarization generating regions;
Each of the plurality of polarization generation regions is a first or second polarization generation region,
The first polarized light generation region generates reflected light of the first linearly polarized light from the unpolarized light when the unpolarized light is incident.
The second polarized light generation region generates reflected light of the second linearly polarized light from the unpolarized light when the unpolarized light is incident, and the polarization direction of the second linearly polarized light is the polarization direction of the first linearly polarized light. A marker characterized by being orthogonal to is provided.

Moreover, in order to achieve the above-mentioned object, according to the present invention, an object identification device for identifying these objects from each other based on a plurality of markers respectively provided on the plurality of objects,
The marker includes a first polarization generation region that generates a first linearly polarized reflected light from the non-polarized light when non-polarized light is incident, and a second polarization-to-second region when the non-polarized light is incident. Having at least one of a second polarized light generating region for generating linearly polarized reflected light;
An imaging device for imaging an imaging range including a marker;
An image processing device for identifying a marker in the imaging range from other markers based on image data of the imaging range obtained by an imaging device;
The imaging device includes an optical unit, a first imaging unit, and a second imaging unit,
When the polarization direction of the first linearly polarized light is orthogonal to the polarization direction of the second linearly polarized light, the optical unit selectively performs first imaging of the first linearly polarized light out of the light traveling from the imaging range. The second linearly polarized light is selectively incident on the second imaging unit,
The first imaging unit generates first image data in the imaging range based on the incident light to the first imaging unit,
The second imaging unit generates second image data of the imaging range based on incident light to the second imaging unit,
The image processing device
(A) For each pixel of the first image data, the luminance of the pixel is a value A, and the luminance of the pixel of the second image data corresponding to the same position as the pixel in the imaging range is a value B. Find the value f (A, B) of the function with B as the independent variable,
(B) Assuming that the first and second polarization generation regions are different types of polarization generation regions, based on the value f (A, B) of each pixel, the first image data or the second image data Specify the type of polarization generation region included, or the arrangement pattern of a plurality of polarization generation regions included in the first image data or the second image data,
(C) Provided is an object identification device that identifies a marker in the first image data or the second image data from another marker based on the specified type or arrangement pattern.

  Preferably, the value f (A, B) is A / B or A / (A + B) or (A−B) / (A + B).

According to a preferred embodiment of the present invention, the image processing apparatus in (B),
(B1) For each pixel of the first image data or the second image data, the value f (A, B) × K obtained by multiplying the value f (A, B) by the correction value K, or the value f (A, B B) determines whether or not it is greater than the first threshold, and if the determination is affirmative, determines that the pixel corresponds to the first polarization generation region;
(B2) For each pixel of the first image data or the second image data, the value f (A, B) × K obtained by multiplying the value f (A, B) by the correction value K, or the value f (A, B It is determined whether or not B) is smaller than a second threshold value that is smaller than the first threshold value. If the determination is affirmative, the pixel corresponds to the second polarization generation region. Judging
(B3) Based on the determination of (B1) and (B2), the type of polarization generation region included in the first image data or the second image data, or the first image data or the second image data The arrangement pattern of the plurality of polarization generation regions included in the is specified.

In order to achieve the above-mentioned object, according to the present invention, there is an object identification method for identifying these objects from each other based on a plurality of markers respectively provided on the plurality of objects,
The marker includes a first polarization generation region that generates a first linearly polarized reflected light from the non-polarized light when non-polarized light is incident, and a second polarization-to-second region when the non-polarized light is incident. Having at least one of a second polarization generation region that generates reflected light of linearly polarized light,
An imaging device for imaging an imaging range including a marker, and an image processing device that identifies a marker in the imaging range from other markers based on image data of the imaging range obtained by the imaging device, The imaging device includes an optical unit, a first imaging unit, and a second imaging unit,
When the polarization direction of the first linearly polarized light is orthogonal to the polarization direction of the second linearly polarized light, the optical unit selectively selects the first linearly polarized light out of the light traveling from the imaging range as a first image. The second linearly polarized light is selectively incident on the second imaging unit,
The first imaging unit generates first image data of the imaging range based on the incident light on the first imaging unit, and the second imaging unit generates the first image data on the second imaging unit based on the incident light on the second imaging unit. Generating second image data of the imaging range;
By image processing device
(A) For each pixel of the first image data, the luminance of the pixel is a value A, and the luminance of the pixel of the second image data corresponding to the same position as the pixel in the imaging range is a value B. Find the value f (A, B) of the function with B as the independent variable,
(B) Assuming that the first and second polarization generation regions are different types of polarization generation regions, based on the value f (A, B) of each pixel, the first image data or the second image data Specify the type of polarization generation region included, or the arrangement pattern of a plurality of polarization generation regions included in the first image data or the second image data,
(C) Provided is an object identification method characterized by identifying a marker in the first image data or the second image data from another marker based on the specified type or arrangement pattern.

  The marker of the present invention described above includes the first polarized light generating region that generates the first linearly polarized reflected light from the non-polarized light when the non-polarized light is incident, and the non-polarized light when the non-polarized light is incident. To at least one of a second polarization generation region that generates reflected light of the second linearly polarized light. Therefore, by specifying the type of polarization generation region in the marker or the arrangement pattern of the plurality of polarization generation regions in the marker, the plurality of markers can be identified and recognized from each other.

Such marker identification is performed by the above-described object identification device or object identification method of the present invention as described below.
Of the light from the imaging range, the first linearly polarized light is selectively incident on the first imaging unit, and the second linearly polarized light is selectively incident on the second imaging unit. First image data is generated, and the second imaging unit generates second image data. Thereafter, the following processes (A) to (C) are performed.
(A) For each pixel of the first image data, the luminance of the pixel is a value A, the luminance of the pixel of the second image data corresponding to the same position as the pixel in the region is a value B, and the values A and B The value f (A, B) of the function is obtained using as an independent variable.
(B) Assuming that the first and second polarization generation regions are different types of polarization generation regions, based on the value f (A, B) of each pixel, the first image data or the second image data The type of the polarization generation region included or the arrangement pattern of the plurality of polarization generation regions included in the first image data or the second image data is specified.
(C) Based on the specified type or arrangement pattern, the markers in the first image data or the second image data are identified from other markers.
In this way, the marker can be identified from other markers.

  Further, since this identification is performed by distinguishing the polarization direction of light, this identification can be made less susceptible to the intensity of light hitting the marker. For example, even when sunlight directly hits the marker, the marker can be identified.

  Furthermore, even when there is only one pixel corresponding to the first or second polarization generation region, it can be specified that the pixel corresponds to the first or second polarization generation region. Therefore, even if the marker size in the first image data or the second image data is small, the type of the polarization generation region included in the first image data or the second image data, or the plurality of polarization generation regions Markers can be identified by specifying an array pattern.

2 shows a configuration of a marker according to an embodiment of the present invention. 1 shows an object identification device according to an embodiment of the present invention. 5 is a flowchart illustrating an object identification method according to an embodiment of the present invention. The example of a change of a target object identification apparatus is shown.

  A preferred embodiment of the present invention will be described with reference to the drawings. In addition, the same code | symbol is attached | subjected to the common part in each figure, and the overlapping description is abbreviate | omitted.

<Contents>
1. Marker 2. 2. Object identification device 3. Object identification method Example of change

1. Marker 1.1. Marker Configuration FIG. 1 shows the configuration of a marker 1 according to an embodiment of the present invention. The marker 1 is provided on the surface of the object 3. FIG. 1A is a perspective view of an object 3 provided with a marker 1, and FIG. 1B is a cross-sectional view taken along line BB in FIG.

  In the marker 1, when non-polarized light (for example, light from the sun) is incident, the first polarized light generation region 1 a that generates reflected light of the first linearly polarized light from the non-polarized light and the non-polarized light has entered. In this case, at least one of the second polarized light generation region 1b for generating reflected light of the second linearly polarized light from the non-polarized light is provided. The polarization direction of the first linearly polarized light is orthogonal to the polarization direction of the second linearly polarized light. Non-polarized light means light that is not polarized, in other words, light in which the vibration direction of the electric field vector or magnetic field vector of light is uniformly distributed.

  Each of the first and second polarized light generating regions 1 a and 1 b has an outer polarizing portion 7 and an inner reflecting portion 9. FIG. 1B is a cross-sectional view of the first polarization generation region 1a, but the second polarization generation region 1b is the first polarization except for the direction of the polarization unit 7 (reference direction described later). It has the same configuration as the generation region 1a.

  The polarizing unit 7 passes linearly polarized light that vibrates in a reference direction fixed to the polarizing unit 7, but does not pass linearly polarized light that vibrates in a direction orthogonal to the reference direction. Such a polarizing unit 7 may be a polarizing filter, for example. In FIG. 1A, the reference direction (for example, the horizontal direction) fixed to the polarization unit 7 of the first polarization generation region 1a is the reference direction (for example, the horizontal direction) fixed to the polarization unit 7 of the second polarization generation region 1b. Perpendicular to the vertical direction).

  The reflection unit 9 is located inside the polarization unit 7. Therefore, the incident light on the polarization generation regions 1 a and 1 b of the marker 1 enters the reflection unit 9 after passing through the polarization unit 7. The reflector 9 reflects this incident light. The reflection part 9 should just be formed so that the light reflected by the reflection part 9 may have a polarization component that can pass through the polarization part 7. The reflection part 9 is preferably formed so as to have a high light reflectance (for example, having a light reflectance of 80% or more), and has, for example, a white or a reflective surface having a color close to white. In addition, the reflection part 9 may diffusely reflect incident light.

With the configuration of the marker 1 described above, the following operation is obtained.
Incident light to the polarization generation regions 1a and 1b of the marker 1 is reflected by the marker 1 to become polarized light in the reference direction as follows. Here, the case of the first polarization generation region 1a will be described, but the same applies to the case of the second polarization generation region 1b. Of the incident light to the polarization generation region 1 a, the linearly polarized component in the reference direction passes through the polarizing unit 7, and the linearly polarized component in the direction orthogonal to the reference direction does not pass through the polarizing unit 7. The linearly polarized light component in the reference direction that has passed through the polarization unit 7 is then reflected by the reflection unit 9 and is incident on the polarization unit 7 again. The light that has passed through the polarization unit 7 again from the reflection unit 9 side is converted into linearly polarized light in the reference direction by the polarization unit 7. Thus, the incident light on the first polarized light generation region 1 a in the marker 1 becomes linearly polarized light in the reference direction (first linearly polarized light) reflected by the marker 1. Similarly, the incident light to the second polarized light generation region 1b in the marker 1 becomes linearly polarized light in the reference direction (second linearly polarized light) reflected by the marker 1.

The marker 1 may have an antireflection film on its surface (for example, the surface of the polarizing unit 7). The antireflection film prevents the incident light from being reflected from the surface of the marker 1, thereby increasing the proportion of the incident light that reaches the polarization unit 7 in the marker 1.
Moreover, the reflection part 9 may be a thing attached to the target object 3 (for example, a film), or may be provided in advance on the target object 3 (for example, the surface of the target object 3). In this case, the marker 1 (polarization unit 7) is attached to the reflection unit 9 of the object 3.

  In addition, the reflection unit 9 may be shared by a plurality of polarization generation regions (first and second polarization generation regions 1a and 1b in FIG. 1A) in the marker 1. That is, the marker 1 may have a single reflecting portion 9 extending over a plurality of polarization generation regions.

1.2. Relationship between Marker and Object A plurality of markers 1 having the above-described configuration are provided on a plurality of objects 3, respectively. These markers 1 have the same number of polarization generation regions. Each marker 1 has two polarization generation regions in the example of FIG. 1 and the example of FIG. 2 described later corresponding to FIG. Instead, the number of polarization generation regions 1a and 1b included in each marker 1 may be one, or may be three or more. Preferably, each marker 1 is provided with one or more polarization generating regions of the same size or shape. More preferably, each marker 1 is provided with one or more polarization generating regions of the same size and shape.

  When each marker 1 has a plurality of (two in the example of FIG. 1) polarization generation regions 1a and 1b, in each marker 1, the plurality of polarization generation regions 1a and 1b are arranged in advance. They are arranged according to (for example, a predetermined shape or rule) (for example, at a constant interval on the same straight line). In the example of FIG. 1 and the example of FIG. 2 described later corresponding to FIG. 1, in each marker 1, the two polarized light generation regions are spaced on the outer periphery of the cylindrical portion 5 in the axial direction of the cylindrical portion 5. Are arranged. Note that the columnar portion 5 may be the entire object 3, may be a part of the object 3, or may be provided on the object 3.

  The plurality of markers 1 can be distinguished from each other by the difference in the arrangement pattern of the polarization generation regions provided on each of the markers 1. For example, in the example of FIG. 2, the plurality of markers 1 having different arrangement patterns include a marker 1 in which a first polarization generation region 1 a and a second polarization generation region 1 b are arranged vertically (upper and lower in FIG. 2). A marker 1 in which the first polarization generation region 1a and the first polarization generation region 1a are arranged above and below, and a marker in which the second polarization generation region 1b and the first polarization generation region 1a are arranged above and below, respectively. 1 and a marker 1 in which a second polarization generation region 1b and a second polarization generation region 1b are arranged on the upper and lower sides, respectively. The identification of the marker 1 based on the difference in the arrangement pattern is performed by an object identification device 10 and an object identification method described later.

  With such a plurality of markers 1 provided on the plurality of objects 3, the reference direction of each first polarized light generation region 1 a is between the markers 1 and in each marker 1. The reference direction of each second polarization generation region 1b faces the same direction, and the reference direction of each first polarization generation region 1a and the reference direction of each second polarization generation region 1a are orthogonal to each other. . In addition, when the direction of the target object 3 with respect to the horizontal plane can be changed, it is assumed that each target object 3 is in the same direction with respect to the horizontal plane (for example, facing the horizontal direction). For example, when the target object 3 is a moving body such as a robot or a vehicle, and the posture (orientation) of the moving body changes with respect to the horizontal plane, the direction of the target object 3 (moving body) with respect to the horizontal plane can change. On the other hand, the posture (direction) of the object 3 may be fixed with respect to the horizontal plane.

Examples of the plurality of objects 3 include the following.
(1) Each object 3 is a moving body such as a robot or a vehicle. In this case, a plurality of moving bodies can be identified from each other by the object identification device 10 or the object identification method according to an embodiment of the present invention described later.
(2) Each object 3 is an index for a moving body such as a robot or a vehicle to recognize its own position. In this case, the marker 1 is provided on each of the plurality of objects 3 in a plurality of known locations, the marker 1 is identified by the object identification device 10 provided on the moving body, and is identified by an appropriate means. The positional relationship between the position of the marker 1 and the moving body is recognized, and the position of the moving body is acquired using the recognized positional relationship.
(3) Each of the plurality of objects 3 is a plurality of types of objects conveyed by a conveyance line (for example, a belt conveyor). In this case, the marker 1 provided on the object is identified by the object identification device 10 or the object identification method according to an embodiment of the present invention described later, and the robot hand holds the article and responds to the identification result. Move to the desired position.

2. Object Identification Device FIG. 2 shows a configuration of the object identification device 10 according to the embodiment of the present invention. The object identification device 10 can identify these objects 3 from each other based on the above-described plurality of markers 1 provided on the plurality of objects 3, respectively.

  The object identification device 10 includes an imaging device 11 and an image processing device 13.

2.1. Imaging Device The imaging device 11 images an imaging range including at least one marker 1 among the plurality of markers 1. The imaging device 11 includes an optical unit 15, a first imaging unit 17, and a second imaging unit 19. Hereinafter, the linearly polarized light polarized in the reference direction of the first polarized light generating region 1a is referred to as first linearly polarized light, and the linearly polarized light polarized in the reference direction of the second polarized light generating region 1b is referred to as second linearly polarized light.

  The optical unit 15 selectively makes the first linearly polarized light incident on the first imaging unit 17 out of the light traveling from the imaging range, and selectively makes the second linearly polarized light enter the second imaging unit 19. Let Here, “selectively allowing the first linearly polarized light to enter the first imaging unit 17” causes the first linearly polarized light to be incident on the first imaging unit 17 (preferably without reducing the intensity). On the other hand, light of other linearly polarized light components is prevented (preferably completely blocked) from entering the first image capturing unit 17, or the intensity of the light of other linearly polarized light components incident on the first image capturing unit 17. Is reduced with respect to the intensity of the first linearly polarized light incident on the first imaging unit 17. Similarly, “selectively causing the second linearly polarized light to enter the second imaging unit 19” means that the second linearly polarized light is incident on the second imaging unit 19 (preferably without reducing the intensity). On the other hand, the light of the other linearly polarized light component is blocked (preferably completely blocked) from entering the second imaging unit 19 or the intensity of the light of the other linearly polarized light component incident on the second imaging unit 19. Is reduced with respect to the intensity of the second linearly polarized light incident on the second imaging unit 19.

  The optical unit 15 includes a polarization beam splitter 15a, a first lens 15b, and a second lens 15c.

  The polarization beam splitter 15a selectively reflects the first linearly polarized light of the incident light toward the first imaging unit 17 and selectively transmits the second linearly polarized light toward the second imaging unit 19 side. . Preferably, the polarization beam splitter 15a is a half mirror. The polarization direction of the linearly polarized light reflected by the polarization beam splitter 15a is orthogonal to the polarization direction of the linearly polarized light transmitted through the polarization beam splitter 15a.

  The first linearly polarized light reflected by the polarizing beam splitter 15a is incident on the first lens 15b. The first lens 15 b is for imaging the first linearly polarized light from the imaging range on the imaging surface 17 a of the first imaging unit 17. The second linearly polarized light transmitted through the polarization beam splitter 15a is incident on the second lens 15c. The second lens 15 c is for imaging the second linearly polarized light from the imaging range on the imaging surface 19 a of the second imaging unit 19.

  The first imaging unit 17 captures an imaging range and generates first image data, and the second imaging unit 19 captures the imaging range and generates second image data.

  The first imaging unit 17 has an imaging surface 17a that receives light from the imaging range via the polarization beam splitter 15a. A number of CCD light receiving elements are two-dimensionally arranged on the imaging surface 17a. The first imaging unit 17 generates first image data (two-dimensional image data in this example) corresponding to the received light. The second imaging unit 19 has an imaging surface 19a that receives light from the imaging range via the polarization beam splitter 15a. A number of CCD light receiving elements are two-dimensionally arranged on the imaging surface 19a. The second imaging unit 19 generates second image data (in this example, two-dimensional image data) corresponding to the received light.

  The optical unit 15 may include a third lens 15d as in the example of FIG. The third lens 15d is located upstream of the polarizing beam splitter 15a in the optical path of the optical unit 15. The third lens 15d makes incident light from the imaging range close to parallel light (for example, parallel light).

  The polarization beam splitter 15 a, the first imaging unit 17, and the second imaging unit 19 may be attached to the support body 21 of the imaging device 11. Thereby, the directions of the polarization beam splitter 15a, the first imaging unit 17, and the second imaging unit 19 are fixed to each other.

With the configuration of the imaging device 11 described above, the following operation is obtained.
When the reflected light from the first polarized light generation region 1a in the marker 1 enters the optical unit 15, the following is performed. The first linearly polarized light that is the reflected light from the first polarized light generation region 1a is reflected toward the first imaging unit 17 by the polarizing beam splitter 15a. Thereby, the first linearly polarized light from the first polarization generation region 1 a is incident on the first imaging unit 17. On the other hand, the polarization beam splitter 15a prevents the first linearly polarized light from the first polarization generation region 1a from passing through itself. Thereby, the first linearly polarized light from the first polarization generation region 1 a does not enter the second imaging unit 19.
When the reflected light from the second polarized light generation region 1b in the marker 1 is incident on the optical unit 15, the following occurs. The second linearly polarized light that is the reflected light from the second polarized light generation region 1b is transmitted through the polarization beam splitter 15a toward the second imaging unit 19 side. As a result, the second linearly polarized light from the second polarization generation region 1 b enters the second imaging unit 19. On the other hand, the polarization beam splitter 15a does not reflect the second linearly polarized light from the second polarization generation region 1b. Thereby, the second linearly polarized light from the second polarization generation region 1 b does not enter the second imaging unit 19.
Thus, the light incident on the first imaging unit 17 has the largest amount of the first linearly polarized light with respect to the linearly polarized light component (ideally, only the first linearly polarized light), and enters the second imaging unit 19. The incident light has the largest amount of the second linearly polarized light with respect to the linearly polarized light component (ideally, only the second linearly polarized light is present).

  The orientation of the support 21 of the imaging device 11 is set with respect to the reference direction of the reflecting portion 9 provided on the marker 1 provided on the object 3 so that such an action is obtained. When the orientation of the object 3 with respect to the horizontal plane is constant, the orientation of the support 21 of the imaging device 11 is set with respect to the reference direction of the first polarization generation region 1a in the marker 1.

2.2. Image Processing Device The image processing device 13 includes an image processing unit 13a and a storage unit 13b.

  The image processing unit 13a calculates the luminance ratio of the pixels of the first image data that are in the same position as the pixels in the imaging range with respect to the pixels of the second image data. That is, for each pixel of the first image data, the luminance (brightness) of the pixel is a value A, and the luminance of the pixel of the second image data corresponding to the same position as the pixel in the imaging range is the value B. The device 13 obtains a function value f (A, B) with the values A and B as independent variables. Based on the value f (A, B), the image processing unit 13a determines the position of the marker 1 in the first image data or the second image data (hereinafter, the first image data or the second image data is also simply referred to as image data). And identifying the marker 1 from other markers 1. In the present embodiment, the value f (A, B) is the ratio A / B of the value A to the value B.

  The storage unit 13b stores marker identification data created in advance for use in identifying the marker 1 by the image processing unit 13a. The marker identification data will be described later.

  The marker 1 is identified as follows.

The image processing unit 13a determines whether the pixel corresponds to the first or second polarization generation region 1a, 1b based on the ratio A / B regarding each pixel of the image data as follows.
For the pixel corresponding to the first polarization generation region 1a, the above-described ratio A / B becomes significantly larger than the other pixels due to the action of the optical unit 15 described above. Therefore, the image processing unit 13a determines whether the ratio A / B of each pixel is larger than a preset first threshold value. When the pixel ratio A / B is larger than the first threshold value, the image processing unit 13a determines that the pixel corresponds to the first polarization generation region 1a. On the other hand, if the pixel ratio A / B is not greater than the first threshold value, the image processing unit 13a determines that the pixel does not correspond to the first polarization generation region 1a.
For the pixel corresponding to the second polarization generation region 1b, the ratio A / B described above is significantly smaller than the other pixels due to the action of the optical unit 15 described above. Therefore, the image processing unit 13a determines whether the ratio A / B of each pixel is smaller than the second threshold value. When the pixel ratio A / B is smaller than the second threshold value, the image processing unit 13a determines that the pixel corresponds to the second polarization generation region 1b. On the other hand, if the pixel ratio A / B is not smaller than the second threshold value, the image processing unit 13a determines that the pixel does not correspond to the second polarization generation region 1b. Note that the second threshold value is smaller than the first threshold value, and may be, for example, the reciprocal of the first threshold value. In one example, the first threshold is 2 and the second threshold is 1/2.
For pixels that do not correspond to any of the first and second polarization generation regions 1a and 1b, the above-described ratio A / B is not too large and not too small due to the action of the optical unit 15 described above ( 1 or a value close to 1). Therefore, the image processing unit 13a determines whether the ratio A / B of each pixel is equal to or less than the first threshold value and equal to or greater than the second threshold value. When the pixel ratio A / B is equal to or lower than the first threshold value and equal to or higher than the second threshold value, the image processing unit 13a determines that the pixel is in the first and second polarization generation regions 1b. Judge that it does not correspond to either.

  When the image processing unit 13a determines, for each pixel, whether the pixel corresponds to the first or second polarization generation region 1b, the image processing unit 13a determines the position of the marker 1 in the image data based on the determination regarding each pixel. At the same time, the marker 1 is identified from other markers 1. At this time, the image processing unit 13 a outputs position data indicating the position of the marker 1 in the image data and identification data for distinguishing the marker 1 from the other marker 1. Here, preferably, the image processing unit 13a outputs the position data and the identification data in a state where the position data and the identification data are associated with each other.

When each marker 1 has n polarization generation regions (here, n is an integer of 2 or more), there are 2 ⁿ possible arrangement patterns of the polarization generation regions in the marker 1. For example, each marker 1, if having two polarized light generation region, possible sequence patterns of polarized light generation region in the marker 1, as in the example of FIG. 2, there are two ² ways. Therefore, a different 2 ⁿ pieces of marker 1 the arrangement pattern to each other, respectively, by providing the 2 ⁿ pieces of object 3, object identification device 10 can identify the 2 ⁿ pieces of marker 1 together. In other words, the object identification device 10 is configured so that each of the n polarization generation regions arranged in accordance with the arrangement reference in the image data (that is, the image based on the image data) is the first or second polarization generation region 1a, 1b. By determining whether or not, the array pattern is specified, and the marker 1 having the specified array pattern is identified from the other markers 1.

  The marker identification data stored in the storage unit 13b includes a plurality of arrangement pattern identification information indicating possible arrangement patterns of the polarization generation regions 1a and 1b in the marker 1, and markers corresponding to the arrangement pattern identification information. This is data in which a plurality of identification data for identifying 1 is associated with each other.

  Note that the image processing unit 13a may identify the n polarized light generation regions existing in the image data as follows. For example, here, the n polarization generation regions of each marker 1 are arranged without a gap in a predetermined direction, and have the same width in this arrangement direction. The image processing unit 13a specifies a region including pixels corresponding to the first polarization generation region 1a and pixels corresponding to the second polarization generation region 1b in the image data. Next, the image processing unit 13a equally divides the identified region into a number n of known polarization generation regions in the arrangement direction. The image processing unit 13a identifies each of the n equally divided areas as n polarization generation regions.

3. Object Identification Method Next, an object identification method according to an embodiment of the present invention will be described with reference to FIG. This object identification method is performed using the object identification device 10 described above.

  At the start of this method, a plurality of markers 1 that can be distinguished from each other are provided on a plurality of objects 3, respectively. The several target object 3 exists in a mutually different position.

  In step S1, the imaging device 11 captures an imaging range including the marker 1 and generates the first image data and the second image data described above. In the example of FIG. 3, it is assumed that one marker 1 among the plurality of markers 1 is located within the imaging range. In the example of FIG. 3, it is assumed that each marker 1 that can be distinguished from each other has a plurality of polarization generation regions.

  In step S2, one pixel in the first image data or the second image data (hereinafter also referred to as image data to be processed) is selected. That is, the image processing unit 13a performs steps S3 to S6 to be described later on each pixel in the image data to be processed. In step S2, among the many pixels constituting the image data to be processed, One pixel for which steps S3 to S6 have not been performed is selected as a pixel to be processed. In the following description and FIG. 3, Step S3 to Step S6 are sequentially performed on a large number of pixels constituting the image data to be processed one by one, but the present invention is not limited to this. For example, step S3 to step S6 may be performed simultaneously on a large number of pixels constituting the image data to be processed.

  In step S3, the image processing unit 13a determines whether or not the above-described ratio A / B is greater than the first threshold value for the pixel to be processed. If this determination is affirmative, the process proceeds to step S4, and if this determination is negative, the process proceeds to step S5.

  In step S4, the image processing unit 13a determines that the pixel to be processed corresponds to the first polarization generation region 1a. Next, the process proceeds to step S7.

  In step S5, the image processing unit 13a determines whether or not the above-described ratio A / B is smaller than the second threshold value for the pixel to be processed. If this determination is affirmative, the process proceeds to step S6, and if this determination is negative, the process proceeds to step S7.

  In step S6, the image processing unit 13a determines that the pixel to be processed corresponds to the second polarization generation region 1b. Next, the process proceeds to step S7.

  In step S7, the image processing unit 13a determines whether steps S3 to S6 have been performed on all of the pixels constituting the image data to be processed. That is, the image processing unit 13a, for all of the pixels constituting the image data to be processed, includes the first polarization generation region 1a, the second polarization generation region 1b, and other pixels in the imaging range. It is determined whether or not it corresponds to a part. If this determination is affirmative, the process proceeds to step S8, and if this determination is negative, the process returns to step S2.

  The image processing unit 13a performs Steps S3 to S6 on all the pixels constituting the image data to be processed, so that the image processing unit 13a has the first polarization generation region 1a in the image data to be processed. And / or a pixel distribution corresponding to the second polarized light generation region 1b.

  In step S8, the image processing unit 13a identifies the arrangement pattern of the polarization generation regions 1a and 1b in the image data to be processed based on the ratio of each pixel. In other words, the image processing unit 13a performs processing based on one or both of the distribution of pixels corresponding to the first polarization generation region 1a and the distribution of pixels corresponding to the second polarization generation region 1b. An arrangement pattern of a plurality of polarization generation regions of the marker 1 in the image data is specified. When each marker 1 has two polarization generation regions, it is specified which array pattern of the four marker 1 shown in FIG. 2 is the two polarization generation regions in the marker 1, for example.

  In step S9, the image processing unit 13a distinguishes the marker 1 in the processing target image data from the other marker 1 based on the arrangement pattern specified in step S8 and the marker identification data stored in the storage unit 13b. Output identification data. Further, preferably, in step S9, the image processing unit 13a outputs position data indicating the position of the marker 1 in the image data to be processed in a state associated with the identification data.

4). Modifications The present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the present invention. For example, any one of the following modification examples 1 to 7 may be employed alone, or modification examples 1 to 7 may be arbitrarily combined and employed. In this case, the points not described below are the same as described above.

4.1. Modification example 1
Each marker 1 may have one polarization generation region. In this case, as markers 1 that can be distinguished from each other, there are a marker 1 having a first polarization generation region 1a and a marker 1 having a second polarization generation region 1b. Therefore, these two markers 1 are provided on the two objects 3 respectively, and the above-described object identification method shown in FIG. 3 is performed.

In the object identification method of FIG. 3, in step S8 described above, the image processing unit 13a assumes that the first and second polarization generation regions 1a and 1b are different types of polarization generation regions, and the ratio of each pixel. Based on the above, the type of polarization generation region included in the image data to be processed is specified. In step S9, the image processing unit 13a identifies a marker in the image data to be processed from other markers based on the type specified in step S8. That is, in step S9, the image processing unit 13a determines that the processing target pixel corresponds to the first or second polarization generation region 1a or 1b in step S4 or step S6 in the processing target image data. Based on this, data indicating which of the first and second polarization generation regions 1 a and 1 b is included in the image data to be processed is output as identification data of the marker 1.
If there is one pixel determined to correspond to the first or second polarization generation region 1a, 1b, step S9 can be executed. If the pixels determined to correspond to the first or second polarized light generation regions 1a and 1b in step S4 or step S6 are adjacent to each other and there are more than the set number, in step S9, the marker 1 The identification data may be output.

4.2. Modification example 2
FIG. 4A shows another configuration example of the object identification device 10. In the example of FIG. 4A, in the optical unit 15 of the imaging device 11, a beam splitter 15a having no polarization characteristics is provided instead of the polarization beam splitter 15a. In this case, the optical unit 15 further includes a first polarizing filter 15e and a second polarizing filter 15f.

The beam splitter 15a divides incident light into reflected light and transmitted light without changing its polarization characteristics. The reflected light is incident on the first polarizing filter 15e, and the transmitted light is incident on the second polarizing filter 15f. Preferably, the beam splitter 15a is a half mirror.
The first polarizing filter 15e selectively transmits the first linearly polarized light (preferably, only the first linearly polarized light) out of the incident light. Therefore, when the reflected light from the beam splitter 15a passes through the first polarizing filter 15e, it becomes the first linearly polarized light (preferably, the complete first linearly polarized light).
The second polarizing filter 15f selectively transmits the second linearly polarized light (preferably, only the second linearly polarized light) out of the incident light. Therefore, when the transmitted light from the beam splitter 15a passes through the second polarizing filter 15f, it becomes second linearly polarized light (preferably, completely second linearly polarized light).

  The first polarizing filter 15e, the second polarizing filter 15f, the first imaging unit 17, and the second imaging unit 19 are attached to the support 21 so that their directions are fixed to each other. The polarization direction of the linearly polarized light transmitted through the first polarizing filter 15e is orthogonal to the polarization direction of the linearly polarized light transmitted through the second polarizing filter 15f.

  Further, in the optical path of the optical unit 15, unlike FIG. 4A, the first polarizing filter 15e may be provided downstream of the first lens 15b, and the second polarizing filter 15f is provided downstream of the second lens 15c. May be.

4.3. Modification example 3
FIG. 4B shows another configuration example of the object identification device 10. In the example of FIG. 4B, the above-described polarizing beam splitter 15a is omitted, and the optical unit 15 includes a first lens 15b, a first polarizing filter 15e, a second lens 15c, a second polarizing filter 15f, Have
Light from the imaging range passes through the first polarizing filter 15 e and enters the first imaging unit 17. Similarly, light from the same imaging range passes through the second polarizing filter 15 f and enters the second imaging unit 19. The first polarizing filter 15e selectively transmits the first linearly polarized light (preferably, only the first linearly polarized light) out of the incident light. Therefore, when light from the imaging range passes through the first polarizing filter 15e, it becomes first linearly polarized light (preferably, complete first linearly polarized light). The second polarizing filter 15f selectively transmits the second linearly polarized light (preferably, only the second linearly polarized light) out of the incident light. Therefore, when light from the imaging range passes through the second polarizing filter 15f, it becomes second linearly polarized light (preferably, completely second linearly polarized light).

  The first polarizing filter 15e, the second polarizing filter 15f, the first imaging unit 17, and the second imaging unit 19 are attached to the support 21 so that their directions are fixed to each other. The polarization direction of the linearly polarized light transmitted through the first polarizing filter 15e is orthogonal to the polarization direction of the linearly polarized light transmitted through the second polarizing filter 15f.

  The imaging device 11 is configured such that the first imaging unit 17 and the second imaging unit 19 form first image data and second image data in the same imaging range or substantially the same imaging range, respectively. Note that when there is a shift in the imaging range between the first image data and the second image data, the image processing unit 13a uses the first image data generated by the first imaging unit 17 and the second imaging unit. The shift of the imaging range from the second image data generated by the first image data 19 is corrected using appropriate means, and each pixel of the first image data corresponds to the same position as the pixel in the imaging range. Corresponding to two image data pixels.

4.4. Modification example 4
The image processing unit 13a may obtain the corrected value f (A, B) × K by multiplying the above-described value f (A, B) by the correction value K. The correction value K is obtained as follows. When uniform unpolarized light is incident on the first imaging unit 17 and the second imaging unit 19 via the optical unit 15, the corrected value f (A, B) A correction value K is obtained in advance so that xK becomes a set value. When f (A, B) is A / B, this set value is 1, for example.

  In step S <b> 3, the image processing unit 13 a determines whether the corrected value f (A, B) × K is greater than the first threshold value for the pixel to be processed. If this determination is affirmative, the process proceeds to step S4, and if this determination is negative, the process proceeds to step S5.

  In step S5, the image processing unit 13a determines whether or not the corrected value f (A, B) × K is smaller than the second threshold value for the pixel to be processed. If this determination is affirmative, the process proceeds to step S6, and if this determination is negative, the process proceeds to step S7.

4.5. Modification Example 5
The object identification device 10 may include a plurality of sets of imaging devices 11 and image processing devices 13. In this case, in the above-described embodiment, the plurality of sets of imaging devices 11 and the image processing device 13 are set such that the polarization directions of the reflected light by the polarization beam splitter 15a of the imaging device 11 are shifted from each other by a set angle. Is placed. However, preferably, the imaging device 11 is arranged so as to capture the same imaging range among a plurality of sets.

Thereby, even if the following inconvenience arises, the marker 1 can be recognized.
It is assumed that the polarization direction of the reflected light by the polarization beam splitter 15a of a certain set of image pickup devices 11 is greatly deviated from the reference direction of the first polarization generation region 1a in the marker 1. Due to this shift, the image processing unit 13a may not be able to recognize pixels corresponding to the first polarized light generation region 1a in the marker 1. That is, there are cases where a pixel for which the determination in step S3 is affirmative cannot be found.
Even if such inconvenience occurs, the polarization direction of the reflected light from the polarization beam splitter 15a of the other set of image pickup devices 11 matches the reference direction of the first polarization generation region 1a in the marker 1, or the reference It is assumed that the direction is close to the direction. In this case, the image processing unit 13a can recognize pixels corresponding to the first polarized light generation region 1a in the marker 1. That is, a pixel for which the determination in step S3 is affirmative is found.

  Similarly, in Modification 2 or Modification 3 described above, a plurality of sets of imaging devices so that the polarization directions of the transmitted light of the first polarizing filter 15e in the imaging device 11 are shifted from each other by a set angle between the plurality of sets. 11 and the image processing apparatus 13 may be arranged. However, preferably, the imaging device 11 is arranged so as to capture the same imaging range among a plurality of sets.

4.6. Modification Example 6
In the above-described embodiment, the second modification example, or the third modification example, the support 21 may be rotatable about an axis that faces the imaging direction of the imaging device 11.

Thereby, even if the following inconvenience arises, the marker 1 can be recognized.
In the above-described embodiment, the polarization direction of the reflected light from the polarizing beam splitter 15a or the transmitted light from the polarizing beam splitter 15a in the imaging device 11 is determined based on the reference of the first polarized light generating region 1a or the second polarized light generating region 1b in the marker 1. Suppose that it is greatly deviated from the direction. Due to this shift, the image processing unit 13a may not be able to recognize pixels corresponding to the first polarization generation region 1a or the second polarization generation region 1b in the marker 1. That is, there is a case where a pixel for which the determination in step S3 or the determination in step S5 is affirmative is not found.
When such inconvenience occurs, for example, all the determinations in step S3 and step S5 are negative for all the pixels to be processed even though the determination in step S7 is affirmative. In such a case, the support 21 is rotated by a suitable means (for example, a driving device) by a set angle (for example, an angle of 10 degrees or more and 45 degrees or less) around the above-described axis. Thereby, the polarization direction of the reflected light from the polarization beam splitter 15a in the imaging device 11 or the transmitted light of the polarization beam splitter 15a coincides with the reference direction of the first polarization generation region 1a or the second polarization generation region 1b in the marker 1. Or, the direction is close to the reference direction. In this state, the object identification method shown in FIG. 3 is performed again.

Similarly, in the above-described modification 2 or 3, the polarization direction by the first polarization filter 15e or the second polarization filter 15f is different from the reference direction of the first polarization generation region 1a or the second polarization generation region 1b in the marker 1. Suppose that it is greatly shifted. Due to this shift, the image processing unit 13a may not be able to recognize pixels corresponding to the first polarization generation region 1a or the second polarization generation region 1b in the marker 1. That is, there is a case where a pixel for which the determination in step S3 or the determination in step S5 is affirmative is not found.
When such inconvenience occurs, for example, all the determinations in step S3 and step S5 are negative for all the pixels to be processed even though the determination in step S7 is affirmative. In such a case, the support 21 is rotated by a suitable means (for example, a driving device) by a set angle (for example, an angle of 10 degrees or more and 45 degrees or less) around the above-described axis. As a result, the polarization direction of the first polarization filter 15e or the second polarization filter 15f matches or is close to the reference direction of the first polarization generation region 1a or the second polarization generation region 1b in the marker 1. Come in the direction. In this state, the object identification method shown in FIG. 3 is performed again.

4.7. Modification example 7
In the above description, the value f (A, B) of the function having the value A and the value B as independent variables is the ratio A / B, but may be determined as appropriate. That is, the value f (A, B) is not limited to the ratio A / B as long as the pixel corresponding to the first polarization generation region 1a and the pixel corresponding to the second polarization generation region 1b can be specified. Other things may be used. In this case, the first threshold value and the second threshold value described above are f () so that the pixel corresponding to the first polarization generation region 1a and the pixel corresponding to the second polarization generation region 1b can be specified. It is determined according to A, B).
For example, the value f (A, B) may be A / (A + B), (A−B) / (A + B), or some other value. When f (A, B) is A / (A + B), (A−B) / (A + B), or the like, calculation that divides the numerator with zero or a denominator close to zero can be avoided.

  In the case of adopting the modified example 7, in the above description, the ratio A / B may be read as the value f (A, B).

DESCRIPTION OF SYMBOLS 1 Marker, 1a 1st polarization production | generation area | region, 1b 2nd polarization production | generation area | region, 3 Object, 5 Cylindrical part, 7 Polarization part, 9 Reflection part, 10 Object identification apparatus, 11 Imaging apparatus, 13 Image processing apparatus , 13a Image processing unit, 13b Storage unit, 15 Optical unit, 15a Beam splitter, 15b First lens, 15c Second lens, 15d Third lens, 15e First polarizing filter, 15f Second polarizing filter, 17 First imaging unit , 17a Imaging surface, 19 Second imaging unit, 19a Imaging surface, 21 Support

Claims (5)

An object identification device for identifying these objects from each other based on a plurality of markers respectively provided on the plurality of objects,
The marker includes a first polarization generation region that generates a first linearly polarized reflected light from the non-polarized light when non-polarized light is incident, and a second polarization-to-second region when the non-polarized light is incident. Having at least one of a second polarized light generating region for generating linearly polarized reflected light;
An imaging device for imaging an imaging range including a marker;
An image processing device for identifying a marker in the imaging range from other markers based on image data of the imaging range obtained by an imaging device;
The imaging device includes an optical unit, a first imaging unit, and a second imaging unit,
When the polarization direction of the first linearly polarized light is orthogonal to the polarization direction of the second linearly polarized light, the optical unit selectively performs first imaging of the first linearly polarized light out of the light traveling from the imaging range. The second linearly polarized light is selectively incident on the second imaging unit,
The first imaging unit generates first image data in the imaging range based on the incident light to the first imaging unit,
The second imaging unit generates second image data of the imaging range based on incident light to the second imaging unit,
The image processing device
(A) For each pixel of the first image data, the luminance of the pixel is a value A, and the luminance of the pixel of the second image data corresponding to the same position as the pixel in the imaging range is a value B. Find the value f (A, B) of the function with B as the independent variable,
(B) Assuming that the first and second polarization generation regions are different types of polarization generation regions, based on the value f (A, B) of each pixel, the first image data or the second image data Specify the type of polarization generation region included, or the arrangement pattern of a plurality of polarization generation regions included in the first image data or the second image data,
(C) An object identification device that identifies a marker in the first image data or the second image data from another marker based on the specified type or arrangement pattern.   2. The object identification according to claim 1, wherein the value f (A, B) is A / B, A / (A + B), or (A−B) / (A + B). apparatus. In the image processing apparatus (B),
(B1) For each pixel of the first image data or the second image data, the value f (A, B) × K obtained by multiplying the value f (A, B) by the correction value K, or the value f (A, B B) determines whether or not it is greater than the first threshold, and if the determination is affirmative, determines that the pixel corresponds to the first polarization generation region;
(B2) For each pixel of the first image data or the second image data, the value f (A, B) × K obtained by multiplying the value f (A, B) by the correction value K, or the value f (A, B It is determined whether or not B) is smaller than a second threshold value that is smaller than the first threshold value. If the determination is affirmative, the pixel corresponds to the second polarization generation region. Judging
(B3) Based on the determination of (B1) and (B2), the type of polarization generation region included in the first image data or the second image data, or the first image data or the second image data The object identification device according to claim 1, wherein an array pattern of a plurality of polarization generation regions included in the object is specified. An object identification method for identifying these objects from each other based on a plurality of markers respectively provided on the plurality of objects,
The marker includes a first polarization generation region that generates a first linearly polarized reflected light from the non-polarized light when non-polarized light is incident, and a second polarization-to-second region when the non-polarized light is incident. Having at least one of a second polarization generation region that generates reflected light of linearly polarized light,
An imaging device for imaging an imaging range including a marker, and an image processing device that identifies a marker in the imaging range from other markers based on image data of the imaging range obtained by the imaging device, The imaging device includes an optical unit, a first imaging unit, and a second imaging unit,
When the polarization direction of the first linearly polarized light is orthogonal to the polarization direction of the second linearly polarized light, the optical unit selectively selects the first linearly polarized light out of the light traveling from the imaging range as a first image. The second linearly polarized light is selectively incident on the second imaging unit,
The first imaging unit generates first image data of the imaging range based on the incident light on the first imaging unit, and the second imaging unit generates the first image data on the second imaging unit based on the incident light on the second imaging unit. Generating second image data of the imaging range;
By image processing device
(A) For each pixel of the first image data, the luminance of the pixel is a value A, and the luminance of the pixel of the second image data corresponding to the same position as the pixel in the imaging range is a value B. Find the value f (A, B) of the function with B as the independent variable,
(B) Assuming that the first and second polarization generation regions are different types of polarization generation regions, based on the value f (A, B) of each pixel, the first image data or the second image data Specify the type of polarization generation region included, or the arrangement pattern of a plurality of polarization generation regions included in the first image data or the second image data,
(C) A target identifying method, wherein a marker in the first image data or the second image data is identified from another marker based on the specified type or arrangement pattern. A marker provided on a surface of the object to distinguish a plurality of objects from each other ;
Having a plurality of polarization generating regions arranged in accordance with a predetermined arrangement standard ;
Each of the plurality of polarization generation regions is a first or second polarization generation region,
The first polarized light generation region generates reflected light of the first linearly polarized light from the unpolarized light when the unpolarized light is incident.
The second polarized light generation region generates reflected light of the second linearly polarized light from the unpolarized light when the unpolarized light is incident, and the polarization direction of the second linearly polarized light is the polarization direction of the first linearly polarized light. A marker characterized by being orthogonal.

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