JP6407372B1 - Underwater ranging device and its ranging method - Google Patents

Abstract

An object distance calibration according to a water temperature in water, a salt concentration of seawater, and the like is provided.
An underwater distance measuring device (1) includes a camera (2) disposed underwater, a support unit (3), a plurality of focusing charts attached to the support unit, and a control device (6). Is an imaging surface, an optical unit having a lens, a moving unit that moves the lens, a focusing unit that controls the moving unit to focus the image on the imaging surface, and a moving distance of the lens when focused The control device 6 outputs a lens moving distance when the focusing chart is in focus, a lens moving distance and a predetermined camera and a plurality of in-focus positions. A calibration unit that calculates a calibration parameter for determining the distance between the subject and the camera based on the distance between the charts, the lens moving distance when the subject image is focused, and the calibration parameter Calculate the distance between the subject and the camera It comprises a calculation unit.
[Selection] Figure 1

Description

  The present invention relates to an underwater distance measuring device and a distance measuring method thereof.

  When constructing offshore structures such as breakwaters and revetments for harbor construction, when subsiding underwater structures such as caissons that make up the offshore structures, the position and orientation of the caissons are worked using satellite positioning devices and transits. A person monitors and moves the caisson to the target position. After installation, a diver measures the installation interval between caisons (called joint interval). It is necessary to accurately measure the joint spacing at the bottom of the caisson during the laying operation.

  For example, Patent Document 1 shows that a camera is used to join a new submerged box to an established mine or an existing submerged box with high accuracy in water. The pattern target installed in the existing burial box is caused to emit light, the light emitted from the pattern target is captured by the camera installed in the new burial box, and the relative position coordinates and orientation of the camera are continuously calculated. Then, it is disclosed that distance measurement and guidance with respect to an existing submergence box at the time of a subsidence operation of a new submergence box are performed based on the relative position coordinates and orientation of the CCD camera.

Japanese Patent Laid-Open No. 2004-043372

  However, since the water temperature in the water and the salt concentration affect the refractive index in the case of seawater, it is necessary to calibrate the subject distance in consideration of these factors.

  The present invention has been made to solve the above-described problems, and can measure the distance between two points in water with high accuracy without being affected by special conditions in measurement in water. It is an object of the present invention to propose an underwater ranging device and a ranging method thereof.

  In order to achieve the above object, an underwater ranging apparatus according to the present invention includes a camera disposed in water, a support unit attached to the camera, a plurality of focusing charts attached to the support unit, and a camera. A camera, an imaging unit having an imaging surface, an optical unit having at least one lens, a moving unit for moving the optical unit, and a plurality of focusing charts A focusing unit that controls the moving unit to focus the image on the imaging surface; and an output unit that outputs the moving distance of the lens of the optical unit when the images of the plurality of focusing charts are focused on the imaging surface; The control device includes an acquisition unit that acquires, from the output unit, a moving distance of the lens of the optical unit when each of the plurality of focusing charts is focused on the imaging surface, and an optical unit acquired by the acquisition unit The lens moving distance and the predetermined A calibration unit that calculates a calibration parameter for determining the distance between the subject and the camera based on the distance between the camera and the plurality of focusing charts, and focuses the subject image on the imaging surface. And a calculation unit that calculates a distance between the subject and the camera from the movement distance of the lens of the optical unit at that time and the calibration parameter.

  Furthermore, in the underwater distance measuring device according to the present invention, it is preferable that the support portion is detachably attached to the camera.

  Furthermore, in the underwater distance measuring device according to the present invention, it is preferable that the support portion is attached to the camera so as to be rotatable from a position parallel to the optical axis of the camera to a position perpendicular to the optical axis.

  Furthermore, in the underwater distance measuring device according to the present invention, the camera preferably further includes a waterproof case.

  An underwater distance measuring device according to the present invention includes a camera disposed underwater, a support unit attached to the camera, a plurality of focusing charts attached to the support unit, a control device connected to the camera, The camera includes an imaging unit having an imaging surface, an optical unit having at least one lens, a moving unit for moving the optical unit, and focusing images of a plurality of focusing charts on the imaging surface. A focusing unit that controls the moving unit and an output unit that outputs a notification that the images of the plurality of focusing charts are focused on the imaging surface, and the control device includes a plurality of focusing charts. An acquisition unit that acquires from the output unit a notification that each is focused on the imaging surface, and the horizontal length of each of the plurality of focusing charts when each of the plurality of focusing charts is focused on the imaging surface Calibration unit that calculates the length as a calibration parameter Based on the horizontal length of the image of the focusing chart attached to the subject and the calibration parameter when the image of the focusing chart attached to the subject is focused on the imaging surface, the distance between the subject and the camera And a calculation unit for calculating the distance.

  A distance measuring method of an underwater distance measuring device according to the present invention is an underwater distance measuring device, which is a camera disposed underwater, a support portion attached to the camera, and a plurality of focusing points attached to the support portion. A chart and a control device connected to the camera, wherein the camera includes an imaging unit having an imaging surface, an optical unit having at least one lens, a moving unit for moving the optical unit, and a plurality of units The focusing unit that controls the moving unit to focus the image of the focusing chart on the imaging surface, and the moving distance of the lens of the optical unit when the images of the plurality of focusing charts are focused on the imaging surface A distance measuring method for an underwater distance measuring device comprising: an output unit that outputs a lens moving distance of an optical unit when each of a plurality of focusing charts is focused on an imaging surface; Step and the acquired lens moving distance of the optical unit Calculating calibration parameters for determining the distance between the subject and the camera based on a predetermined distance between the camera and the plurality of focusing charts; and imaging the subject image Calculating the distance between the subject and the camera from the moving distance of the lens of the optical unit when the lens is focused and the calibration parameter.

  A distance measuring method of an underwater distance measuring device according to the present invention is an underwater distance measuring device, which is a camera disposed underwater, a support portion attached to the camera, and a plurality of focusing points attached to the support portion. A chart and a control device connected to the camera, wherein the camera includes an imaging unit having an imaging surface, an optical unit having at least one lens, a moving unit for moving the optical unit, and a plurality of units A focusing unit that controls the moving unit to focus the image of the focusing chart on the imaging surface; and an output unit that outputs a notification that the images of the plurality of focusing charts are focused on the imaging surface. In the distance measuring method of the underwater distance measuring device, a step of acquiring from the output unit a notification that each of the plurality of focusing charts is focused on the imaging surface, and each of the plurality of focusing charts is aligned with the imaging surface. Images of multiple focusing charts when in focus Calculating the horizontal length of the image as a calibration parameter and the horizontal direction of the image of the focusing chart attached to the subject when the image of the focusing chart attached to the subject is focused on the imaging surface Calculating the distance between the subject and the camera from the length of the camera and the calibration parameter.

  According to the underwater distance measuring device and the distance measuring method according to the present invention, the distance between two points in water can be measured with high accuracy.

It is a figure explaining an example of the underwater ranging apparatus and the ranging method which concern on this invention. It is a figure which shows the block structural outline of an example of a camera. It is a 3rd page figure which shows the external appearance of an example of a waterproof case. It is a figure which shows an example of attachment of the support part to a camera. It is a figure which shows the attachment method which attaches a support part to a waterproof case. It is a figure which shows an example of schematic structure block of a control apparatus. It is a figure explaining an example of a calibration method. It is a figure explaining the modification of a calibration method. It is a figure which shows an example of the operation | movement sequence between a camera and a control apparatus. It is a figure which shows an example of the operation | movement sequence between a camera and a control apparatus. It is a figure which shows an example of a holder. It is a figure which shows the usage example of a holder.

  Hereinafter, an underwater distance measuring device and a distance measuring method according to an aspect of the present disclosure will be described with reference to the drawings. However, it should be noted that the technical scope of the present disclosure is not limited to the embodiments, and extends to the invention described in the claims and equivalents thereof. In the following description and drawings, components having the same functional configuration are denoted by the same reference numerals, and redundant description is omitted.

(Outline of the underwater distance measuring device and the distance measuring method according to the present invention)
FIG. 1 is a diagram illustrating an underwater distance measuring device and a distance measuring method according to the present invention, taking the underwater distance measuring device and the distance measuring method according to the embodiment as an example.

(Outline of the underwater ranging device according to the present invention)
FIG. 1A is a diagram illustrating an outline of an example of the underwater distance measuring device 1. The underwater distance measuring device 1 has a camera 2 for imaging a subject underwater and a control device 6 connected to the camera 2 via a connection cable 5. A support portion 3 is attached to the front surface of the camera 2 so as to be parallel to the optical axis O of the camera extending from the camera 2 in the shooting direction. A plurality of chart plates 41, 42, 43 used for calibration for improving the accuracy of distance measurement in water are attached to the tip of the support unit 3 so as to be perpendicular to the optical axis O of the camera 2. A focusing chart 411.421.431 is attached to the camera side plane of each of the chart plates 41, 42, 43. The distance from the camera side plane of each chart plate 41, 42, 43 and the lens of the camera 2 to each focusing chart 411.421.431 is known. The camera 2 has a waterproof case 26 that protects the camera body in water. A fixing base 261 for fixing to a tripod may be provided on the bottom surface of the waterproof case 26.

  An imaging signal captured by the underwater camera 2 is transmitted to the control device 6 on the ground or water through the connection cable 5. The imaging signal received by the control device 6 is displayed on the display unit of the control device 6. The control device 6 controls the camera 2 through the connection cable 5. Further, the control device 6 uses the information signal from the camera 2 to perform distance measurement calculation processing and calibration processing.

(Outline of construction pretreatment of the underwater ranging device according to the present invention)
FIG. 1B is a diagram for explaining calibration of the camera 2 in water. When the camera 2 is used in water, the water temperature in the water, and in the case of seawater, the salinity concentration affects the refractive index, etc., so that the camera 2 can be used in the water at the construction site before use in order to improve distance measurement accuracy. Need to be calibrated. The calibration may be performed immediately before use, but is preferably placed in water from the day before use. This is because if the camera 2 stays in water for a long time, the temperature of the camera 2 becomes stable.

  In order to perform calibration, the control device 6 sequentially instructs the camera 2 to focus on the focusing charts 411, 421, 431 of the chart plates 41, 42, 43. For example, when the focusing chart 411 on the chart plate 41 is in focus, that is, when the focusing is achieved, the control device 6 acquires the moving distance of the lens of the camera 2. Here, the moving distance of the lens is a moving distance of the lens from the reference position of the lens, for example, the lens position with respect to the infinity point or the lens position with respect to the closest position (hereinafter the same). The control device 6 repeats the focusing instruction regarding the respective focusing charts 411, 421 and 431. Since the distance between the lens and each focusing chart is actually measured and known, the control device 6 can obtain a plurality of pairs of the distance between the lens and the focusing chart and the moving distance of the lens. . Using a plurality of pairs of the distance between the lens and the focusing chart and the moving distance of the lens, the control device 6 can calculate a calibration parameter related to distance measurement. By using the calibration parameters of the camera 2, the distance measurement accuracy of the underwater distance measuring device 1 is improved.

(Outline of distance measurement work of the underwater distance measuring device according to the present invention)
FIG. 1C is a diagram showing an example of use of the underwater distance measuring device 1 when the caisson B is installed underwater adjacent to the existing caisson A. The construction worker installs the camera 2 in water before the caisson B is installed, and completes the calibration work. In the construction work, in order to improve the accuracy of the construction work, the construction worker knows the joint spacing d between the caisson A and the caisson B accurately, and installs the caisson B at a predetermined joint spacing, for example, 10 cm away from the caisson A. There is a need to. The construction worker applies the optical axis O of the camera 2 of the underwater ranging device 1 to the ridge line of the adjacent surface of the caisson A in water, and measures the distance between the ridge line and the lens. Since the distance from the lens to the rotation axis R of the camera 2 is known, the control device 6 can determine the distance D1 from the ridge line of the adjacent surface of the caisson A to the rotation axis. Next, the installation operator rotates the camera 2 horizontally around the rotation axis, places the optical axis O of the camera 2 on the ridge line of the adjacent surface of the caisson B, and measures the distance between the ridge line and the lens. Distance. Similarly to the distance D1, the control device 6 can determine the distance D2 from the ridge line of the adjacent surface of the caisson B to the rotation axis. The rotation angle θ at this time is assumed. For example, the rotation angle θ can be measured using a potentiometer. The joint distance d between caisson A and caisson B is the cosine theorem,
(Expression 1) d ² = D1 ² + D2 ² -2 · D1 · D2 · cos θ
Can be obtained from

  In practice, the construction worker measures the distance D1 from the ridge line of the caisson A, and aligns the optical axis O of the camera 2 in advance at a required position where the joint distance between the caisson A and the caisson B is d = 10 cm. Since the rotation angle θ at this time is known, (Equation 1) can be solved for D2. The construction worker uses the underwater ranging device 1 so that the ridge line of the adjacent surface of the caisson B intersects the optical axis O of the camera 2 in the water, that is, the ridge line is at the center of the captured image, and the caisson. It is preferable to perform the construction work by monitoring the distance from the ridge line of B to D2. Examples will be described below.

(Embodiment of an underwater ranging device according to the present invention)
FIG. 2 is a diagram showing a schematic block configuration of an example of the camera 2. The camera 2 includes an imaging unit 21, an optical unit 22, a moving unit 23, a focusing unit 24, and a focusing microcomputer 245. The imaging unit 21 includes an imaging sensor 212 such as a CCD sensor or a CMOS sensor that receives a light beam from a subject on the imaging surface 211 and converts the subject image into an image signal. The captured image signal is transmitted to the focusing unit 24. The optical unit 22 is mounted on the imaging surface 211 side of the imaging unit 21, and the optical unit 22 guides light from the subject to the imaging surface 211. The optical unit 22 includes a focus lens 221, a focus ring 222 that translates the focus lens 221 in the optical axis O direction, a zoom lens 223, a zoom ring 224 that translates the zoom lens 223 in the optical axis O direction, an aperture 225, and an aperture A diaphragm ring 226 and the like for adjusting 226 are provided. Each lens may be constituted by a lens group including a plurality of lenses, which is limited to one lens. The optical unit 22 is preferably capable of wide-angle shooting. This is because a plurality of focusing charts can be shot simultaneously.

  A moving unit 23 is attached to the side surface of the optical unit 22, and focus adjustment is performed by moving and adjusting the position of the focus lens 221 of the optical unit 22. The moving unit 23 includes actuators such as a focus motor (M) 231, a focus motor driving circuit 232 that drives the focus motor (M) 231, a moving unit microcomputer 233 that controls the focus motor driving circuit 232, and the focus motor (M). A position sensor (PS) 234 for detecting the amount of movement of the focus lens by driving 231 is provided. The focus lens movement amount from the position sensor (PS) 234 is input to the moving unit microcomputer 233 and further sent to the focusing control unit 246 of the focusing microcomputer 245. Other adjustments of the optical unit 22 can be adjusted by the photographer turning each ring. Furthermore, the moving unit 23 may have a function of adjusting zoom, exposure, and the like by adjusting the zoom lens, the diaphragm, and the like of the optical unit 22.

  The camera 2 has a focusing unit 24 in order to control the moving unit 23 for optimal focusing. The control device 6 activates the focusing unit 24 and transmits the AF frame information displayed on the display unit 61 of the control device 6 to the focusing unit 24. The focusing unit 24 determines the focusing state from the captured image, and controls the moving unit 23 to perform focusing. The camera 2 can focus with high accuracy on the subject to be distance-measured by the focusing unit 24, and can perform distance measurement with high accuracy. The focusing unit 24 includes an image branching unit 241, a high-pass filter (HPF) 242, a gate circuit 243, an adder 244, a focusing microcomputer 245, a focusing control unit 246, and an output unit 247.

  The image branching unit 241 receives an image signal from the imaging unit 21, for example, an HD-SDI (High Definition Serial Digital Interface) standard image signal. The image branching unit 241 sends the received signal to the next-stage high-pass filter (HPF) 242 and transmits it to the control device 6 via the connection cable 5. A high pass filter (HPF) 242 filters high frequency components of the image signal from the image branching unit 241. This is to increase the accuracy of contrast comparison for focusing. The gate circuit 243 extracts the in-frame image signal portion of the AF frame instructed from the control device 6 from the image signal filtered by the high pass filter (HPF) 242. This is because only the image signal within the AF frame is necessary for determining the accuracy of focusing. The image signal within the AF frame output from the gate circuit 243 is added by the adder 244, and based on the addition result, the focus control unit 246 calculates the contrast ratio to determine the focus accuracy, and achieves the highest accuracy. The moving part 23 is controlled so that it becomes. For example, when the contrast ratio is low, the focus control unit 246 moves the focus lens as fast as possible in the direction in which the contrast ratio increases. The focus control unit 246 controls the contrast ratio by using the level of the contrast ratio and the magnitude of the differential amount so as to decelerate the movement of the focus lens as the contrast ratio increases and to stop at a point where the contrast ratio is high with high accuracy. Such a method is generally called a hill-climbing autofocus method. Usually, the focusing control unit 246 is implemented by a processing program of the focusing microcomputer 245.

  The output unit 247 of the focusing microcomputer 245 transmits the movement amount of the focus lens 221 from the moving unit microcomputer 233 when the focus is achieved to the control device 6 via the connection cable 5. Usually, the output unit 247 is mounted by a processing program of the focusing microcomputer 245. The control device 6 is connected to the camera 2 via the connection cable 5 and displays an image captured by the camera 2 and controls the camera 2. The connection cable 5 passes the image signal from the focusing unit 24, the control signal for the imaging unit 21, and the control signal for the focusing unit 24. For example, a combination of three cables, one image signal cable such as HD-SDI standard and two control signal cables such as RS232C standard, may be used.

  FIG. 3 is a three-view diagram illustrating an appearance of an example of the waterproof case 26 included in the camera 2. Since the camera 2 is used underwater, a waterproof case 26 for housing the camera body is required. The waterproof case 26 has a cylindrical shape, and a fixed base 261 for mounting on a camera stand, a tripod or the like is attached to the lower part of the cylindrical side surface. A carrying handle 262 is attached to the upper part of the cylindrical side surface. A glass window 263 is provided on the front surface of the waterproof case 26 to allow light from the subject to pass through the camera. A transparent material such as a transparent acrylic plate may be used instead of glass. The lower part of the front surface of the waterproof case 26 has support part mounting parts 264 and 265 for mounting the support part 3. An image signal cable outlet 266 and a control signal cable outlet 267 are provided on the back surface of the waterproof case 26. Each outlet is structured to prevent water leakage using packing or the like. It should be noted that the image signal and the control signal cable may be combined into one cable and the extraction port may be combined into one.

  FIG. 4 is a diagram illustrating an example of the support portion 3. 4A is a side view of the support unit 3 attached to the waterproof case 26, and FIG. 4B is a plan view of the support unit 3 attached to the waterproof case 26. FIG. FIG. For example, the support unit 3 includes support members 311 and 312. Furthermore, reinforcement members 321 and 322 may be provided in a ladder shape between the support member 311 and the support member 312 for reinforcement. The support member 311 and the support member 312 are fixed or detachably attached to attachment portions 264 and 265 in the lower front portion having the glass window 263 of the waterproof case 26 so as to be parallel to the optical axis O. A plurality of rectangular chart plates 41, 42, and 43 are attached in parallel to each other from the focus lens 221 of the camera 2 toward the subject at the distal ends of the support member 311 and the support member 312 of the support unit 3. Each chart plate 41, 42, 43 is mounted such that the plate surface of the chart plate is perpendicular to both support members 311, 312. Focusing charts 411, 421, and 431 are attached to the camera side planes of the chart plates 41, 42, and 43, respectively. Since both support members 311 and 312 are parallel to the optical axis O, the plate surface of each chart plate is perpendicular to the optical axis O. Each chart plate 41, 42, 43 has both support members 311, so that the plate surface on which the focusing chart is attached is at a predetermined distance from the position of the focus lens 221, for example, the reference position of the focus lens 221. 312 is attached. For example, the first chart plate 41 closest to the focus lens is attached at a position away from the focus lens 221 by L1 = 400 mm with reference to the focusing chart attachment surface. The second chart plate 42 that is second closest to the focus lens 221 is attached at a position L2 = 500 mm away from the focus lens 221 with reference to the focusing chart attachment surface. Further, the third chart plate 43 that is third closest to the focus lens 221 is attached at a position that is L3 = 600 mm away from the focus lens 221 with reference to the focusing chart attachment surface. Regarding the respective charts for focusing on the first chart plate 41, the second chart plate 42, and the third chart plate 43, the amount of movement of each focus lens when the focusing unit 24 is in focus is known. Since the distances L1, L2, and L3 of the focusing charts 411, 421, and 431 with the focus lens are known, the control device 6 determines the amount of movement of the focus lens when the focusing unit 24 focuses. This can be used to calculate calibration parameters for ranging.

  FIG. 4C is a diagram illustrating an example of a focusing chart that is attached to the plate surface on the camera 2 side of the chart plates 41, 42, and 43. The focusing chart has a rectangular shape with a length of 10 cm and a width of 12 cm. The focusing chart is drawn so that a black and white pattern radiates from the center of the chart, and is suitable for a hill-climbing autofocus system that uses a contrast ratio for focusing. The focusing chart may be any chart as long as the contrast ratio can be clearly measured. For example, the focusing chart may be a chart in which four white circles are arranged at the upper, lower, left, and right positions on a black background.

  In the embodiment shown in FIG. 4, the support portion 3 has two support members, but one or three or more support members may be used. The number of chart plates used for distance measurement calibration may be changed as appropriate according to the calibration method to be used, but at least two chart plates are required.

  FIG. 5 is a view showing a modification of the attachment method for attaching the support portion 3 to the waterproof case 26. FIG. 4 shows an example in which both support members 311 and 312 of the support portion 3 are fixedly or detachably attached to attachment portions 264 and 265 provided in the waterproof case 26. FIG. 5A shows the support portion 3 having the holder portion 33. The holder portion 33 has a hollow cylindrical shape, and can be attached to and detached from the waterproof case 26 by being fitted into the front portion of the waterproof case 26. Support members 311 and 312 are provided in parallel to the optical axis O in the subject direction below the cylindrical edge of the holder portion 33.

  FIG. 5B is a view showing another modification of the attachment method for attaching the support portion 3 to the waterproof case 26. The attachment portion 264 on the front surface of the waterproof case 26 has a rib shape. The rib 264 is provided with two through holes 268 and 269 parallel and horizontally to the front surface of the waterproof case 26. On the other hand, two through holes 313 and 314 corresponding to the two through holes of the rib 264 are also provided at the tip of the waterproof case side of the support member 311 of the support portion 3. When the rivet 315 is fixed through the through hole 268 of the rib 264 and the through hole 313 of the support member 311, the support member 311 is waterproof so that it can be rotated between a position perpendicular to the optical axis O and a position perpendicular to the optical axis O. It will be attached to the case 26. The operator passes the fixing pin 316 through the other through hole 269 and the through hole 314 of the support member 311, so that the support member 311 is fixed at a position horizontal to the optical axis O. If the operator pulls out the fixing pin 316, the support member 311 can hang down in the direction perpendicular to the optical axis O under its own weight. If the mounting portion 265 and the support member 312 have the same structure, the support portion 3 hangs down in the direction perpendicular to the optical axis O under its own weight when the operator pulls out the two fixing pins. Therefore, the support portion 3 does not interfere with the distance measurement by the worker or the like using the camera 2.

  FIG.5 (c) is the modification which combined the attachment method which attaches the support part 3 to the waterproof case 26 shown to Fig.5 (a) and (b). A mounting portion for attaching the support portion is not directly provided on the waterproof case 26, but a rib 331 is provided on the holder portion 33 of the support portion 3. The rib 331 is provided with two through holes 332 and 333. The support portion 3 side is the same as that shown in FIG. According to this modification, the support part 3 can be easily attached to the waterproof case 26 and does not interfere with the distance measurement by the operator using the camera 2.

  FIG. 6 is a diagram illustrating an example of a schematic configuration block of the control device 6 according to the present embodiment. The control device 6 is connected to the camera 2 via the connection cable 5 and displays an image captured by the camera 2 and controls the camera 2. The connection cable 5 passes the image signal from the focusing unit 24, the control signal for the imaging unit 21, and the control signal for the focusing unit 24. The connection cable 5 may be, for example, a combination of three cables: one image signal cable such as HD-SDI standard and two control signal cables such as RS232C standard. This is because if the cables are combined into one, handling such as cable routing becomes easy. The control device 6 displays an image taken by the camera 2 on the display unit 61 in accordance with the operation of the operation unit 62 (keyboard, mouse, touch panel display, etc.) operated by a construction worker or the like. Further, the control device 6 performs calibration processing and distance measurement processing based on data from the camera 2. Therefore, the control device 6 includes a display unit 61, an operation unit 62, a storage unit 63, and a processing unit 64.

  In the present embodiment, a notebook personal computer (PC) is assumed as the control device 6, but the present invention is not limited to a notebook PC. For example, a tablet PC, a personal digital assistant (PDA), or the like may be used.

  The display unit 61 may be any device that can display a video corresponding to the imaging performance of the camera 2, such as a moving image or a still image, such as a liquid crystal display or an organic EL (Electro-Luminescence) display. It is. In this embodiment, the image signal from the camera 2 is directly input to the display unit 61, but may be passed through a conversion device or the like. The operation unit 62 may be any device as long as the operation of the control device 6 is possible, for example, a touch panel, a keyboard, a mouse, a touch pad, and the like. An operator such as a construction worker can input characters, numbers, and the like using the operation unit 62, and can also perform enlargement, reduction, movement, etc. of a figure such as an AF frame displayed on the display unit 61. Can be operated. When operated by the operator, the operation unit 62 generates a signal corresponding to the operation. The generated signal is supplied to the processing unit 64 as an instruction from the operator.

  The storage unit 63 includes, for example, at least one of a semiconductor memory device, a magnetic disk device, and an optical disk device. The storage unit 63 stores an operating system program, a driver program, an application program, data, and the like used for processing in the processing unit 64. For example, the storage unit 63 stores, as a driver program, an input device driver program that controls the operation unit 62, a display device driver program that controls the display unit 61, and the like. The storage unit 63 also stores a focusing instruction program for the camera 2, a calibration parameter calculation program, and the like as application programs. The storage unit 63 also stores display data, image data, and the like for focusing on the subject as data. Further, the storage unit 63 stores the calibration parameter 631 calculated by the calibration unit 644. The storage unit 63 may temporarily store temporary data related to a predetermined process.

  The processing unit 64 includes one or a plurality of processors and their peripheral circuits. The processing unit 64 controls the overall operation of the control device 6 and is, for example, a CPU (Central Processing Unit). The processing unit 64 operates the display unit 61, the camera 2, and the like so that various processes of the control device 6 are executed in an appropriate procedure according to the program stored in the storage unit 63, the operation of the operation unit 62, and the like. To control. The processing unit 64 executes processing based on programs (operating system program, driver program, application program, etc.) stored in the storage unit 63. The processing unit 64 can execute a plurality of programs (such as application programs) in parallel. The processing unit 64 includes a setting unit 641, an instruction unit 642, an acquisition unit 643, a calibration unit 644, a writing unit 645, a calculation unit 646, and the like. Each of these units included in the processing unit 64 is a functional module implemented by a program executed on a processor included in the processing unit 64. Alternatively, each of these units included in the processing unit 64 may be mounted on the control device 6 as an independent integrated circuit, a microprocessor, or firmware.

FIG. 7 is a diagram for explaining a calibration method used in this embodiment. It is known that the distance between the subject and the focus lens 221 is approximately inversely proportional to the moving ratio of the focus lens 221 when focusing on the subject. FIG. 7A shows a graph showing an inversely proportional relationship. The horizontal axis (X axis) is the movement ratio [%] of the focus lens 221. The point at infinity is 0%, and the position of the closest point is 100%. The vertical axis (Y axis) is the distance [m] of the subject from the focus lens 221. The inverse relationship is
(Formula 2) Y = a / (X−b) + c
It is represented by a, b, and c are constants. If the values of the constants a, b, and c are known, the distance [m] of the subject from the focus lens 221 can be calibrated by (Expression 2) Y = a / (X−b) + c. Therefore, if the three points (X, Y) on the graph are known, the constants a, b, and c as calibration parameters can be determined. The moving ratio [%] of the focus lens 221 is
(Expression 3) (movement distance of focus lens 221 / maximum movement distance of focus lens 221) × 100
Is calculated by

FIG. 7B is a table showing actually measured values in water for calibration. The measured distances between the three focusing charts 411, 421, 431 and the focus lens 221 on each chart plate attached to the support unit 3 are L1 = 1.2 m, L2 = 1.5 m, and L3 = 2.0 m, respectively. Yes, the lens movement ratio is 60%, 30%, and 20%. Therefore, simultaneous equations (Equation 4) 1.2 = a / (60−b) + c
(Formula 5) 1.5 = a / (30−b) + c
(Formula 6) 2.0 = a / (20−b) + c
And a relational expression (expression 7) between the movement ratio and distance of the calibrated lens shown in FIG. 7C. Y = 10 / (x−10) +1
Get. Constants a = 10, b = 10, and c = 1 as calibration parameters are stored in the storage unit 63 of the control device 6 and used for calculating the distance between the subject and the focus lens 221.

FIG. 8 is a diagram for explaining a modification of the calibration method used in the present embodiment. The embodiment of the calibration method shown in FIG. 7 is a calibration method using the fact that the distance between the subject and the focus lens 221 is approximately inversely proportional to the movement ratio of the focus lens 221 when focusing on the subject. Met. This modification utilizes the fact that the distance between the subject and the focus lens is related to, for example, the width of the photographed subject image. As shown in FIG. 9A, the plurality of focusing chart images displayed on the display unit 61 are displayed smaller as they are farther away. FIG. 9B shows this relationship graphically. A triangle ABC having a base BC corresponding to the horizontal width W1 of the first focusing chart can be drawn with the infinity point as the vertex A. The line segment DE corresponds to the horizontal width W2 of the second focusing chart, and the line segment FG corresponds to the horizontal width W3 of the third focusing chart. Focusing on the similarity of triangles, as shown in FIG. 9C, the distance L from the point A to the side BC is
(Formula 8) L = W1 (L3-L1) / (W1-W3)
Thus, there is a subject with the same size of the focusing chart between the first focusing chart and the third focusing chart, and up to the chart when the horizontal width WX of the pasted focusing chart is The distance LX is
(Formula 9) LX = {(W1-WX) / (W1-W3)} L3
+ {(WX-W3) / (W1-W3)} L1
L1 and L3 are known, and if W1 and W3 are obtained as calibration parameters, they can be used for calibration. For example, the horizontal width of the subject is the number of horizontal imaging pixels of the subject on the imaging surface 211 of the camera 2 or the number of horizontal display pixels of the subject on the display unit 61 of the control device 6.

  Hereinafter, an example of the processing operation for obtaining the calibration parameter between the camera 2 and the control device 6 will be described with reference to the operation sequences shown in FIGS. The operation described below is executed in cooperation with each element of the control device 6 by the processing unit 64 mainly including a CPU or the like based on a program stored in the storage unit 63 in advance.

  FIG. 9 is a diagram illustrating an example of an operation sequence between the camera 2 and the control device 6 for obtaining the calibration parameter described in FIG. The calibration method shown in FIG. 7 is a calibration method using the fact that the distance between the subject and the focus lens 221 is approximately inversely proportional to the movement ratio of the focus lens 221 when focusing on the subject. The image branching unit 241 of the camera 2 branches the captured image signal and transmits it to the control device 6 (ST901). Display unit 61 of control device 6 displays the received image signal (ST902). Setting section 641 sets an autofocus (AF) frame on the focusing chart in the displayed image (ST903). When the AF frame is installed, instructing unit 642 sends a focusing instruction signal and an AF frame signal to focusing unit 24 (ST904). Upon receiving the focusing instruction signal, the focusing unit 24 controls the moving unit 23 to focus on the focusing chart selected in the AF frame (ST905). The moving unit 23 moves the focus lens 221 (ST906). The moving unit 23 measures the lens moving amount of the focus lens 221 and outputs a moving amount signal to the focusing unit 24 (ST907). Steps ST905-ST906-ST907-ST905 are repeated until focusing is performed as a feedback loop. The focusing unit 24 transmits a lens movement amount signal when in focus to the control device 6 (ST908). The acquisition unit 643 of the signal control device 6 acquires a lens movement amount signal (ST909). Steps ST903 to ST909 are repeated at least three times. This is because the determination of the calibration parameter requires data on at least three focusing charts. When data relating to at least three focusing charts is acquired, calibration unit 644 calculates calibration parameters (ST910). Writing unit 645 writes the calculated calibration parameter into storage unit 63 (ST911).

  When the camera 2 is calibrated, distance measurement using the underwater distance measuring device 1 is performed at a construction site or the like. A construction worker or the like operates the operation unit 62 while selecting the display unit 61 of the control device 6 to select a subject to be sparse, and the instruction unit 642 focuses the camera 2 on the underwater subject. Instructs the execution of the process to burn. The camera 2 outputs a movement distance signal of the focus lens 221 when the subject is focused. The acquisition unit 643 acquires a movement distance signal. Next, the calculation unit 646 of the control device 6 uses the movement distance of the focus lens 221 when focused on the subject and the calibration parameter obtained by the operation sequence shown in FIG. 9 when focusing on the subject. The distance between the subject and the camera 2 is calculated. The calculated distance is displayed on the display unit 61 of the control device 6.

  FIG. 10 is a diagram illustrating an example of an operation sequence between the camera 2 and the control device 6 for obtaining the calibration parameter described in FIG. The modification of the calibration method shown in FIG. 8 utilizes the fact that the distance between the subject and the focus lens is related to, for example, the horizontal width of the photographed subject image. The image branching unit 241 of the camera 2 branches the captured image signal and transmits it to the control device 6 (ST1001). Display unit 61 of control device 6 displays the received image signal (ST1002). Setting section 641 sets an autofocus (AF) frame on a chart in the displayed image (ST1003). When the AF frame is installed, the instruction unit 642 sends a focusing instruction signal to the focusing unit 24. In addition, an AF frame information signal is also sent (ST1004). The focusing unit 24 that has received the focusing instruction signal controls the moving unit 23 to focus on the chart selected in the AF frame (ST1005). The moving unit 23 moves the focus lens 221 (ST1006). The moving unit 23 measures the lens moving amount of the focus lens 221 and outputs a moving amount signal to the focusing unit 24 (ST1007). Steps ST1005-ST1006-ST1007-ST1005 are repeated until in-focus as a feedback loop. When the in-focus state is achieved, the in-focus unit 24 transmits an in-focus notification signal notifying the in-focus state to the control device 6 (ST1008). Acquisition unit 643 of control device 6 acquires a focus notification signal (ST1009). When acquisition unit 643 acquires the focus notification signal, calibration unit 644 calculates the number of horizontal pixels as the horizontal width of the focusing chart when focused (ST1010). Steps ST1003 to ST1010 are repeated at least twice. This is because the lateral width data relating to at least two focusing charts is necessary for determining the calibration parameter. The writing unit 645 writes the calculated lateral width data relating to at least two focusing charts to the storage unit 63 as a calibration parameter (ST1010). The distance between the focusing chart attached to each chart plate and the camera 2 is known, and is stored in the storage unit 63 as a calibration parameter.

  When the camera 2 is calibrated, distance measurement using the underwater distance measuring device 1 is performed at a construction site or the like. A construction worker or the like operates the operation unit 62 while looking at the display unit 61 of the control device 6 to select the focusing chart attached to the subject to be measured. The instruction unit 642 instructs the camera 2 to execute a process of focusing, that is, focusing, the camera 2 on a focusing chart attached to an underwater subject. The camera 2 outputs a signal notifying that the in-focus chart attached to the subject is in focus. The acquisition unit 643 acquires a signal to be notified. Next, the calculation unit 646 of the control device 6 uses the horizontal width of the focusing chart pasted on the subject when the subject is focused and the calibration parameter obtained in the operation sequence shown in FIG. The distance between the subject and the camera 2 when in focus is calculated. The calculated distance is displayed on the display unit 61 of the control device 6.

(Example in construction work of underwater structure of underwater distance measuring device according to the present invention)
An embodiment of the underwater distance measuring apparatus 1 in construction work of an underwater structure, for example, caisson installation work will be described.

  FIG. 11 is a diagram illustrating an example of the holder 7 when the caisson B is installed next to the existing caisson A. FIG. The holder 7 has a mounting part 71, an arm part 72, and a collar part 73 on which the camera 2 is placed. The attachment portion 71 is attached to the surface side orthogonal to the surface of the caisson A that faces the caisson B that is installed in water, for example, the crane is lowered using water. The arm portion 72 extends at an angle of 90 ° from one end of the attachment surface of the caisson A, and is bent at an angle of 45 ° closer to the caisson B. The attachment portion 71 and the arm portion 72 may be formed by bending a single thick flat sheet metal. On the arm portion 72, a collar portion 73 that holds the camera 2 is attached.

A support 3 is attached to the front surface of the camera 2. The camera 2 is held by the flange 73 so that the optical axis O looks at the ridge surfaces of two orthogonal surfaces of the caisson B. The center of the lens surface of the focus lens 221 of the camera 2 is a point A. Let B be the foot of the perpendicular line from the point A to the surface where the holder of the caisson A is attached, and C be the foot of the perpendicular line dropped from the point A to the slope of the caisson B. The triangle ABC is an isosceles right triangle with a right angle of ∠ABC, and the caisson B may be lowered into the water so that the joint distance between the caisson B and the caisson A is d = 10 cm. When the joint distance between caisson B and caisson A is d, the distance between AB is LABcm, and the distance between AC is LACcm, the point B is a distance of (LAB-d) from the surface facing caisson B of caisson A. 7 is attached to caisson A. The distance between AC is measured by the underwater ranging device 1,
(Formula 10) LAC = (square root of 2) × LAB
The caisson B is installed so that Further, the caisson B is installed so that the slope of the caisson B is displayed at the center of the captured image from the camera 2 displayed on the display unit 61 of the control device 6. On the slope of caisson B, it is preferable that the focusing chart shown in FIG. This is because focusing and ranging are performed accurately. The caisson slope may not be required. When there is no slope, it will be aligned with the ridgeline. In addition, the bending angle of the arm part 72 of the holder 7 may be known other than 45 °.

  FIG. 12 is a diagram illustrating another example of using the holder 7 of the camera 2 when the caisson B is installed next to the existing caisson A. FIG. This is an embodiment in which another set of the camera 2 and the holder 7 that holds the camera 2 shown in FIG. For example, the captured images from the two cameras 2 are displayed by dividing the screen of the display unit 61 of the control device 6 into left and right, respectively. A work supervisor or the like gives a work instruction to install the caisson B while looking at the display unit 61. By monitoring work with the two cameras 2, the construction accuracy becomes higher.

  It should be understood by those skilled in the art that various changes, substitutions, and modifications can be made thereto without departing from the spirit and scope of the present invention.

DESCRIPTION OF SYMBOLS 1 Underwater ranging device 2 Camera 21 Imaging part 211 Imaging surface 22 Optical part 23 Moving part 24 Focusing part 26 Waterproof case 3 Support part 41,42,43 Chart board 411,421,431 Focusing chart 5 Connection cable 6 Control Device 61 Display unit 62 Operation unit 63 Storage unit 64 Processing unit 7 Holder

Claims (7)

An underwater ranging device,
A camera placed underwater,
A support attached to the camera;
A plurality of focusing charts attached to the support;
A control device connected to the camera,
The camera
An imaging unit having an imaging surface;
An optical part having at least one lens;
A moving unit for moving the optical unit;
A focusing unit that controls the moving unit to focus the images of the plurality of focusing charts on the imaging surface;
An output unit that outputs the moving distance of the lens of the optical unit when the images of the plurality of focusing charts are focused on the imaging surface;
The control device includes:
An acquisition unit that acquires, from the output unit, a moving distance of the lens of the optical unit when each of the plurality of focusing charts is focused on the imaging surface;
The distance between the subject and the camera based on the movement distance of the lens of the optical unit acquired by the acquisition unit and a predetermined distance between the camera and the plurality of focusing charts. A calibration unit for calculating a calibration parameter for determining
A calculation unit for calculating a distance between the subject and the camera from a moving distance of the lens of the optical unit when the image of the subject is focused on the imaging surface and the calibration parameter; An underwater ranging device characterized by that.   The underwater ranging apparatus according to claim 1, wherein the support portion is detachably attached to the camera.   The underwater ranging apparatus according to claim 1, wherein the support unit is attached to the camera so as to be rotatable from a position parallel to the optical axis of the camera to a position perpendicular to the optical axis.   The underwater distance measuring device according to claim 1, wherein the camera further includes a waterproof case. An underwater ranging device,
A camera placed underwater,
A support attached to the camera;
A plurality of focusing charts attached to the support;
A control device connected to the camera,
The camera
An imaging unit having an imaging surface;
An optical part having at least one lens;
A moving unit for moving the optical unit;
A focusing unit that controls the moving unit to focus the images of the plurality of focusing charts on the imaging surface;
An output unit that outputs a notification that the images of the plurality of focusing charts are focused on the imaging surface;
The control device includes:
An acquisition unit that acquires from the output unit a notification that each of the plurality of focusing charts is focused on the imaging surface;
A calibration unit that calculates the horizontal length of each of the plurality of focusing charts as a calibration parameter when each of the plurality of focusing charts is focused on the imaging surface;
From the horizontal length of the image of the focusing chart attached to the subject when the image of the focusing chart attached to the subject is focused on the imaging surface and the calibration parameter, the subject and An underwater ranging apparatus comprising: a calculation unit that calculates a distance to the camera. An underwater ranging device,
A camera placed underwater,
A support attached to the camera;
A plurality of focusing charts attached to the support;
A control device connected to the camera,
The camera
An imaging unit having an imaging surface;
An optical part having at least one lens;
A moving unit for moving the optical unit;
A focusing unit that controls the moving unit to focus the images of the plurality of focusing charts on the imaging surface;
An output unit that outputs a moving distance of the lens of the optical unit when the images of the plurality of focusing charts are focused on the imaging surface;
Obtaining from the output unit the movement distance of the lens of the optical unit when each of the plurality of focusing charts is focused on the imaging surface;
In order to determine the distance between the subject and the camera based on the acquired movement distance of the lens of the optical unit and a predetermined distance between the camera and the plurality of focusing charts. Calculating calibration parameters for
Calculating a distance between the subject and the camera from a movement distance from a reference position of the lens of the optical unit when the image of the subject is focused on the imaging surface and the calibration parameter;
A distance measuring method for an underwater distance measuring device. An underwater ranging device,
A camera placed underwater,
A support attached to the camera;
A plurality of focusing charts attached to the support;
A control device connected to the camera,
The camera
An imaging unit having an imaging surface;
An optical part having at least one lens;
A moving unit for moving the optical unit;
A focusing unit that controls the moving unit to focus the images of the plurality of focusing charts on the imaging surface;
An output unit that outputs a notification that the images of the plurality of focusing charts are in focus on the imaging surface;
Obtaining a notification that each of the plurality of focusing charts is focused on the imaging surface from the output unit;
Calculating a horizontal length of an image of each of the plurality of focusing charts as a calibration parameter when each of the plurality of focusing charts is focused on the imaging surface;
From the horizontal length of the image of the focusing chart attached to the subject when the image of the focusing chart attached to the subject is focused on the imaging surface and the calibration parameter, the subject and the Calculating the distance to the camera;
A distance measuring method for the underwater distance measuring device.

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