Silhouette shooting system

Abstract

A silhouette imaging system (1) is a system (1-4) that images the silhouette of an observation target (40) in water (30), said system comprising: a planar light source (10) that has a light-emitting surface (11) which emits light (12); an imaging device (20, 70, 80) that has a detection unit which is disposed facing the light-emitting surface (11) with the water (30) therebetween, and that outputs an imaging signal on the basis of light which is part of the light (12) emitted from the light-emitting surface (11) and which has passed through the water (30) and reached the detection unit without being blocked by the observation target (40); and a control unit (50) that controls the planar light source (10) and the imaging device (20, 70, 80).

Description

Technical Field

[0006] ,

[0001] The present disclosure relates to a silhouette imaging system that captures the silhouette of an observation target in water.

Background Art

[0002] There has been a proposal for a monitoring device including a camera, a lighting device arranged on the opposite side of the camera across an aquarium, and a light diffusing plate (for example, ground glass) arranged between the lighting device and the aquarium, enabling an aquatic animal (for example, a fish) as an observation target to be recognized as a silhouette of a black object (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The above conventional device captures the silhouette of an aquatic animal irradiated with light emitted from the lighting device and passing through the ground glass, but there is a problem that the image of the silhouette of the observation target tends to be blurred due to turbidity of the water in the aquarium.

[0005] An object of the present disclosure is to provide a silhouette imaging system capable of capturing a clear silhouette of an observation target even when water turbidity occurs.

Means for Solving the Problems

[0006] The silhouette imaging system of the present disclosure captures the silhouette of an observation target in water CA surface light source having a light-emitting surface that emits light; an imaging device having a detection unit positioned to face the light-emitting surface across the water, which outputs an imaging signal based on the light emitted from the light-emitting surface that travels through the water without being obstructed by the object being observed and reaches the detection unit; and a control unit that controls the surface light source and the imaging device. , a marker pattern provided within the shooting range of the aforementioned shooting device and The control unit comprises, The marker pattern was obtained by photographing it. The characteristic feature is that the wavelength of the light emitted from the light-emitting surface is changed based on the aforementioned imaging signal. [Effects of the Invention]

[0007] According to the silhouette imaging system disclosed herein, a clear silhouette of the object to be observed can be captured even when the water becomes turbid. [Brief explanation of the drawing]

[0008] [Figure 1] This is a schematic side view showing the configuration of the silhouette imaging system according to Embodiment 1. [Figure 2] This is a schematic plan view showing the configuration of the silhouette imaging system according to Embodiment 1. [Figure 3] This is a block diagram showing the configuration of the control system of the silhouette imaging system according to Embodiment 1. [Figure 4] This is a schematic perspective view showing the surface light source of the silhouette imaging system according to a modified example 2 of Embodiment 1. [Figure 5] This is a schematic side view showing the configuration of the silhouette imaging system according to Embodiment 2. [Figure 6] This is a block diagram showing the configuration of the control system of the silhouette imaging system according to Embodiment 2. [Figure 7] This is a schematic side view showing the configuration of the silhouette imaging system according to Embodiment 3. [Figure 8] This is a perspective view illustrating the configuration of the silhouette imaging system according to Embodiment 3. [Figure 9]This is a block diagram showing the configuration of the control system of the silhouette imaging system according to Embodiment 3. [Figure 10] This is a schematic side view showing the configuration of the silhouette imaging system according to Embodiment 4. [Figure 11] This is a schematic perspective view showing the configuration of the silhouette imaging system according to Embodiment 4. [Figure 12] This is a block diagram showing the configuration of the control system of the silhouette imaging system according to Embodiment 4. [Figure 13] This is a schematic perspective view showing the configuration of a silhouette imaging system according to a modified example of Embodiment 4. [Figure 14] This is a block diagram showing the configuration of the control system of a silhouette imaging system according to a modified example of Embodiment 4. [Modes for carrying out the invention]

[0009] The silhouette imaging system according to the embodiment will be described below with reference to the drawings. The following embodiment is merely an example, and it is possible to combine the embodiments as appropriate and modify each embodiment as appropriate.

[0010] Embodiment 1 Figure 1 is a schematic side view showing the configuration of the silhouette imaging system 1 according to Embodiment 1. Figure 2 is a schematic top view showing the configuration of the silhouette imaging system 1. The silhouette imaging system 1 is a system for capturing the silhouette of an object 40 to be observed in water 30.

[0011] In Figures 1 and 2, the water 30 is contained within the tank 31, but the water 30 may also be seawater or freshwater from an aquaculture farm partitioned by nets for cultivating aquatic organisms (e.g., fish, shellfish, crustaceans, etc.), or water from a pond in a facility for fish spawning, hatching, etc. A typical example of the object of observation 40 in the water 30 within the tank 31 is, for example, a fish kept as an ornamental animal.

[0012] The observation target 40 may be an organism other than fish, shellfish, and crustaceans (for example, an animal or a plant). Note that the observation target 40 may be an object other than an organism.

[0013] The silhouette imaging system 1 includes a surface light source 10 and a camera 20 as an imaging device. In FIGS. 1 and 2, the surface light source 10 is disposed below the bottom surface of the water tank 31, and the camera 20 is disposed in the water 30 of the water tank 31. However, the surface light source 10 may be disposed in the water 30 by having a waterproof function. Further, the camera 20 may be disposed above the water surface 32 of the water 30. Also, the surface light source 10 and the camera 20 may be disposed in the vicinity of the outside or the inside of the side surface of the water tank 31 so as to sandwich the water 30.

[0014] The surface light source 10 has a light emitting surface 11 that emits light 12. The surface light source 10 emits light with a uniform intensity from the light emitting surface 11. The light emitting surface 11 is a flat surface, but may be a curved surface. The surface light source 10 is, for example, an edge light type lighting device including a plurality of light emitting diodes (LEDs) as a plurality of light emitting elements and a plate-like light guide member that guides and emits the light emitted from the plurality of LEDs. Also, the surface light source 10 may be a lighting device including a plurality of LEDs arranged in a matrix. By providing a plurality of types of LEDs having different colors of emitted light (that is, wavelengths of the emitted light) as the plurality of LEDs, the surface light source 10 can emit light of a plurality of different colors. Also, by providing a plurality of LEDs arranged in a matrix, a part of the light emitting surface 11 can be made into a light emitting region, and the light emitting region can be moved.

[0015] The camera 20 includes a detection unit 21 consisting of an image sensor such as a CCD (Charge-Coupled Device) sensor or a CMOS (Complementary Metal-Oxide-Semiconductor) sensor and an optical lens, and outputs the light input to the image sensor as a shooting signal (i.e., video data). The detection unit 21 of the camera 20 is positioned to face the light-emitting surface 11 across the water 30. The camera 20 outputs a shooting signal based on the light 12 emitted from the light-emitting surface 11 that travels through the water 30 without being obstructed by the object being observed 40 and reaches the detection unit 21. In addition, either an area sensor or a line sensor can be used as the camera 20.

[0016] Figure 3 is a block diagram showing the configuration of the control system of the silhouette imaging system 1. The silhouette imaging system 1 includes a control unit 50 as a control circuit for controlling the area light source 10 and the camera 20, and a display device 90 such as a liquid crystal display. In Embodiment 1, the control unit 50 controls the wavelength of the light 12 emitted from the area light source 10. For example, in Embodiment 1, the control unit 50 controls the wavelength of the light 12 emitted from the area light source 10 based on the image captured by the camera 20.

[0017] The control circuit includes, for example, a processor such as a CPU (Central Processing Unit), memory as a storage device, and an interface. The control circuit may be a dedicated processing circuit, or it may be a processor that executes a program stored in memory. The control circuit may be a mixture of components consisting of processing circuits and components consisting of processors. Furthermore, the control unit 50 may be a computer (for example, a desktop personal computer, a smartphone, a tablet terminal, etc.) that can communicate with the area light source 10 and the camera 20.

[0018] Light 12 emitted from the light-emitting surface 11 of the surface light source 10 toward the water 30 travels through the water 30 toward the water surface 32 and enters the camera 20 with the detection unit 21 facing downwards. At this time, the camera 20 captures an image in which the object of observation 40 does not exist. When the object of observation 40 (for example, a captive animal) is between the surface light source 10 and the camera 20, a portion of the light 12 emitted from the surface light source 10 is blocked, so the silhouette of the object of observation 40 appears in the image captured by the camera 20.

[0019] By placing the camera 20 in the water 30, the distance from the object to be observed 40 to the detection unit 21 of the camera 20 can be shortened. In this case, the effect of light scattering due to the turbidity of the water 30 can be suppressed, making it easier to obtain clear images. By placing the camera 20 in the water 30, for example, if the object to be observed 40 is a captive animal that prefers to stay at the bottom of the tank 31, or if it is a captive animal that moves along the bottom of the tank 31 in search of food that sinks in the water 30, a clear silhouette image can be obtained.

[0020] Furthermore, the control unit 50 can select the wavelength of the light 12 emitted from the surface light source 10 from two or more options. When the water 30 is not very turbid (i.e., the turbidity is low), the clarity of the silhouette is determined by the light transmittance of the water 30 itself, so it is desirable to use light with the wavelength that has the highest light transmittance of the water (for example, light in the range of approximately 450 nm to 500 nm) for the light 12 emitted from the light-emitting surface 11 of the surface light source 10. When the water 30 is not very turbid, for example, it is the case that the turbidity is less than or equal to that of seawater far offshore from land. Also, "using light in the range of 450 nm to 500 nm" means light in which the peak of the wavelength distribution is in the range of 450 nm to 500 nm.

[0021] Furthermore, if the water 30 is highly turbid (i.e., has high turbidity), from the standpoint of the wavelength sensitivity of the image sensor of the detection unit 21 of the camera 20, it is desirable that the light 12 emitted from the light-emitting surface 11 of the surface light source 10 be long-wavelength light that is less affected by turbidity (for example, light in the range of approximately 800 nm to 900 nm). Also, "light in the range of 800 nm to 900 nm" means light in which the peak of the wavelength distribution is in the range of 800 nm to 900 nm.

[0022] Furthermore, if the turbidity of the water 30 is moderate, it is desirable that the light 12 emitted from the surface light source 10 has the wavelength with the highest light transmittance in the superposition of the transmission characteristics of the water 30 and the turbidity particles. For example, if the water 30 is coastal seawater close to land, it is desirable that the light 12 emitted from the surface light source 10 has a wavelength in the range of approximately 500 nm to 550 nm. "Light in the range of 500 nm to 550 nm" means light whose wavelength distribution peak is in the range of 500 nm to 550 nm. The wavelength range of light 12 described above is merely an example of wavelengths that can be used, and is not limited to these ranges.

[0023] The degree of turbidity in the water 30, the type of turbidity in the water 30 (for example, the particle size and type of the turbidity-causing substances), and the light transmittance of the reared organisms (observation target 40) at each wavelength change depending on the number of days elapsed and the growth status of the reared organisms (observation target 40), and accordingly, the wavelength of the surface light source 10 that can obtain the clearest image changes. Generally, the longer the wavelength of light, the greater its ability to penetrate matter. Therefore, if the observation target 40 is a highly transparent juvenile fish, using long-wavelength light as light 12 will result in the silhouette of the juvenile fish being almost invisible, making it difficult to detect the silhouette of the juvenile fish. Thus, there is a trade-off relationship between measures to reduce the turbidity of the water 30 and the light transmittance of the observation target 40. The control unit 50 takes this trade-off relationship into consideration and selects light of the optimal wavelength as light 12. The control unit 50 may also select the optimal wavelength using a trained model obtained by machine learning using artificial intelligence (AI).

[0024] As described above, by using the silhouette imaging system 1 according to Embodiment 1, a surface light source 10 and a camera 20 as an imaging device can be used, so even if turbidity occurs in the water 30, a clear silhouette image of the object to be observed 40 can be obtained.

[0025] Furthermore, by using the silhouette imaging system 1 according to Embodiment 1, the wavelength of the light 12 emitted from the surface light source 10 can be adjusted. Therefore, even if turbidity occurs in the water 30, a clear silhouette image of the object to be observed 40 can be obtained by adjusting the wavelength of the light 12.

[0026] Modification 1 of Embodiment 1 The silhouette imaging system according to Modification 1 of Embodiment 1 differs from the silhouette imaging system 1 described with reference to Figures 1 to 3 in that the control unit 50 performs either emission intensity control, which periodically changes the intensity of the light 12 emitted from the light-emitting surface 11, or blinking control, which periodically turns the surface light source 10 on and off.

[0027] For example, in the silhouette imaging system according to Modification 1, by performing a flashing control that periodically repeats flashes of light for an extremely short duration of about 1 / 100th of a second, synchronized with the exposure timing of the camera 20, the intensity of light perceived by the observed subject 40 can be reduced. This control can reduce stress on the animals.

[0028] Alternatively, in the silhouette photography system according to Modification 1, by controlling the light intensity by gradually increasing the intensity of the light emitted from the light-emitting surface 11 before the start of shooting by the camera 20, and gradually decreasing the intensity of the light emitted from the light-emitting surface 11 after the end of shooting by the camera 20, it is possible to reduce stress on the animals due to sudden changes in light intensity.

[0029] By performing the above-described light intensity control or flashing control, it is possible to set the brightness change of the light-emitting surface 11 or the lighting time of the surface light source 10 so that the animals being observed (40) cannot be recognized or have little effect on them, thereby reducing the stress on the animals being raised.

[0030] With respect to matters other than those described above, the silhouette imaging system according to Modification 1 of Embodiment 1 is the same as the silhouette imaging system 1 described with reference to Figures 1 to 3.

[0031] Modification 2 of Embodiment 1 Figure 4 is a schematic perspective view showing the surface light source of a silhouette imaging system according to Modification 2 of Embodiment 1. The silhouette imaging system according to Modification 2 of Embodiment 1 differs from the silhouette imaging system 1 described using Figures 1 to 3 in that the light-emitting surface 11 of the surface light source 10 further has a marker pattern 13 which is a predetermined mark. Modification 2 of Embodiment 1 shows an example in which four marker patterns 13 are provided near the corners of the light-emitting surface 11 of the surface light source 10 within the shooting range 22 of the camera 20. However, the number, shape, and position of the marker patterns 13 are not limited to the example in Figure 4.

[0032] In a modified example 2 of Embodiment 1, the marker pattern 13 is photographed for each emission wavelength while changing the emission wavelength of the surface light source 10, and by comparing the images of the obtained marker patterns 13, the wavelength at which the clearest image is obtained can be selected as the optimal wavelength.

[0033] In Modification 2 of Embodiment 1, the type of image processing or various parameters used in image processing can also be selected based on the video footage of the marker pattern 13. For example, in Modification 2 of Embodiment 1, the radius or intensity of the unsharp mask, which is a filter that has the effect of emphasizing the contours of the entire video or the subject to make them appear sharper, can be adjusted according to how the boundaries of the marker pattern 13 blur. Furthermore, the control unit 50 of Modification 2 of Embodiment 1 may use a trained model obtained by a machine learning method using AI to select the optimal wavelength of light 12 used for image processing such as sharpening (for example, processing using an unsharp mask), contrast correction, color correction, and animal detection.

[0034] Furthermore, by using the position and shape of the marker pattern 13 on the image, camera parameters consisting of external parameters such as the relative position and orientation of the camera 20 and the area light source 10, and internal parameters such as the focal length and distortion of the camera 20's lens, can be estimated and used for various image correction processes. As a result, even if the camera parameters change during operation, images with the same field of view can be acquired.

[0035] With respect to matters other than those described above, the silhouette imaging system according to the modified example 2 of Embodiment 1 is the same as the silhouette imaging system 1 described with reference to Figures 1 to 3.

[0036] Embodiment 2 Figure 5 is a schematic side view showing the configuration of the silhouette imaging system 2 according to Embodiment 2. In Figure 5, components identical to or corresponding to those shown in Figure 1 are denoted by the same reference numerals as those shown in Figure 1. Figure 6 is a block diagram showing the configuration of the control system of the silhouette imaging system 2. In Figure 6, components identical to or corresponding to those shown in Figure 3 are denoted by the same reference numerals as those shown in Figure 3.

[0037] The silhouette imaging system 2 according to Embodiment 2 differs from the silhouette imaging system 1 according to Embodiment 1 in that it has at least one of a turbidity measuring instrument 60 for measuring the turbidity of water 30 and a particle size measuring instrument 61 for measuring the particle size distribution of fine particles dispersed in the water 30, and that the control unit 50 changes (i.e., selects) the wavelength of light 12 emitted from the surface light source 10 based on at least one of the measured turbidity (amount of fine particles per unit volume) and particle size distribution (distribution of particle size).

[0038] By using the silhouette imaging system 2 according to Embodiment 2, the wavelength of the light 12 emitted from the surface light source 10 can be adjusted. Therefore, even if turbidity occurs in the water 30, a clear silhouette image of the object to be observed 40 can be obtained by adjusting the wavelength of the light 12.

[0039] Furthermore, by using the silhouette imaging system 2 according to Embodiment 2, the wavelength of light 12 emitted from the surface light source 10 can be adjusted based on the detection value of at least one of the turbidity meter 60 and the particle size meter 61 (i.e., at least one value of turbidity and particle size distribution), thus reducing the amount of information processing performed by the control unit 50 compared to Embodiment 1.

[0040] Furthermore, in the silhouette imaging system 2 according to Embodiment 2, if a particle size analyzer 61 is included, the cause of turbidity (turbidity due to leftover food, turbidity due to excrement, turbidity due to bacterial products, etc.) can be inferred from the size of the particles that cause turbidity in the water 30. Therefore, the wavelength of the light 12 emitted from the surface light source 10 can be adjusted to a wavelength suitable for the type of turbidity. As a result, a clear silhouette image of the object to be observed 40 can be obtained.

[0041] Embodiment 3 Figure 7 is a schematic side view showing the configuration of the silhouette imaging system 3 according to Embodiment 3. In Figure 7, components that are the same as or corresponding to those shown in Figure 1 are denoted by the same reference numerals as those shown in Figure 1. Figure 8 is a schematic perspective view showing the configuration of the silhouette imaging system 3.

[0042] Figure 9 is a block diagram showing the configuration of the control system of the silhouette imaging system 3. In Figure 9, components that are the same as or corresponding to those shown in Figure 3 are denoted by the same reference numerals as those shown in Figure 3.

[0043] The silhouette imaging system 3 according to Embodiment 3 differs from the silhouette imaging system 1 according to Embodiment 1 in that the control unit 50 estimates the position of the object to be observed 40 based on the imaging signal, partially illuminates the light-emitting surface 11, moves the partially illuminated light-emitting region 14 based on the position of the object to be observed 40, and includes a camera 70 as an imaging device for capturing the silhouette of the object to be observed 40. The camera 70 is the same as the camera 20 in Embodiment 1 or 2. In other words, in Embodiment 3, as shown in Figures 7 and 8, the control unit 50 moves the light-emitting region 14 according to the position of the object to be observed 40, irradiates the object to be observed 40 with light, and projects a silhouette image 73 onto the camera 70 through the lens 71. The camera 70 and lens 71 may be housed in a waterproof container 72. A transparent window made of glass or acrylic is formed on the surface of the waterproof container 72 facing the light-emitting surface 11.

[0044] By using the silhouette imaging system 3 according to Embodiment 3, the surface light source 10 selectively emits light from only a portion of the water 30, thus suppressing the effects of reflected and scattered light, and allowing the camera 70 to acquire a clear image.

[0045] With respect to matters other than those described above, the silhouette imaging system 3 according to Embodiment 3 is the same as the silhouette imaging system according to Embodiment 1 or 2.

[0046] Embodiment 4 Figure 10 is a schematic side view showing the configuration of the silhouette imaging system 4 according to Embodiment 4. In Figure 10, components that are the same as or corresponding to those shown in Figure 1 are denoted by the same reference numerals as those shown in Figure 1. Figure 11 is a schematic perspective view showing the configuration of the silhouette imaging system 4.

[0047] Figure 12 is a block diagram showing the configuration of the control system of the silhouette imaging system 4. In Figure 12, components that are the same as or corresponding to those shown in Figure 3 are denoted by the same reference numerals as those shown in Figure 3.

[0048] The silhouette imaging system 4 according to Embodiment 4 differs from the silhouette imaging system 1 according to Embodiment 1 in that the imaging device includes an area sensor or a line sensor 80 having a plurality of one-dimensionally arranged photoelectric conversion elements, and a line sensor moving unit 83 that moves the line sensor 80 in a predetermined direction 84, and the control unit 50 partially illuminates the light-emitting surface 11 and moves the partially illuminated light-emitting region 14 in the same direction 85 as direction 84. In other words, in Embodiment 4, as shown in Figures 10 and 11, the waterproof container 82 housing the line sensor 80 and the optical lens 81 is moved in a direction 84 perpendicular to the longitudinal direction of the line sensor 80, and the partially illuminated light-emitting region (a line-shaped region corresponding to the line sensor 80) is moved in the same direction 85 as direction 84 according to the position of the moving line sensor 80, thereby capturing the silhouette of the object to be observed 40. The light-emitting region may be illuminated only in the area being exposed, synchronized with the scanning of the line sensor or the exposure timing of the rolling shutter of the area sensor. In summary, the control unit 50 synchronizes the scanning by the line sensor 80 with the movement of the light-emitting area on the light-emitting surface 11.

[0049] By using the silhouette imaging system 4 according to Embodiment 4, the surface light source 10 selectively emits light from only a portion of the water 30, thereby suppressing the effects of reflected and scattered light, and enabling the line sensor 80 to acquire a clear image.

[0050] Figure 13 is a schematic perspective view showing the configuration of a silhouette imaging system 4a according to a modified example of Embodiment 4. Figure 14 is a block diagram showing the configuration of the control system of the silhouette imaging system 4a according to a modified example of Embodiment 4. The silhouette imaging system 4a includes a surface light source 10, an area sensor 80a as an imaging device having a rolling shutter function, and a control unit 50a. The surface light source 10 and the area sensor 80a may be placed near the outside or inside of the side surface of the water tank 31, with the water 30 in between.

[0051] The area sensor 80a is an imaging device having a two-dimensional arrangement of multiple photoelectric conversion elements and a rolling shutter exposure function. The control unit 50a is a control device that partially illuminates the light-emitting surface 11 and controls the partially illuminated light-emitting region 15 to move in the direction of the arrow (direction 85) in accordance with the movement of the position of the area being exposed by the area sensor 80a (direction of arrow 86).

[0052] In the silhouette imaging system 4a, as shown in Figures 12 and 13, the light-emitting area 15 of the light-emitting surface 11 is moved in the direction of the arrow (direction 85), and in synchronization with this movement, the position of the area being exposed on the area sensor 80a is moved in the direction of arrow 86 using rolling shutter control. By using the silhouette imaging system 4a, since the surface light source 10 selectively emits light from only a portion of it, the effects of reflected and scattered light in the water 30 are suppressed, and the area sensor 80a can acquire a clear image.

[0053] With respect to matters other than those described above, the silhouette imaging system 4 according to Embodiment 4 and the silhouette imaging system 4a according to a modified example of Embodiment 4 are the same as the silhouette imaging system according to any of Embodiments 1 to 3. [Explanation of Symbols]

[0054] 1-4, 4a Silhouette imaging system, 10 Surface light source, 11 Light-emitting surface, 12 Light, 13 Marker pattern, 20 Camera (imaging device), 21 Detection unit, 22 Imaging range, 30 Water, 31 Water tank, 32 Water surface, 40 Object to be observed, 50 Control unit, 60 Turbidity meter, 61 Particle size analyzer, 70 Camera (imaging device), 80 Line sensor (imaging device), 80a Area sensor (imaging device), 90 Display device.

Claims

1. A silhouette photography system that captures the silhouette of an object underwater, A surface light source having a light-emitting surface, A photographic device having a detection unit positioned to face the light-emitting surface with the water in between, and outputting a photographic signal based on the light that travels through the water without being obstructed by the object being observed and reaches the detection unit from the light-emitting surface, A control unit that controls the surface light source and the imaging device, The device comprises a marker pattern provided within the shooting range of the aforementioned shooting device, The control unit changes the wavelength of the light emitted from the light-emitting surface based on the imaging signal obtained by photographing the marker pattern. A silhouette photography system characterized by the following features.

2. A silhouette photography system that captures the silhouette of an object underwater, A surface light source having a light-emitting surface, A photographic device having a detection unit positioned to face the light-emitting surface with the water in between, and outputting a photographic signal based on the light that travels through the water without being obstructed by the object being observed and reaches the detection unit from the light-emitting surface, The system comprises a control unit that controls the surface light source and the imaging device, The control unit, Based on the aforementioned imaging signal, the position of the object to be observed is estimated. The aforementioned light-emitting surface is partially illuminated, Based on the position of the object being observed, the partially emitting light-emitting region is moved. A silhouette photography system characterized by the following features.

3. The aforementioned imaging device is an area sensor having a plurality of photoelectric conversion elements arranged in a two-dimensional array. The silhouette shooting system according to claim 1 or 2, characterized by the above.

4. A silhouette photography system that captures the silhouette of an object underwater, A surface light source having a light-emitting surface, A photographic device having a detection unit positioned to face the light-emitting surface with the water in between, and outputting a photographic signal based on the light that travels through the water without being obstructed by the object being observed and reaches the detection unit from the light-emitting surface, The system comprises a control unit that controls the surface light source and the imaging device, The imaging device includes a line sensor having a plurality of photoelectric conversion elements arranged in one dimension, and a line sensor moving unit that moves the line sensor in a predetermined direction. The control unit, The aforementioned light-emitting surface is partially illuminated, The partially illuminated light-emitting region is moved according to the position of the moving line sensor. A silhouette photography system characterized by the following features.

5. A silhouette photography system that captures the silhouette of an object underwater, A surface light source having a light-emitting surface, A photographic device having a detection unit positioned to face the light-emitting surface with the water in between, and outputting a photographic signal based on the light that travels through the water without being obstructed by the object being observed and reaches the detection unit from the light-emitting surface, The system comprises a control unit that controls the surface light source and the imaging device, The aforementioned imaging device is an area sensor having a plurality of photoelectric conversion elements arranged in a two-dimensional array and a rolling shutter exposure function, The control unit, The aforementioned light-emitting surface is partially illuminated, The light-emitting region that partially emits light is moved according to the position of the area being exposed by the area sensor. A silhouette photography system characterized by the following features.

6. The control unit performs light intensity control, which periodically changes the intensity of the light emitted from the light-emitting surface, or blinks the surface light source, which periodically turns on and off. A silhouette imaging system according to any one of claims 1, 2, 4, and 5.

7. The aforementioned surface light source is positioned with its light-emitting surface facing upwards. The imaging device is positioned with the detection unit facing downwards. A silhouette imaging system according to any one of claims 1, 2, 4, and 5.

8. The system further comprises a water tank for containing the aforementioned water, The aforementioned surface light source is positioned below the bottom surface of the aquarium with its light-emitting surface facing upwards. The aforementioned imaging device is positioned above the water tank with the detection unit facing downwards. A silhouette imaging system according to any one of claims 1, 2, 4, and 5.

9. The water may be freshwater or seawater. The object of observation is an animal or plant in the water. A silhouette imaging system according to any one of claims 1, 2, 4, and 5.

10. The system further includes a display device that displays images based on the aforementioned shooting signal. A silhouette imaging system according to any one of claims 1, 2, 4, and 5.

Images