Object detection system, object detection method and program

Abstract

To provide an object detection system which is difficult to give a load to processing more than conventional ones.SOLUTION: An object detection system includes image acquisition means for acquiring a first image and a second image captured at different times by a movable body, expansion amount calculation means for calculating an expansion amount in expansion processing to the second image, expansion processing means for expanding the second image on the basis of the expansion amount calculated by the expansion amount calculation means and acquiring an expanded image of the second image, and detection means for subtracting the expanded image of the second image from the first image to detect an object. The expansion amount is calculated on the basis of directional stability of the movable body that captures the first image and the second image.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an object detection system, an object detection method, and a program. [Background technology]

[0002] With the recent progress in space development, the number of rockets and artificial satellites being launched has been rapidly increasing. As a result, in addition to natural objects such as space dust, a large number of space debris (hereinafter referred to as "space objects") of various sizes, such as retired rockets, artificial satellites, or their parts and fragments, exists and orbits in space around the Earth. Therefore, the risk of such space objects colliding with launched rockets or artificial satellites in use is gradually increasing.

[0003] There are technologies to detect the presence of space objects and measure the direction and distance to them in order to avoid collisions with them. For example, one technology involves continuously capturing images in the direction where the imaging directions of two artificial satellites intersect, and then continuously distinguishing between space debris and stars by synthesizing the two intersection images so that the star patterns overlap (pattern matching), and determining the space object position vector from the geometric relationship between the star patterns and debris light spots (Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 11-271056 Summary of the Invention [Problem to be solved by the invention]

[0005] Processing using pattern matching of star patterns, such as the technology described in Patent Document 1, imposes a heavy computational load and may result in processing delays and performance degradation in artificial satellites.

[0006] Furthermore, even on the ground, object detection using pattern matching, such as the conventional technology described in Patent Document 1, may result in processing delays and performance degradation.

[0007] In view of the above, an object of the present invention is to provide an object detection system that places less of a load on processing than conventional systems. [Means for solving the problem]

[0008] In view of the above, an object detection system according to the present invention comprises: The system comprises an image acquisition means for acquiring a first image and a second image taken at different times by a moving body, an expansion amount calculation means for calculating the expansion amount in the expansion processing for the second image, an expansion processing means for expanding the second image based on the expansion amount calculated by the expansion amount calculation means and acquiring an expanded image of the second image, and a detection means for detecting an object by subtracting the expanded image of the second image from the first image, wherein the expansion amount is calculated based on the directional stability of the moving body that captured the first image and the second image. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide an object detection system that places less of a load on processing than conventional systems. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a diagram showing the configuration of an object detection system according to an embodiment of the present invention. [Figure 2] FIG. 1 is a block diagram showing an example of the functional configuration of an imaging calculation apparatus according to an embodiment of the present invention. [Figure 3] 1 is a block diagram showing a hardware configuration of an on-board computer according to an embodiment of the present invention; [Figure 4] FIG. 2 is a block diagram showing an example of the functional configuration of a ground station according to the embodiment of the present invention. [Figure 5] FIG. 2 is a block diagram showing the hardware configuration of an operation unit according to the embodiment of the present invention. [Figure 6]FIG. 2 is a sequence diagram of the object detection system according to the embodiment of the present invention. [Figure 7] 1A and 1B are conceptual diagrams of images captured multiple times in succession according to an imaging plan according to an embodiment of the present invention. [Figure 8] 10A and 10B are conceptual diagrams illustrating subtraction processing according to an embodiment of the present invention. [Figure 9] 10 is a flowchart showing a process of detecting an object according to an embodiment of the present invention. [Figure 10] 1 is a flowchart showing a process of detecting an object candidate according to an embodiment of the present invention. [Figure 11] FIG. 10 is a diagram showing an example of expansion processing (8-neighbor processing) according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that the following embodiments do not limit the invention according to the claims. Although multiple features are described in the embodiments, not all of these multiple features are necessarily essential to the invention, and multiple features may be combined arbitrarily. Furthermore, in the drawings, the same reference numerals are used to designate the same or similar components, and redundant explanations will be omitted.

[0012] <System Overview> First, the configuration of the object detection system according to this embodiment will be described with reference to the system configuration diagram of FIG.

[0013] As shown in FIG. 1, the object detection system according to the present invention is composed of imaging processing units 10 and 11 and a ground station 20. The imaging processing units 10 and 11 are two artificial satellites (mobile bodies) orbiting the Earth in outer space. The ground station 20 issues various instructions to the imaging processing units 10 and 11, such as instructions regarding attitude control, instructions for capturing images of target points, and image processing. The imaging processing units 10 and 11 perform attitude control, capture images, and image processing in accordance with the instructions received from the ground station 20, and transmit the obtained data to the ground station 20. Note that the imaging targets of the imaging processing units in this system will be described as a space object 30 and a celestial body 40. The space object 30 is a space object floating in outer space, and the celestial body 40 is a celestial body targeted for imaging.

[0014] The above-described configuration is merely an example, and for example, one ground station 20 is shown in FIG. 1 for simplicity, but in reality there may be multiple ground stations. Also, while this embodiment is configured with two imaging and calculation devices, it may be configured with three or more imaging and calculation devices. Furthermore, the imaging and calculation devices 10 and 11 and the ground station 20 may have any configuration as long as they are capable of executing the processes described below.

[0015] <Device configuration of imaging calculation device> Next, the imaging calculation devices 10 and 11 will be described with reference to Fig. 2. Fig. 2 is a block diagram showing an example of the functional configuration of an imaging calculation device according to an embodiment of the present invention. Here, for simplicity of explanation, the hardware configuration of the imaging calculation device 10 will be described. The imaging calculation devices 10 and 11 may have any configuration as long as they are capable of executing the processes described below.

[0016] As shown in FIG. 2, the imaging calculation device 10 is composed of a receiver 110, a transmitter 120, a GPS (Global Positioning System) 130, an attitude control device 140, an optical detector 150, and an on-board computer (hereinafter referred to as "OBC") 160.

[0017] The receiver 110 receives radio waves including an imaging command, which will be described later, from the ground station 20 .

[0018] The transmitter 120 transmits radio waves related to the data acquired by the imaging and processing device 10 to the ground station 20.

[0019] The GPS 130 is a global positioning system that acquires the position information of the imaging processing device 10 and the current time information.

[0020] The attitude control device 140 controls the attitude of the imaging calculation device 10. In this embodiment, the attitude control of the imaging calculation device is performed so that an image of a specific target point can be captured at a specified time.

[0021] The optical detector 150 is, for example, an optical camera, and captures images of outer space and acquires image information in accordance with instructions from the ground station 20. The optical detector 150 is not limited to an optical camera, and an infrared camera or any other imaging device may be used. Furthermore, the imaging calculation device 10 may be equipped with multiple cameras, and an appropriate camera may be switched for use as needed.

[0022] The OBC 160 is an information processing device that issues commands to each component in the imaging calculation device. The OBC 160 includes an identification calculation unit 161, an orientation calculation unit 162, and a storage 163. The identification calculation unit 161 detects space objects 30 from image information acquired by the optical detector 150. The orientation calculation unit 162 calculates a direction vector of the space object 30 detected by the identification calculation unit 161 as seen from the imaging calculation device. The storage 163 is a memory area configured by the memory device 1604 (described later), and stores information such as image information acquired by the optical detector 150, information about the space object 30 detected by the identification calculation unit 161, and the orientation vector of the space object 30 calculated by the orientation calculation unit 162.

[0023] These devices are connected within the imaging calculation devices 10 and 11 via a network.

[0024] <Hardware Configuration of OBC160> FIG. 3 is a block diagram showing a hardware configuration example of an information processing apparatus (computer) applicable to OBC160 according to an embodiment of the present invention.

[0025] A CPU (Central Processing Unit) 1601 controls the entire computer using computer programs and data stored in a RAM 1602 and a ROM 1603 described later. When this computer is applied to OBC160, the CPU 1601 executes each process described later as what OBC160 does.

[0026] A RAM (Random Access Memory) 1602 has an area for temporarily storing a computer program and data loaded from a storage device 1604 described later, and an area for temporarily storing various data received from an external device via an I / F (interface) 1607. Further, the RAM 1602 also has a work area used when the CPU 1601 executes various processes. Thus, the RAM 1602 can appropriately provide various areas.

[0027] In a ROM (Read Only Memory) 1603, setting data and a boot program of this computer are stored.

[0028] The storage device 1604 is a large-capacity information storage device typified by a hard disk drive device. In this storage device 1604, an OS (Operating System), a computer program and data for causing the CPU 1601 to execute each process described later as what this device does are stored. The computer program and data stored in the storage device 1604 are appropriately loaded into the RAM 1602 according to the control by the CPU 1601 and become processing targets by the CPU 1601.

[0029] The input device 1605 is composed of a mouse, keyboard, etc., and can be operated by an operator of this device to input various instructions to the CPU 1601. Note that the input device 1605 is used on the ground and is not an essential component in space.

[0030] The I / F (interface) 1607 is configured with various interfaces. For example, when this computer is applied to the OBC 160, this device can perform data communication with other devices in the imaging calculation device 10 connected to the network via this interface 1607.

[0031] All of the above components are connected to a bus 1608 .

[0032] <Ground station equipment configuration> Next, the ground station 20 will be described with reference to Fig. 4. Fig. 4 is a block diagram showing an example of the functional configuration of the ground station 20 according to the embodiment of the present invention.

[0033] As shown in FIG. 4, the ground station 20 includes an antenna 210 and an operation unit 220 provided in a predetermined area where communication with the imaging and processing devices 10 and 11 is possible.

[0034] The antenna 210 tracks the imaging calculation devices 10 and 11, transmits radio waves including imaging commands (to be described later) to each imaging calculation device, and receives radio waves including data sets (to be described later) from the imaging calculation devices 10 and 11.

[0035] The operation unit 220 is an information processing device such as a computer (Personal Computer), and controls the antenna 210, operates the imaging and calculation devices 10 and 11, and stores data received from the imaging and calculation devices 10 and 11 via the antenna 210. The operation unit 220 also has a data analysis unit 221. The data analysis unit 221 calculates position information and orbit information of the space object 30 based on data (data set) related to the space object 30 acquired from the imaging and calculation devices 10 and 11.

[0036] The antenna 210 and the operation unit 220 are connected via a network.

[0037] <Hardware configuration of the operation unit 220> FIG. 5 is a block diagram showing an example of the hardware configuration of a computer applicable to the operation unit 220. As shown in FIG.

[0038] The CPU 2201, RAM 2202, ROM 2203, storage device 2204, I / F 2207, and bus 2208 have the same configuration as the CPU 1601, RAM 1602, ROM 1603, storage device 1604, I / F 1607, and bus 1608 in the imaging calculation devices 10 and 11, and therefore description thereof will be omitted. When this computer is applied to the operation unit 220, the CPU 2201 executes each process described below as being performed by the operation unit 220.

[0039] The input device 2205 is composed of a mouse, keyboard, etc., and can be operated by the operator of this device to input various instructions to the CPU 2201.

[0040] The display device 2206 is configured with, for example, an organic EL or liquid crystal display, and can display the results of processing by the CPU 2201 as images, text, and the like.

[0041] For ease of explanation, the present embodiment will be described assuming that the operation unit 220 is a computer having the configuration shown in FIG. 5, but the computer configuration is not limited to this.

[0042] <Object detection system> An object detection system according to an embodiment of the present invention will be described with reference to Fig. 6 and Fig. 7. Fig. 6 is a sequence diagram of the object detection system according to this embodiment. Fig. 7 is a conceptual diagram of images captured multiple times in succession according to the imaging plan according to this embodiment.

[0043] First, in S601, an imaging plan is formulated at the ground station 20. In this embodiment, the imaging plan involves imaging a specific celestial body 40 designated by the imaging plan planner, with the imaging calculation devices 10 and 11 each imaging the celestial body 40 multiple times consecutively from different positions at the same time. Furthermore, the position of the celestial body 40 in images captured by a given imaging calculation device is set so that it is at the center of all images. Since the imaging calculation devices 10 and 11 each acquire time information using their own GPS 130, each imaging calculation device can capture images at the same time. In this embodiment, the imaging plan is described as being formulated at the ground station 20, but this is not a limitation. For example, the imaging plan may be received and used from an external network, or the imaging calculation devices 10 and 11 may autonomously formulate the imaging plan.

[0044] In S601, the operation unit 220 of the ground station 20 creates an imaging command to share this imaging plan with the imaging calculation devices 10 and 11. The imaging command includes setting information specifying the position information of the celestial body 40 to be imaged, the time of imaging, the attitude setting during imaging, imaging condition settings (imaging interval, camera settings (gain, exposure, etc.)), and the attitude setting after imaging is completed. This command may also include other setting information (heater settings, etc.).

[0045] Next, in S602, the imaging command created by the operation unit 220 is transmitted to each of the imaging calculation devices 10 and 11 via the antenna 210. Since the processing in the imaging calculation devices 10 and 11 from this point on is the same, for simplicity of explanation, the following description will focus on the imaging calculation device 10.

[0046] In S603, when the imaging calculation device 10 receives the imaging command transmitted from the ground station 20 in S602 via the receiver 110, it images the celestial body 40 at the specified time in accordance with the setting information included in the received communication command. Specifically, the attitude control device 140 controls the attitude of the imaging calculation device 10 based on the setting information, and the optical detector 150 images the celestial body 40 so that it is centered in the image. For example, as shown in FIG. 7 , the optical detector 150 captures an image at a first time to acquire a first image, and then captures an image again at a second time with the celestial body 40 as the target to acquire a second image. By repeating this process, continuous imaging is performed to acquire consecutive images. If a space object 30 is present within the imaging range, the space object 30 is imaged by changing its position on the images, as shown in FIG. 7 , in the first image, second image, third image, and so on. The images captured by the optical detector 150 are stored in the storage 163.

[0047] Next, the discrimination calculation unit 161 performs space object detection processing using the image information captured in S603 (S604).

[0048] Processing in step S604 (object detection processing) Details of the processing in step S604 above will be described with reference to FIGS. 8, 9, and 10. FIG. 8 is an image diagram illustrating the subtraction processing according to an embodiment of the present invention. Furthermore, FIG. 8(a) is a diagram illustrating the image subtraction processing when expansion processing is not performed, (b) is a diagram illustrating the image subtraction processing when expansion processing is performed, and (c) is a diagram illustrating the image subtraction processing performed by switching the subtracted image and the subtracted image. FIG. 9 is a flowchart illustrating the object detection processing according to an embodiment of the present invention. Furthermore, FIG. 10 is a flowchart illustrating the object candidate detection processing according to an embodiment of the present invention.

[0049] In the space object detection process in step S604, space object 30 is detected by performing image subtraction processing on two images. Note that image subtraction means subtracting the brightness values ​​(pixel values) of pixels that exist at the same position in two images captured by the same optical detector, and in this explanation, the image to be subtracted is defined as the subtracted image, and the image to be subtracted is defined as the subtracted image.

[0050] As shown in Figure 8(a), when the subtraction image is simply subtracted from the subtracted image, the position of the celestial body 40 on the subtracted image and the subtracted image may change (be blurred) depending on the precision of controlling the attitude of the imaging calculation device (pointing stability). In this case, by performing image subtraction processing on the subtracted image and the subtracted image, not only is the space object 30 detected, but the deviation of the celestial body 40 also remains in the difference image (A). As a result, although it is intended to detect only the space object 30, the celestial body 40 may also be erroneously detected as a possible space object. In order to avoid such erroneous detection, the image subtraction processing is performed after performing the binarization processing and expansion processing described below.

[0051] The flow of the object detection process in step S604 above will be described with reference to the flowchart in FIG.

[0052] First, in S901, space object candidates are detected. A space object candidate is an object that is a candidate for a space object detected in S901. The space object candidate detection process in S901 will be described with reference to the flowchart in FIG.

[0053] First, in S1001, from among the continuous images stored in the storage 163, the image (first image) captured at the earliest time (first time) is acquired as the attenuated image.

[0054] Next, in S1002, from the continuous images stored in the storage 163, an image (second image) captured next to the subtracted image acquired in S1001 is acquired as a subtracted image.

[0055] Next, in S1003, binarization processing is performed on the subtracted image as a preprocessing step for the image subtraction processing between the subtracted image and the subtracted image. Specifically, for pixels in the subtracted image that have a brightness value equal to or greater than a brightness value set as a threshold, the brightness values ​​are maximized, and for pixels that have a brightness value equal to or less than the brightness value set as the threshold, the brightness values ​​are minimized, thereby obtaining a binarized image. This processing maximizes the brightness values ​​of pixels in which celestial bodies or space objects are captured, and minimizes the brightness values ​​of pixels that reflect high-sensitivity noise, etc. This prevents erroneous detection even when the brightness values ​​of the space object 30 or celestial body 40 differ slightly between the subtracted image and the subtracted image. Note that if the influence of other noise is present, binarization processing may be performed after applying other noise removal.

[0056] Next, in S1004, an expansion process is performed on the binarized subtracted image to eliminate the influence of the positional shift of the celestial body 40 between the subtracted image and the subtracted image due to pointing stability. The expansion amount in the expansion process is determined using the pointing stability of the imaging calculation device 10 that performed the image capture. The specific method of the expansion process is described below.

[0057] For the expansion process, the amount of expansion is calculated using the horizontal length (mm), vertical length (mm), and focal length (mm) of the image sensor of the camera used at the time of image capture, the number of pixels in both the vertical and horizontal directions of the captured image, and the pointing stability of the imaging calculation device 10 (artificial satellite).

[0058] First, calculate the horizontal angle of view (°) in the horizontal direction and the vertical angle of view (°) in the vertical direction of the captured image. The calculation formulas for the horizontal angle of view and the vertical angle of view are as follows: Horizontal angle of view (°) = 2 × atan (horizontal image sensor length (mm) / (2 × focal length (mm))) Vertical angle of view (°) = 2 × atan (vertical image sensor length (mm) / (2 × focal length (mm)))

[0059] Next, the horizontal and vertical angles of view per pixel are calculated from the calculated horizontal and vertical angles of view. The formulas for calculating the horizontal and vertical angles of view per pixel are as follows: Horizontal angle of view per pixel (°) = Horizontal angle of view (°) / Horizontal pixel of captured image (pixel) Vertical angle of view per pixel (°) = Vertical angle of view (°) / Vertical pixel of captured image (pixel)

[0060] Then, the amount of pixel expansion is calculated based on the calculated horizontal and vertical angles of view per pixel and the pointing stability. The calculation formula for the amount of expansion is as follows: Amount of lateral expansion = Pointing stability of imaging calculation device 10 (°) / 1 pixel horizontal angle of view (°) Amount of vertical expansion = Pointing stability of imaging calculation device 10 (°) / 1 pixel vertical angle of view (°)

[0061] Then, based on the calculated expansion amount, expansion processing is performed on the binarized subtracted image. A specific expansion method will be explained using the conceptual diagram of an example of expansion processing (8-neighbor processing) in Figure 11. Figure 11 shows a pixel group with the maximum brightness value that exists in a part of the binarized subtracted image, and explains a case where the horizontal expansion amount and vertical expansion amount are "2". Note that the expansion amount in this processing will be explained as a case where the horizontal and vertical expansion amounts are calculated to be the same value because the pixels are square.

[0062] Expansion processing is performed for all pixels in the subtracted image that have the maximum brightness value by the calculated expansion amount. Specifically, processing is performed to maximize the brightness values ​​of the eight surrounding pixels (eight neighbors) for the pixel with the maximum brightness value the number of times calculated by the expansion amount (hereinafter referred to as 8-neighbor processing). In this case, the expansion amount is 2, so the 8-neighbor processing is repeated twice. This makes it possible to obtain a subtracted image (dilated image) in which the pixel group has expanded, as in the image after expansion processing in Figure 11.

[0063] However, the present invention is not limited to this, and different expansion amounts may be used in the vertical and horizontal directions, taking into account errors caused by movement of the imaging calculation device, etc. In such a case, if the values ​​of the vertical expansion amount and the horizontal expansion amount are different, expansion processing may be performed by expanding all pixels with the maximum brightness value by the vertical expansion amount in the up and down direction for the pixel with the maximum brightness value, and then expanding the pixels by the horizontal expansion amount to the left and right. Also, expansion processing may be performed by calculating the barycentric coordinates of the pixel group (the average of the coordinates of the pixels included in the pixel group) and expanding from the barycentric center based on the expansion amount calculated using the directional stability.

[0064] Furthermore, in this embodiment, the expansion process is performed after the binarization process. However, the original subtracted image (multi-valued image) may be expanded to pixels having a brightness value equal to or greater than a predetermined threshold, the expanded image may be binarized, and the image may be subtracted. Alternatively, the image may be subtracted and then binarized. Furthermore, after the multi-valued image is expanded to pixels having a brightness value equal to or greater than a predetermined threshold and the image is subtracted, offset correction may be performed instead of the binarization process. Furthermore, when a multi-valued image is used for the expansion process without being binarized, the expansion amount calculated using the directional stability may be corrected according to the brightness value of the image, and then the expansion process may be performed.

[0065] Furthermore, the pointing stability may not be a fixed value, but may be some parameter equivalent to the pointing stability based on some parameter acquired from the imaging calculation device each time.

[0066] Furthermore, if the horizontal and vertical expansion amounts have decimal points, they may be rounded up or down. The expansion method is not limited to the above-mentioned method, as long as the expansion is based on the expansion amount calculated using the pointing stability for the space material.

[0067] Next, in S1005 of Fig. 10, an image subtraction process is performed in which the dilated subtraction image is subtracted from the subtracted image. As a result, the deviation of the celestial body 40 is no longer detected, as in the first difference image shown in Fig. 8(b), and it becomes possible to detect only objects that are thought to be space objects other than celestial bodies (space object candidates).

[0068] Thereafter, in S1006, it is determined whether or not a space object candidate has been detected by the subtraction process performed in S1005. Whether or not a space object candidate has been detected is determined by whether or not a pixel group equal to or greater than a certain threshold is included in the difference image obtained by subtracting the subtraction image from the subtracted image. Note that the present invention is not limited to this, and whether or not a space object candidate has been detected may be determined by other methods. If a space object candidate has been detected, the process in S901 of FIG. 9 is terminated, and the process proceeds to S902. On the other hand, if a space object candidate has not been detected, the process proceeds to S1007.

[0069] In S1007, it is determined whether there is an image (here, a third image) captured after the image (second image) used as the subtracted image. If there is a next captured image, the process returns to S1002, and the next captured image (third image) is acquired as the subtracted image and the same process is performed. If there is no next captured image, the process proceeds to S1008.

[0070] In S1008, it is determined whether there is an image (here, a second image) captured after the image (first image) used as the subtracted image. If there is a next captured image, the process returns to S1001, and the next image (second image) is acquired as the subtracted image and the same process is performed. If there is no next captured image, it is determined that no space object exists, and this process ends.

[0071] 9, the subtracted image and the subtracted image are swapped, and similarly to S901, the subtracted image is subjected to binarization processing (S1003) and expansion processing (S1004), and subtraction processing (S1005) in which the subtracted image is subtracted from the subtracted image, and then space object candidate detection (S1006) is performed (FIG. 8(c)). As a result, space object candidate images captured in the second image are detected, as shown in the second difference image in FIG. 8(c).

[0072] Next, in S903, it is determined whether the space object candidates detected in S901 and S902 are the same space object. A specific method of determination will be described below.

[0073] First, in S901, the brightness value and size of the space object candidate detected in the first difference image are calculated. Next, in S902, the brightness value and size are calculated similarly for the space object candidate detected in the second difference image. Then, the brightness values ​​and sizes of the space object candidate detected in the first difference image and the second difference image are compared to determine whether they are the same space object. To determine whether they are the same space object, the brightness value and size of the detected space object are compared, and if they are within a predetermined threshold value, they are determined to be the same space object. However, the present invention is not limited to this, and other methods may be used.

[0074] In the present invention, the size of a space object candidate is assumed to be calculated based on the number of pixels in the pixel group of the space object candidate, but other methods may be used. Also, in this embodiment, a comparison of brightness value and size is used to determine whether detected space object candidates are the same space object, but the present invention is not limited to this, and other methods such as the shape of the space object may also be used to determine.

[0075] If it is determined in S903 that the space object candidates detected in S901 and S902 are the same space object, the process in S604 in Fig. 6 is terminated and the process proceeds to S605. On the other hand, if it is determined that they are not the same space object, the process proceeds to S904.

[0076] In S904, it is determined whether there is an image (third image in this case) captured next to the image (second image) used as the subtracted image. If there is a next captured image, proceed to S901, obtain the next captured image as the subtracted image, and perform the same processing thereafter. On the other hand, if there is no next captured image, proceed to S905.

[0077] In S905, it is determined whether there is an image (in this case, a second image) captured after the image (first image) used as the subtracted image. If there is a next captured image, the process proceeds to S901, where the next captured image is acquired as the subtracted image, and the same process is performed thereafter. On the other hand, if there is no next captured image, it is determined that no space object exists, and this process ends.

[0078] 6, if a space object is detected, the process proceeds to S605, where the orientation calculation unit 162 performs a process of calculating the direction vector of the space object. If a space object is not detected (does not exist), a message to that effect is transmitted to the ground station 20, and the object detection process of the present invention is terminated.

[0079] In S605, a direction vector of the space object 30 as seen from the imaging calculation device is calculated based on the position information and attitude information of the imaging calculation device 10. A known technique (such as the technique described in Japanese Patent Laid-Open No. 11-271056) can be used to calculate the direction vector, and therefore a description thereof will be omitted.

[0080] Thereafter, the OBC 160 compiles the data relating to the imaging time, the position information of the imaging calculation device 10 at the time of imaging, and the direction vector of the space object calculated in S605 into a data set, and then transmits the data set from the transmitter 120 to the ground station 20 (S606).

[0081] When the ground station 20 receives the data set from the imaging and processing devices 10 and 11 via the antenna 210, the data analysis unit 221 estimates the trajectory of the space object in S607 (S607). The location information of the space object is estimated by using triangulation to obtain the location information of the space object from the data set acquired from the imaging and processing devices 10 and 11. If location information cannot be obtained during triangulation, it is determined that these objects are not the same space object, and subsequent processing is not performed. Note that although triangulation is used to obtain the location information, other methods may also be used. Then, the velocity vector and orbital elements of the space object are calculated based on the location information obtained when the imaging and processing devices 10 and 11 captured the space object.

[0082] As described above, according to the present invention, it is possible to provide an object detection system that imposes less of a processing load than conventional systems.

[0083] In this embodiment, the orbital information of the space object is calculated by the ground station 20, but the present invention is not limited to this. For example, inter-satellite communication may be performed between the imaging calculation devices 10 and 11, a data set from the imaging calculation device 11 may be transmitted to the imaging calculation device 10, and the orbital information of the space object may be calculated by the imaging calculation device 10.

[0084] Furthermore, in this embodiment, image processing is performed within the imaging and calculation device, but this is not limitative and image processing may also be performed in the ground station 20.

[0085] In this embodiment, two optical detectors may be mounted on one imaging and computing device, so that the detection of space objects and the estimation of their orbits can be performed by one imaging and computing device.

[0086] In addition, the orbital information of the detected space object may be configured to be transmitted into outer space for the safety of other artificial satellites.

Claims

1. an image acquisition means for acquiring a first image and a second image captured at different times by a moving object; an expansion amount calculation means for calculating an expansion amount in expansion processing for the second image; an expansion processing means for expanding the second image based on the expansion amount calculated by the expansion amount calculation means, and acquiring an expanded image of the second image; a detection means for detecting an object by subtracting an expanded image of the second image from the first image; and An object detection system, characterized in that the expansion amount is calculated based on the directional stability of a moving object that captured the first image and the second image.

2. The object detection system according to claim 1, characterized in that the expansion processing means binarizes the second image, expands the binarized second image based on the expansion amount, and obtains an expanded image of the second image.

3. 2. The object detection system according to claim 1, wherein the detection means detects an object by binarizing the dilated image of the second image and subtracting the binarized dilated image of the second image from the first image.

4. 2. The object detection system according to claim 1, wherein the detection means subtracts an expanded image of the second image from the first image, binarizes the resulting difference image, and detects the object.

5. 2. The object detection system according to claim 1, wherein the detection means subtracts an expanded image of the second image from the first image, performs offset correction on the resulting difference image, and detects the object.

6. the expansion processing means binarizes the first image, expands the binarized first image based on the expansion amount, and obtains an expanded image of the first image; The object detection system according to claim 2, characterized in that the detection means detects an object by subtracting an expanded image of the first image from the second image, determines whether the object detected from the first image and the object detected from the second image are the same, and detects them as the same object.

7. 7. The object detection system according to claim 6, wherein whether the object detected from the first image and the object detected from the second image are the same is determined based on the size and brightness values ​​of the object detected from the first image and the object detected from the second image.

8. 8. The object detection system according to claim 7, wherein the moving body has an imaging means for capturing the first image and the second image.

9. 9. The object detection system according to claim 8, wherein the imaging means includes a first imaging means and a second imaging means, and when a first object detected from an image captured by the first imaging means and a second object detected from an image captured by the second imaging means are considered to be the same object, position information and trajectory information of the object are calculated.

10. 10. The object detection system according to claim 1, further comprising a storage unit for storing the first image and the second image.

11. The object detection system according to any one of claims 1 to 10, wherein the moving object is an artificial satellite.

12. an image acquisition step of acquiring a first image and a second image captured by a moving object at different times; an expansion amount calculation step of calculating an expansion amount in expansion processing for the second image; an expansion processing step of expanding the second image based on the expansion amount calculated in the expansion amount calculation step, and acquiring an expanded image of the second image; a detection step of detecting an object by subtracting the dilated image of the second image from the first image; and An object detection method, characterized in that the expansion amount is calculated based on the directional stability of a moving object that captured the first image and the second image.

13. A computer program for causing a computer to function as each of the means of the object detection system according to claim 1.

Images