Underwater monitoring method and underwater monitoring system

Abstract

To provide an underwater monitoring method and an underwater monitoring system capable of easily specifying measuring positional information acquired by the measuring device underwater.SOLUTION: An underwater monitoring system acquires measuring data by a measuring device 4 and image data IDn of a positional specification object 10 by an imaging device 3 while moving an underwater movable body 2. The system calculates the positional relationship between the image device 3 at the time when the image data IDn are acquired and the set coordinate reference position 10a for the positional specification object 10 based on the image data IDn acquired by the imaging device 3, and specifies the imaging positional information at the time when the image data IDn are acquired. The system specifies the measuring positional information of the measuring device 4 at the time when the image data IDn are acquired based on the relative positional relationship between the imaging device 3 and the measuring device 4, and on the specified imaging positional information, and generates associated data obtained by associating the specified measuring positional information with the measuring data at the time when the image data IDn are acquired.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an underwater monitoring method and an underwater monitoring system, and more particularly to an underwater monitoring method and an underwater monitoring system that can more easily identify measurement position information at the time when a measuring device acquires measurement data underwater. [Background technology]

[0002] As part of the maintenance and inspection work for structures such as sheet pile quays facing water bodies, monitoring is carried out to determine the deterioration state of the structures underwater. When performing this underwater monitoring, an underwater vehicle equipped with a measuring device such as an electric field sensor is used to determine the deterioration state of the structure. However, because it is not possible to receive satellite radio waves from the Global Navigation Satellite System (GNSS) underwater, it is difficult to accurately determine the position information (position coordinates and attitude) of the underwater vehicle. This makes it difficult to identify the measured position information (measurement position coordinates and measurement attitude) at the time the measuring device acquired measurement data underwater.

[0003] Methods for determining the position of an underwater moving body in water include, for example, methods using an acoustic positioning device or an inertial navigation system. However, acoustic positioning devices have a problem in that their measurement accuracy decreases near structures due to the effects of multipath and the like. Inertial navigation systems are very expensive, making them difficult to install on underwater moving bodies used for monitoring, and inertial navigation systems also have the tendency to accumulate errors over time. Therefore, various methods for determining the position of underwater moving bodies in water have been proposed (see, for example, Patent Document 1).

[0004] In the underwater positioning system proposed in Patent Document 1, a positioning mobile object (aerial drone) placed on the water surface receives water surface position information (GPS signals) indicating its current position on the water surface and an acoustic pulse signal transmitted from a position target mobile object (underwater drone) moving underwater, and determines the underwater position of the position target mobile object based on the received water surface position information and acoustic pulse signal. However, this underwater positioning system requires the positioning mobile object to be deployed on the water surface, and the positioning mobile object and the position target mobile object each need to be equipped with various devices for communicating acoustic pulse signals. Therefore, a large amount of equipment is required for underwater monitoring, and the equipment costs required for monitoring are relatively high. Furthermore, the range in which the position of the position target mobile object can be determined underwater is limited to the range in which the position target mobile object and the position target mobile object can communicate with each other. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2023-49652 Summary of the Invention [Problem to be solved by the invention]

[0006] An object of the present invention is to provide an underwater monitoring method and an underwater monitoring system that can more easily identify measurement position information at the time when a measurement device acquires measurement data underwater. [Means for solving the problem]

[0007] In order to achieve the above-mentioned object, the underwater monitoring method of the present invention is characterized by carrying out the following steps: an actual measurement step in which an underwater moving body equipped with a photographing device that acquires image data of an object for position determination underwater and a measuring device that acquires measurement data including at least one of information indicating the state of the object to be measured underwater or information indicating the underwater environment is moved underwater, and the measurement data is acquired by the measuring device; a photographing position information determination step in which, based on the image data acquired by the photographing device, the positional relationship between the photographing device and a coordinate reference position set for the object for position determination at the time the image data was acquired is calculated, thereby determining the photographing position information of the photographing device relative to the coordinate reference position at the time the image data was acquired; a measurement position information determination step in which, based on the relative positional relationship between the photographing device and the measuring device and the determined photographing position information, the measurement position information of the measuring device relative to the coordinate reference position at the time the image data was acquired; and a linking data creation step in which the determined measurement position information is created linking the determined measurement position information with the measurement data acquired by the measuring device at the time the image data was acquired.

[0008] The underwater monitoring system of the present invention comprises a photographing device that acquires image data of an object for position identification underwater, a measuring device that acquires measurement data including at least one of information indicating the state of a measurement object underwater and information indicating the underwater environment, an underwater moving body equipped with the photographing device and the measuring device, and a computing device to which the image data acquired by the photographing device and the measurement data acquired by the measuring device are input, and while the underwater moving body moves underwater, the measurement data is acquired by the measuring device and the image data is acquired by the photographing device, and the computing device calculates the image data input from the photographing device. Based on this, the positional relationship between the photographing device at the time the image data was acquired and the coordinate reference position set for the object for position identification is calculated, thereby identifying photographing position information of the photographing device relative to the coordinate reference position at the time the image data was acquired, and based on the relative positional relationship between the photographing device and the measuring device and the identified photographing position information, identifying measurement position information of the measuring device relative to the coordinate reference position at the time the image data was acquired, and creating linked data that links the identified measurement position information with the measurement data acquired by the measuring device at the time the image data was acquired. [Effects of the Invention]

[0009] According to the present invention, by mounting a photographing device and a measuring device on an underwater vehicle and using image data of a position-identifying object acquired by the photographing device, it is possible to identify photographing position information of the photographing device relative to the coordinate reference position at the time the image data was acquired. Then, from the relative positional relationship between the photographing device and the measuring device and the identified photographing position information, it is possible to easily identify measurement position information of the measuring device relative to the coordinate reference position at the time the image data was acquired. Then, by creating linked data that links the identified measurement position information with the measurement data acquired by the measuring device at the time the image data was acquired, it is possible to more easily identify the measurement position at the time the measuring device acquired the measurement data underwater. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is an explanatory diagram illustrating, in plan view, a situation in which underwater monitoring is being performed using the underwater monitoring system of the present invention, with the measurement object and the position identification object being a sheet pile quay wall. [Figure 2] FIG. 2 is a view taken along the arrow A in FIG. [Figure 3] 1 is an explanatory diagram illustrating a schematic example of a three-dimensional model of an object for position identification (object to be measured) generated by a computing device. [Figure 4] FIG. 10 is an explanatory diagram illustrating a schematic example of linked data created by a computing device. [Figure 5] FIG. 10 is an explanatory diagram schematically illustrating a graph showing a time series of measurement data created by a computing device. [Figure 6] FIG. 10 is an explanatory diagram illustrating a distribution map created by a computing device. [Figure 7] FIG. 1 is an explanatory diagram illustrating, in plan view, a situation in which underwater monitoring is being performed using the underwater monitoring system of the present invention, with a sheet pile quay wall as the measurement object and another structure as the location identification object. DETAILED DESCRIPTION OF THE INVENTION

[0011] The underwater monitoring method and underwater monitoring system of the present invention will be described below based on the embodiment shown in the drawings. In the drawings, the X direction indicates the horizontal extension direction (lateral direction) of the object 10 for position identification, the Y direction indicates the depth direction of the object 10 for position identification that is perpendicular to the X direction in the horizontal direction, and the Z direction indicates the up-down direction.

[0012] As illustrated in Figures 1 and 2, the present invention provides a method and system that enables easy identification of measurement position information at the time when a measurement device 4 mounted on an underwater vehicle 2 acquires measurement data when monitoring an underwater measurement object 11 or the underwater environment using the measurement device 4.

[0013] In this embodiment, a sheet pile quay wall made up of a plurality of steel pipe sheet piles is used as the measurement object 11, and a case where the deterioration state of the measurement object 11 is monitored is exemplified. The measurement object 11 is not limited to a sheet pile quay wall, and may be, for example, another artificial structure such as a caisson, or a non-artificial structure such as ground or a stratum. The present invention is not limited to monitoring the measurement object 11, and can also be used to monitor the underwater environment, such as the turbidity and temperature of the water.

[0014] As illustrated in FIGS. 1 and 2, the underwater monitoring system 1 of the present invention includes a photographing device 3 that acquires image data IDn (ID1, ID2, ID3, ...) of an underwater object 10 for position identification, and a measuring device 4 that acquires measurement data including at least one of information indicating the state of a measurement object 11 underwater or information indicating the underwater environment. The underwater monitoring system 1 further includes an underwater vehicle 2 on which the photographing device 3 and the measuring device 4 are mounted, and a computing device 5 to which the image data IDn acquired by the photographing device 3 and the measurement data MDn acquired by the measuring device 4 are input. In this embodiment, the object 10 for position identification, which is the subject of photographing by the photographing device 3, is a sheet-pile quay wall, the same as the measurement object 11. Note that, as will be illustrated in another embodiment later, the object 10 for position identification and the measurement object 11 can also be different objects.

[0015] The underwater vehicle 2 may be, for example, an underwater drone or an underwater robot that can move underwater. There are no particular limitations on the structure, shape, size, performance, etc. of the underwater vehicle 2. The imaging device 3 may be, for example, a digital camera that can capture images underwater. In this embodiment, the imaging device 3 is installed on the top of the underwater vehicle 2, but the installation position of the imaging device 3 relative to the underwater vehicle 2 is not particularly limited, and the imaging device 3 may also be installed in another position on the underwater vehicle 2. For example, an existing camera mounted on the underwater vehicle 2 may be used as the imaging device 3. When the illuminance underwater is low, for example, a lighting device may be provided that adjusts the imaging range of the imaging device 3 to a certain illuminance. For example, an infrared night-vision camera or a low-illuminance camera (high-sensitivity camera) that can capture images even in dark places may also be used as the imaging device 3.

[0016] The measuring device 4 can employ various measuring instruments and sensors that acquire measurement data including at least information indicating the state of the measurement object 11 in water or information indicating the underwater environment. Examples of the information indicating the state of the measurement object 11 include information indicating the deterioration state of the measurement object 11 (including corrosion, damage, breakage, and the state of internal cavities), information indicating the shape of the measurement object 11, information indicating the temperature of the measurement object 11, and information indicating the components (properties) of the measurement object 11. Examples of the information indicating the underwater environment include information on the temperature of the water, information on the turbidity of the water, information on the hydrogen ion exponent (pH) of the water, and information on the components contained in the water.

[0017] Examples of the measuring device 4 that can be used include a deterioration state measuring sensor that measures the deterioration state of the object 11 (specifically, for example, an electric field sensor or a non-contact type tapping sensor that uses ultrasonic waves), a shape measuring device that measures the shape of the object 11 (specifically, for example, a narrow multi-beam sonar or a profiling sonar), a distance measuring device that measures the distance to the object 11 (specifically, for example, a distance sensor that uses ultrasonic waves), a thermometer that measures the temperature of the object 11, and a component analyzer that analyzes the components of the object 11. Examples of the measuring device 4 that can be used include a thermometer that measures the temperature of water, a turbidity meter that measures the turbidity of water, a hydrogen ion measuring device (pH meter) that measures the hydrogen ion exponent in water, a component analyzer that analyzes the components contained in water, and a magnetic sensor that is used to search for foreign objects on the bottom of the water.

[0018] In this embodiment, one deterioration state measuring sensor that measures the deterioration state of the measurement object 11 is installed as the measuring device 4 at the lower part (bottom) of the underwater moving body 2, but there are no particular limitations on the installation position of the measuring device 4 relative to the underwater moving body 2 or the number of measuring devices 4 installed relative to the underwater moving body 2. For example, the measuring device 4 can be installed at another position on the underwater moving body 2, and multiple measuring devices 4 of the same or different types can be installed on the underwater moving body 2.

[0019] The arithmetic device 5 is configured as a computer or the like. In this embodiment, the arithmetic device 5 is mounted on the underwater moving body 2, and the image data IDn acquired by the photographing device 3 and the measurement data MDn acquired by the measuring device 4 are each sequentially input to the arithmetic device 5. The arithmetic device 5 does not necessarily have to be mounted on the underwater moving body 2, and the arithmetic device 5 can also be configured as, for example, a personal computer or the like placed on the water (on land, on a ship, etc.).

[0020] When the arithmetic unit 5 is not mounted on the underwater vehicle 2, for example, a storage medium for storing image data IDn acquired by the photographing device 3 and measurement data MDn acquired by the measuring device 4 may be provided in the underwater vehicle 2, and after the underwater vehicle 2 carrying the photographing device 3 and measurement device 4 is brought to the surface of the water, the image data IDn and measurement data MDn stored in the storage medium may be input to the arithmetic unit 5. The image data IDn acquired by the photographing device 3 and the measurement data MDn acquired by the measuring device 4 may be stored in the same storage medium or in separate storage media. For example, instead of mounting the arithmetic unit 5 on the underwater vehicle 2, the arithmetic unit 5 may be placed on the water and connected to the photographing device 3 and the measuring device 4 by a communication cable, and the image data IDn acquired by the photographing device 3 and the measurement data MDn acquired by the measuring device 4 may be input to the arithmetic unit 5 on the water via the communication cable.

[0021] Next, we will explain an underwater monitoring method using this underwater monitoring system 1. In the present invention, the following steps are carried out: actual measurement step, photographing position information specifying step, measurement position information specifying step, and linked data creation step.

[0022] 1 and 2, in the measurement step, an underwater moving body 2 equipped with an image capturing device 3 and a measuring device 4 is moved underwater, and measurement data MDn including at least one of information indicating the state of a measurement object 11 underwater or information indicating the underwater environment is acquired by the measuring device 4, and image data IDn of a position identification object 10 is acquired by the image capturing device 3. The control of the movement of the underwater moving body 2 underwater and the control of the image capturing device 3 and the measuring device 4 can be configured to be performed by remote operation by an operator on the water, or can be configured to be automatically controlled based on a pre-entered program or the like. In FIG. 2, the route along which the underwater moving body 2 moves is illustrated by a thick solid arrow, but the route along which the underwater moving body 2 moves underwater is not particularly limited and can be determined as appropriate.

[0023] The measurement data MDn may be acquired continuously or intermittently by the measuring device 4. When the measurement data MDn is acquired intermittently by the measuring device 4, the measurement cycle is not particularly limited, and the measurement data MDn may be acquired at a predetermined fixed measurement cycle, or, for example, an operator may remotely operate the measuring device 4 to acquire the measurement data MDn at irregular timing. For example, when an electric field sensor is used as the measuring device 4 (deterioration state measuring sensor), the electric field sensor measures the potential difference of the X, Y, and Z components in three dimensions to acquire the measurement data MDn (measurement value) of the electric field (reaction of the sacrificial anode, etc. in the measurement object 11).

[0024] The photographing by the photographing device 3 may be continuous still image capture or video capture. The photographing cycle for acquiring image data IDn of the object 10 for position identification by the photographing device 3 is not particularly limited, and the image data IDn may be acquired at a predetermined fixed photographing cycle, or, for example, an operator may remotely operate the photographing device 3 to acquire the image data IDn at irregular timing. However, as will be described in detail later, in the present invention, measurement position information (measurement position coordinates Cn and measurement posture Pn) at time Tn when the measurement data MDn is acquired by the measuring device 4 is identified based on image data IDn acquired at the same time Tn as the measurement data MDn. Therefore, acquisition of measurement data MDn by the measuring device 4 and acquisition of image data IDn of the object 10 for position identification by the photographing device 3 are performed in parallel so as to acquire image data IDn at the same time Tn as the measurement data MDn for identifying the measurement position information.

[0025] As shown in FIG. 2, in this embodiment, the surface of the target area of ​​the object 10 for location identification is subdivided and photographed by the photographing device 3, and a large number of image data IDn are acquired, with adjacent pieces of image data IDn having overlapping areas. In this embodiment, the underwater wall surface of the sheet pile wharf, which is the target area of ​​the object 10 for location identification, is subdivided and photographed by the photographing device 3. In FIG. 2, the photographing range of each piece of image data IDn (ID1 to ID11) acquired by the photographing device 3 is illustrated by a dashed dotted line. Note that in FIG. 2, the photographing ranges of image data IDn from image data ID11 onwards are omitted and not shown.

[0026] The area of ​​the photographing range for each piece of image data IDn, the distance between the object for position identification 10 and the photographing device 3 during photographing (hereinafter referred to as the photographing distance), the overlap ratio between adjacent image data IDn, etc. can be determined appropriately depending on the measurement conditions of the measurement device 4, the photographing conditions of the photographing device 3, the turbidity of the water, etc. The area of ​​the photographing range for each piece of image data IDn can be set appropriately depending on the photographing distance. When the photographing distance is 30 cm, the area of ​​the photographing range for each piece of image data IDn is, for example, 0.10 m 2 ~0.30m 2 When the shooting distance is 10 m, the area of ​​the shooting range for each image data IDn is, for example, 130 m 2 ~200m 2 The overlap rate between adjacent image data IDn should be, for example, 60% or more, and more preferably 80% or more.

[0027] The photographing of the object for position identification 10 by the photographing device 3 is preferably performed under conditions in which feature points present on the object for position identification 10 are clearly captured (enough to be identified by image analysis) in the image data IDn acquired by the photographing device 3. Specific examples of feature points present on the object for position identification 10 include the shape of the surface of the object for position identification 10 (such as unevenness or grooves), damaged areas Wa or corroded areas present on the surface of the object for position identification 10, attachments (such as bolts) or deposits (such as shells) present on the surface of the object for position identification 10, members (such as sheet piles) or joints between members (such as joints in sheet piles) that make up the object for position identification 10, and dirt or stains present on the surface of the object for position identification 10.

[0028] The measurement data MDn (measurements, etc.) acquired by the measuring device 4 are input to the arithmetic device 5 in a state linked to the respective time points Tn (times) at which the measurement data MDn was acquired. Similarly, the image data IDn acquired by the photographing device 3 are input to the arithmetic device 5 in a state linked to the respective time points Tn (times) at which the image data IDn was acquired. In this embodiment, the measurement data MDn acquired by the measuring device 4 and the image data IDn acquired by the photographing device 3 are configured to be input sequentially to the arithmetic device 5. If the arithmetic device 5 is not mounted on the underwater moving body 2, after the underwater moving body 2 carrying the photographing device 3 and the measuring device 4 is lifted to the surface, the measurement data MDn and image data IDn stored in the storage medium are input to the arithmetic device 5 in a state linked to the respective time points Tn (times) at which the data IDn and MDn were acquired.

[0029] In the photographing position information identification step, the arithmetic device 5 calculates the positional relationship between the photographing device 3 at the time Tn when the image data IDn was acquired and the coordinate reference position 10a set for the object 10 for position identification, based on the image data IDn acquired by the photographing device 3, thereby identifying photographing position information of the photographing device 3 relative to the coordinate reference position 10a at the time when the image data IDn was acquired. In this embodiment, a case is exemplified in which the photographing position coordinates Cn (Xn, Yn, Zn) and the photographing direction Pn (in other words, the orientation of the photographing device 3) of the photographing device 3 relative to the coordinate reference position 10a at the time when the image data IDn was acquired are identified as the photographing position information. When using a measuring device 4 such as an electric field sensor that needs to identify the measurement position coordinates Cn' (Xn', Yn', Zn') and measurement attitude Pn' (in other words, the measurement direction, the orientation of the measuring device 4) at the time Tn when the measurement data MDn is acquired, the photographing position coordinates Cn and the photographing direction Pn of the photographing device 3 are configured to be identified as the photographing position information. For example, when using a measuring device 4 such as a thermometer, which only needs to identify the measurement position coordinates Cn' at the time Tn when measurement data MDn is acquired and does not need to identify the measurement posture Pn', the configuration can be such that only the shooting position coordinates Cn of the shooting device 3 are identified as the shooting position information.

[0030] The coordinate reference position 10a can be set at any position. In this embodiment, the coordinate reference position 10a is set at the top end of the wall surface of the object for position identification 10 (sheet pile quay) facing the water area. From the feature points of the object for position identification 10 captured in the image data IDn acquired by the photographing device 3, it is possible to determine the relative positional relationship between the object for position identification 10 and the photographing device 3 (photographing position coordinates Cn) and the relative direction of the photographing device 3 with respect to the object for position identification 10 (photographing direction Pn).

[0031] As illustrated in FIG. 3, in the photographing position information identifying step of this embodiment, the arithmetic device 5 generates a 3D model M of a target range of the object 10 for position identification by image processing based on a large number of image data IDn input from the photographing device 3. Then, the arithmetic device 5 identifies photographing position information at the time Tn when the image data IDn was acquired based on the positional relationship between the generated 3D model M and the image data IDn used to generate a portion of the 3D model M. In FIG. 3, the range of each image data IDn (ID1 to ID11) used to generate the 3D model is illustrated by a dashed dotted line. Note that in FIG. 3, the range of image data IDn from image data ID11 onwards is omitted and not shown.

[0032] Image processing for generating a 3D model M of the target range of the object 10 for localization based on a large number of image data IDn can be performed using known SfM (Structure from Motion) software. In the image processing (SfM processing) described above, a large number of image data IDn are analyzed to detect feature points present in each image data IDn. Then, feature points common to adjacent image data IDn are used to match the image data IDn, and a point cloud is generated by multi-viewpoint image measurement, thereby generating the 3D model M.

[0033] As in this embodiment, by generating a three-dimensional model M of the target range of the object 10 for position identification, it is possible to identify the position corresponding to the three-dimensional model M of each image data IDn acquired by the photographing device 3, and therefore it is possible to identify the photographing position information (photographing position coordinates Cn and photographing direction Pn) of the photographing device 3 relative to the coordinate reference position 10a at the time Tn when each image data IDn was acquired.

[0034] In the measurement position information determination step, the calculation device 5 determines measurement position information of the measuring device 4 relative to the coordinate reference position 10a at the time Tn when the image data IDn was acquired, based on the relative positional relationship between the photographing device 3 and the measuring device 4 and the photographing position information of the photographing device 3 relative to the coordinate reference position 10a at the time Tn when the image data IDn was acquired, which was determined in the photographing position information determination step. In this embodiment, the measurement position information described above is exemplified by determining the measurement position coordinates Cn' and measurement attitude Pn' of the measuring device 4 relative to the coordinate reference position 10a at the time Tn when the image data IDn was acquired. For example, when using a measuring device 4 such as an electric field sensor that needs to determine the measurement position coordinates Cn' and measurement attitude Pn' at the time Tn when the measurement data MDn was acquired, the measurement position coordinates Cn' and measurement attitude Pn' of the measuring device 4 are determined as the measurement position information. For example, when using a measuring device 4 such as a thermometer, where it is only necessary to identify the measurement position coordinate Cn' at the time Tn when measurement data MDn is acquired and there is no need to identify the measurement posture Pn', it is possible to configure the device 4 to identify only the measurement position coordinate Cn' as measurement position information.

[0035] Because the photographing device 3 and the measuring device 4 are mounted on the underwater moving body 2, it is possible to know in advance the relative positional relationship between the photographing device 3 and the measuring device 4. Therefore, by inputting data on the relative positional relationship between the photographing device 3 and the measuring device 4 into the computing device 5 in advance, it is possible to identify the measurement position information (measurement position coordinates Cn' and measurement attitude Pn') of the measuring device 4 at the time Tn when the image data IDn was acquired from the photographing position information (photographing position coordinates Cn and photographing direction Pn) of the photographing device 3 at the time Tn when the image data IDn was acquired.

[0036] When specifying the measurement position coordinate Cn' of the measuring device 4 using absolute coordinates, the absolute position coordinates of the coordinate reference position 10a are acquired using a GNNS receiving device or the like, thereby specifying the absolute coordinate position of the measuring device 4. When it is not necessary to specify the measurement position coordinate Cn' of the measuring device 4 using absolute coordinates, the coordinate reference position 10a can be set to the origin (X=0, Y=0, Z=0), for example, to specify the relative coordinate position of the measuring device 4 with respect to the coordinate reference position 10a.

[0037] As illustrated in Figure 4, in the linked data creation step, linked data RD is created that links the measurement position information of the measuring device 4 relative to the coordinate reference position 10a at the time Tn when the image data IDn identified in the measurement position information identification step was acquired with the measurement data MDn acquired by the measuring device 4 at the time Tn when the image data IDn was acquired.

[0038] 4 illustrates linked data RD, which is a chronological arrangement of image data IDn, shooting position coordinates Cn (Xn, Yn, Zn), shooting direction Pn, measurement data MDn, measurement position coordinates Cn' (Xn', Yn', Zn'), and measurement posture Pn' at each time point Tn. When the linked data RD is created by the calculation device 5, a graph showing the time series of the measurement data MDn (measured values) can also be created based on the linked data RD, as illustrated in FIG. 5. Because the measurement position coordinates Cn' at each time point Tn can be identified, creating a graph such as that illustrated in FIG. 5 makes it easier to understand the differences in the measurement data MDn (measured values) at each measurement position coordinate Cn'.

[0039] When the measurement position coordinates Cn' and the measurement attitude Pn' are specified as the measurement position information as in this embodiment, the measurement data MDn can also be corrected based on the measurement attitude Pn' of the measurement device 4. Specifically, for example, when using a measurement device 4 that acquires measurement data (environmental quantities) having directional components (e.g., three-dimensional X, Y, and Z components) such as an electric field sensor, the measurement direction (orientation of the measurement device 4) of the measurement device 4 relative to the measurement object 11 at each measurement position coordinate Cn' may not be constant. In such cases, by performing a correction that rotates the directional components of the measurement data MDn based on the measurement attitude Pn', it is possible to obtain measurement results equivalent to those obtained when measurements are taken with the measurement direction of the measurement device 4 relative to the measurement object 11 at each measurement position coordinate Cn' kept constant.

[0040] For example, when a non-contact type hammering sensor or distance sensor using ultrasonic waves is used as the measuring device 4, it becomes possible to identify the position where ultrasonic waves are irradiated by the measuring device 4 by specifying the measurement position coordinates Cn' and the measurement attitude Pn' as the measurement position information. For example, when a magnetic sensor is used as the measuring device 4, it becomes possible to identify the position of the detected object (foreign object, etc.) detected by the measuring device 4 by specifying the measurement position coordinates Cn' and the measurement attitude Pn' as the measurement position information.

[0041] In the linking data creation step, for example, the arithmetic device 5 can create a distribution map based on the linking data RD, as shown in FIG. 6, in which the distribution of the measurement data MDn is superimposed on the image data IDn acquired by the photographing device 3. In FIG. 6, the distribution of the measurement data MDn at the measurement position coordinates Cn' is superimposed on the three-dimensional model M of the sheet pile wharf, which is the object for position identification 10 and the object for measurement 11, generated in the photographing position information identification step. In the distribution map shown in FIG. 6, the shaded area indicates the range determined to be the deteriorated area Da based on the numerical value of the measurement data MDn acquired by the measuring device 4 (deterioration state measurement sensor). In the distribution map shown in FIG. 6, the difference in the numerical value of the measurement data MDn (the difference in the degree of deterioration of the deteriorated area Da) is visualized by the difference in the direction of the shaded area. However, the method for visualizing the difference in the numerical value of the measurement data MDn is not particularly limited. For example, the difference in the numerical value of the measurement data MDn can also be visualized by changing the color or color intensity.

[0042] As described above, in the present invention, the underwater moving body 2 is equipped with the photographing device 3 and the measuring device 4, and by using image data IDn of the object 10 for position identification acquired by the photographing device 3, it is possible to identify photographing position information of the photographing device 3 relative to the coordinate reference position 10a at the time Tn when the image data IDn was acquired. Then, from the relative positional relationship between the photographing device 3 and the measuring device 4 and the identified photographing position information, it is possible to easily identify measurement position information of the measuring device 4 relative to the coordinate reference position 10a at the time Tn when the image data IDn was acquired. Then, by creating linked data RD that links the identified measurement position information with measurement data MDn acquired by the measuring device 4 at the time Tn when the image data IDn was acquired, it is possible to more easily identify measurement position information at the time Tn when the measuring device 4 acquired the measurement data MDn underwater.

[0043] In the present invention, by utilizing an imaging device 3 mounted on an underwater vehicle 2 and a position-identifying target 10 underwater, it is possible to easily identify the measurement position information of the time Tn when the measuring device 4 acquired measurement data MDn underwater, despite a simple configuration. Furthermore, the present invention does not require a positioning vehicle, separate from the underwater vehicle 2, to be deployed on the water, as is required in conventional technology. Therefore, the present invention does not require extensive equipment for underwater monitoring, and is advantageous in keeping the equipment costs required for monitoring low. Furthermore, in the present invention, the range of movement of the underwater vehicle 2 is not particularly limited as long as it is within a range in which the position-identifying target 10 can be photographed. Therefore, it is possible to identify the measurement position of the measuring device 4 over a relatively wider range than in conventional technology using a positioning vehicle on the water. Therefore, the present invention is very useful to those skilled in the art.

[0044] As in this embodiment, in the actual measurement step, the surface of the target area of ​​the object 10 for position identification is subdivided and photographed by the photographing device 3, and a large number of image data IDn having overlapping areas between adjacent pieces of image data are acquired. In the photographing position information identification step, a 3D model M of the target area of ​​the object 10 for position identification can be generated with high accuracy by image processing based on the large number of image data IDn acquired in the actual measurement step. Then, based on the positional relationship between the generated 3D model M and the image data IDn used to generate part of the 3D model M, photographing position information at the time the image data IDn was acquired can be identified with high accuracy.

[0045] As in this embodiment, when the imaging device 3 captures an image of the measurement object 11 as the object 10 for position identification, and the measuring device 4 acquires measurement data MDn containing information indicating the state of the measurement object 11, it becomes possible to understand the surface state of the measurement object 11 from the image data IDn of the measurement object 11 acquired by the imaging device 3. Therefore, by using the image data IDn of the measurement object 11 acquired by the imaging device 3 and the measurement data MDn acquired by the measuring device 4, it becomes possible to analyze the state of the measurement object 11 from multiple angles.

[0046] In particular, when a deterioration state measuring sensor is used as the measuring device 4, damaged areas Wa and the like on the surface of the measurement object 11 can be ascertained from the image data IDn of the measurement object 11 acquired by the photographing device 3, and deteriorated areas Da (corroded areas) that are difficult to identify from the surface of the measurement object 11 can also be ascertained from the measurement data MDn indicating the deterioration state of the measurement object 11 acquired by the measuring device 4. This is advantageous for accurately ascertaining the deterioration state of the measurement object 11. Furthermore, if the photographing device 3 is configured to photograph the measurement object 11 as the position identification object 10 and generate a three-dimensional model M of the target range of the measurement object 11 (position identification object 10), it becomes possible to three-dimensionally ascertain damaged areas Wa and the like on the surface of the measurement object 11, which is even more advantageous for accurately ascertaining the deterioration state of the measurement object 11.

[0047] In this embodiment, the case where the 3D model M is generated using feature points that are originally present in the target range of the position identification object 10 has been exemplified. However, for example, if there are few feature points originally present in the target range of the position identification object 10, it is also possible to distribute and place marks or indicators that function as feature points in the target range of the position identification object 10 by diving or the like before performing the actual measurement step. Increasing the number of feature points by distributing and placing marks or indicators is advantageous for generating the 3D model M with high accuracy. Accordingly, it is advantageous for improving the accuracy of identifying the photographing position information in the photographing position information identifying step and the accuracy of identifying the measurement position information in the measurement position information identifying step.

[0048] By configuring in this embodiment to create a distribution map showing the distribution of measurement data MDn for each measurement position, it becomes much easier to grasp the differences in measurement data MDn for each measurement position. In this embodiment, as exemplified in Fig. 6, the case where the distribution of measurement data MDn at each measurement position is superimposed and displayed on a three-dimensional model M of the measurement object 11 has been illustrated. However, it is also possible, for example, to generate a two-dimensional model showing the target range of the measurement object 11 in a planar manner based on multiple image data IDn acquired by the imaging device 3, and then create a distribution map displaying the distribution of measurement data MDn at each measurement position superimposed on the two-dimensional model.

[0049] In this embodiment, the underwater vehicle 2 is equipped with a computing device 5, and image data IDn acquired by the photographing device 3 and measurement data MDn acquired by the measuring device 4 are sequentially input to the computing device 5. This allows the computing device 5 to execute the photographing location information determination step, measurement location information determination step, and linked data creation step using the image data IDn and measurement data MDn already input while the underwater vehicle 2 is moving underwater and performing the actual measurement step. This is advantageous for quickly creating the linked data RD. A similar effect can be achieved when the computing device 5 located on the surface of the water is connected to the photographing device 3 and the measuring device 4 by a communication cable, and the image data IDn acquired by the photographing device 3 and the measurement data MDn acquired by the measuring device 4 are input to the computing device 5 on the surface of the water via the communication cable.

[0050] As in another embodiment illustrated in Fig. 7, in the present invention, monitoring can also be performed by using different objects as the object 10 for position identification and the object 11 for measurement. In the embodiment illustrated in Fig. 7, the object 11 for measurement is a sheet pile wharf, and underwater monitoring is performed by using the object 10 for position identification as an object different from the sheet pile wharf.

[0051] Even when the position identification target 10 and the measurement target 11 are different targets as in this embodiment, the positional relationship between the camera device 3 at the time Tn when the image data IDn of the position identification target 10 was acquired by the camera device 3 and the coordinate reference position 10a set for the position identification target 10 can be calculated based on the image data IDn of the position identification target 10 acquired by the camera device 3. This allows the camera device 3 to identify the image capture position information relative to the coordinate reference position 10a at the time Tn when the image data IDn was acquired. Then, based on the relative positional relationship between the camera device 3 and the measuring device 4 and the identified image capture position information, the measurement position information of the measuring device 4 relative to the coordinate reference position 10a at the time Tn when the image data IDn was acquired can be identified. Then, by linking the identified measurement position information with the measurement data MDn acquired by the measuring device 4 at the time Tn when the image data IDn was acquired, linked data RD can be created.

[0052] In the embodiment exemplified above, the object to be measured 11 is monitored using a measuring device 4 that measures the object to be measured 11. However, in the present invention, the underwater environment can also be monitored in a similar manner when a measuring device 4 that acquires information indicating the underwater environment (such as the temperature and turbidity in the water) as measurement data MDn is used.

[0053] In the embodiment exemplified above, a preferred form of the present invention is illustrated as a case where linked data RD is created in which image data IDn, shooting position coordinates Cn, shooting direction Pn, measurement data MDn, measurement position coordinates Cn', and measurement posture Pn' at each time point Tn are arranged in chronological order. However, in the present invention, in the linked data creation step, it is sufficient to create linked data RD that links at least the measurement position information of the measuring device 4 at a certain time point Tn with the measurement data MDn, and the present invention is not limited to creating linked data RD in which the measurement data MDn and measurement position information are arranged in chronological order. [Explanation of symbols]

[0054] 1. Underwater monitoring system 2 Underwater Vehicles 3. Imaging equipment 4. Measuring equipment 5 Computing device 10. Location-specific objects 10a Coordinate reference position 11 Measurement object IDn image data RD Linked Data M 3D model of the target area for localization Wa Damaged area Da Deterioration area

Claims

1. an actual measurement step of moving an underwater moving body equipped with a photographing device that acquires image data of an object for position identification underwater and a measuring device that acquires measurement data including at least one of information indicating the state of the object to be measured underwater and information indicating the underwater environment underwater, and acquiring the measurement data by the measuring device and acquiring the image data by the photographing device; a photographing position information specifying step of calculating a positional relationship between the photographing device at the time the image data was acquired and a coordinate reference position set for the object for position identification based on the image data acquired by the photographing device, thereby specifying photographing position information of the photographing device with respect to the coordinate reference position at the time the image data was acquired; a measurement position information specifying step of specifying measurement position information of the measuring device relative to the coordinate reference position at the time the image data was acquired, based on the relative positional relationship between the photographing device and the measuring device and the specified photographing position information; An underwater monitoring method characterized by carrying out a linked data creation step of creating linked data that links the identified measurement position information with the measurement data acquired by the measuring device at the time the image data was acquired.

2. In the photographing position information specifying step, a photographing position coordinate and a photographing direction of the photographing device relative to the coordinate reference position are specified as the photographing position information; 2. The underwater monitoring method according to claim 1, wherein the measurement position information specifying step specifies, as the measurement position information, measurement position coordinates and measurement attitude of the measuring device relative to the coordinate reference position.

3. In the actual measurement step, the surface of the target area of ​​the object for position identification is divided into small pieces and photographed by the photographing device, and a large number of image data sets are obtained in which adjacent pieces have overlapping areas; 3. An underwater monitoring method as described in claim 1 or 2, wherein in the photographing location information identification step, a three-dimensional model of the target range of the object for location identification is generated by image processing based on a large number of image data acquired in the actual measurement step, and the photographing location information at the time the image data was acquired is identified based on the positional relationship between the generated three-dimensional model and the image data used to generate part of the three-dimensional model.

4. In the step of identifying the photographing position information, the photographing position information of the photographing device at the time when each image data acquired by the photographing device was acquired is identified; In the measurement position information specifying step, the measurement position information of the measuring device at the time when each image data was acquired is specified based on a relative positional relationship between the photographing device and the measuring device and the photographing position information of the photographing device at the time when each image data was acquired; The underwater monitoring method described in claim 1 or 2, wherein the linked data creation step links each of the identified measurement position information with the measurement data acquired by the measuring device at the time each image data was acquired, and creates a distribution diagram showing the distribution of the measurement data for each measurement position.

5. 3. An underwater monitoring method as described in claim 1 or 2, wherein the photographing device photographs the object to be measured as the object to be located, and the measuring device acquires the measurement data including information indicating the state of the object to be measured.

6. 3. The underwater monitoring method according to claim 1, wherein a deterioration state measuring sensor for acquiring the measurement data indicating the deterioration state of the object to be measured is used as the measuring device.

7. The system comprises a photographing device that acquires image data of an underwater object for position identification, a measuring device that acquires measurement data including at least one of information indicating the state of the underwater object to be measured and information indicating the underwater environment, an underwater moving body equipped with the photographing device and the measuring device, and a computing device to which the image data acquired by the photographing device and the measurement data acquired by the measuring device are input, While the underwater moving object is moving in the water, the measurement data is acquired by the measuring device and the image data is acquired by the photographing device, The underwater monitoring system is characterized in that the arithmetic device is configured to calculate, based on the image data input from the photographing device, the positional relationship between the photographing device and the coordinate reference position set for the object for position identification at the time the image data was acquired, thereby identifying photographing position information of the photographing device relative to the coordinate reference position at the time the image data was acquired, and based on the relative positional relationship between the photographing device and the measuring device and the identified photographing position information, identify measurement position information of the measuring device relative to the coordinate reference position at the time the image data was acquired, and create linked data that links the identified measurement position information with the measurement data acquired by the measuring device at the time the image data was acquired.

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