Patent Description:
Conventionally, an apparatus for measuring size of a fish by imaging the fish swimming in water is well known in the prior art. In this type of device, a side of the fish is illuminated by light during imaging. For example, a Light Emitting Diode (LED) is placed around a camera to illuminate the fish in the imaging direction. A device of this kind is disclosed in the following European Patent document: <CIT>.

However, in inland aquaculture, a fish cage is installed under indoor conditions, thus natural light is less likely to enter the water from the water surface than in marine aquaculture. Therefore, in the above-described configuration in which the fish is illuminated in the imaging direction, the brightness of an upper part of a body of the fish is likely to be insufficient. To solve this problem, when illumination intensity is increased, the brightness of a lower part of the body of the fish becomes excessive, and it becomes difficult to accurately acquire characteristic features of the fish from an image of the fish. In inland aquaculture, background in the imaging direction is often dark or has a special color or pattern. Therefore, in the captured image, boundary between the fish and the background is unclear, and the characteristic features of the fish may not be accurately acquired. Further, when density of the fish is high in the fish cage, it is difficult to secure a distance between the fish and the camera, necessary for measuring the fish.

In view of these problems, it is an object of the present invention to provide a fish measuring device and a fish measuring method capable of accurately measuring a fish from a captured image.

<CIT> discloses a multi-chamber lighting controller for aquaculture. An imaging station is used to capture an image of a fish. Pairs of imaging assemblies coordinate pulsing light of a first and a second color and capturing images of the fish while the fish is illuminated by the first and the second color. In one embodiment, a tube feeds into a multi-chamber fish imaging station.

According to one aspect of the invention there is provided a fish measuring device as defined in claim <NUM>.

According to another aspect of the invention there is provided a fish measuring method as defined in claim <NUM>.

Preferred features of the invention are recited in the dependent claims.

In the fish measuring device, the fish pass is illuminated from above by the first illuminating device, and the fish pass is illuminated from side by the second illuminating device. Therefore, both an upper part and a lower part of the body of the fish may be well illuminated by adjusting illumination intensity and illumination ratio of the first illuminating device and the second illuminating device according to fish species. Further, the background board is arranged in the field of view of the imaging device, and therefore the contrast between the fish and the background is enhanced. Further, the portion of the fish pass on the imaging device side is blocked by the fish blocking device, therefore the number of fish included in an imaging region may be reduced even when a density of fish is high, and a distance necessary for measuring the fish may be secured between the fish and the imaging device. Thus, a high-quality fish image may be acquired, and the fish swimming in the water may be accurately measured.

In the fish measuring device, according to the first aspect, the fish blocking device may be placed in the fish pass such that the shortest distance between the background board and the fish blocking device is smaller than the shortest distance between the background board and the imaging device.

According to this configuration, the fish may be easily separated from the imaging device by a difference between the shortest distance between the background board and the fish blocking device and the shortest distance between the background board and the imaging device.

In the fish measuring device, according to the present aspect, the fish blocking device includes one or more boards.

The board and a direction in which the imaging device faces make an oblique angle in a plan view.

In the plan view, the board is closer to an entrance of the fish pass on the background board side than on the imaging device side.

According to this configuration, the fish entering the imaging region through a space between the first board and the background board may be separated from the imaging device.

Preferably, the board may include one or more holes for water to flow. Thus, resistance of water flow to the board may be reduced.

In the fish measuring device, according to the present aspect, the fish blocking device may further include a second board different from the first board. The second board and the direction in which the imaging device faces may make a second oblique angle in a plan view.

In this case, in the plan view, the second board may be closer to an exit of the fish pass on the background board side than on the imaging device side.

According to this configuration, the fish, which passes through the imaging region towards the space between the second board and the background board, may be separated from the imaging device.

Preferably, the second board may include one or more holes for water to flow. Thus, resistance of the water flow to the second board may be reduced.

In the fish measuring device, according to the present aspect, the imaging device may substantially face in a horizontal direction. The second illuminating device may illuminate at least in a direction substantially the same as the direction in which the imaging device faces.

According to present aspect, the fish swimming in the pass may be illuminated in the imaging direction by the second illuminating device.

In the fish measuring device, according to the present aspect, the second illuminating device may include an array of a plurality of light emitting diodes (LEDs) grouped into a first group and a second group, wherein the first group illuminates horizontally and the second group illuminates in a different illumination direction than the first group.

According to this configuration, the fish swimming in the pass may be horizontally illuminated by the second illuminating device and may be illuminated in a direction different from the horizontal direction.

The illumination direction of the second group may be vertical. Thus, the fish swimming in the pass may be vertically illuminated by the first illuminating device and the second group of the second illuminating device.

The fish measuring device, according to the present aspect, may further include a frame on which the imaging device, the background board, the first illuminating device, the second illuminating device, and the fish blocking device are attached, and a rail to vertically move the frame.

According to this configuration, by moving the frame along the rail, the imaging device, the background board, the first illuminating device, the second illuminating device, and the fish blocking device, may be moved integrally in a depth direction. Therefore, the fish pass and an imaging position of the fish may be positioned at a depth position suitable for the fish species to be measured.

In the fish measuring device, according to the present aspect, the processing circuitry may be configured to calculate a size of the fish swimming in the fish pass from the captured image.

According to this configuration, the size of the fish may be calculated with high accuracy based on high-quality fish images.

In the fish measuring method, according to the second aspect, the same effect as that of the fish measuring device, according to the first aspect, may be achieved.

As described above, according to the present invention, it is possible to provide a fish measuring device and a fish measuring method capable of accurately measuring a fish from a captured image.

The effect or significance of the present disclosure will become more apparent from the description of the following embodiments. However, the following embodiments are only example embodiments of the present disclosure, and the present disclosure is not limited to those examples described in the following embodiments.

Embodiments of the present disclosure will be described below with reference to the drawings. In the embodiments, a fish measuring device is installed in an indoor fish cage. For convenience, XYZ axes orthogonal to each other are appropriately appended to the drawings. The X-axis direction and Y-axis direction are horizontal, and the Z-axis direction is vertical. The positive X-axis direction is the direction in which fish move.

<FIG> is a perspective view of a fish measuring device <NUM>. <FIG> and <FIG> are side views of the fish measuring device <NUM> when viewed in the X-axis positive direction and the X-axis negative direction, respectively.

As shown in <FIG>, the fish measuring device <NUM> may include a support frame <NUM> (which may also be referred to as frame <NUM>), a lifting device <NUM>, an imaging device <NUM>, a first illuminating device <NUM>, a second illuminating device <NUM>, a background board <NUM>, a fish blocking device <NUM>, and a processing unit <NUM>.

A fish pass A1 is formed between the imaging device <NUM> and the background board <NUM> by arranging the background board <NUM> opposite to the imaging device <NUM>. The first illuminating device <NUM> illuminates the fish pass A1 from above. The second illuminating device <NUM> illuminates the fish pass A1 from a side of the imaging device <NUM>. The fish blocking device <NUM> secures a distance between the imaging device <NUM> and the fish by blocking a part of the fish pass A1 on the imaging device <NUM> side.

The support frame <NUM> includes an upper frame <NUM> and a lower frame <NUM>. The lifting device <NUM> includes a pair of rails <NUM> arranged in the X-axis direction, and protrusions <NUM>, <NUM>. The protrusion <NUM> projects in the negative Y-axis direction from the center of a beam connecting upper ends of the pair of rails <NUM> in the X-axis direction. The protrusion <NUM> projects in the positive Y-axis direction from the center of a beam connecting lower ends of the pair of rails <NUM> in the X-axis direction. The upper frame <NUM> and the lower frame <NUM> may be supported by the pair of rails <NUM> to be movable in the vertical direction by a plurality of guide rollers <NUM> and a plurality of guide rollers <NUM>.

As shown in <FIG>, the fish measuring device <NUM> is installed in a fish cage <NUM> by hanging the protrusion <NUM> on an edge of the fish cage <NUM>. The protrusion <NUM> may be fixed to the edge of the fish cage <NUM> by a predetermined fixing tool. The support frame <NUM> may be submerged in water from a water surface <NUM> while being guided by the lifting device <NUM>. In this state, the lifting device <NUM> may be separated from a net 2a of the fish cage <NUM> by a predetermined distance. A user moves a rope <NUM> to position the imaging device <NUM> at a depth where the fish to be measured swim. Thereafter, the user fixes the rope <NUM> to the edge of the fish cage <NUM>. Thus, the installation of the fish measuring device <NUM> is completed.

The water in the fish cage <NUM> may be flowed in the X-axis negative direction by a water flow device. Thus, the fish in the fish cage <NUM> swim in the X-axis positive direction. When swimming, a part of the fish in the fish cage <NUM> passes through the fish pass A1. Thus, the fish may be imaged by the imaging device <NUM>. The captured fish image may be transmitted from the processing unit <NUM> to a terminal (not shown) on the fish cage <NUM> via a communication cable (not shown). Thus, a size of the fish may be measured at the terminal from the image of the fish. The direction in which the water in the fish cage <NUM> flows is not limited to the X-axis negative direction and may be the X-axis positive direction.

<FIG> is a perspective view showing a configuration of the support frame <NUM> and the lifting device <NUM>.

The upper frame <NUM> may be integrally provided with two arch portions 11a, an arch portion 11b, and a loop portion 11c. In a plan view, the loop portion 11c may be a rectangle long in the Y-axis direction. The two arch portions 11a are formed in parallel in the Y-axis direction to straddle two long sides of the loop portion 11c. The two arch portions 11a are rectangular when viewed in the Y-axis direction. The two arch portions 11a have the same shape. The arch portion 11b may be formed in the center of the short side of the Y-axis negative side of the loop portion 11c. The arch portion 11b is rectangular when viewed in the Y-axis direction. The arch portion 11b has the same height as the two arch portions 11a, and its width in the X-axis direction is narrower than that of the two arch portions 11a.

The lower frame <NUM> may be integrally provided with two beam portions 12a, a loop portion 12b, two protrusions 12c, and a plate portion 12d. When viewed in the Y-axis direction, the loop portion 12b may be a rectangle long in the X-axis direction. The two beam portions 12a are formed side by side in the X-axis direction to connect the two long sides of the loop portion 12b. The two protrusions 12c may protrude in the Y-axis positive direction from the upper two corners of the loop portion 12b. The plate portion 12d is formed to connect the two long sides of the loop portion 12b. The Y-axis positive side surface of the plate portion 12d is included in the same plane as the Y-axis positive side surface of the loop portion 12b. The Y-axis negative side of the plate portion 12d protrudes from the Y-axis negative side surface of the loop portion 12b.

The upper frame <NUM> is symmetrical in the X-axis direction and symmetrical in the Y-axis direction. The lower frame <NUM> is symmetrical in the X-axis direction and symmetrical in the Z-axis direction. The upper frame <NUM> and the lower frame <NUM> are constituted of a material having high rigidity and hardly rusting. The upper frame <NUM> and the lower frame <NUM> are made of, for example, a metal material such as stainless steel (SUS). The cross sections of the upper frame <NUM> and the lower frame <NUM> are substantially square. The pair of rails <NUM>, the protrusion <NUM>, and the protrusion <NUM> of the lifting device <NUM> are also made of a material having high rigidity such as SUS and hard to rust. The cross sections of the pair of rails <NUM> are substantially square.

In the upper frame <NUM>, two guide rollers <NUM> of the plurality of guide rollers <NUM> are installed on the X-axis positive side of the arch portion 11b, and two guide rollers <NUM> of the plurality of guide rollers <NUM> are installed on the X-axis negative side of the arch portion 11b. The plurality of guide rollers <NUM> may include a pair of rollers 24a arranged in the Y-axis direction. The pair of rollers 24a sandwich the pair of rails <NUM> in the Y-axis direction. Thus, the upper frame <NUM> is supported by the pair of rails <NUM> to be movable in the vertical direction while being restricted from moving in the Y-axis direction.

Further, two guide rollers <NUM> are provided on the Y-axis negative side of the loop portion 11c. The guide roller <NUM> includes one roller 25a. Of the two guide rollers <NUM> installed on the loop portion 11c, the roller 25a of the guide roller <NUM> on the X-axis positive side abuts on the X-axis positive side surface of the rail <NUM> on the X-axis positive side, and the roller 25a of the guide roller <NUM> on the X-axis negative side abuts on the X-axis negative side surface of the rail <NUM> on the X-axis negative side. Thus, the upper frame <NUM> is supported by the pair of rails <NUM> to be movable in the vertical direction while being restricted from moving in the X-axis direction.

In the lower frame <NUM>, two guide rollers <NUM> of the plurality of guide rollers <NUM> are installed on the beam portion 12a on the X-axis positive side, and two guide rollers <NUM> of the plurality of guide rollers <NUM> are installed on the beam portion 12a on the X-axis negative side. The pair of rails <NUM> are sandwiched in the Y-axis direction by the pair of rollers 24a of the plurality of guide rollers <NUM>. Thus, the lower frame <NUM> is supported by the pair of rails <NUM> to be movable in the vertical direction while being restricted from moving in the Y-axis direction.

Further, two guide rollers <NUM> are installed on the upper side of the loop portion 12b. Among the guide rollers <NUM>, the roller 25a of the guide roller <NUM> on the X-axis positive side abuts on the X-axis positive side surface of the rail <NUM> on the X-axis positive side, and the roller 25a of the guide roller <NUM> on the X-axis negative side abuts on the X-axis negative side surface of the rail <NUM> on the X-axis negative side. Thus, the lower frame <NUM> is supported by the pair of rails <NUM> to be movable in the vertical direction while being restricted from moving in the X-axis direction.

Thus, the upper frame <NUM> and the lower frame <NUM> are supported on the pair of rails <NUM> by the plurality of guide rollers <NUM> and the plurality of guide rollers <NUM>, to be movable in the vertical direction. A downward movement of the lower frame <NUM> is regulated by the protrusion <NUM>. That is, the lower surface of the loop portion 12b is brought into contact with the upper surface of the protrusion <NUM>, thereby preventing the lower frame <NUM> from slipping downward from the lifting device <NUM>.

The upper frame <NUM> is supported by the two protrusions 12c of the lower frame <NUM>. In this state, the Y-axis negative side of the loop portion 11c and the upper side of the loop portion 12b are bound together at position B1, for example. Thus, the upper frame <NUM> and the lower frame <NUM> are unified. The rope <NUM> is connected to the upper side of the arch portion 11b. Thus, the support frame <NUM> may be moved upward by lifting the rope <NUM> upward.

Note that the lifting device <NUM> does not have a structure for restricting upward movement of the support frame <NUM>. Therefore, the support frame <NUM> may be easily removed from the lifting device <NUM>. The support frame <NUM> may be easily mounted on the lifting device <NUM> by introducing the pair of rails <NUM> into the plurality of guide rollers <NUM> and the plurality of guide rollers <NUM> from the top.

<FIG> is a perspective view showing a structure of the fish measuring device <NUM> shown in <FIG> without the lifting device <NUM>, the background board <NUM> and the fish blocking device <NUM>.

The imaging device <NUM> includes two cameras <NUM>, <NUM> arranged in the X-axis direction. The cameras <NUM> and <NUM> constitute a stereo camera for measuring the size of the fish. The cameras <NUM> and <NUM> may be attached to the lower frame <NUM> via a support plate <NUM>. That is, the support plate <NUM> is disposed on the plate portion 12d of the lower frame <NUM>, and the cameras <NUM> and <NUM> are disposed on the lower surface of the support plate <NUM>. The support plate <NUM> is made of a material such as SUS having high rigidity and hard to rust.

Imaging directions of the cameras <NUM> and <NUM> are substantially horizontal. The imaging direction of the camera <NUM> is inclined in the X-axis positive direction by a predetermined angle from the Y-axis positive direction. The imaging direction of the camera <NUM> is inclined in the X-axis negative direction by a predetermined angle from the Y-axis positive direction. The inclination angles of the cameras <NUM> and <NUM> in the imaging direction with respect to the Y-axis direction, are the same.

The first illuminating device <NUM> includes two lighting units <NUM>, <NUM> arranged in the X-axis direction. The lighting unit <NUM> includes a pair of LED arrays 41a extending in the Y-axis direction and a flat base plate 41b supporting the pair of LED arrays 41a. In the LED array 41a, a plurality of LEDs (Light Emitting Diodes) may be arranged side by side in the Y-axis direction. Each LED emits white light at a predetermined spread angle. The base plate 41b is composed of a rust-resistant material. When the base plate 41b is mounted on the lower surfaces of the two arch portions 11a of the upper frame <NUM>, the lighting unit <NUM> is installed on the upper frame <NUM>.

The lighting unit <NUM> has the same configuration as the lighting unit <NUM>. The lighting unit <NUM> includes a pair of LED arrays 42a extending in the Y-axis direction and a flat base plate 42b supporting the LED arrays 42a. In the LED array 42a, a plurality of LEDs is arranged side by side in the Y-axis direction. When the base plate 42b is mounted on the lower surfaces of the two arch portions 11a of the upper frame <NUM>, the lighting unit <NUM> of the two lighting units <NUM>, <NUM> is installed on the upper frame <NUM>.

The second illuminating device <NUM> includes two lighting units <NUM>, <NUM> arranged in the X-axis direction. A lighting unit <NUM> may include <NUM> pairs of LED arrays 51a, 51b, 51c extending in parallel with each other, and a flat base plate 51d supporting the LED arrays 51a, 51b, 51c. In the LED arrays 51a, 51b, and 51c, a plurality of LEDs is arranged side by side in the direction in which the LED arrays extend. Each LED emits white light at a predetermined spread angle. The base plate 51d is bent in two steps at two bending lines parallel to the X axis. The base plate 51d is composed of a rust-resistant material.

The pair of LED arrays 51a is disposed in a portion of the base plate 51d parallel to the X-Z plane. The pair of LED arrays 51b is disposed in a portion of the base plate 51d parallel to the X-Y plane. The pair of LED arrays 51c is disposed in a portion of the base plate 51d inclined with respect to the X-Z plane and the X-Y plane. Therefore, the plurality of LEDs arranged in the lighting unit <NUM> is divided into a first group included in the pair of LED arrays 51a, a second group included in the pair of LED arrays 51b, and a third group included in the pair of LED arrays 51c by the two bending lines.

The portion parallel to the X-Z plane of the base plate 51d is installed on the front surface of the X-axis negative side of the loop portion 12b, and the portion parallel to the X-Y plane of the base plate 51d is installed on the lower surface of one of the two protrusions 12c on the X-axis negative side. Thus, the lighting unit <NUM> is installed on the lower frame <NUM>.

The lighting unit <NUM> has a configuration similar to that of the lighting unit <NUM>. The lighting unit <NUM> includes <NUM> pairs of LED arrays 52a, 52b, 52c extending in parallel with each other, and a flat base plate 52d supporting the LED arrays. The installation method of the lighting unit <NUM> is the same as that of the lighting unit <NUM>. The base plate 52d bent in two steps is installed on the Y-axis positive side surface of the X-axis positive side loop portion 12b of the lower frame <NUM> and the lower surface of one of the two protrusions 12c on the X-axis positive side, whereby the lighting unit <NUM> is installed on the X-axis positive side end part of the lower frame <NUM>. The plurality of LEDs arranged in the lighting unit <NUM> is divided into a first group included in the pair of LED arrays 52a, a second group included in the pair of LED arrays 52b, and a third group included in the pair of LED arrays 52c.

An illumination direction of the pair of LED arrays 51a, 52a (first group of LEDs) is substantially horizontal (positive Y-axis direction). An illumination direction of the pair of LED arrays 51b, 52b (second group of LEDs) is substantially vertically down (negative Z-axis direction). An illumination direction of the pair of LED arrays 51c, 52c (third group of LEDs) is a direction inclined vertically downward by a predetermined angle (for example <NUM>°) from the horizontal direction (Y-axis positive direction).

The processing unit <NUM> may be installed on the upper surface of the support plate <NUM>. The processing unit <NUM> may be constituted by housing a circuit board in a box provided with a waterproof structure. Processing circuitry for controlling the imaging device <NUM>, the first illuminating device <NUM>, and the second illuminating device <NUM>, and a communication interface for communicating with the terminal installed on land outside the fish cage are mounted on the circuit board. The processing unit <NUM> and the terminal are connected by a communication cable (not shown).

<FIG> is a perspective view showing an installation state of the background board <NUM> with respect to the upper frame <NUM>.

The background board <NUM> may be installed on the upper frame <NUM> via a support plate <NUM>. That is, the support plate <NUM> is provided on the Y-axis positive side surface of the loop portion 11c of the upper frame <NUM>, and the background board <NUM> is provided on the Y-axis negative side surface of the support plate <NUM>. The support plate <NUM> is composed of a metal material having high rigidity and hardly rusting. The background board <NUM> is a plate-like part having a uniform thickness. The background board <NUM> is made of a rust-resistant material such as resin. The background board <NUM> is disposed on the upper frame <NUM> so that its Y-axis negative side surface is perpendicular to the Y-axis direction.

The background board <NUM> is plain and has a uniform color. As a color of the background board <NUM>, a color having a high contrast with the fish on the captured image is selected. For example, when target fish species is mackerel, white may be selected as the color of the background board <NUM>.

<FIG> is an enlarged perspective view of the structure of the fish measuring device <NUM> in the vicinity of the support frame <NUM>. <FIG> is a plan view showing a configuration near the support frame <NUM>.

The fish blocking device <NUM> includes a first board <NUM> and a second board <NUM> arranged in the X-axis direction. The first board <NUM> is disposed at the X-axis negative end of the upper surface of the support plate <NUM>, and the second board <NUM> is disposed at the X-axis positive end of the upper surface of the support plate <NUM>.

The first board <NUM> and the second board <NUM> are formed with a plurality of circular holes 71a and 72a (see <FIG> for the holes 72a) for allowing water to flow. The holes 71a and 72a need not necessarily be plural and may not be circular. For example, only one large rectangular hole that a fish cannot pass through may be formed near the center of the first board <NUM> and the second board <NUM>.

As shown in <FIG>, the imaging directions of the cameras <NUM> and <NUM> are inclined in opposite directions from each other by the same angle from the Y-axis direction. However, the direction in which the imaging device <NUM> faces is the positive direction of the Y-axis. That is, a direction connecting a middle position between the cameras <NUM> and <NUM> in the X-axis direction and a middle position in the X-axis direction in a range where fields of view FV1 and FV2 of the cameras <NUM> and <NUM> overlap is a direction towards which the imaging device <NUM> faces. Therefore, the direction in which the imaging device <NUM> faces is the positive direction of the Y-axis.

In a plan view, the first board <NUM> and the direction in which the imaging device <NUM> faces form a first oblique angle θ1, and the second board <NUM> and the direction in which the imaging device <NUM> faces form a second oblique angle θ2. The first oblique angle θ1 and the second oblique angle θ2 are not <NUM> nor <NUM> degrees with respect to the direction in which the imaging device <NUM> faces. Here, the first oblique angle θ1 and the second oblique angle θ2 are the same. However, the first oblique angle θ1 and the second oblique angle θ2 may be different from each other.

In a plan view, the first board <NUM> is closer to an entrance A11 of the fish pass A1 on the background board <NUM> side than on the imaging device <NUM> side, and the second board <NUM> is closer to an exit A12 of the fish pass A1 on the background board <NUM> side than on the imaging device <NUM> side. That is, the farther from the imaging device <NUM>, the longer the distance between the first board <NUM> and the second board <NUM> in the X-axis direction is, and therefore, the first board <NUM> and the second board <NUM> are in a state of opening to the outside.

The fish blocking device <NUM> may be arranged in the fish pass A1 so that the shortest distance D2 between the background board <NUM> and the fish blocking device <NUM> (the first board <NUM> and the second board <NUM>) is smaller than the shortest distance D1 between the background board <NUM> and the imaging device <NUM>. The background board <NUM> has a size such that the background board <NUM> is at least partially arranged in the fields of view FV1 and FV2 of the imaging device <NUM>.

<FIG> is a diagram schematically showing an operation of the fish blocking device <NUM>. <FIG> is a diagram schematically showing a state in which the fish blocking device <NUM> is not used (comparative example).

As shown in <FIG>, when the fish blocking device <NUM> (first board <NUM>, second board <NUM>) is installed, fish F1 swim in the X-axis positive direction through a space of the fish pass A1 between the fish blocking device <NUM> and the background board <NUM>. Thus, a distance between the fish F1 and the imaging device <NUM> is secured.

On the other hand, as shown in <FIG>, when the fish blocking device <NUM> (first board <NUM>, second board <NUM>) is not installed, the fish F1 swim in an entire width range of the fish pass A1. Therefore, the distance between the fish F1 and the imaging device <NUM> cannot be secured, and the fish F1 are too close to the imaging device <NUM>.

<FIG> is a diagram schematically showing a captured image P1 of the camera <NUM> in the case where the fish blocking device <NUM> is installed. <FIG> illustrates a diagram schematically showing the captured image P1 of the camera <NUM> in the case where the fish blocking device <NUM> is not installed (comparative example).

As shown in <FIG>, when the fish blocking device <NUM> is installed, the distance between the fish F1 and the imaging device <NUM> is secured at a distance that is preferable for imaging the fish, so that a whole fish image P11 is easily included in the captured image P1. Since the number of fish swimming in the fish pass A1 is limited by the fish blocking device <NUM>, the fish images P11 are easily separated from each other in the captured image P1. Therefore, an area of the fish indicated by the broken line may be smoothly extracted from the captured image P1, and the characteristic features of the fish may be smoothly calculated.

On the other hand, in the case where the fish blocking device <NUM> is not installed, since the distance between the fish F1 and the imaging device <NUM> is not secured, an image P12 of a fish approaching the imaging device <NUM> occupies a large area in the captured image P1, as shown in <FIG>. In this case, the fish is too close to the camera <NUM> to be hardly included in the field of view of the camera <NUM>. Since most of that fish is included only in the field of view of the camera <NUM>, it is difficult for the other camera <NUM> to capture it. Therefore, it is difficult to measure the size of the fish by the parallax of the stereo camera.

Also, since fish behind that fish are hidden by that fish, it is difficult to capture an overall image. Furthermore, in the absence of the fish blocking device <NUM>, since the number of fish swimming in the fish pass A1 is not limited, the pass A1 is densely populated with fish. Therefore, as shown in <FIG>, the fish overlap each other in the captured image P1, making it difficult to acquire a whole fish image of another fish. Therefore, it is difficult to measure the size of fish from images of other fish.

As described above, according to the fish measuring device <NUM> having the structure according to the present embodiment, by installing the fish blocking device <NUM>, captured images suitable for measuring fish size may be acquired by the cameras <NUM> and <NUM> (imaging device <NUM>). Therefore, the size of the fish may be properly measured from the captured images of the cameras <NUM> and <NUM>.

<FIG> is a diagram schematically showing a captured image P1 in a case where the background board <NUM> is omitted from the configuration of the present embodiment (another comparative example).

As shown in <FIG>, without the background board <NUM>, fish overlap in the Y-axis direction and background is dark, which makes it difficult to extract the fish image P11 from the captured image P1. On the other hand, when the background board <NUM> is installed, as shown in <FIG>, the number of fish to be imaged is limited, and contrast between background of the imaged fish and the fish is increased. Therefore, the fish image P11 may be properly extracted from the captured image P1. Thus, the size of fish may be properly measured from the image P11 of the fish.

<FIG> is a diagram schematically showing a captured image P1 in a case where the first illuminating device <NUM> is omitted from the configuration of the present embodiment (still another comparative example).

As shown in <FIG>, in the absence of the first illuminating device <NUM>, indoor light may hardly reach to the depth of the imaging device <NUM>. As a result, the entire captured image P1 is darkened, and the back of the fish is darkened in the fish image P11. Therefore, the fish image P11 may not be properly extracted from the captured image P1.

Further, when an amount of light from the second illuminating device <NUM> is increased, the above problem is solved, but the side surface and the belly of the fish become too bright, and halation occurs. For this reason, the characteristic features located where the halation occurs are lost, and the measurement of the fish may not be properly performed.

On the other hand, when the first illuminating device <NUM> is installed, the fish pass A1 may be illuminated from above. Therefore, as shown in <FIG>, the captured image P1 that is bright as a whole and the fish image P11 with bright fish back, may be acquired. Thus, the size of the fish may be properly measured from the image P11 of the fish.

In the configuration of the present embodiment, light amounts of the first illuminating device <NUM> and the second illuminating device <NUM> may be adjusted to obtain a good fish image P11 and avoid halation. The adjustment may be changed according to the kind of fish stored in the fish cage <NUM>, that is, the kind of fish to be measured. Thus, the fish may be appropriately measured from the captured image according to the fish species.

<FIG> is a block diagram showing a configuration of the fish measuring device <NUM>.

The processing unit <NUM> may include processing circuitry <NUM> and a communication interface <NUM>. The processing circuitry <NUM> includes an arithmetic processing circuit such as a CPU (Central Processing Unit) and a memory such as ROM (Read Only Memory) and RAM (Random Access Memory), and executes processing related to imaging by a program stored in the memory. The processing circuitry <NUM> may include a field-programmable gate array (FPGA). The communication interface <NUM> communicates with a terminal <NUM> on the ground via a communication cable.

The terminal <NUM> may include a control circuit <NUM>, a display <NUM>, and a communication interface <NUM>. The terminal <NUM> may not necessarily be a dedicated machine but may be a tablet terminal. The control circuit <NUM> is provided with an arithmetic processing circuit such as a CPU and a memory such as ROM and RAM, and executes processing relating to measurement of fish by a program stored in the memory. When the terminal <NUM> is a tablet terminal, a program related to fish measurement is downloaded and stored in the memory. The display <NUM> is configured by, for example, a touch panel, displays a display including predetermined information, and receives input through the display. The communication interface <NUM> communicates with the underwater processing unit <NUM> via the communication cable.

The user inputs a start instruction of fish measurement through the display <NUM> of the terminal <NUM>. The control circuit <NUM> of the terminal <NUM> transmits the start instruction to the processing unit <NUM> via the communication interface <NUM>. Thus, the processing circuitry <NUM> of the processing unit <NUM> causes the imaging device <NUM> (cameras <NUM>, <NUM>) to start capturing images, and sequentially transmits the captured images to the terminal <NUM>. The control circuit <NUM> of the terminal <NUM> detects fish from the received captured images and calculates the size of each fish.

More specifically, the control circuit <NUM> detects fish in the images acquired by the cameras <NUM> and <NUM> and calculates the size of the detected fish based on the images of the detected fish. The control circuit <NUM> calculates fork length (i.e., body length of the fish) and body height of the fish in the images. From this calculation result, the control circuit <NUM> further calculates body weight (estimated value) of the fish. The fork length and body height may be calculated based on an area of the fish on the image and a distance to the fish calculated by the parallax of the cameras <NUM>, <NUM>. The species of the fish may be added to the calculation of the body weight (estimated value).

The control circuit <NUM> may identify the fish species of the fish included in the image based on the image including the fish. In this case, the control circuit <NUM> may include a trained processing module that outputs the fish species of the fish when an image including the fish is inputted. The trained processing module is trained beforehand with images of the fish of a predetermined fish species. The training may be based on Artificial Intelligence (AI).

The control circuit <NUM> may cause the display <NUM> to display the calculated size of the fish. In this case, the size of the fish (fork length, body height, body weight, etc.) may be displayed as an average size, a histogram showing a frequency of each size, or the like.

The user may adjust the light amount of the first illuminating device <NUM> and the second illuminating device <NUM> via the display <NUM>. In this case, the user inputs an instruction for light amount adjustment through the display <NUM> prior to measurement. As a result, the processing circuitry <NUM> drives the first illuminating device <NUM> and the second illuminating device <NUM> with a default amount of light and causes the imaging device <NUM> to capture images. The captured images acquired by the imaging device <NUM> are sequentially transmitted to the terminal <NUM> and displayed on the display <NUM>.

The user may adjust the light amount of the first illuminating device <NUM> and the second illuminating device <NUM> via the display <NUM> while referring to the images displayed on the display <NUM>. The user may adjust the light amount of the first illuminating device <NUM> and the second illuminating device <NUM> so that the images of the fish to be measured become clear and halation does not occur in the images of the fish.

When the light amount adjustment is completed, the user may notify adjustment completion via the display <NUM>. Thereby, a notification of the adjustment completion is transmitted from the terminal <NUM> to the processing unit <NUM>. The processing circuitry <NUM> of the processing unit <NUM> may store light amount (gradations of light amount) after adjustment to the first illuminating device <NUM> and the second illuminating device <NUM>. During measurement operation, the processing circuitry <NUM> may drive the first illuminating device <NUM> and the second illuminating <NUM> with the stored light amount.

In the present embodiment, when the fish measuring device <NUM> is installed in the indoor fish cage <NUM>, the light amount of the first illuminating device <NUM> is usually set larger than that of the second illuminating device <NUM>. That is, the fish pass A1 is brightly illuminated by the first illuminating device <NUM>, and the amount of light lacking thereby is compensated by the second illuminating device <NUM>.

<FIG> is a flowchart showing the processing performed by the processing circuitry <NUM> of the processing unit <NUM> when the fish measurement start instruction is received.

Upon receiving the start instruction, at step S11, the processing circuitry <NUM> drives the first illuminating device <NUM> and the second illuminating device <NUM> with a predetermined amount of light, respectively. The light amount of the first illuminating device <NUM> and the second illuminating device <NUM> are set, for example, to the light amount previously adjusted by the user as described above. In addition, the light amount of the first illuminating device <NUM> and the second illuminating device <NUM> may be default light amount predetermined for each fish species. In this case, the processing circuitry <NUM> stores beforehand the light amount for each fish species, and sets the light amount corresponding to the fish species received with the start instruction from the terminal <NUM> to the first illuminating device <NUM> and the second illuminating device <NUM>.

Next, at step S12, the processing circuitry <NUM> causes the imaging device <NUM> (cameras <NUM>, <NUM>) to start capturing images. At step S13, the processing circuity <NUM> sequentially outputs the captured images captured by the cameras <NUM> and <NUM> to the terminal <NUM> via the communication interface <NUM>. The processing circuitry <NUM> continues capturing images and outputting the captured images until an instruction to end measurement is received from the terminal <NUM> (S14: NO). Thereafter, when the instruction to end measurement is received from the terminal <NUM> (S14: YES), the processing circuitry <NUM> stops the first illuminating device <NUM> and the second illuminating device <NUM> at step S15, and stops the imaging device <NUM> at step S16. This completes the processing shown in <FIG>.

According to the configuration of this embodiment, the following effects may be achieved.

As shown in <FIG> and <FIG>, the fish measuring device <NUM> forms the fish pass A1 between the imaging device <NUM> and the background board <NUM> by arranging the background board <NUM> at least partially in the field of view FV1, FV2 of the imaging device <NUM>, separates the fish swimming in the pass A1 from the imaging device <NUM> by blocking the part of the fish pass A1 on the imaging device <NUM> side with the fish blocking device <NUM>, illuminates the fish pass A1 from above and from the side of the imaging device <NUM> with the first illuminating device <NUM> and the second illuminating device <NUM>, captures images of the fish swimming in the fish pass A1 with the imaging device <NUM>, and processes the captured images (output of the captured images: at step S13 in <FIG>).

Thereby, both the upper part and the lower part of the body of the fish may be well illuminated by adjusting illumination intensity (light amount) and illumination ratio of the first illuminating device <NUM> and the second illuminating device <NUM> according to fish species. Further, since the background board <NUM> is disposed in the background of the fish pass A1, the contrast between the fish and the background may be enhanced in any kind of fish cage environment. Furthermore, since the portion of the fish pass A1 on the imaging device <NUM> side is blocked by the fish blocking device <NUM>, the number of fish included in the imaging region may be reduced even when the density of fish is high in the fish cage <NUM>, and the distance necessary for measuring the fish may be secured between the fish and the imaging device <NUM>. As a result, as shown in <FIG>, the fish image P11 of high quality may be acquired, and the fish swimming in the water may be measured with high accuracy.

As shown in <FIG>, the fish blocking device <NUM> may be placed in the fish pass A1 such that the shortest distance D2 between the background board <NUM> and the fish blocking device <NUM> is smaller than the shortest distance D1 between the background board <NUM> and the imaging device <NUM>. Thus, the fish is easily separated from the imaging device <NUM> by a difference between the shortest distance D2 between the background board <NUM> and the fish blocking device <NUM> and the shortest distance D1 between the background board <NUM> and the imaging device <NUM>. Therefore, as described with reference to <FIG> and <FIG>, a good fish image P11 may be obtained.

As shown in <FIG>, the fish blocking device <NUM> may include one or more boards. More specifically, the fish blocking device <NUM> may include the first board <NUM>, and the first board <NUM> and the direction in which the imaging device <NUM> faces may make a first oblique angle θ1 in a plan view. In the plan view, the first board <NUM> may be closer to the entrance A11 of the fish pass A1 on the background board <NUM> side than on the imaging device <NUM> side. Thus, as shown in <FIG>, the fish F1 entering the imaging region through the space between the first board <NUM> and the background board <NUM>, may be separated from the imaging device <NUM>.

As shown in <FIG>, the fish blocking device <NUM> may further include a second board <NUM> different from the first board <NUM>, the second board <NUM>, and the direction in which the imaging device <NUM> faces may make a second oblique angle θ2 in a plan view. In the plan view, the second board <NUM> may be closer to the exit A12 of the fish pass A1 on the background board <NUM> side than on the imaging device <NUM> side. As a result, as shown in <FIG>, the fish F1, which pass through the imaging region towards the space between the second board <NUM> and the background board <NUM>, may be separated from the imaging device <NUM>.

As shown in <FIG> and <FIG>, the first board <NUM> and the second board <NUM> may include one or more holes 71a, 72a for water to flow. Thus, the resistance of water flow to the first board <NUM> and the second board <NUM> may be reduced, and the first board <NUM> and the second board <NUM> may be maintained in a stable state.

As shown in <FIG>, the imaging device <NUM> (cameras <NUM>, <NUM>) may substantially face in the horizontal direction (direction parallel to the X-Y plane), and the second illuminating device <NUM> may illuminate at least in the direction substantially the same as the direction in which the imaging device <NUM> faces (positive Y-axis direction). Thus, the fish swimming in the pass A1 may be illuminated in the imaging direction by the second illuminating device <NUM>.

As shown in <FIG>, the second illuminating device <NUM> may include an array (LED arrays 51a - 51c, 52a- 52c) of a plurality of LEDs grouped into a first group (LED arrays 51a, 52a) and a second group (LED arrays 51b, 52b and/or LED arrays 51c, 52c), wherein the first group illuminates horizontally and the second group illuminates a different illumination direction from the first group. Thus, the fish swimming in the pass A1 may be horizontally illuminated by the second illuminating device <NUM> and may be illuminated in a direction different from the horizontal direction.

As shown in <FIG>, the illumination direction of the second group (LED arrays 51b, 52b) may be vertical. Thus, the fish swimming in the pass A1 may be vertically illuminated by the first illuminating device <NUM> and the second group of the second illuminating device <NUM>.

As shown in <FIG>, the fish measuring device <NUM> may further include the support frame <NUM> on which the imaging device <NUM>, the background board <NUM>, the first illuminating device <NUM>, the second illuminating <NUM>, and the fish blocking device <NUM> are attached, and the pair of rails <NUM> to vertically move the support frame <NUM>. Thus, by moving the support frame <NUM> along the pair of rails <NUM>, the imaging device <NUM>, the background board <NUM>, the first illuminating device <NUM>, the second illuminating device <NUM>, and the fish blocking device <NUM>, may be moved integrally in the depth direction. Thus, the fish pass A1 and an imaging position of the fish may be positioned at a depth position suitable for the fish species to be measured.

The user may easily remove the support frame <NUM> from the pair of rails <NUM> by lifting the support frame <NUM> upwards. Therefore, the user may detach the support frame <NUM> from the pair of rails <NUM> appropriately after installation of the fish measuring device <NUM>, and may easily replace and detach parts (for example, background board <NUM>) mounted on the support frame <NUM>. Further, the user may easily transport the fish measuring device <NUM> by appropriately separating the support frame <NUM> on which the respective parts are mounted from the lifting device <NUM>.

The processing circuitry <NUM> has performed processing for outputting the captured image to the terminal <NUM> (step S13 in <FIG>) as processing for the captured image, but the processing performed by the processing circuitry <NUM> is not limited to this. In accordance with a first modification, for example, the processing circuitry <NUM> may perform processing to calculate the size of the fish swimming in the fish pass A1 from the captured image and output the calculation result to the terminal <NUM>.

<FIG> is a flowchart showing the processing in this case.

In the flowchart of <FIG>, step S13 of the flowchart of <FIG> is changed to step S21. The other steps in <FIG> are the same as the corresponding steps in <FIG>.

At step S21, the processing circuitry <NUM> calculates the size (fork length, body height, body weight, etc.) of the fish based on the captured images acquired by the imaging device <NUM> (cameras <NUM>, <NUM>), and sequentially outputs the calculation results to the terminal <NUM>. The calculation method of the fish size is the same as the calculation method performed by the terminal <NUM> in the above embodiment.

With this configuration, the size of the fish may be calculated with high accuracy based on the high-quality fish images shown in <FIG>, as in the above embodiment. Since the calculation processing of the size of the fish is performed on the processing unit <NUM> side, the processing load of the terminal <NUM> may be reduced.

In the processing of <FIG>, the processing circuitry <NUM> may further output the captured image acquired by the imaging device <NUM> to the terminal <NUM>. Thus, the terminal <NUM> may display the state of the fish swimming in the water on the display <NUM> together with the calculation result of the size of the fish, and the user may grasp the state of the fish in the fish cage <NUM> together with the size of the fish.

In accordance with a second modification, the configuration of the fish blocking device <NUM> is not limited to the configuration shown in the above embodiment and may be varied in various ways.

For example, as shown in <FIG>, the second board <NUM> may be omitted, and the fish blocking device <NUM> may include only the first board <NUM>. In this case, as in the above-described embodiment, the fish F1 entering the imaging region from the entrance A11 may be separated from the imaging device <NUM>.

However, in this case, since the exit A12 is not restricted by the second board <NUM>, it is easy for the fish F1 that have passed between the first board <NUM> and the background board <NUM> to change swimming direction to gradually approach the imaging device <NUM>. Therefore, as compared with the above-described embodiment, the fish F1 may be easily imaged with a slight inclination, and the distance between the fish F1 and the imaging device <NUM> may be easily shortened from an ideal distance. Therefore, to obtain a high-quality image of the fish, it is preferable that the second board <NUM> be disposed together with the first board <NUM>, as in the above embodiment.

Further, as shown in <FIG>, the first board <NUM> and the second board <NUM> may be disposed without tilting with respect to the direction in which the imaging device <NUM> faces (i.e., the positive direction of the Y-axis). In this case, as in the above-described embodiment, the fish F1 entering the imaging region from the entrance A11, may be separated from the imaging device <NUM>, and the fish F1 advancing in the imaging region toward the exit A12, may be separated from the imaging device <NUM>.

However, in this case, since the fish F1 facing the first board <NUM> on the entrance side is hardly guided in the Y-axis negative direction by the first board <NUM>, the fish F1 may be directed to the space between the first board <NUM> and the background board <NUM>. Therefore, the density of fish passing through the space increases, and more fish are easily included in the captured image than in the case of the above embodiment.

If the fish F1 that have passed between the first board <NUM> and the background board <NUM> accidentally approach the imaging device <NUM>, the second board <NUM> on the exit side may become an obstacle, and the fish F1 may circle between the first board <NUM> and the second board <NUM> as shown by an arrow in <FIG>. This makes it difficult to obtain a proper image of the fish while the fish F1 are circling.

On the other hand, in the above embodiment, since the first board <NUM> is inclined as shown in <FIG>, the fish F1 facing the first board <NUM>, are easily guided in the negative Y-axis direction by the first board <NUM>. Therefore, the increase of density of the fish F1 passing through the space between the first board <NUM> and the background board <NUM>, may be suppressed, and the number of fish included in the captured image, may be reduced. Therefore, the fish may be easily separated on the captured images.

Also, as shown in <FIG>, since the second board <NUM> is also tilted, even if the fish F1 accidentally head in a direction approaching the imaging device <NUM>, the fish F1 are guided to a range between the second board <NUM> and the background board <NUM> by the second board <NUM>. Therefore, the circling of the fish F1 between the first board <NUM> and the second board <NUM>, may be suppressed, and an appropriate image of the fish may be stably obtained.

The number of boards provided in the fish blocking device <NUM> is not limited to <NUM> or <NUM> but may be <NUM> or more. For example, the first board <NUM> on the entrance side, may be divided into a plurality of pieces in the Z-axis direction, and the second board <NUM> on the exit side, may be divided into a plurality of pieces in the Z-axis direction.

The shapes of the first board <NUM> and the second board <NUM> are not limited to the shape shown in the above embodiment but may be other shapes. For example, the first board <NUM> may be bent so that both ends of the first board <NUM> in the Z-axis direction are closer to the exit A12 of the pass A1 than the center in the Z-axis direction, or the first board <NUM> may be arcuately bent. Thus, the fish entering the pass A1 and facing the first board <NUM> may be easily released up and down.

The second board <NUM> may be bent so that both ends of the second board <NUM> in the Z-axis direction are further away from the entrance A11 of the pass A1 than the center in the Z-axis direction, or the second board <NUM> may be arcuately bent. As a result, after entering through the space between the first board <NUM> and the background board <NUM>, the fish which accidentally move in a direction approaching the imaging device <NUM> and face the second board <NUM> may be easily released up and down.

The first board <NUM> and the second board <NUM> may have a shape in which a width in the Z-axis direction becomes wider towards the tip. The holes 71a and 72a may not be formed in the first board <NUM> and the second board <NUM>. The fish blocking device <NUM> may have another obstacle structure such as a frame instead of the first board <NUM> and the second board <NUM>.

In the above embodiment, white is exemplified as the color of the background board <NUM>, but the color of the background board <NUM> is not limited to this. For example, if the color of the fish of the target fish species is close to white, a color having a high contrast with the fish of the target fish species, such as blue, may be selected as the color of the background board <NUM>. The user may install, on the support frame <NUM>, a background board <NUM> of a color having a high contrast with the fish according to the kind of the fish to be measured and housed in the fish cage <NUM>.

Further, in the above embodiment, the second illuminating device <NUM> illuminates not only in the horizontal direction but also in the direction vertically down and the oblique direction, but the configuration of the second illuminating device <NUM> is not limited to this. For example, the second illuminating device <NUM> may illuminate only in the horizontal direction. However, as in the above-described embodiment, when the second illuminating device <NUM> illuminates not only in the horizontal direction but also in the direction vertically down and the oblique direction, the back and the fin of the fish which tend to be dark in an indoor fish cage may be illuminated from various angles by the second illuminating device <NUM>. Thus, a higher quality image of the fish may be acquired, and the measurement of the fish may be performed with high accuracy.

The illumination direction of the second illuminating device <NUM> may be further increased from the <NUM> directions described in the above embodiment. The illumination direction of the second illuminating device <NUM> may be smoothly changed instead of being changed stepwise. In this case, the base plate 51d of the second illuminating device <NUM> may be changed to a shape in which an arc-shaped curved portion is connected to an upper end of a portion parallel to the X-Z plane, for example.

The light sources of the first illuminating device <NUM> and the second illuminating device <NUM> may be light sources other than LEDs, such as lamps, or may be a mixture of LEDs and other types of light sources.

In the above embodiment, the fish measuring device <NUM> is applied to the fish cage <NUM> installed indoors, but the fish measuring device <NUM> having the above structure may also be applied to the fish cage <NUM> installed outdoors. In this case, the first illuminating device <NUM> may be removed from the fish measuring device <NUM>, or the first illuminating device <NUM> may be turned off when sufficient light reaches the imaging region, such as on a clear day. In this case as well, a high-quality image of the fish may be obtained by the action of the fish blocking device <NUM>, and the measurement of the fish may be performed with high accuracy.

In the above embodiment, the support frame <NUM> is composed of the upper frame <NUM> and the lower frame <NUM>, but the support frame <NUM> may be composed of one frame or three or more frames.

In the above embodiment, the stereo camera is constituted by the cameras <NUM> and <NUM> arranged in the X-axis direction, but the stereo camera may be constituted by three or more cameras. The direction in which the cameras <NUM> and <NUM> is arranged does not have to be the X-axis direction but may be another direction.

In the above embodiment, the imaging device <NUM> includes the cameras <NUM> and <NUM>, but the imaging device <NUM> may include only one camera. In this case, the distance to the fish on the image that was acquired by the cameras may be acquired, for example, by echo data from an underwater ultrasonic device. The underwater ultrasonic device is arranged side by side with the camera and transmits and receives ultrasonic waves to a range including the imaging region. The distance to the fish first detected by ultrasound in a direction corresponding to a position of the fish on the captured image may be used as the distance to the fish on the captured image.

The fish measuring device <NUM> may be used for facilities other than fish cages. That is, the fish measuring device <NUM> may be used in other situations for measuring fish swimming in water.

Claim 1:
A fish measuring device (<NUM>) comprising:
an imaging device (<NUM>) configured to capture an image of a fish swimming in water;
a background board (<NUM>) at least partially placed in a field of view of the imaging device (<NUM>);
a first illuminating device (<NUM>) configured to illuminate a fish pass (A1) between the imaging device (<NUM>) and the background board (<NUM>) from above the fish pass (A1);
a second illuminating device (<NUM>) configured to illuminate the fish pass (A1) from a side of the imaging device (<NUM>);
a fish blocking device (<NUM>) configured to block a part of the fish pass (A1) on the imaging device (<NUM>) side; and
processing circuitry (<NUM>) configured to process the captured image of the fish swimming in the fish pass (A1),
characterized in that:
the fish blocking device (<NUM>) comprises a first board (<NUM>);
in a plan view, the first board (<NUM>) and a direction in which the imaging device (<NUM>) faces make an oblique angle (θ1); and
in a plan view, the first board (<NUM>) is closer to an entrance (A11) of the fish pass (A1) on the background board (<NUM>) side than on the imaging device (<NUM>) side.