Depth measurement device, depth measurement method and depth measurement program

Abstract

To provide a depth measurement device capable of suppressing deterioration of measurement precision of depth due to reconstitution of a plurality of picked-up images acquired with the position of a radiation source changed.SOLUTION: A depth measurement device includes a radiation source and a detector that has a detection surface directly facing the radiation source and maintains a fixed distance between the detection surface and the radiation source. The depth measurement device: acquires a picked-up image that images an object located at a first position away from the radiation source in a depth direction by a first distance, and away from the radiation source in a direction along the detection surface by a second distance, by using the detector which continues light exposure, until the object reaches a second position at the first distance in the depth direction and at a third distance in the direction along the detection surface; identifies a deviation amount of an image of the object during a period during which the object moves from the first position to the second position, on the basis of a distance between end parts of the image of the object included in the picked-up image in the direction along the detection surface; and calculates the first distance on the basis of the fixed distance, the difference between the second distance and the third distance, and the deviation amount.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to a depth measurement device, a depth measurement method, and a depth measurement program, and more particularly to a depth measurement device, a depth measurement method, and a depth measurement program that measure using radiation. [Background technology]

[0002] Conventionally, radiation has been used to obtain internal information of an object through images. Among these, tomosynthesis technology is becoming increasingly popular. Tomosynthesis technology is a technology that obtains highly accurate internal information of an object by reconstructing multiple images obtained by irradiating the object with radiation while changing the position of the radiation source.

[0003] For example, the tomographic image generating device disclosed in Patent Document 1 performs tomosynthesis imaging by moving a radiation source relative to a detection surface of a detector and irradiating a subject with radiation at the positions of multiple radiation sources. The tomographic image generating device disclosed in Patent Document 1 is said to be able to obtain high-quality tomographic images of the subject.

[0004] Because radiation spreads radially, when a subject is irradiated with radiation, if the position of the radiation source changes, the angle of incidence of the radiation on the subject changes, and the shape of the image of the subject shown in the captured image obtained for each different radiation source position changes.

[0005] For this reason, when obtaining internal information of a subject by reconstructing multiple images taken by changing the angle at which radiation is irradiated onto the subject, there was concern that inconsistencies in the shapes of the subject's images in the multiple images would be a factor in reducing the accuracy of the internal information of the subject.

[0006] The tomographic image generating device disclosed in Patent Document 1 reconstructs multiple captured images acquired by moving the radiation source relative to the detection surface of the detector, so there is a risk that inconsistencies in the shapes of the subject's images in the multiple captured images could cause degradation in the image quality of the subject's tomographic images.

[0007] Furthermore, even in depth measurement devices that use tomosynthesis technology to measure the depth of an object inside a subject, the previous method of reconstructing multiple captured images obtained by changing the position of the radiation source could result in a decrease in the accuracy of the measured depth, as with the tomographic image generation device disclosed in Patent Document 1. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Re-tabled publication No. 2020-067475 Summary of the Invention [Problem to be solved by the invention]

[0009] Therefore, an object of the present invention is to provide a depth measurement device, a depth measurement method, and a depth measurement program that suppress a decrease in depth measurement accuracy caused by reconstruction of multiple captured images obtained by changing the position of a radiation source. [Means for solving the problem]

[0010] That is, the depth measurement device of the first aspect is characterized by comprising: a radiation source that emits radiation; a detector that has a detection surface facing the radiation source and detects the radiation emitted by the radiation source, and maintains a fixed distance between the detection surface and the radiation source; an acquisition unit that causes the radiation source to continue irradiating radiation onto an object located at a first position where the distance from the radiation source in a depth direction from the radiation source toward the detection surface is a first distance and the distance from the radiation source in a direction along the detection surface is a second distance, until the object reaches a second position where the distance in the depth direction is the first distance and the direction along the detection surface is a third distance different from the second distance, thereby capturing an image of the object moving from the first position to the second position and acquiring it as a single captured image; an identification unit that identifies the amount of positional deviation of the image of the object projected on the detection surface while the object moves from the first position to the second position, based on the distance between the ends of the image of the object included in the captured image in a direction along the detection surface; and a calculation unit that calculates the first distance based on the fixed distance, the difference between the second distance and the third distance, and the amount of deviation.

[0011] A second aspect is a depth measurement device according to the first aspect, which includes a movement mechanism that moves the radiation source and the detection surface the same distance in the same direction along the detection surface while keeping the object stationary between the radiation source and the detection surface and maintaining a fixed distance between the radiation source and the detection surface, and the difference may be the distance moved by the radiation source between the start and end of exposure of the detection surface.

[0012] A third aspect may be a depth measurement device according to the first aspect, further comprising a movement mechanism that keeps the radiation source and the detection surface stationary and moves the object between the radiation source and the detection surface in a direction along the detection surface, and the difference may be the distance the object moves between the start and end of exposure of the detection surface.

[0013] A fourth aspect is a depth measurement device according to the first aspect, which is provided with a movement mechanism that moves only the radiation source in a direction along the detection surface while keeping the detection surface and the object stationary and maintaining a fixed distance between the radiation source and the detection surface, and the difference may be the distance traveled by the radiation source between the start and end of exposure of the detection surface.

[0014] According to a fifth aspect, in the depth measurement device according to any one of the second to fourth aspects, the movement mechanism may be a robot arm.

[0015] According to a sixth aspect, in the depth measurement device according to the second or third aspect, the calculation unit may calculate the first distance by dividing the difference by the amount of deviation and multiplying the result by a fixed distance.

[0016] According to a seventh aspect, in the depth measurement device according to the fourth aspect, the calculation unit may calculate the first distance by dividing the difference by the sum of the deviation amount and the difference, and multiplying the result by a fixed distance.

[0017] In an eighth aspect, in the depth measurement device of the first aspect, the identification unit may identify the deviation amount as a value obtained by adding the distance over which the brightness of the image of the object included in the captured image is constant in a direction along the detection surface to half the distance over which the brightness of the image of the object changes in a direction along the detection surface.

[0018] According to a ninth aspect, the depth measurement device according to the first aspect may further include an output section that outputs the first distance.

[0019] A depth measurement method according to a tenth aspect is characterized in that a computer capable of communicating with a radiation source that emits radiation and a detector that is provided with a detection surface directly facing the radiation source and that detects the radiation emitted by the radiation source, and that maintains a fixed distance between the detection surface and the radiation source, carries out the following steps: an acquisition step in which the radiation source continues to irradiate radiation onto the object, while the object is located at a first position where the distance from the radiation source in a depth direction from the radiation source toward the detection surface is a first distance and the distance from the radiation source in a direction along the detection surface is a second distance, until the object reaches a second position where the distance in the depth direction is the first distance and the direction along the detection surface is a third distance different from the second distance, to acquire an image of the object moving from the first position to the second position; an identification step in which the amount of shift of the image of the object projected on the detection surface while the object moves from the first position to the second position is determined based on the distance between ends of the image of the object included in the captured image in a direction along the detection surface; and a calculation step in which the first distance is calculated based on the fixed distance, a difference between the second distance and the third distance, and the amount of shift.

[0020] A depth measurement program according to an eleventh aspect of the present invention is characterized in that the depth measurement program is implemented in a computer capable of communicating with a radiation source that emits radiation and a detector that has a detection surface facing the radiation source and detects the radiation emitted by the radiation source, and that maintains a fixed distance between the detection surface and the radiation source. The computer has the following features: an acquisition function that causes the radiation source to continue irradiating radiation to an object located at a first position where the distance from the radiation source in a depth direction from the radiation source toward the detection surface is a first distance and the distance from the radiation source in a direction along the detection surface is a second distance, until the object moves from the first position to the second position where the distance in the depth direction is the first distance and the direction along the detection surface is a third distance different from the second distance, thereby capturing an image of the object moving from the first position to the second position and acquiring it as a single captured image; a determination function that determines an amount of deviation of an image of the object projected on the detection surface while the object moves from the first position to the second position, based on the distance between ends of the image of the object included in the captured image in a direction along the detection surface; and a calculation function that calculates the first distance based on the fixed distance, a difference between the second distance and the third distance, and the amount of deviation. [Effects of the Invention]

[0021] The depth measurement device according to the present invention includes a radiation source that emits radiation, a detection surface that directly faces the radiation source and detects the radiation emitted by the radiation source, and a detector that maintains a fixed distance between the detection surface and the radiation source, and a detector that causes the radiation source to irradiate radiation to the object while the object is at a first position where the distance from the radiation source in a depth direction toward the detection surface is a first distance and the distance from the radiation source in a direction along the detection surface is a second distance, the distance being the first distance in the depth direction and a third distance different from the second distance in a direction along the detection surface. The imaging device is characterized by comprising an acquisition unit that continuously images an object moving from a first position to a second position and acquires it as a single captured image; an identification unit that identifies the amount of shift in the position of the image of the object projected onto the detection surface while the object moves from the first position to the second position based on the distance between the ends of the image of the object included in the captured image in a direction along the detection surface; and a calculation unit that calculates the first distance based on the fixed distance, the difference between the second distance and the third distance, and the amount of shift, thereby making it possible to suppress a decrease in the accuracy of depth measurement caused by reconstruction of multiple captured images acquired by changing the position of the radiation source. In addition, the depth measurement method and depth measurement program according to the present invention can similarly suppress a decrease in depth measurement accuracy caused by the reconstruction of multiple captured images obtained by changing the position of the radiation source. [Brief explanation of the drawings]

[0022] [Figure 1] FIG. 1 is a diagram for explaining a mathematical formula for calculating the depth (first distance L1) used by the depth measurement device according to this embodiment. [Figure 2] FIG. 2 is a diagram for explaining a captured image acquired by the depth measurement device according to this embodiment. [Figure 3] FIG. 3 is a diagram for explaining the formula (7) used by the depth measurement device according to this embodiment to determine the amount of deviation X. [Figure 4] FIG. 4 is a block diagram for explaining an example of the hardware configuration of the depth measurement device according to this embodiment. [Figure 5]FIG. 5 is an example of a flowchart of an imaging method for depth measurement by the depth measurement device according to this embodiment. [Figure 6] FIG. 6 is a block diagram for explaining an example of the functional configuration of the depth measurement device according to this embodiment. [Figure 7] FIG. 7 is an example of a flowchart of the depth measurement program according to this embodiment. [Figure 8] FIG. 8 is an example of a flowchart of a depth measurement program according to another embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0023] (Overview of the depth measurement device 10) A depth measurement device 10 according to one embodiment of the present disclosure will be described with reference to FIGS. First, with reference to FIG. 1, an overview of a depth measurement device 10 according to this embodiment will be described. FIG. 1 is a diagram for explaining the mathematical formula used by the depth measurement device 10 to calculate the depth (first distance L1). The depth measurement device 10 is a device that irradiates the subject 1 and the object 9 with radiation 4 (see Figure 2) to measure the depth of the object 9 located inside the subject 1, and is a type of information processing device, electronic calculator, computer, etc. The depth refers to the depth of the position of the object 9 inside the subject 1, and refers to the distance from the radiation source 7 to the object 9 in the depth direction from the radiation source 7 toward the detection surface 8c (the Y direction in Fig. 1), and refers to the first distance L1 shown in Fig. 1. The X direction in Fig. 1 is the direction along the detection surface 8c and perpendicular to the Y direction. The specimen 1 may include components made of metal, non-metallic material, organic material, etc. Non-metallic materials include, for example, ceramics, glass, cement, stone, clay, manganese, graphite, etc. Organic materials include, for example, plastic, rubber, wood, paper, oil, and fat. The object 9 is a member or space that exists inside the subject 1 and has a different radiation transmittance than the subject 1. The space includes gaps, cracks, bubbles, etc. that occur inside the subject 1. The object 9 in this embodiment is a space that exists inside the subject 1, but is not limited to this.

[0024] The depth measuring device 10 comprises a radiation source 7 and a detector 8 . The radiation source 7 emits radiation 4 (see FIG. 2). The detector 8 has a detection surface 8c that faces the radiation source 7 and detects the radiation 4 emitted by the radiation source 7, and the distance between the detection surface 8c and the radiation source 7 is kept fixed at a fixed distance L. The fixed distance L is the distance between the radiation source 7 and the detection surface 8c, and is a known value that is measured in advance. The radiation 4 irradiated onto the subject 1 from the radiation source 7 passes through the subject 1 and the object 9 and reaches the detection surface 8c. The detector 8 converts the two-dimensional distribution of the luminance (amount of transmitted radiation) of the radiation 4 that reaches the detection surface 8c into a captured image. The detector 8 that is used is one that can be exposed continuously for a predetermined period of time, as described below, i.e., a detector 8 that is capable of long-term exposure. "Directly facing" refers to a state in which the radiation source 7 and the detection surface 8c face each other directly, and a line drawn straight down from the radiation source 7 to the detection surface 8c is perpendicular to the detection surface 8c. Note that, because the radiation 4 spreads radially, it is desirable that a line drawn straight down from the radiation source 7 to the detection surface 8c intersect at the center of the detection surface 8c in the X direction. Radiation 4 refers to particle radiation, which is material particles flowing with high kinetic energy, and electromagnetic radiation, which is high-energy electromagnetic waves. Particle radiation includes, for example, alpha rays, beta rays, neutron rays, and proton rays. Electromagnetic radiation includes, for example, gamma rays and X-rays.

[0025] The depth measurement device 10 measures the depth (first distance L1) by capturing images while moving any one of the radiation source 7, the detector 8, and the object 9. There are three ways of moving the radiation source 7, the detector 8, and the object 9 as follows. In the first pattern, the object 9 is placed stationary between the radiation source 7 and the detection surface 8c, and while the distance between the radiation source 7 and the detection surface 8c is maintained at a fixed distance L, the radiation source 7 and the detection surface 8c are moved in the same direction along the detection surface 8c by the same distance. In the second pattern, the radiation source 7 and the detection surface 8c are kept stationary, and the object 9 is moved between the radiation source 7 and the detection surface 8c in a direction along the detection surface 8c. In the third pattern, the detection surface 8c and the object 9 are kept stationary, and while the distance between the radiation source 7 and the detection surface 8c is kept at a fixed distance L, only the radiation source 7 is moved in a direction along the detection surface 8c. The first pattern and the second pattern can be treated as being the same in that the object 9 is moved relative to the radiation source 7 and the detection surface 8c without changing the relative positional relationship between the radiation source 7 and the detection surface 8c, and the third pattern is different from the first pattern and the second pattern in that the radiation source 7 is moved relative to the detection surface 8c and the object 9 without changing the relative positional relationship between the detection surface 8c and the object 9.

[0026] The mathematical formula used to calculate the depth (first distance L1) of the depth measurement device 10 will be described with reference to FIG. When the object 9 moves relative to the radiation source 7 and the detection surface 8c without changing the relative positional relationship between the radiation source 7 and the detection surface 8c, i.e., in the case of the first pattern and the second pattern, the depth measurement device 10 calculates the depth (first distance L1) using the following formula (1). When the radiation source 7 moves relative to the detection surface 8c and the object 9 without changing the relative positional relationship between the detection surface 8c and the object 9, i.e., in the case of the third pattern, the depth measurement device 10 calculates the depth (first distance L1) using the following formula (2). In both equations (1) and (2), the fixed distance L, the difference d, and the deviation amount X are all known values, so the depth measurement device 10 can calculate the first distance L1 (depth) from the radiation source 7 to the object 9. The fixed distance L is the distance between the detection surface 8c and the radiation source 7, as described above. The difference d is the difference between the second distance L2 and the third distance L3, as will be described later. As will be described later, the deviation amount X is the distance traveled by the image of the object 9 projected onto the detection surface 8c while the object 9 moves from the first position (point P1) to the second position (point P2).

[0027]

number

[0028] (Derivation of Equation (1)) The derivation of equation (1) will be described with reference to FIG. 1(a). 1(a) shows a state in which the radiation source 7 and the detection surface 8c are relatively stationary, while the object 9 moves relative to the radiation source 7 and the detection surface 8c, and illustrates both the first and second patterns. In FIG. 1(a), the object 9 before and after movement is distinguished as object 9a before movement and object 9b after movement. In FIG. 1(a), the position of the radiation source 7 is indicated by point P0. 1(a), the position of the object 9a before movement is indicated by point P1, and the position of the object 9b after movement is indicated by point P2. Note that the positions of the objects 9 (9a, 9b) refer to the center positions of the objects 9 (9a, 9b). The point P1 is at a first distance L1 from the point P0 in the Y direction, and at a second distance L2 from the point P0 in the X direction. The point P2 is at a first distance L1 from the point P0 in the Y direction, and at a third distance L3 from the point P0 in the X direction, which is different from the second distance L2. The difference d is the difference between the third distance and the second distance, and is therefore expressed as (L3-L2).

[0029] The image of the object 9a before movement projected by the radiation 4 from the radiation source 7 appears at the position of point P3 on the detection surface 8c in Figure 1(a), and the image of the object 9b after movement projected by the radiation 4 appears at the position of point P4 on the detection surface 8c in Figure 1(a). The deviation amount X is the distance between P3 and P4.

[0030] As shown in Figure 1(a), the first triangle with vertices P0, P1, and P2 and the second triangle with vertices P0, P3, and P4 are similar to each other, so the following formula (3) holds. Rearranging both sides of formula (3) gives formula (4). Converting formula (4) into a formula with L1 as the solution gives formula (1) above.

[0031]

number

[0032] (Derivation of Equation (2)) The derivation of equation (2) will be described with reference to FIG. 1(b) shows a third pattern in which the detection surface 8c and the object 9 are relatively stationary, while the radiation source 7 moves relative to the detection surface 8c and the object 9. In FIG. 1(b), the radiation source 7 before and after the movement is distinguished as radiation source 7a before the movement and radiation source 7b after the movement. In FIG. 1(b), the position of the object 9 is indicated by point Q0. In FIG. 1(b), the position of the radiation source 7a before movement is indicated by point Q1, and the position of the radiation source 7b after movement is indicated by point Q2. The position of the object 9 (point Q0) relative to the position of the radiation source 7a before movement (point Q1) is a first distance L1 in the Y direction and a second distance L2 in the X direction from point Q1. The position of the object 9 (point Q0) based on the position of the radiation source 7b after movement (point Q2) is at a first distance L1 in the Y direction from point Q2, and at a third distance L3 in the X direction from point Q2, which is different from the second distance L2. The difference d is the difference between the third distance and the second distance, and is therefore expressed as (L3-L2) in the same way as in FIG. 1(a). In the case of the third pattern, the first position of the object 9 is a position (point Q0) based on the position of the radiation source 7a before movement (point Q1), and the second position of the object 9 is a position (point Q0) based on the position of the radiation source 7a after movement (point Q2).

[0033] The image of the object 9 projected by the radiation 4 of the radiation source 7a before movement appears at the position of point Q3 on the detection surface 8c in Figure 1(b), and the image of the object 9 projected by the radiation 4 of the radiation source 7b after movement appears at the position of point Q4 on the detection surface 8c in Figure 1(b). The deviation amount X is the distance between Q3 and Q4, as in the case of FIG. 1(a).

[0034] As shown in Figure 1(b), the third triangle with vertices Q0, Q1, and Q2 and the fourth triangle with vertices Q0, Q3, and Q4 are similar to each other, so the following formula (5) holds. Rearranging both sides of formula (5) gives formula (6). Converting formula (6) into a formula with L1 as the solution gives formula (2) above.

[0035]

number

[0036] (Method for determining the amount of deviation X of the depth measurement device 10) Next, a method for determining the amount of deviation X of the depth measurement device 10 will be described with reference to FIGS. FIG. 2 is a diagram for explaining the captured image 20 acquired by the depth measurement device 10, and FIG. 3 is a diagram for explaining the mathematical formula (7) used by the depth measurement device 10 to determine the amount of deviation X. Below, with reference to Figures 2 and 3, we will explain the captured image 20 acquired by the depth measurement device 10 and equation (7) used by the depth measurement device 10 to determine the amount of deviation X, using the first and second patterns described above as examples. In the case of the third pattern, the depth measurement device 10 can also determine the amount of deviation X using the acquired captured image 20 and equation (7), as in the cases of the first and second patterns.

[0037] The depth measurement device 10 causes the detector 8 to continue exposing the object 9 while it is moving, and captures the moving object 9 in a single captured image 20. As shown in FIG. 2(a), the subject 1 includes objects 9c and 9d as objects 9. Figure 2(a) shows how radiation 4 is irradiated onto a moving subject 1 and object 9 to capture an image 20, and Figure 2(b) shows the captured image 20 of the moving subject 1 and object 9. The left side of FIG. 2(a) shows the subject 1 and the object 9 at the start of their movement, and the left side of FIG. 2(b) shows a captured image 20 captured at the start of their movement. The central view of FIG. 2(b) shows the subject 1 and the object 9 in motion, and the central view of FIG. 2(b) shows a captured image 20 of the subject 1 and the object 9 in motion. The right-hand side of Figure 2(a) shows the end of the movement of the subject 1 and the object 9, i.e., the state when the movement distance of the subject 1 and the object 9 reaches the difference d, and the right-hand side of Figure 2(b) shows an image 20 captured of the subject 1 and the object 9 at the end of the movement. The left side of Figure 2(a) shows the state in which the object 9, which is the subject of depth measurement among objects 9c and 9d, is located at the first position (point P1), the center of Figure 2(a) shows the state in which the object 9 is moving from the first position (point P1) to the second position (point P2), and the right side of Figure 2(a) shows the state in which the object 9 is located at the second position (point P2). The subject 1 includes two objects 9c and 9d, and in this case, to find the depth of each (first distance L1), it is necessary to obtain known values ​​of the fixed distance L, difference d, and displacement amount X for each of the objects 9c and 9d and use formula (1) or formula (2). In other words, the depths (first distances L1) of the objects 9c and 9d must be measured individually, and the depths (first distances L1) of the objects 9c and 9d cannot be measured simultaneously.

[0038] 2(b) shows the change over time of an image 20 acquired by the depth measurement device 10, where the left side of FIG. 2(b) shows an image 20 acquired when the subject 1 and the object 9 start to move, i.e., when the exposure of the detector 8 starts, the center of FIG. 2(b) shows an image 20 acquired while the subject 1 and the object 9 are moving, and the right side of FIG. 2(b) is an image 20 acquired when the movement of the subject 1 and the object 9 ends, i.e., when the exposure of the detector 8 ends. As shown in FIG. 2(b), the image 20 includes an image 21 of the subject 1, an image 23 of the object 9c, and an image 22 of the object 9d. The depth measurement device 10 exposes the detector 8 from the start of movement of the subject 1 and the object 9 to the end of movement. Therefore, the captured image 20 on the right side of FIG. 2(b) includes images of the subject 1 and the object 9 from the start of movement to the end of movement. In other words, the image 23 of the object 9c and the image 22 of the object 9d shown in the right diagram of Fig. 2(b) represent the amount of shift X between the image 23 of the object 9c and the image 22 of the object 9d when the subject 1 moves a distance (difference d) from the first position (point P1) to the second position (point P2). Therefore, the captured image 20 shown in the right diagram of Fig. 2(b) is used to calculate the amount of shift X between the images, which will be described later with reference to Fig. 3. Furthermore, the captured image 20 on the right side of Figure 2(b) may include an image of the subject 1 and object 9 in a stationary state before the movement begins, or may include an image of the subject 1 and object 9 in a stationary state after the movement has ended. In Figure 2(b), the amount of stretching of the image 23 of object 9c and the image 22 of object 9d increases as you move to the right side of the diagram. This is because the exposure time becomes longer and the amount of image lag increases as you move to the right side of the diagram. In Figure 2(b), the image 23 of object 9c and the image 22 of object 9d in the right side of the diagram are most stretched when captured. 2(b), the image 22 of the object 9d is elongated longer than the image 23 of the object 9c because the first distance L1 (depth) of the object 9d is smaller than that of the object 9c. The smaller the first distance L1 (depth), the longer the image of the object 9 captured in the captured image 20 is elongated.

[0039] In the case of the third pattern, unlike the situation shown in FIG. 2(a), the detection surface 8c and the object 9 are stationary, and the radiation source 7 moves from right to left along the detection surface 8c while irradiating the subject 1 and the object 9 with radiation 4. However, even in the case of this third pattern, the captured image 20 obtained is the captured image 20 shown in FIG. 2(b). In the case of the third pattern, when the moving distance of the radiation source 7 reaches the difference d, the captured image 20 shown in the right diagram of FIG. 2(b) is obtained. In the case of the third pattern, the depth measurement device 10 exposes the detector 8 from the start to the end of the movement of the radiation source 7. Therefore, the captured image 20 on the right side of FIG. 2(b) includes images of the subject 1 and the object 9 from the start to the end of the movement of the radiation source 7. In other words, the image 23 of the object 9c and the image 22 of the object 9d shown in the right diagram of Fig. 2(b) represent the amount of deviation X between the image 23 of the object 9c and the image 22 of the object 9d when the radiation source 7 moves a distance (difference d) from the first position (point Q1) to the second position (point Q2). Therefore, the captured image 20 shown in the right diagram of Fig. 2(b) is used to calculate the amount of deviation X between the images, which will be described later with reference to Fig. 3. Furthermore, the captured image 20 on the right side of Figure 2(b) may include an image of the subject 1 and the object 9 in a stationary state before the radiation source 7 starts to move, or may include an image of the subject 1 and the object 9 in a stationary state after the movement of the radiation source 7 has finished.

[0040] Next, a method for calculating the deviation amount X will be described with reference to FIG. Figure 3(a) is an enlarged view of the captured image 20 in the right-hand diagram of Figure 2(b), Figure 3(b) is a diagram for explaining the evaluation section 28, and Figure 3(c) is a graph of the brightness (amount of transmitted radiation) obtained in the evaluation section 28. The evaluation section 28 refers to the range in which the change in brightness value in the direction along the detection surface 8c of the acquired captured image 20 is acquired and evaluated, and refers to a section that is divided into a straight section 31, a left-inclined section 30, and a right-inclined section 32, and the length of each section is acquired. In FIG. 3, of two objects 9c and 9d included in the subject 1, the object 9c will be described as an example of an object for which depth measurement is to be performed. The captured image 20 shown in Figure 3(a) includes an image 21 of the subject 1, an image 23 of the object 9c, and an image 22 of the object 9d, and the depth measurement device 10 acquires the image 22 of the object 9d within the frame 25. 3(b), the brightness is acquired by setting an evaluation section 28 in the width direction of a central portion 27 in the vertical direction of the image 22 of the object 9d. The evaluation section 28 is set in the central portion 27 because the central portion in the vertical direction is the location of the image 22 of the object 9d where the brightness difference is clear and brightness evaluation is easy, but the evaluation section 28 is not limited to this, and a location shifted vertically from the central portion 27 can also be used as the evaluation section 28. The horizontal width of evaluation section 28 is the distance between the ends of image 22 of object 9d included in captured image 20 in the direction along detection surface 8c, and a brightness threshold is set in advance, and a range of brightness equal to or greater than the threshold is defined as the effective range of evaluation section 28, and the length of this effective range is defined as the horizontal width of evaluation section 28. Therefore, the ends of image 22 of object 9d in the direction along detection surface 8c have brightness of this threshold. It has been confirmed that the image 22 of the object 9d included in the captured image 20 needs to have a certain degree of clarity as an image, and that the accuracy of the depth measurement value decreases when the image clarity decreases. Therefore, if the clarity of the image 22 of the object 9d included in the captured image 20 does not meet a predetermined standard, the accuracy of the depth measurement cannot be guaranteed.

[0041] FIG. 3(c) is a graph showing the luminance values ​​in the evaluation section 28, with the horizontal axis representing the position in the evaluation section 28 and the vertical axis representing the luminance values. In the evaluation section 28 shown in FIG. 3(c), a section where the luminance value is constant is defined as a straight line section 31, and the length of the straight line section 31 is defined as S. In the evaluation section 28 shown in FIG. 3(c), the section to the left of the straight section 31 is defined as a left inclined section 30, and the length of the left inclined section 30 is defined as DL. In the evaluation section 28 shown in FIG. 3(c), the section to the right of the straight section 31 is defined as a right inclined section 32, and the length of the right inclined section 32 is defined as DR. Although the straight-line section 31 of the evaluation section 28 is defined as a section where the luminance value is constant, this is not limiting and the straight-line section 31 may be defined based on, for example, the rate of change of the luminance value. When theoretically modeled, the straight-line section 31 is expressed as a section where the slope (rate of change) of the luminance value graph is zero. However, considering that the luminance values ​​are actually measured values, the straight-line section 31 is expressed as a section where the slope (rate of change of the luminance value) of the luminance value graph is approximately zero. Therefore, the straight-line section 31 is expressed as "-threshold (e.g., 0.1) ≦ rate of change of the luminance value ≦ + threshold." That is, the straight-line section 31 may be set as a range where the absolute value of the rate of change of the luminance value is equal to or less than a threshold, including zero. In this case, assuming that the straight-line section 31 is expressed as "-threshold (e.g., 0.1) ≦ rate of change of the luminance value ≦ + threshold," the left-slope section 30 is expressed as "+threshold ≦ rate of change of the luminance value," and the right-slope section 32 is expressed as "rate of change of the luminance value ≦ -threshold." That is, the left inclination section 30 is defined as a range in which the rate of change of the brightness value is greater than the range determined by the threshold (-threshold (e.g., 0.1) ≦ rate of change of the brightness value ≦ + threshold), and the right inclination section 32 is defined as a range in which the rate of change of the brightness value is smaller than the range determined by the threshold (-threshold (e.g., 0.1) ≦ rate of change of the brightness value ≦ + threshold). The deviation amount X is expressed by equation (7) using the length S of the straight section 31, the length DL of the left inclined section 30, and the length DR of the right inclined section 32. Equation (7) is derived from a geometrical viewpoint. The deviation amount X is calculated by substituting the length S of the straight section 31, the length DL of the left inclined section 30, and the length DR of the right inclined section 32, which are known based on the evaluation section 28, into equation (7).

[0042]

number

[0043] (Hardware configuration of depth measurement device 10) Next, an example of the hardware configuration of the depth measurement device 10 will be described with reference to FIG. FIG. 4 is a block diagram for explaining an example of the hardware configuration of the depth measurement device 10. As shown in FIG. The depth measurement device 10 includes a communication interface 10a, a read-only memory (ROM) 10b, a random access memory (RAM) 10c, a storage unit 10d, a calculation unit 10e, and an input / output interface 10f. Furthermore, the depth measurement device 10 includes an input device 10g and an output device 10h that input and output data via an input / output interface 10f. The input device 10g is an external device that inputs data to the depth measurement device 10, and includes, for example, the detector 8, the keyboard 11, and the mouse 12. The output device 10h is an external device that outputs data generated by the depth measurement device 10, and includes the robot arm 5, which is a moving mechanism, the radiation source 7, the monitor 14, the printer 15, the speaker 16, and the like.

[0044] The radiation source 7 irradiates the subject 1 with radiation 4, and the detector 8 detects the radiation 4 that has passed through the subject 1. An example of the detector 8 may be an X-ray detector that detects X-rays, which are the radiation 4. More specifically, the detector 8 may be a photographic plate, photographic film, an imaging plate (IP), a flat panel detector (FPD), or the like. The radiation 4 detected by the detector 8 is displayed as a captured image, which is a two-dimensional distribution of the brightness of the radiation 4. The keyboard 11 is a type of computer input device, and is a device for transmitting data to the depth measurement device 10 by pressing keys for inputting characters and performing operations. The mouse 12 is a type of computer input device, and is used to point to and select the location of an object displayed on the screen of the monitor 14 of the depth measurement device 10. The robot arm 5, which is a movement mechanism, moves different objects depending on the first, second, and third patterns. The robot arm 5 is a type of industrial robot that functions like a human arm, and the operation of the robot arm 5 is controlled by the depth measurement device 10. The robot arm 5 includes, for example, a vertical articulated robot, a horizontal articulated robot, a parallel link robot, and an orthogonal robot. In the first pattern, the robot arm 5, which is a moving mechanism, places the object 9 between the radiation source 7 and the detection surface 8c, and moves the radiation source 7 and the detection surface 8c by the same distance in the same direction along the detection surface 8c while maintaining the distance between the radiation source 7 and the detection surface 8c at a fixed distance L. In the second pattern, the robot arm 5, which is a moving mechanism, keeps the radiation source 7 and the detection surface 8c stationary and moves the object 9 between the radiation source 7 and the detection surface 8c in a direction along the detection surface 8c. In the third pattern, the robot arm 5, which is a moving mechanism, keeps the detection surface 8c and the object 9 stationary, and moves only the radiation source 7 in a direction along the detection surface 8c while maintaining the distance between the radiation source 7 and the detection surface 8c at a fixed distance L.

[0045] The radiation source 7 is a radiation generating device for irradiating the subject 1 with radiation 4, and the operation of the radiation source 7, such as the timing of irradiation of the radiation 4, is controlled by a depth measurement device 10. The monitor 14 is a device that displays and visualizes the data generated by the depth measurement device 10 on a screen. The printer 15 is a printing machine that prints the data generated by the depth measurement device 10 onto a paper medium or the like. The speaker 16 is a device that converts an electrical signal based on the data generated by the depth measurement device 10 into sound and emits it into the surrounding space.

[0046] The communication interface 10a has a function of performing two-way communication with other information processing devices via the information communication network 19. The depth measurement device 10 may transmit and receive data to and from the detector 8, the robot arm 5, and the radiation source 7 via the communication interface 10a instead of the input / output interface 10f. In this case, the communication interface 10a may perform bidirectional communication with the detector 8, the robot arm 5, and the radiation source 7, either by wired communication or wireless communication. The wireless communication method is not particularly limited, and may be Wi-Fi (registered trademark), LoRa (registered trademark), Bluetooth (registered trademark), Zigbee (registered trademark), infrared wireless communication, microwave wireless, broadcast wireless, satellite communication, or the like.

[0047] The ROM 10b can be used as a recording device, and stores a BIOS (Basic Input Output System) required for controlling the operation of each functional unit of the depth measurement device 10, various data used by the BIOS, and the like. The RAM 10c is used to configure the main memory accessed by the calculation unit 10e, and is also used to temporarily store various data acquired or generated by the depth measurement device 10 before storing it in the memory unit 10d. The storage unit 10d is realized by an HDD (Hard Disk Drive), an SSD (Solid State Drive), online storage, etc., and stores the OS, a depth measurement program (described later), other application software, various data used by these programs, etc. The storage unit 10d also stores various data acquired or generated by the depth measurement device 10.

[0048] The calculation unit 10e includes a CPU (Central Processing Unit), an MPU (Micro Processing Unit), a GPU (Graphics Processing Unit), etc., and is realized by a logic circuit (hardware) formed by an integrated circuit (IC (Integrated Circuit) chip, LSI (Large Scale Integration)), etc., or a dedicated circuit. The input / output interface 10f is an interface for transmitting and receiving data to and from the input device 10g and the output device 10h. The input / output interface 10f may use different standards depending on the data being handled, and may be compatible with multiple standards, such as HDMI (registered trademark), USB 2.0, USB 3.0, RS-232C, IEEE 1394, SCSI, and SASI.

[0049] (Imaging method for measuring depth by the depth measurement device 10) Next, with reference to FIG. 5, an imaging technique for measuring depth by the depth measurement device 10 will be described. FIG. 5 is an example flowchart of an imaging method for depth measurement by the depth measurement device 10.

[0050] First step: Obtaining a captured image 20 2, in the case of the first and second patterns, the subject 1 and the object 9 are moved relative to the radiation source 7 and the detection surface 8c. The depth measurement device 10 captures the moving subject 1 and object 9 in one captured image 20 (FIG. 5: step S40). Also, as described above, for the third pattern, the depth measurement device 10 moves the radiation source 7 relative to the stationary subject 1 and detection surface 8c, and while the radiation source 7 is moving, images of the subject 1 and the object 9 are captured and stored in a single captured image 20.

[0051] Second step: The length S of the straight section 31, the length DL of the left inclined section 30, and the length DR of the right inclined section 32 are obtained from the brightness of the acquired image. As described above, the depth measurement device 10 obtains the length S of the straight section 31, the length DL of the left inclined section 30, and the length DR of the right inclined section 32 in the evaluation section 28 based on the acquired captured image 20 (Figure 5: step S41).

[0052] Third step: Substitute S, DL, and DR into equation (7) to calculate the image shift amount X. The depth measurement device 10 substitutes the known length S of the straight section 31, the length DL of the left inclined section 30, and the length DR of the right inclined section 32 into equation (7) to calculate the image shift amount X (Figure 5: step S42).

[0053] Step 4: Substitute the difference d, the fixed distance L, and the deviation X into formula (1) or (2) to calculate the depth L1. In the case of the first and second patterns, the depth measurement device 10 calculates the depth (first distance L1) by substituting the known difference d, fixed distance L, and deviation amount X into equation (1). In the case of the third pattern, the depth measurement device 10 substitutes the known difference d, the fixed distance L, and the amount of deviation X into equation (2) to calculate the depth (first distance L1) (FIG. 5: step S43).

[0054] (Functional configuration of depth measurement device 10) Next, the functional configuration of the depth measurement device 10 will be described with reference to FIG. FIG. 6 is a block diagram for explaining an example of the functional configuration of the depth measurement device 10. As shown in FIG. The depth measurement device 10 loads a depth measurement program (described later) stored in the storage unit 10d into a main memory configured with a RAM 10c, etc. The calculation unit 10e accesses the main memory into which the depth measurement program has been loaded and executes the depth measurement program. By executing the depth measurement program, the depth measurement device 10 provides functional units such as an acquisition unit 50, an identification unit 51, a calculation unit 52, and an output unit 53 in the calculation unit 10e.

[0055] The acquisition unit 50 causes the radiation source 7 to continue irradiating the object 9 with radiation 4 until the object 9, which is located at a first position where the distance from the radiation source 7 in the depth direction (Y direction) from the radiation source 7 toward the detection surface 8c is a first distance L1 and the distance from the radiation source 7 in the direction along the detection surface 8c (X direction) is a second distance L2, reaches a second position where the distance in the depth direction (Y direction) is the first distance L1 and the distance in the direction along the detection surface 8c (X direction) is a third distance L3 different from the second distance L2, and captures an image of the object 9 moving from the first position to the second position and acquires it as a single captured image 20.

[0056] In the first and second patterns, the acquisition unit 50 causes the radiation source 7 to continue irradiating the object 9 (9a, 9b) with radiation 4 until the object 9a, which is located at a first position (point P1) that is a first distance L1 from the radiation source 7 (position: point P0) in the depth direction (Y direction) from the radiation source 7 toward the detection surface 8c and a second distance L2 from the radiation source 7 (position: point P0) in the direction along the detection surface 8c (X direction), reaches a second position (point P2) that is the first distance L1 from the radiation source 7 (position: point P0) in the depth direction (Y direction) and a third distance L3 different from the second distance L2 from the radiation source 7 (position: point P0) in the direction along the detection surface 8c (X direction), to capture an image of the object 9 (9a, 9b) moving from the first position (point P1) to the second position (point P2) and acquires the image as a single captured image 20.

[0057] In the case of the third pattern, the acquisition unit 50 acquires the target 9 at a first position (point Q0) that is a first distance L1 from the radiation source 7a (position: point Q1) in the depth direction (Y direction) from the radiation sources 7a, 7b toward the detection surface 8c, and a second distance L2 from the radiation source 7a (position: point Q1) in the direction along the detection surface 8c (X direction), and the target 9 is at a second distance L2 from the radiation source 7b (position: point Q2) in the depth direction (Y direction). The radiation source 7 (7a, 7b) continues to irradiate the object 9 with radiation 4 until the object 9 reaches a second position (point Q0) at a third distance L3, which is a distance L1 from the radiation source 7b (position: point Q2) in the direction along the detection surface 8c (X direction), that is different from the second distance L2. The object 9 is then imaged as it moves from the first position (point Q0 as seen from point Q1) to the second position (point Q0 as seen from point Q2), and a single captured image 20 is obtained.

[0058] The determination unit 51 determines the amount of positional deviation X of the image of the object 9 projected onto the detection surface 8c while the object 9 moves from the first position to the second position, based on the distance between the ends of the image of the object 9 included in the captured image 20 in a direction along the detection surface 8c (X direction). That is, the determination unit 51 determines the deviation amount X as the value obtained by adding the distance (length S of the straight section 31) over which the brightness of the image of the object 9 included in the captured image 20 is constant in the direction along the detection surface 8c (X direction) to the distance (half the distances (DR and DL) of the sections (left inclined section 30 and right inclined section 32) over which the brightness of the image of the object 9 changes in the direction along the detection surface 8c (X direction). As described above, the distance between the ends refers to the distance of the evaluation section 28 shown in FIG. As described above, the determination unit 51 calculates the deviation amount X by substituting the length S of the straight section 31, the length DL of the left inclined section 30, and the length DR of the right inclined section 32, which are obtained based on the distance of the evaluation section 28, which is the distance between the end points, into formula (7).

[0059] In the first and second patterns, the period during which the object 9 moves from the first position to the second position refers to the period during which the object 9a, which is located at the first position (point P1), moves to the second position (point P2), as shown in FIG. 1(a). In addition, in the third pattern, the period during which the object 9 moves from the first position to the second position refers to the relative movement of the stationary object 9 as seen from the moving radiation source 7 (7a, 7b), as shown in Figure 1(b), and refers to the relative movement of the object 9 from the first position (point Q0 as seen from point Q1) to the second position (point Q0 as seen from point Q2) when the stationary object 9 is seen from the radiation source 7 (7a, 7b) moving from point Q1 to point Q2.

[0060] The calculation unit 52 calculates the first distance L1 based on the fixed distance L, the difference d between the second distance L2 and the third distance L3, and the deviation amount X. The fixed distance L is the distance between the radiation source 7 and the detection surface 8c, and is obtained in advance. In the case of the first pattern, the difference d is the distance traveled by the radiation source 7 from the start to the end of exposure of the detection surface 8c. In the first pattern, the target object 9 is placed stationary between the radiation source 7 and the detection surface 8c, and the radiation source 7 and the detection surface 8c are moved in the same direction along the detection surface 8c (X direction) by the same distance. In the case of the second pattern, the difference d is the distance traveled by the object 9 from the start to the end of exposure of the detection surface 8c. In the second pattern, the radiation source 7 and the detection surface 8c are kept stationary, and the object 9 is moved between the radiation source 7 and the detection surface 8c in a direction along the detection surface 8c (X direction). In the case of the third pattern, the difference d is the distance traveled by the radiation source 7 from the start to the end of exposure of the detection surface 8c. In the third pattern, detection surface 8c and object 9 are kept stationary, and only radiation source 7 is moved in a direction along detection surface 8c (X direction).

[0061] In the case of the first pattern and the second pattern, the calculation unit 52 calculates the first distance L1 by dividing the difference d by the deviation amount X and multiplying the result by the fixed distance L. That is, in the case of the first pattern and the second pattern, the calculation unit 52 calculates the first distance L1 using Equation (1). In the case of the third pattern, the calculation unit 52 calculates the first distance L1 by dividing the difference d by the sum of the deviation amount X and the difference d and multiplying the result by the fixed distance L. That is, in the case of the third pattern, the calculation unit 52 calculates the first distance L1 using equation (2).

[0062] The output unit 53 outputs the first distance L1. The output unit 34 outputs the first distance L1, which is the depth of the object 9, to a monitor 14, a printer 15, a speaker 16, and the like connected to the depth measurement device 10.

[0063] (Depth measurement method and depth measurement program) Next, a depth measurement program according to one embodiment of the present invention will be described together with a depth measurement method with reference to Fig. 7. Fig. 7 is a flowchart of the depth measurement program according to this embodiment. The depth measurement method is executed by the calculation unit 10e of the depth measurement device 10 based on the depth measurement program. The depth measurement program includes an acquisition step S50, a determination step S51, and a calculation step S52. The depth measurement program causes the calculation unit 10e of the depth measurement device 10 to perform an acquisition function, a specification function, a calculation function, etc. These functions are executed in the order shown in the flowchart of Figure 7, but the order can be changed as needed. Note that each function overlaps with the description of the various functional units of the depth measurement device 10 described above, and therefore detailed description thereof will be omitted.

[0064] The acquisition function causes the radiation source 7 to continue irradiating radiation 4 onto the object 9 while the object 9, which is located at a first position where the distance from the radiation source 7 in the depth direction (Y direction) from the radiation source 7 toward the detection surface 8c is a first distance L1 and the distance from the radiation source 7 in the direction along the detection surface 8c (X direction) is a second distance L2, reaches a second position where the distance in the depth direction (Y direction) is the first distance L1 and the distance in the direction along the detection surface 8c (X direction) is a third distance L3 different from the second distance L2, and captures an image of the object 9 moving from the first position to the second position and acquires it as a single captured image 20 (step S50: acquisition step). In the first and second patterns, the first position of the object 9 is a point P1, and the second position of the object 9 is a point P2 (see FIG. 1(a)). In the third pattern, the first position of the object 9 is a relative position (point Q0) based on the position of the radiation source 7a before movement (point Q1), and the second position of the object 9 is a relative position (point Q0) based on the position of the radiation source 7a after movement (point Q2) (see Figure 1(b)).

[0065] The identification function identifies the amount of positional deviation X of the image of the object 9 projected onto the detection surface 8c while the object 9 moves from the first position to the second position, based on the distance between the ends of the image of the object 9 included in the captured image 20 in the direction along the detection surface 8c (X direction) (S51: identification step). In the first and second patterns, the period during which the object 9 moves from the first position to the second position refers to the period during which the object 9a located at the first position (point P1) moves to the second position (point P2), as described above (see FIG. 1(a)). In addition, in the third pattern, the period during which the object 9 moves from the first position to the second position refers to the relative movement of the stationary object 9 as seen from the moving radiation source 7 (7a, 7b), as described above, and refers to the relative movement of the object 9 from the first position (point Q0 as seen from point Q1) to the second position (point Q0 as seen from point Q2) when the stationary object 9 is seen from the radiation source 7 (7a, 7b) moving from point Q1 to point Q2 (see Figure 1(b)).

[0066] The calculation function calculates the first distance L1 based on the fixed distance L, the difference d between the second distance L2 and the third distance L3, and the deviation amount X (S52: calculation step).

[0067] (Other embodiments of the depth measurement method and depth measurement program) Next, a depth measurement program according to another embodiment of the present invention will be described together with a depth measurement method according to another embodiment with reference to Fig. 8. Fig. 8 is an example of a flowchart of the depth measurement program according to another embodiment. The flowchart of the depth measurement program according to another embodiment shown in FIG. 8 differs from the flowchart of the depth measurement program shown in FIG. 7 in that an output step S53 is added. The depth measurement method according to the other embodiment is executed by the calculation unit 10e of the depth measurement device 10 based on the depth measurement program according to the other embodiment shown in FIG. The depth measurement program according to another embodiment shown in FIG. 8 includes an acquisition step S50, a determination step S51, a calculation step S52, and an output step S53.

[0068] The depth measurement program according to another embodiment shown in Fig. 8 causes the calculation unit 10e of the depth measurement device 10 to realize an acquisition function, a specification function, a calculation function, an output function, etc. These functions are executed in the order shown in the flowchart of Fig. 8, but the order can also be changed as appropriate. Hereinafter, the depth measurement method and depth measurement program according to another embodiment shown in FIG. 8 will be described, focusing only on the differences from the depth measurement method and depth measurement program shown in FIG. Furthermore, since each function overlaps with the description of the various functional parts of the depth measurement device 10 described above, detailed description thereof will be omitted. The output function outputs the first distance L1 (S53: output step).

[0069] (Effects of the embodiment) According to the depth measurement device 10 of the above-described embodiment, the amount of image shift X of the object 9 is determined based on one captured image 20 and the depth (first distance L1) is calculated. Therefore, compared to the conventional case in which the depth (first distance L1) is calculated by reconstructing multiple captured images, it is possible to prevent a decrease in accuracy due to inconsistencies in the shapes of the images of the object 9 included in multiple captured images.

[0070] Furthermore, according to the depth measurement device 10 of the above-described embodiment, the amount of image shift X of the object 9 is determined based on one captured image 20, and the depth (first distance L1) is calculated. Therefore, compared to the conventional case in which the depth (first distance L1) is calculated by reconstructing multiple captured images, there is no need to associate the images of the object 9 contained in the multiple captured images with each other, making processing by the depth measurement device 10 easier.

[0071] Furthermore, according to the depth measurement device 10 of the above-described embodiment, the depth (first distance L1) can be measured regardless of whether the relative relationship between the radiation source 7, the detection surface 8c, and the object 9 is the first pattern, the second pattern, or the third pattern.

[0072] The present invention is not limited to the depth measurement device 10, depth measurement method, and depth measurement program according to the above-described embodiments, and can be implemented by various other modified examples or application examples without departing from the gist of the present invention as set forth in the claims. Also, although the term "data" is used in the above-described embodiments, the term "data" can be replaced with "information," and the term "information" can be replaced with "data." [Explanation of symbols]

[0073] 1. Subject 4. Radiation 5 Robot arm (movement mechanism) 7 Radiation source 7a Radiation source before moving 7b Radiation source after transfer 8 Detectors 8c Detection surface 9 Objects 9a Object before movement 9b Object after movement 9c Object 9d Object 10 Depth measuring device 10a Communication Interface 10b ROM 10c RAM 10d storage section 10e Calculation unit 10f Input / Output Interface 10g input device 10h output device 11 Keyboard 12 Mouse 14 monitors 15 Printers 16 speakers 19 Information and Communications Networks 20 Captured images 21 Image of the subject 22 Image of object 9d 23 Image of Object 9c 25 slots 27 Central part 28 Evaluation interval 30 Left-sloping section 31 Straight Section 32 Right-sloping section 50 Acquisition Department 51 Specific section 52 Calculation section 53 Output section d Difference (travel distance) DL Length of the left-sloping section DR Length of right-sloping section L fixed distance L1 1st distance (depth) L2 2nd distance L3 Third distance Point P0 (position of radiation source 7) Point P1 (position of object 9a before movement) Point P2 (position of object 9b after movement) P3 point P4 points Point Q0 (position of object 9) Point Q1 (position of radiation source 7a before movement) Point Q2 (position of radiation source 7b after movement) Q3 points Q4 points S Length of the straight section X deviation amount

Claims

1. a radiation source that emits radiation; a detector having a detection surface facing the radiation source to detect radiation emitted from the radiation source, the detector maintaining a fixed distance between the detection surface and the radiation source; an acquisition unit that causes the radiation source to continue irradiating radiation onto an object that is present at a first position where the distance from the radiation source in a depth direction from the radiation source toward the detection surface is a first distance and the distance from the radiation source in a direction along the detection surface is a second distance, and captures an image of the object moving from the first position to the second position and acquires the image as a single captured image, until the object reaches a second position where the distance in the depth direction is the first distance and a third distance in a direction along the detection surface is different from the second distance; an identification unit that identifies an amount of deviation of a position of the image of the object projected on the detection surface while the object is moving from the first position to the second position, based on a distance between ends of the image of the object included in the captured image in a direction along the detection surface; a calculation unit that calculates the first distance based on the fixed distance, a difference between the second distance and the third distance, and the deviation amount; A depth measurement device comprising:

2. a moving mechanism that moves the radiation source and the detection surface by the same distance in the same direction along the detection surface while keeping the object stationary between the radiation source and the detection surface and maintaining the distance between the radiation source and the detection surface at the fixed distance, 2. The depth measurement device according to claim 1, wherein the difference is a distance traveled by the radiation source from the start to the end of exposure of the detection surface.

3. a moving mechanism that moves the object between the radiation source and the detection surface in a direction along the detection surface while keeping the radiation source and the detection surface stationary; 2. The depth measurement device according to claim 1, wherein the difference is a distance traveled by the object between the start and end of exposure of the detection surface.

4. a moving mechanism that moves only the radiation source in a direction along the detection surface while keeping the detection surface and the object stationary and maintaining the distance between the radiation source and the detection surface at the fixed distance, 2. The depth measurement device according to claim 1, wherein the difference is a distance traveled by the radiation source from the start to the end of exposure of the detection surface.

5. 5. The depth measurement device according to claim 2, wherein the moving mechanism is a robot arm.

6. 4. The depth measurement device according to claim 2, wherein the calculation unit calculates the first distance by dividing the difference by the amount of deviation and multiplying the result by the fixed distance.

7. The depth measurement device according to claim 4 , wherein the calculation unit calculates the first distance by dividing the difference by the sum of the deviation amount and the difference, and multiplying the result by the fixed distance.

8. The depth measurement device described in claim 1, characterized in that the determination unit determines the amount of deviation as a value obtained by adding half the distance over which the brightness of the image of the object included in the captured image is constant in a direction along the detection surface to the distance over which the brightness of the image of the object changes in a direction along the detection surface.

9. The depth measurement device according to claim 1 , further comprising an output unit that outputs the first distance.

10. a computer capable of communicating with a radiation source that emits radiation and a detector that is provided with a detection surface that directly faces the radiation source and detects the radiation emitted by the radiation source, the detection surface maintaining a fixed distance from the radiation source; an acquiring step of causing the radiation source to continue irradiating radiation onto an object that is present at a first position where the distance from the radiation source in a depth direction from the radiation source toward the detection surface is a first distance and the distance from the radiation source in a direction along the detection surface is a second distance, until the object reaches a second position where the distance in the depth direction is the first distance and the distance in the direction along the detection surface is a third distance different from the second distance, thereby capturing an image of the object moving from the first position to the second position and acquiring the image as a single captured image; a specifying step of specifying a positional deviation amount of the image of the object projected on the detection surface while the object moves from the first position to the second position, based on a distance between ends of the image of the object included in the captured image in a direction along the detection surface; a calculation step of calculating the first distance based on the fixed distance, a difference between the second distance and the third distance, and the deviation amount; A depth measurement method comprising:

11. a computer that is capable of communicating with a radiation source that emits radiation and a detector that is provided with a detection surface that directly faces the radiation source and detects the radiation emitted from the radiation source, and that maintains a fixed distance between the detection surface and the radiation source; an acquisition function of causing the radiation source to continue irradiating radiation onto an object that is present at a first position, where the distance from the radiation source in a depth direction from the radiation source toward the detection surface is a first distance and the distance from the radiation source in a direction along the detection surface is a second distance, until the object reaches a second position, where the distance in the depth direction is the first distance and the distance in the direction along the detection surface is a third distance different from the second distance, thereby capturing an image of the object that moves from the first position to the second position and acquiring the image as a single captured image; a specifying function for specifying a positional deviation amount of the image of the object projected on the detection surface while the object moves from the first position to the second position, based on a distance between ends of the image of the object included in the captured image in a direction along the detection surface; and a calculation function for calculating the first distance based on the fixed distance, a difference between the second distance and the third distance, and the deviation amount; A depth measurement program characterized by realizing the above.

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