Echo image display device, echo image display control method, and program

Abstract

To provide an echo image display device, an echo image display control method, and a program capable of clearly displaying an echo image of a school of fish even when the school of fish moves.SOLUTION: The underwater detection device 10 includes an echo intensity acquiring module 11b configured to acquire an echo intensity at each location on a latitude-longitude plane over time, a fish school echo estimating module 11c configured to estimate an echo intensity of a fish school based on the echo intensity, a mean value calculating module 11d configured to set a weight of the echo intensity of the fish school larger than weights of other echo intensities, and calculate a mean value at each location by weighted averaging processing in which the respective weights are applied to the echo intensities, and an image generating module 11e configured to generate an echo image at the location based on the mean value at the location.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a display device, a display control method, and a program for displaying an image of an echo obtained by underwater detection using ultrasonic waves. [Background technology]

[0002] Underwater detection devices for detecting underwater targets are known. These devices transmit ultrasonic waves into the water, receive the reflected waves, calculate the echo intensity from each position in the water, and display an echo image.

[0003] For example, an underwater detection device transmits umbrella-shaped transmission waves along a conical surface from a transducer having multiple ultrasonic transducers, and receives the reflected waves. From the electrical signals output from each ultrasonic transducer of the transducer in response to the received reflected waves, multiple reception beams are formed circumferentially on the conical surface by beamforming, and a reception signal is generated for each reception beam. From the reception signals thus generated, an echo image corresponding to the scanning range of the reception beam is generated and displayed.

[0004] In this type of underwater detection device, each position on the conical surface is converted to a position in the L (latitude) / L (longitude) / D (depth) coordinate system consisting of latitude, longitude, and depth, and the echo intensity at each converted position is obtained as the echo intensity for a point on the L (latitude) / L (longitude) coordinate plane that overlaps each position in the depth direction, and an echo image in which these echo intensities are distributed two-dimensionally is displayed.

[0005] Such echo images may contain noise images based on echoes from schools of fish as well as floating objects in the water. One method for suppressing these noise images is to calculate the average value of the echo intensity for each point on the L / L coordinate plane and use this average value as the echo intensity for that point.

[0006] That is, because the conical surface moves as the ship moves, echo intensities at different depths are acquired sequentially for each ping (ultrasonic wave transmission and reception period) at each point on the L / L coordinate plane. The series of echo intensities are then averaged to obtain the average value mentioned above. Here, because the depth range of floating objects is narrow, the number of pings from which floating object echoes are obtained at each point is small. Therefore, the average value at each point is less affected by the echoes of floating objects. This allows noise images of floating objects, etc. to be effectively suppressed from the echo image.

[0007] However, with this configuration, the echo intensity from the fish school as well as the echo intensity from noise at each point is weakened by averaging, making it difficult to clearly capture the echoes from the fish school in the echo image.

[0008] In response to this, Patent Document 1 below describes an echo image display device that can display echo images of schools of fish more clearly. In this display device, multiple layers are set in the depth direction. For each point, the display device calculates the average value of the echo intensity for each layer and displays the echo image for that point based on the largest average value among these average values.

[0009] This method can suppress the effects of noise through averaging. Furthermore, since schools of fish tend to be distributed over a relatively wide area on one of the layers, the average echo intensity on that layer can be increased according to the size of the school of fish. Therefore, by displaying the echo image of a given point based on the largest average value among the average values ​​obtained for each layer, as described above, the echo image of the school of fish can be displayed more clearly. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] Patent No. 4781240 Summary of the Invention [Problem to be solved by the invention]

[0011] However, with the above method, as the fish school moves, the number of times the echo intensity of the school of fish is acquired at the point directly below the school of fish decreases. Then, when the fish school moves away from the point directly below the school of fish, the average echo intensity at that point continues to be applied at a level close to zero. This causes the maximum average value at that point to decrease, and after the fish school moves away from the point directly below the school of fish, the average value gradually decreases. As a result, the image of the school of fish on the echo image becomes unclear and fades further over time.

[0012] In view of such problems, the present invention aims to provide an echo image display device, an echo image display control method, and a program that can clearly display echo images of schools of fish even when the schools of fish are moving. [Means for solving the problem]

[0013] A first aspect of the present invention relates to a display device that displays an image of echoes obtained by underwater detection using ultrasonic transmission and reception. The display device according to this aspect includes an echo intensity acquisition unit that acquires echo intensities for each point on a latitude and longitude plane over time, a fish school echo estimation unit that estimates the echo intensities of a school of fish based on the echo intensities, an average calculation unit that weights the echo intensities of the school of fish more heavily than the weights of the other echo intensities and calculates an average value for each point using a weighted averaging process in which the weights are applied to the echo intensities, and an image generation unit that generates an echo image for each point based on the average value for that point, and updates and displays the echo image for each point as the ship moves.

[0014] According to the display device of this aspect, weighted averaging can suppress the influence of noise echo intensity from floating objects and the like on the echo image. Furthermore, since the weighting of the echo intensity of a school of fish is higher than the weighting of the echo intensity of other objects, the average value can be increased at each point. Therefore, by generating an echo image at each point using the average value, the echoes of the school of fish can be displayed more clearly. Furthermore, at a point where a school of fish is present directly below, the weighting applied to the echo intensity decreases after the school of fish passes, making the weighted average value less likely to decrease over time. Therefore, even after the school of fish passes, the average value at that point is less likely to decrease, and the echo image of the school of fish is less likely to fade. Therefore, the echo image of the school of fish can be displayed clearly even when the school of fish is moving.

[0015] In the display device of this aspect, the echo intensity acquisition unit acquires the echo intensity over time for each of multiple layers obtained by dividing a specified range underwater in the depth direction, the average value calculation unit calculates the average value of each point for each layer, and the image generation unit can be configured to generate an echo image at each point based on the maximum value of the average values ​​of each point.

[0016] In this case, the range of each layer can be set to partially overlap with the range of the layer adjacent to it in the depth direction.

[0017] These configurations make it easier for schools of fish to be predominantly included in one of the layers, increasing the average value for that layer. Therefore, by generating an echo image for a point from the maximum value of the average values ​​acquired at each point, it is possible to display a clear echo image of the school of fish.

[0018] A second aspect of the present invention relates to a control method for an apparatus that displays images of echoes obtained by underwater detection using ultrasonic transmission and reception. The control method according to this aspect acquires echo intensities for each point on a latitude and longitude plane over time, estimates the echo intensities of a school of fish based on the echo intensities, weights the echo intensities of the school of fish greater than the weights of the other echo intensities, calculates an average value for each point using a weighted averaging process in which the weights are applied to the echo intensities, generates an echo image for each point based on the average value for that point, and displays the echo image for each point while updating it as the ship moves.

[0019] According to the underwater detection method of this aspect, the same effects as those of the echo image display device of the first aspect can be achieved.

[0020] A third aspect of the present invention relates to a program for causing a control unit of a device for displaying images of echoes obtained by underwater detection using ultrasonic transmission and reception to execute predetermined functions. The program causes the control unit to acquire echo intensities for each point on a latitude and longitude plane over time, estimate the echo intensities of a school of fish based on the acquired echo intensities, calculate an average value for each point by weighting the echo intensities of the school of fish higher than the weights of the other echo intensities and applying the respective weights to the echo intensities, generate an echo image for each point based on the average value for that point, and display the echo image for each point while updating it as the ship moves.

[0021] According to the program of this aspect, the same effects as those of the echo image display device of the first aspect can be achieved. [Effects of the Invention]

[0022] As described above, according to the present invention, it is possible to provide an echo image display device, an echo image display control method, and a program that can clearly display images of schools of fish even when the schools of fish are moving.

[0023] The effects and significance of the present invention will become more apparent from the following description of the embodiments, however, the embodiments shown below are merely examples of how the present invention can be implemented, and the present invention is not limited to the embodiments described below. [Brief explanation of the drawings]

[0024] [Figure 1] FIG. 1 is a diagram showing a schematic view of underwater searching by an underwater detection device according to an embodiment. [Figure 2] FIG. 2 is a diagram showing a schematic view of underwater searching by an underwater detection device according to an embodiment. [Figure 3] FIG. 3 is a block diagram showing the configuration of an underwater detection device according to an embodiment. [Figure 4] FIG. 4 is a diagram illustrating a method for obtaining an average value of echo intensity for each layer according to the embodiment. [Figure 5] FIG. 5 is a diagram illustrating a schematic diagram of how echo intensities of a school of fish are acquired when the school of fish is moving, according to the embodiment. [Figure 6] FIG. 6 is a flowchart showing a process for generating and displaying an echo image according to an embodiment. [Figure 7] FIG. 7 is a flowchart showing a process for labeling each point (coordinate position) in the L / L / D coordinate system as to whether it corresponds to a school of fish or not, according to an embodiment. [Figure 8] FIG. 8 is a flowchart showing the echo image display process according to the embodiment. [Figure 9] 9(a) is a diagram showing an example of a display of an echo image according to an embodiment, and FIG. 9(b) is a diagram showing an example of a display of an echo image according to a comparative example. [Figure 10] FIG. 10 is a diagram showing the configuration of a system including a display device according to a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0025] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. For convenience, mutually orthogonal X, Y, and Z axes are indicated in the drawings as appropriate. The X-axis and Y-axis directions are horizontal, and the Z-axis direction is vertical. The positive X-axis direction is the direction in which the ship moves.

[0026] In the following embodiments, the underwater detection device 10 corresponds to the "echo image display device" described in the claims. However, the following embodiments are merely examples of how the present invention can be realized, and do not limit the present invention in any way.

[0027] 1 and 2 are diagrams that schematically show how underwater detection is performed by an underwater detection device 10. FIG.

[0028] In FIGS. 1 and 2, φ is the azimuth angle centered on the transducer 13 installed on the bottom of the ship S1, and θ is the tilt angle of a scanning plane SP1 (to be described later) relative to the horizontal plane (XY plane).

[0029] The underwater detection device 10 includes a transducer 13 installed on the bottom of a vessel S1 such as a fishing boat. The underwater detection device 10 transmits a pulse of sound waves (transmission pulse) from the transducer 13 and receives sound waves (echoes) reflected (backscattered) by objects such as fish present in the water with the same transducer 13. The underwater detection device 10 detects objects present in the water based on the echoes received by the transducer 13.

[0030] The transducer 13 is equipped with a large number of ultrasonic transducers. When transmitting, each ultrasonic transducer converts an input electrical signal into a sound wave and emits it, and when receiving, it converts the incident sound wave into an electrical signal and outputs it. Typically, the transducer 13 is cylindrical, with several hundred ultrasonic transducers regularly arranged on its side.

[0031] Here, the area to be detected by the underwater detection device 10 is a conical surface. The axis of this conical surface is parallel to the vertical direction (Z-axis direction). This conical surface is called the scanning surface SP1, and the apex and axis of this scanning surface SP1 are called the origin and the scanning axis, respectively. The origin coincides with the position of the transducer 13, and the scanning axis extends vertically downward from this origin. In this case, the scanning axis coincides with the Z-axis. The angle that the scanning surface SP1 makes with the horizontal plane (XY plane) is the tilt angle θ mentioned above.

[0032] As shown in Fig. 1, the underwater sounding device 10 transmits a transmission beam TB1 having the maximum intensity on the scanning plane SP1 over the entire circumference during transmission. This transmission beam TB1 has an intensity distribution that is symmetrical with respect to the scanning axis (Z-axis in Fig. 1), and its width in the vertical direction is relatively narrow.

[0033] 2, the underwater detection device 10 forms multiple receiving beams RB1 with maximum sensitivity on the scanning plane SP1 during wave reception. The receiving beams RB1 are formed by applying beamforming processing to the electrical signals output from multiple ultrasonic transducers arranged in the transducer 13.

[0034] Each receive beam RB1 is a pencil beam with a narrow width in both the vertical and horizontal directions, and has the same directivity. The beam axis of each receive beam RB1 is a straight line that passes through the origin and points in the direction in which the sensitivity of the receive beam RB1 is maximum. Multiple receive beams RB1 are formed in a line at regular angular intervals in the direction of the azimuth angle φ around the entire circumference of the scan plane SP1. The underwater sounding device 10 converts the intensity of the sound waves received by each receive beam RB1 into color and displays it as an echo image. The method of generating the echo image will be explained later with reference to Figures 4 to 7.

[0035] FIG. 3 is a block diagram showing the configuration of the underwater detection device 10.

[0036] The underwater detection device 10 comprises a control unit 11, a memory unit 12, a transducer 13, a transmission processing unit 14, a reception processing unit 15, a transmission / reception switching unit 16, a display unit 17, a display processing unit 18, an input unit 19, and an input processing unit 20. The transducer 13 is installed on the bottom of the ship S1 as described above, and the other components such as the control unit 11 are installed in the wheelhouse or the like of the ship S1. The underwater detection device 10 constantly acquires the position and heading of the ship S1 from a navigation device 100 equipped with a GPS function or the like.

[0037] The control unit 11 includes an arithmetic processing circuit such as a CPU (Central Processing Unit), and executes the control processing described below using programs stored in the storage unit 12. The storage unit 12 includes storage media such as a ROM (Read Only Memory), a RAM (Random Access Memory), and a hard disk. The storage unit 12 stores programs for the control unit 11 to execute the control processing.

[0038] As described above, the transducer 13 includes a plurality of ultrasonic transducers 13a. In each transmission and reception period (ping), the transducer 13 transmits an ultrasonic wave as the transmission beam TB1 in FIG. 1, and receives the reflected wave at each ultrasonic transducer.

[0039] The transmission processing unit 14 outputs a transmission signal for transmitting ultrasonic waves to the transducer 13 via the transmission / reception switching unit 16 in accordance with control from the control unit 11. The transmission signal is a signal that vibrates at a predetermined amplitude for a fixed period of time, as shown in FIG. 3. During one transmission of the transmission beam TB1, this transmission signal is supplied to each ultrasonic transducer 13a of the transducer 13 via the transmission / reception switching unit 16. As a result, as shown in FIG. 3, ultrasonic waves corresponding to the transmission signal are transmitted from each ultrasonic transducer 13a. The ultrasonic pulse transmitted during one transmission is called a transmission pulse.

[0040] The reception processing unit 15 receives, via the transmission / reception switching unit 16, the electrical signals output by each ultrasonic transducer 13a of the transmitter / receiver 13 upon receiving reflected ultrasonic waves, and performs amplification and noise removal (bandpass filter) processing on the received electrical signals. The reception processing unit 15 outputs the electrical signals that have undergone these processes to the control unit 11.

[0041] When transmitting the transmission beam TB1, the transmission / reception switching unit 16 outputs the transmission signal output from the transmission processing unit 14 to the transmitter / receiver 13 (ultrasonic vibrator 13a), and outputs the electrical signal output from the transmitter / receiver 13 (ultrasonic vibrator 13a) to the reception processing unit 15 for a certain period of time from the timing when the transmission of the transmission beam TB1 is completed.

[0042] 3 shows one transmission processing unit 14 and one reception processing unit 15, the above-described processing in the transmission processing unit 14 and the reception processing unit 15 is performed for each ultrasonic transducer 13a arranged in the transducer 13. Therefore, the electrical signals output from each ultrasonic transducer 13a are amplified and subjected to noise removal processing, and the resulting electrical signals are individually input to the control unit 11. When these electrical signals are input to the control unit 11, they are converted by an A / D converter into digital signals with a predetermined sampling period.

[0043] The display unit 17 includes a display device such as a liquid crystal display. The display processing unit 18 displays a predetermined image on the display unit 17 in response to control from the control unit 11. The input unit 19 includes input means such as operation keys and a mouse. The input processing unit 20 outputs a signal corresponding to an operation on the input unit 19 to the control unit 11 in response to control from the control unit 11. The display unit 17 and the input unit 19 may be configured as a liquid crystal panel in which a touch panel is superimposed on a liquid crystal display.

[0044] In this embodiment, the functions of a received signal generating unit 11a, an echo intensity acquiring unit 11b, a fish school echo estimating unit 11c, an average value calculating unit 11d, and an image generating unit 11e are given to the control unit 11 by a program stored in the memory unit 12.

[0045] The reception signal generation unit 11a performs beamforming on the electrical signals (digital signals) output from each ultrasonic transducer 13a to form the reception beam RB1 shown in Fig. 2, and generates reception signals corresponding to sound waves incident on the transducer 13 from the beam axis direction (the direction of a predetermined azimuth angle φ and tilt angle θ) of each reception beam RB1. Furthermore, the reception signal generation unit 11a performs band limitation and envelope detection processing on the reception signals in each beam axis direction to acquire envelope signals in each beam axis direction.

[0046] Here, the band limiting process is a process for extracting frequency components of the transmission signal output from the transmission processing unit 14. This process is performed when the transmission signal output from the transmission processing unit 14 is a signal with a constant frequency (CW signal).

[0047] On the other hand, when the transmission signal output from the transmission processing unit 14 is not a signal with a constant frequency (CW signal) but a frequency-modulated chirp signal (FM signal), the reception signal generation unit 11a performs matched filter processing on the reception signal in each beam axis direction instead of band-limiting processing.The reception signal generation unit 11a then performs envelope detection processing on the signal after matched filter processing to obtain an envelope signal in each beam axis direction.

[0048] The envelope signal thus acquired is a signal indicating the echo intensity (sound wave strength) that changes according to the time elapsed since the transmission timing of the transmission beam TB1 (ultrasound wave). Here, the time elapsed since the transmission timing corresponds to the distance from the transducer 13 in each beam axis direction.

[0049] The echo intensity acquisition unit 11b acquires the echo intensity at each distance position in each beam axis direction from the envelope signal by associating the elapsed time from the transmission timing with the distance. The echo intensity is acquired with a predetermined distance resolution. Furthermore, the echo intensity acquisition unit 11b converts each distance position into a position in an L (latitude) / L (longitude) / D (depth) coordinate system consisting of latitude, longitude, and depth, and acquires the echo intensity for a point on the L (latitude) / L (longitude) coordinate plane that overlaps each position in the depth direction.

[0050] The echo intensity acquiring unit 11b acquires the echo intensity over time for each point on each of a plurality of layers obtained by dividing the search range in the depth direction. This process will be described later with reference to FIG. 4.

[0051] The fish school echo estimation unit 11c estimates the echo intensity of a school of fish based on the echo intensity acquired by the echo intensity acquisition unit 11b. More specifically, the fish school echo estimation unit 11c labels positions in the L / L / D coordinate system that correspond to schools of fish based on the echo intensity acquired for each ping. This labeling determines whether the echo intensity at each position corresponds to the echo intensity of a school of fish. The labeling process will be described later with reference to FIG. 7.

[0052] The average value calculation unit 11d assigns weights to the echo intensities and calculates the average value of the echo intensities at each point for each layer. More specifically, the average value calculation unit 11d sets a weight for the echo intensities of the school of fish greater than the weight for the other echo intensities, and calculates the average value of each point for each layer by weighted averaging processing in which each weight is applied to the echo intensities. In this embodiment, a weighted average value is calculated as the average value. The process of calculating the average value will be described later with reference to FIG. 4.

[0053] The image generating unit 11e generates an echo image at each point based on the maximum value of the average values ​​of each layer for that point. The process of generating an echo image will be described later with reference to FIG.

[0054] FIG. 4 is a diagram showing a method for obtaining the average value of the echo intensity for each of layers L1, L2, and L3.

[0055] Figure 4 shows a schematic view of the underwater environment from the left side of the ship S1. Therefore, Figure 4 shows a cross section of the umbrella-shaped scanning plane SP1 cut by a plane that includes its vertex (origin), axis (Z-axis), and the direction of travel of the ship S1. Two reception beams RB1, one before the other, are shown in this cross section. As the ship S1 travels, the two reception beams RB1 move along with the scanning plane SP1. In Figure 4, the beam axis of the reception beam RB1 for the current ping is shown by a solid line, and the beam axes of the reception beam RB1 for the past few pings are shown by short-dashed lines. Furthermore, the beam axis of the reception beam RB1 for the next ping is shown by a long-dashed line.

[0056] In this embodiment, the underwater search range is divided in the depth direction to set multiple layers. Here, three layers L1 to L3 are set. The search range is divided into four in the depth direction. Layer L1 is formed by merging the two upper divided ranges, layer L2 is formed by merging the two middle divided ranges, and layer L3 is formed by merging the two lower divided ranges. In other words, the range of each layer partially overlaps the range of the layer adjacent in the depth direction. Here, adjacent layers overlap half at a time.

[0057] A school of fish F1 is located near the center of the search range in the depth direction. Three floating objects N1 to N3 are also located within the search range. For convenience, the school of fish F1 and floating objects N1 to N3 are indicated by hatching that indicates echo intensity. The denser the hatching, the higher the echo intensity.

[0058] P1 to P4 are points at L (latitude) / L (longitude) included in the cross section where part of the school of fish F1 and floating objects N1 to N3 exist in the depth direction. Part of the school of fish F1 is located vertically below point P1, and floating objects N1 to N3 exist at points P2 to P3, respectively.

[0059] For point P1, the echo intensity of school of fish F1 (shown by circles on the dash-dotted lines extending from point P1) is acquired using receive beam RB1 of the current and past few pings. For points P2 to P3, the echo intensity of floating objects N1 to N3 (shown by circles on the dash-dotted lines extending from points P2 to P3, respectively) is acquired using only receive beam RB1 of the current ping. While no pings with near-zero echo intensities are shown on each dash-dotted line, near-zero echo intensities do exist on these lines.

[0060] The bottom part of Fig. 4 shows schematic diagrams of echo images of the points (cross sections) included in the cross section when the echo intensities of these points are acquired using different methods. In these echo images, the echo intensities are also indicated by hatching. The higher the density of the hatching, the higher the echo intensity.

[0061] The top method (peak hold) holds the maximum echo intensity among the series of echo intensities acquired at each point. The echo image at each point reflects this maximum echo intensity. This method allows the echo image of the school of fish F1 to be displayed clearly. However, because the echo intensity of floating objects is held as the maximum echo intensity, the echo image of the floating objects remains clearly visible in the echo image.

[0062] The second method from the top (average) calculates the average value of the series of echo intensities acquired at each point. The calculated average value is reflected in the echo image at each point. With this method, the averaging process weakens the echo intensity of floating objects, so that the echo intensity of floating objects has virtually no effect on the echo image. However, on the other hand, the echo intensity of the fish school F1 is also weakened by the averaging, so the echo image of the fish school F1 becomes unclear.

[0063] In the third method from the top (Average Peak L1 / L3), the series of echo intensities acquired at each point are averaged for each layer L1 and L3, and the maximum average value is set as the echo intensity for the corresponding point. The echo image for each point reflects the set maximum average value. In this method, the averaging process weakens the echo intensity of floating objects, making the echo image less susceptible to their influence. In addition, because the maximum echo intensity is set for each point, the echo image of fish school F1 is clearer than with the averaging method in the second row from the top. In this method, the echo image of fish school F1 can be made even clearer by increasing the number of layers and dividing the search range in the depth direction.

[0064] In the fourth-row method (Average Peak L1-L3), the series of echo intensities acquired at each point are averaged for each of the layers L1, L2, and L3, and the maximum average value is set as the echo intensity for the corresponding point. This method differs from the third-row Average Peak L1 / L3 method in that an additional layer L2 is set, overlapping adjacent layers. The maximum average value set is reflected in the echo image for each point. This method also weakens the echo intensity of floating objects through the averaging process, reducing their influence on the echo image. Furthermore, because the maximum echo intensity is set for each point, the echo image of the fish school F1 is clearer than with the second-row Average method. Furthermore, the addition of layer L2 makes it easier for the fish school F1 to be predominantly included in one of the layers. Therefore, this method produces a clearer echo image of the fish school F1 than the third-row Average Peak L1 / L3 method. In this method as well, the echo image of the fish school F1 can be made clearer by increasing the number of layers by dividing the search range in the depth direction.

[0065] As described above, the average peak L1 / L3 method and the average peak L1-L3 method can clearly display echo images of schools of fish while suppressing noise caused by floating objects and other factors. However, with these methods, as shown in Figure 5, once the fish school F1 moves and moves away from directly below point P1, a near-zero echo intensity continues to be applied to the average at point P1. In the example shown in Figure 5, the echo intensity of the fish school F1 is only acquired from the current ping and the previous ping. As a result, the maximum average value at point P1 is small, and the maximum average value gradually decreases as the averaging process for subsequent pings progresses. As a result, as shown in the echo image in the bottom row, the echo image of the fish school F1 becomes unclear and then gradually fades over time (as the ping progresses).

[0066] Therefore, in this embodiment, control is performed that enables the image of the school of fish to be displayed more clearly even when the school of fish is moving. This control will be described below.

[0067] FIG. 6 is a flowchart showing a process for generating and displaying an echo image according to an embodiment.

[0068] In this flowchart, the processes of steps S101, S106, and S107 are performed by the function of the average value calculation unit 11d in Fig. 3, and the processes of steps S102 to S104 are performed by the function of the received signal generation unit 11a in Fig. 3. Furthermore, the process of step S105 is performed by the function of the echo intensity acquisition unit 11b in Fig. 3. The processes of steps S108 and S109 are performed by the function of the image generation unit 11e in Fig. 3. The labeling in step S106 is performed by the function of the fish school echo estimation unit 11c in Fig. 3, through the process in Fig. 7. The following description will be given assuming that the control unit 11 executes the processes of the corresponding steps using these functions.

[0069] When the operation of displaying an echo image starts, the control unit 11 initializes the formula for calculating the average value in step S107 (S101). The average value is calculated by the following formula. Here, the average value is obtained by weighted averaging.

[0070]

number

[0071]

number

[0072]

number

[0073] LevelSum is the sum of the echo intensities obtained for each layer L1, L2, and L3 shown in Figure 5 for each point. Li is the echo intensity obtained for that point in the current ping, and Wi is the weighting applied to the echo intensity at that point in the current ping. The weighting is set to either a value (e.g., 0.9) when the echo intensity at that point corresponds to a school of fish, or a value (e.g., 0.1) when the echo intensity at that point does not correspond to a school of fish. Weight is the sum of the weighted average weights obtained for layers L1, L2, and L3. Average is the weighted average value obtained for layers L1, L2, and L3.

[0074] In equation (1), the echo intensity Li obtained by the current ping is multiplied by its weight Wi, and the result is added to the LevelSum calculated up to the previous ping to update LevelSum. In equation (2), the echo intensity Li obtained by the current ping is multiplied by its weight Wi, and the result is added to the Weight calculated up to the previous ping to update Weight. In equation (3), the LevelSum calculated in equation (1) is multiplied by the Weight calculated in equation (2) to calculate the Average for the current ping.

[0075] 6, the control unit 11 resets the values ​​of the parameters in the above formulas (1) to (3) to zero for all layers L1, L2, and L3 of all points (L / L coordinate points) included in the search range in planar view. After that, when the control unit 11 acquires the echo intensity for one ping (S102: YES), it determines whether or not the level conversion process has been set (S103).

[0076] Level conversion processing is processing to lower the level of echo signals from the seabed based on seabed detection in order to prevent the seabed echo from being superimposed. Instead of level conversion processing, filter processing to remove noise may be performed. Both level conversion processing and filter processing may be performed. These processing settings are made by the user via the input unit 19. If level conversion processing or the like has been set (step S103: YES), the control unit 11 performs the above-mentioned level conversion processing in step S104. If level conversion processing or the like has not been set (S103: NO), the control unit 11 skips the processing of step S104.

[0077] Next, the control unit 11 converts each position on the conical scanning surface SP1 into each coordinate position in the L (latitude) / L (longitude) / D (depth) coordinate system (three-dimensional coordinate system) (S105). The control unit 11 sets a weight Wi based on the labeling of the presence or absence of a school of fish for each converted coordinate position (S106). Using the set weight Wi and the echo intensity Li at each coordinate position, the control unit 11 calculates an average value Average (weighted average value) for each layer L1, L2, and L3 of each point (L / L coordinate point) using the above formulas (1) to (3) (S107).

[0078] The control unit 11 compares the average values ​​of layers L1, L2, and L3 for each point and acquires the largest average value among them (S108). The control unit 11 executes display processing of the echo image based on the largest average value acquired for each point (S109). If the display operation has not ended (S110: NO), the control unit 11 returns the processing to step S102 and executes the same processing. The control unit 11 repeatedly executes the processing of steps S102 to S109 until the display operation ends (S110: NO). This causes the echo image to be updated for each ping. Thereafter, when the display operation ends (S110: YES), the control unit 11 terminates the processing of FIG. 6.

[0079] FIG. 7 is a flowchart showing the process of labeling each point (coordinate position) in the L / L / D coordinate system as to whether it corresponds to a school of fish or not.

[0080] As described above, the labeling process in Fig. 7 is performed by the control unit 11 using the function of the fish school echo estimation unit 11c in Fig. 3. The control unit 11 resets the echo intensity at each coordinate position in the L / L / D coordinate system to 0 to initialize the labeling process (S201). When the echo intensity for one ping is acquired (S202: YES), the control unit 11 executes or skips the level conversion process (S204) depending on whether or not the level conversion process is set (S203). Next, the control unit 11 performs a binarization process using a threshold value on the echo intensity at each position on the scanning plane SP1 (S205). As a result, the echo intensity of strong echoes generated by schools of fish or floating objects is set to 1, and the echo intensity of other weak echoes is set to 0.

[0081] Thereafter, the control unit 11 performs contraction / expansion processing on the echo intensity at each binarized position (S206). This processing changes any 0 values ​​that suddenly appear among a group of 1 values ​​to 1, and any 1 value that suddenly appears among a group of 0 values ​​to 0. As a result, the echo intensity at each position corresponding to the school of fish becomes 1, and the echo intensity at positions corresponding to floating objects is replaced with a value of 0.

[0082] The control unit 11 labels, among the positions on the scanning plane SP1, positions set with a value of 1 as positions of a school of fish, and positions set with a value of 0 as positions of no school of fish (S207). The control unit 11 then converts these labeled positions into coordinate positions in the L / L / D coordinate system (S208). This labels these coordinate positions as positions corresponding to a school of fish or not. In step S106 of FIG. 6, a weight is assigned to each coordinate position based on this labeling. For example, a weight of 0.9 is assigned to a coordinate position corresponding to a school of fish, and a weight of 0.1 is assigned to a coordinate position not corresponding to a school of fish. The control unit 11 executes the process of FIG. 7 for each ping to label each coordinate position in the L / L / D coordinate system.

[0083] FIG. 8 is a flowchart showing the echo image display process executed in step S109 of FIG.

[0084] As described above, the display process of FIG. 8 is performed by the control unit 11 using the function of the image generating unit 11e of FIG.

[0085] When the control unit 11 acquires the maximum average value for each point in step S108 of FIG. 6, it determines whether or not a setting to display a normal echo image has been made (S302). Whether or not to display a normal echo image is set in advance in the input unit 19. A normal echo image is an echo image that reflects the echo intensity of each point (L / L coordinate point) obtained in the current ping. If a setting to display a normal echo image has been made (S301: YES), the control unit 11 executes a process to display a normal echo image. On the other hand, if a setting to display a normal echo image has not been made (S301: NO), the control unit 11 skips step S302.

[0086] Furthermore, the control unit 11 executes a process of displaying an echo image at each point according to the maximum average value at each point acquired in step S108 of FIG. 6 (S303). At this time, if a normal echo image display process is executed in step S302, an echo image based on the maximum average value acquired in step S303 is displayed superimposed on the normal echo image. This makes the echo image easier to view for users who are accustomed to viewing normal echo images. The control unit 11 further adds additional information such as a grid to the echo image (S304). This causes the control unit 11 to end the process of FIG. 8.

[0087] Fig. 9(a) is a diagram showing an example of an echo image displayed by the processing of Fig. 6. Fig. 9(b) is a diagram showing an echo image generated by the average peak L1-L3 method (without weighting) shown in Fig. 4 using the same echo data as Fig. 9(a).

[0088] In Figure 9(a), multiple layers are set so that adjacent layers partially overlap, similar to Figure 5. The layer setting method in Figure 9(b) is the same as in Figure 9(b). In Figures 9(a) and (b), normal echo images are not overlaid. For convenience, echo images are shown in grayscale in Figures 9(a) and (b), with the closer to black the image, the higher the echo intensity.

[0089] As can be seen by comparing Figures 9(a) and (b), the echo images F11, F12, and F13 of the schools of fish can be displayed clearly and without fading over time by changing the weighting depending on whether the position corresponds to a school of fish or not, using the processing in Figure 6. This allows the user to more clearly grasp the position and size of the schools of fish from the echo images.

[0090] <Effects of the embodiment> According to the above embodiment, the following effects can be achieved.

[0091] 3 and 4, the underwater detection device 10 (display device) includes an echo intensity acquisition unit 11b that acquires echo intensities for each point on a latitude-longitude plane over time for each of multiple layers L1 to L3 obtained by dividing a predetermined underwater area in the depth direction, a fish school echo estimation unit 11c that estimates the echo intensities of schools of fish based on the acquired echo intensities, an average value calculation unit 11d that calculates the average value of each point for each layer by weighting the echo intensities of schools of fish higher than the weights of other echo intensities and applying the respective weights to the echo intensities, and an image generation unit 11e that generates an echo image at each point based on the maximum average value of each point. As shown in Fig. 6, the control unit 11 updates and displays the echo images at each point for each ping (S102: YES) as the ship moves (S103 to S109).

[0092] As shown in Figures 6 and 7, the control method for the underwater detection device 10 (display device) involves acquiring the echo intensity for each point on the latitude and longitude plane over time for each of multiple layers L1 to L3 obtained by dividing a specified underwater range in the depth direction (S102 to S106), estimating the echo intensity of the school of fish based on the echo intensity (steps S201 to S206), setting a weight for the echo intensity of the school of fish greater than the weight for other echo intensities, and calculating the average value for each point for each layer using a weighted averaging process in which the respective weights are applied to each echo intensity (S107), generating an echo image at that point based on the maximum value of the average values ​​at each point (S108, S109), and displaying the echo image at each point while updating it as the ship moves (S109).

[0093] With this configuration, weighted averaging suppresses the influence of noise echo intensity from floating objects and the like on the echo image. Furthermore, because the weighting of the echo intensity of a school of fish is higher than the weighting of the echo intensity of other objects, the average value of the layer containing the school of fish can be increased at each point. Therefore, by generating an echo image for each point using the maximum average value, the echoes of the school of fish can be displayed more clearly. Furthermore, at points where a school of fish is present directly below, the weighting applied to the echo intensity decreases after the school of fish passes, so the weighted average value of the layer that contained the school of fish is less likely to decrease over time. Therefore, even after the school of fish passes, the maximum average value at that point is less likely to decrease, and the echo image of the school of fish is less likely to fade. Therefore, the echo image of the school of fish can be displayed clearly even when the school of fish is moving.

[0094] As shown in FIG. 4, the range of each of the layers L1 to L3 is set so as to partially overlap with the range of the layer adjacent in the depth direction.

[0095] This configuration makes it easier for the school of fish to be primarily included in one of the layers, increasing the maximum average value at the point directly below where the school of fish is located, thereby enabling the echo image of the school of fish to be displayed more clearly.

[0096] <Example of change> In the above embodiment, the underwater detection device 10 constitutes the display device, and an echo image using the average value is displayed on the display unit 17 of the underwater detection device 10. However, this is not limited to this, and a display device may be arranged separately from the underwater detection device 10, and the echo data acquired by the underwater detection device 10 may be provided to the display device, and the above-mentioned processing may be performed on the display device.

[0097] For example, as shown in Figure 10, a personal computer may be used as a display device 30 for an echo image, and echo data may be transmitted from the underwater detection device 10 to the display device 30 via an external communication network 40 such as the Internet. In this case, the display device 30 performs the same processing as in Figures 6 to 8 on the received echo data, and displays an echo image on the display unit 31. A wireless communication unit (wireless communication module) for connecting to the external communication network 40 is added to the underwater detection device 10.

[0098] The control unit (CPU) of the display device 30 executes functions similar to those of the received signal generation unit 11a, echo intensity acquisition unit 11b, fish school echo estimation unit 11c, average value calculation unit 11d, and image generation unit 11e using a program stored in the storage unit. Step S102 in Figure 6 is replaced by a determination of whether or not the echo intensity for one ping has been received from the underwater detection device 10.

[0099] The display device 30 (personal computer) may be installed in the ship S1 (wheelhouse). In this case, the display device 30 may be connected to the underwater detection device 10 via a communication line. Alternatively, instead of sending and receiving echo data online, data collected by the underwater detection device 10 may be recorded on a recording medium such as a USB memory, and the recording medium may be inserted into the display device 30 (personal computer), thereby transferring the echo data to the display device 30. In this case, the display device 30 may sequentially perform the processes of FIGS. 6 to 8 on the echo data for each ping, and display an echo image on the display unit 31.

[0100] Furthermore, in the display example of Fig. 9(a), the layer setting method used is a method in which adjacent layers partially overlap, similar to the average peak L1-L3 method shown in Fig. 4, but the layer setting method to which the present invention can be applied is not limited to this. For example, the processing of Fig. 6 may be performed using a method in which the boundaries of adjacent layers coincide, similar to the average peak L1 / L3 method shown in Fig. 4. Even with this method, the processing of Fig. 6 increases the weighting of the echo intensity from the school of fish to the weighting of other echo intensities to obtain a weighted average value, so that the echo image of the school of fish can be clearly displayed while suppressing noise images such as floating objects on the echo image.

[0101] Alternatively, an echo image may be generated by applying the weighted averaging process described above to the averaging method of FIG. 4. In this case, in step S107 of FIG. 6, a weighted average value is calculated for each point using the above formulas (1) to (3) for one layer including the search range. Step S108 of FIG. 6 is omitted. Then, in step S303 of FIG. 8, an echo image of each point is generated and displayed based on the weighted average value calculated for each point. This process also increases the weighting of the echo intensity from the school of fish to the weighting of other echo intensities to obtain a weighted average, so that the echo image of the school of fish can be displayed clearly while suppressing noise images such as floating objects on the echo image.

[0102] Furthermore, the formula for calculating the weighted average value is not limited to the above formulas (1) to (3). For example, formula (2) may be changed to the following formula (4).

[0103]

number

[0104] When this formula (4) is used, the echo image of the fish school is less likely to fade over time, and a clear echo image of the fish school can be displayed.

[0105] In the above embodiment, the reception signal generating unit 11a and the like shown in Fig. 3 are realized as functions based on programs stored in the storage unit 12, but these do not necessarily have to be realized by programs stored in the storage unit 12. For example, one or more of these functions may be configured by hardware that integrates an FPGA (field-programmable gate array) or logic circuits.

[0106] Furthermore, the process for generating and displaying echo images is not limited to the process in Figure 5 and can be modified as appropriate. For example, the level conversion processes in steps S103 and S104 in Figure 6 may be omitted, and the process of overlaying normal echo images may be omitted. Alternatively, the cropping process shown in Patent Document 1 may be added to the process in Figure 5. The method for estimating echo intensities from a school of fish is not limited to the labeling method described above, and any well-known method for estimating the range of a school of fish from echo data may be used.

[0107] In the above embodiment, the underwater detection device 10 transmits and receives waves along a conical scanning surface SP1, but the present invention may be applied to an underwater detection device 10 that transmits and receives waves in other ways. For example, the present invention may be applied to an underwater detection device that transmits and receives waves along a semicircular or arc-shaped scanning surface with a predetermined depression angle, thereby generating and displaying echo images of each point. Furthermore, the transmitter for transmitting waves and the receiver for receiving waves may be arranged separately.

[0108] In addition, the embodiments of the present invention can be modified in various ways as appropriate within the scope of the claims. [Explanation of symbols]

[0109] 10 Underwater detection equipment 11 Control section 11b Echo intensity acquisition unit 11c Fish school echo estimation unit 11d Average value calculation section 11e Image generation section 12 Storage section 13 Transmitter / Receiver 13a Ultrasonic vibrator L1, L2, and L3 layers

Claims

1. A display device that displays an image of an echo obtained by underwater detection using ultrasonic transmission and reception, an echo intensity acquisition unit that acquires echo intensities for each point on a latitude and longitude plane over time; a fish school echo estimation unit that estimates the echo intensity of a school of fish based on the echo intensity; an average value calculation unit that sets a weight for the echo intensities of the school of fish greater than the weight for the other echo intensities, and calculates an average value for each point by weighted averaging processing in which the weights are applied to the echo intensities; an image generating unit that generates an echo image at each point based on the average value at that point, As the ship moves, echo images at each point are updated and displayed.

1. A display device for an echo image, comprising:

2. 2. The display device according to claim 1, the echo intensity acquisition unit acquires the echo intensity over time for each of a plurality of layers obtained by dividing a predetermined range underwater in a depth direction; the average value calculation unit calculates an average value of each of the points for each of the layers, The image generation unit generates an echo image at each point based on the maximum value of the average values ​​at the points. An echo image display device characterized by:

3. 3. The echo image display device according to claim 2, The range of each layer is set so as to partially overlap with the range of the layer adjacent to it in the depth direction.

1. A display device for an echo image, comprising:

4. A control method for a device that displays an image of an echo obtained by underwater detection using ultrasonic transmission and reception, comprising: The echo intensity for each point on the latitude and longitude plane is acquired over time. Estimating the echo intensities of a school of fish based on the echo intensities; The weight of the echo intensity of the school of fish is set to be greater than the weight of the other echo intensities, and the average value of each point is calculated by weighted averaging processing in which the weights are applied to the echo intensities; generating an echo image at each point based on the average value at that point; As the ship moves, echo images at each point are updated and displayed. A method for controlling the display of an echo image.

5. The control unit of the device that displays the echo image obtained by underwater detection through ultrasonic transmission and reception, A function to acquire echo intensity over time for each point on the latitude and longitude plane; a function of estimating the echo intensity of a school of fish based on the echo intensity; a function of setting a weight for the echo intensity of the school of fish greater than the weight for the other echo intensities, and calculating an average value for each point by weighted averaging processing in which the weights are applied to the echo intensities; a function of generating an echo image at each point based on the average value at that point; A function that updates and displays echo images at each point as the ship moves, A program that executes the following.

Images