JP7485155B2 - Data encoding program and data encoding device - Google Patents

Description

The present invention relates to a data encoding device, a data decoding device, a data communication system, and a data communication method for encoding or decoding in-plane displacement data obtained from an image of an object, and further relates to a program for implementing these.

Technologies have been proposed for determining the condition of structures such as bridges without contact (see, for example, Patent Document 1). With such determination technologies, inspectors can inspect the structure without touching it. Such determination technologies are particularly useful for structures that are grounded in places that inspectors cannot easily reach.

Patent document 1 discloses a device that derives in-plane displacement components of a portion to be judged from an image of a structure such as a bridge as a subject, and judges the state of the structure based on the derived in-plane displacement components.

Specifically, the device disclosed in Patent Document 1 first acquires multiple images in chronological order from a visible camera. Then, the device disclosed in Patent Document 1 derives the in-plane displacement component by subtracting the component resulting from the displacement of the entire surface to be determined from the optical flow of the acquired images or from the displacement vector field obtained by the image correlation method.

Next, the device disclosed in Patent Document 1 calculates an in-plane displacement distribution from the derived in-plane displacement components, and compares the calculated in-plane displacement distribution with a reference in-plane displacement distribution. At this time, if damage such as openings due to cracks has occurred, differences will arise between the two in-plane distributions, and the device disclosed in Patent Document 1 detects defects such as cracks from the comparison results.

International Publication No. 2016/152075

Incidentally, the data of the in-plane displacement components derived by the device disclosed in Patent Document 1 is transmitted to a data server or the like via a network for recording, and stored there. However, the data of the in-plane displacement components obtained in this manner has the characteristic that the data volume is very large, and there is a problem in that it requires a large cost to transmit and store the data via a network.

For example, suppose the conditions for video data of a structure are 2048 x 2048 pixels, a frame rate of 80 fps, and a duration of 10 seconds. In this case, if displacements in the X and Y directions (each 32-bit floating point) are obtained for each pixel coordinate, the amount of data for the in-plane displacement components will be approximately 26 GB.

In addition, MPEG has long been known as a compression format for video data, and it is thought that costs can be reduced by compressing the in-plane displacement component data using such a compression format. However, while MPEG is a compression method for efficiently compressing two-dimensional time-series data, the in-plane displacement component data consists of input signals in floating-point format. For this reason, even if costs can be reduced, there is a possibility that the accuracy of determining the condition through damage detection will be significantly reduced due to the distortion that occurs when compressing at a high compression rate.

In addition, while it is possible to reduce the size of the data by using methods such as thinning (reducing) the resolution, it is difficult to reduce the data size to a practical level that allows for cost reduction while maintaining sufficient spatial resolution for damage detection.

One example of the object of the present invention is to provide a data encoding device, a data decoding device, a data communication system, a data communication method, and a program that can solve the above problems and reduce the costs of transmission and storage while maintaining sufficient spatial resolution in encoding or decoding data indicating in-plane displacement extracted from an image.

In order to achieve the above object, a data encoding device according to one aspect of the present invention comprises:
a reference signal generating unit that generates a reference signal whose level changes according to a stress generated on the specific surface of the object, based on an overall surface displacement on the specific surface of the object measured from time-series images of the object and an in-plane displacement on the specific surface of the object measured from the overall surface displacement and the time-series images;
a regression coefficient calculation unit that calculates a regression coefficient indicating a degree of correlation between a time series change in a level of the reference signal and a time series change in the in-plane displacement, using the reference signal and the in-plane displacement;
a data output unit that outputs the reference signal and the regression coefficient as data indicating the in-plane displacement;
The present invention is characterized in that it is equipped with:

In order to achieve the above object, a data decoding device according to one aspect of the present invention comprises:
a data acquisition unit that acquires a reference signal whose level changes in accordance with stress generated on a specific surface of the object, and a regression coefficient that indicates a degree of correlation between a time series change in the level of the reference signal and a time series change in an in-plane displacement on the specific surface of the object;
a data decoding unit that reconstructs an in-plane displacement on a specific surface of the object using the acquired reference signal and the regression coefficients;
Equipped with
It is characterized by:

In order to achieve the above object, a data communication system according to one aspect of the present invention comprises a data encoding device and a data decoding device,
The data encoding device comprises:
a reference signal generating unit that generates a reference signal whose level changes according to a stress generated on the specific surface of the object, based on an overall surface displacement on the specific surface of the object measured from time-series images of the object and an in-plane displacement on the specific surface of the object measured from the overall surface displacement and the time-series images;
a regression coefficient calculation unit that calculates a regression coefficient indicating a degree of correlation between a time series change in a level of the reference signal and a time series change in the in-plane displacement, using the reference signal and the in-plane displacement;
a data output unit that outputs the reference signal and the regression coefficient as data indicating the in-plane displacement;
The data decoding device comprises:
a data acquisition unit that acquires a reference signal whose level changes in accordance with stress generated on a specific surface of the object, and a regression coefficient that indicates a degree of correlation between a time series change in the level of the reference signal and a time series change in an in-plane displacement on the specific surface of the object;
and a data decoding unit that uses the acquired reference signal and the regression coefficients to reconstruct an in-plane displacement on the specific surface of the object.
It is characterized by:

In order to achieve the above object, a data communication method according to one aspect of the present invention is a data communication method using a data encoding device and a data decoding device, comprising:
(a) generating, by the data encoding device, a reference signal whose level changes in accordance with a stress generated on the specific surface of the object, from an overall surface displacement on the specific surface of the object measured from time-series images of the object, and an in-plane displacement on the specific surface of the object measured from the overall surface displacement and the time-series images;
(b) calculating, by the data encoding device, a regression coefficient indicating a degree of correlation between a time series change in a level of the reference signal and a time series change in the in-plane displacement, using the reference signal and the in-plane displacement;
(c) outputting, by the data encoding device, the reference signal and the regression coefficients as data indicating the in-plane displacement;
(d) acquiring, by the data decoding device, a reference signal whose level changes in accordance with the stress generated on the specific surface of the object, and a regression coefficient indicating a degree of correlation between a time series change in the level of the reference signal and a time series change in the in-plane displacement on the specific surface of the object;
(e) recovering, by the data decoding device, an in-plane displacement on a specific surface of the object using the acquired reference signal and the regression coefficients;
The present invention is characterized in that it has the following features:

Furthermore, in order to achieve the above object, a first program according to one aspect of the present invention comprises:
On the computer,
(a) generating a reference signal whose level changes in accordance with a stress generated on a specific surface of the object from an overall surface displacement on the specific surface of the object measured from time-series images of the object and an in-plane displacement on the specific surface of the object measured from the overall surface displacement and the time-series images;
(b) calculating a regression coefficient indicating a degree of correlation between a time series change in a level of the reference signal and a time series change in the in-plane displacement, using the reference signal and the in-plane displacement;
(c) outputting the reference signal and the regression coefficients as data indicative of the in-plane displacement;
The present invention is characterized in that the above-mentioned is executed.

Furthermore, in order to achieve the above object, a second program according to one aspect of the present invention comprises:
On the computer,
(a) acquiring a reference signal whose level changes in accordance with stress generated on a specific surface of an object, and a regression coefficient indicating a degree of correlation between a time series change in the level of the reference signal and a time series change in an in-plane displacement on the specific surface of the object;
(b) recovering an in-plane displacement of a particular surface of the object using the acquired reference signal and the regression coefficients;
The present invention is characterized in that the above-mentioned is executed.

As described above, according to the present invention, when encoding or decoding data indicating in-plane displacement extracted from an image, it is possible to reduce the costs of transmission and storage while maintaining sufficient spatial resolution.

FIG. 1 is a block diagram showing a configuration of a data communication system according to an embodiment of the present invention. FIG. 2 is a block diagram showing in more detail the configuration of the data communication system according to the embodiment of the present invention. FIG. 3 is a diagram illustrating components included in the displacement observed on the imaging surface of the imaging device at a certain point when an image of a measurement target area of an object is captured. FIG. 4 is a diagram showing a simulation of a two-dimensional spatial distribution of displacement (δx _ij , δy _ij ) observed in a specific region on an image obtained by photographing a measurement target region. 5A to 5C are diagrams for explaining the processing performed by the regression coefficient calculation unit in the embodiment of the present invention. FIG. 6 is a flow chart showing the operation of the data encoding device according to the embodiment of the present invention. FIG. 7 is a flow chart showing the operation of the data decoding device in the embodiment of the present invention. FIG. 8 is a block diagram showing an example of a computer that realizes a data encoding device or a data decoding device according to an embodiment of the present invention.

(Embodiment)
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A data encoding device, a data decoding device, a data communication system, a data communication method, and a program according to embodiments of the present invention will be described below with reference to FIGS.

[System configuration]
First, the configurations of a data encoding device, a data decoding device, and a data communication system according to the present embodiment will be described with reference to Fig. 1. Fig. 1 is a block diagram showing the configuration of a data communication system according to the embodiment of the present invention.

The data communication system 10 in this embodiment shown in FIG. 1 is a system for performing data communication of in-plane displacement data obtained from an image of an object. As shown in FIG. 1, the data communication system 10 includes a data encoding device 20 and a data decoding device 30. In addition, the data encoding device 20 and the data decoding device 30 are connected via a network 40 such as the Internet.

The data encoding device 20 shown in FIG. 1 is a device that encodes in-plane displacement data obtained from an image of an object. As shown in FIG. 1, the data encoding device 20 includes a reference signal generating unit 21, a regression coefficient calculating unit 22, and a data output unit 23.

Of these, the reference signal generating unit 21 generates a reference signal whose level changes according to the stress generated on a specific surface of the object from the overall surface displacement and the in-plane displacement.

The regression coefficient calculation unit 22 also uses the reference signal and the in-plane displacement to calculate a regression coefficient indicating the degree of correlation between the time series change in the level of the reference signal and the time series change in the in-plane displacement. The data output unit 23 outputs the reference signal and the regression coefficient to the data decoding device 30 as data indicating the in-plane displacement.

The data decoding device 30 shown in FIG. 2 is a device that decodes data indicating in-plane displacement output from the data encoding device 20. The data decoding device 30 shown in FIG. 2 includes a data acquisition unit 31 and a data decoding unit 32.

The data acquisition unit 31 acquires the reference signal and regression coefficients output by the data encoding device 20. The data decoding unit 32 uses the reference signal and regression coefficients to reconstruct the in-plane displacement on a specific surface of the object.

In this way, in this embodiment, the data indicating the in-plane displacement is not reduced in size itself, but is converted into a reference signal and a regression coefficient before being transmitted. Therefore, according to this embodiment, it is possible to reduce the costs of transmission and storage while maintaining sufficient spatial resolution in encoding or decoding data indicating the in-plane displacement extracted from an image.

Next, the configurations and functions of the data encoding device 20, data decoding device 30, and data communication system 10 in this embodiment will be described in more detail with reference to Figures 2 to 5. Figure 2 is a block diagram showing in more detail the configuration of the data communication system in this embodiment of the present invention.

As shown in FIG. 2, in this embodiment, the object for which in-plane displacement is measured is a bridge 60, and when the bridge 60 is deflected due to the weight of a vehicle 61 passing over the bridge 60, the in-plane displacement is measured in a measurement target area set on the bridge 60. Examples of the measurement target area include the bridge girders, deck slabs, etc.

As shown in FIG. 2, an imaging device 50 is connected to the data encoding device 20. The imaging device 50 is a camera capable of capturing moving images, and outputs time-series images frame by frame. Specifically, the imaging device 50 captures images at set intervals and continuously outputs image data of the captured images. In this embodiment, as shown in FIG. 2, the imaging device 50 is positioned so as to capture an image of the deck (bottom surface), which is the measurement target area of the bridge 60.

Furthermore, as shown in FIG. 2, in this embodiment, the data encoding device 20 includes an image data acquisition unit 24, an entire surface displacement measurement unit 25, an in-plane displacement measurement unit 26, and a memory unit 27 in addition to the reference signal generation unit 21, the regression coefficient calculation unit 22, and the data output unit 23 described above.

When image data is output from the imaging device 50, the image data acquisition unit 24 acquires the output image data and outputs the acquired image data to the entire surface displacement measurement unit 25 and the in-plane displacement measurement unit 26.

The entire surface displacement measuring unit 25 measures the entire surface displacement on a specific surface of an object from time-series images of the object. In this embodiment, the entire surface displacement measuring unit 25 acquires time-series images output by the imaging device 50, and takes an image captured at an arbitrary time as a reference image, and the rest as processed images. Then, for each point in an area in the reference image that corresponds to the measurement target area on the specific surface (hereinafter referred to as a "specific area"), the entire surface displacement measuring unit 25 searches for the corresponding position in the processed image for each point, and calculates the displacement. The displacement for the specific area for each processed image calculated in this way becomes the displacement distribution.

Specifically, the entire surface displacement measurement unit 25 searches for a location (coordinate) in the processed image that is most similar to a certain location (coordinate) in the specific region, and calculates the displacement of the identified location (coordinate). Examples of methods for identifying similar locations include a method of searching for the most highly correlated position (coordinate) using a similarity correlation function such as SAD (Sum of Squared Difference), SSD (Sum of Absolute Difference), NCC (Normalized Cross-Correlation), and ZNCC (Zero-means Normalized Cross-Correlation) using the luminance values of a certain location (coordinate) and its surrounding coordinates.

By repeatedly performing this calculation process for each coordinate in the specific region, it is possible to obtain the distribution of displacement for the specific region in the processed image. In addition, by performing the same process for each processed image, it is possible to obtain the distribution of displacement for the specific region for each processed image. Here, the specific coordinates of the measurement target region are represented as (i,j) and the calculated displacement is represented as (δx _ij , δy _ij ).

Next, the entire surface displacement measuring unit 25 calculates the amount of movement (Δx, Δy) in the surface direction of the measurement target area and the amount of movement (Δz) in the normal direction from the calculated displacements (δx _ij , δy _ij ) and the imaging information. The calculated displacements (δx _ij , δy _ij ) and the amount of movement (Δx, Δy, Δz) by the entire surface displacement measuring unit 25 become the entire surface displacement. The entire surface displacement measuring unit 25 stores the calculated displacements (δx _ij , δy _ij ) and the amount of movement (Δx, Δy, Δz) in the storage unit 27 as the entire surface displacement information. Examples of the imaging information include the size of one pixel of the solid-state imaging element in the imaging device 50, the focal length of the lens, the imaging distance from the imaging device 50 to the measurement target area, the imaging frame rate, and the like.

The in-plane displacement measuring unit 26 measures the in-plane displacement on the specific surface of the bridge 60 from the amount of movement (Δx, Δy, Δz) calculated by the entire surface displacement measuring unit 25 and the time-series images. Here, the in-plane displacement is expressed as (δδx _ij , δδy _ij ).

Next, the processing in the entire surface displacement measuring unit 25 and the in-plane displacement measuring unit 26 will be specifically described with reference to Figures 3 and 4. Figure 3 is a diagram explaining the components contained in the displacement observed on the imaging surface of the imaging device at a certain point when the measurement target area of the object is photographed. Figure 3 also shows a state in which a bridge 60, which is the object, is subjected to a load by a passing vehicle 61, and as a result, the measurement target area has moved in three dimensions by a movement amount (Δx, Δy, Δz).

Here, consider a coordinate system whose origin is the center of the imaging surface of the imaging device 50, that is, the point corresponding to the imaging center, which is the intersection point between the optical axis of the lens and the imaging surface. In this coordinate system, consider the displacement (δx _ij , δy _ij ) observed at point A at coordinates (i, j) on the imaging surface of the imaging device 50. Note that the coordinates (i, j) on the imaging surface of the imaging device 50 can also be replaced with coordinates on a captured image.

In the state shown in Figure 3, the measurement target area of the bridge 60 has movement amounts (Δx, Δy, Δz) in the horizontal and vertical directions (X and Y directions) on the screen, and in the normal direction (Z direction). The measurement target area moves parallel to the imaging surface of the imaging device 50 by the amount of movement (Δx, Δy) in the horizontal and vertical directions (X and Y directions) on the screen. The measurement target area also moves closer to the imaging device 50 by the amount of movement (Δz) in the normal direction (Z direction). As a result, the imaging distance is shortened by the amount of movement Δz.

3, a displacement δzxij due to a movement amount Δz occurs in addition to a displacement δx caused by a movement amount Δx of the measurement target region in the horizontal direction (X direction) relative to the imaging surface of the imaging device 50. Similarly, a displacement _δzyij due to a movement amount Δz also occurs on the imaging surface of the imaging device 50 in addition to a displacement δy caused by a movement amount Δy of the imaging device 50 in the vertical direction ( _Y direction) relative to the screen.

Furthermore, when the bridge 60 is subjected to a load and the surface of the measurement target region is deformed (ΔΔX _ij , ΔΔY _ij ), an in-plane displacement (δδx _ij , δδy _ij ) is also superimposed on the imaging surface of the imaging device 50 accordingly.

Here, the in-plane displacement (δδx _ij , δδy _ij ) accompanying deformation of the surface of the measurement target area changes continuously in a sound area without defects such as cracks, whereas in an area spanning a crack, the surface displacement does not change continuously but changes discontinuously. Thus, sound areas without defects and areas with some kind of defect have different distributions of surface displacement.

In the measurement target area, all the generated displacements are added together and observed as a resultant vector. That is, the displacement (δx _ij , δy _ij ) observed at point A(i,j) can be expressed by the following Equations 1 and 2, as shown in FIG. 4, which will be described later.

Here, if the imaging distance from the principal point of the lens to the measurement target area is L, the lens focal length of the imaging device 50 is f, and the coordinates from the imaging center are (i, j), the displacement (δx, δy) associated with the movement (Δx, Δy) of the object 60 in the planar direction and the displacement (δzx _ij , δzy _ij ) associated with the movement (Δz) in the normal direction are expressed by the following equations 3 and 4, respectively.

If we assume that the entire measurement target area is moving in the same three-dimensional manner, it can be seen that the displacements (δx, δy) associated with the movement in the planar direction (Δx, Δy) shown in the above equations 3 and 4 are constant regardless of the coordinates of point A. It can also be seen that the displacements (δzx _ij , δzy _ij ) associated with the movement in the normal direction (Δz) become larger the farther the coordinates of point A are from the origin. On the other hand, the in-plane displacements (δδx _ij , δδy _ij ) of the measurement target area show a distribution of continuous and discontinuous displacements depending on the position of defects such as surface cracks, regardless of the coordinates of point A.

Fig. 4 is a diagram showing a simulated two-dimensional spatial distribution (hereinafter, referred to as displacement distribution) of displacements (δx _ij , δy _ij ) observed in a specific region on an image captured of the measurement target region. As shown in Fig. 4, the displacements (δx _ij , δy _ij ) of each coordinate of the specific region calculated by the entire surface displacement measuring unit 25 are expressed as a displacement vector. In this case, the displacement vector is expressed as a composite component of a displacement (δx, δy) associated with a surface direction movement (Δx, Δy) observed with a uniform direction and magnitude on the entire screen, a displacement (δzx _ij , δzy _ij ) associated with a normal direction movement (Δz) observed as a group of radial vectors from the imaging center of the screen, and an in-plane displacement (δδx _ij , δδy _ij ) associated with a deformation of the surface of the measurement target region.

Next, a method for calculating the displacement (δx, δy) associated with the movement (Δx, Δy) in the planar direction will be described. As shown in FIG. 4, the displacement (δx, δy) associated with the movement (Δx, Δy) in the planar direction is basically observed in a uniform direction and magnitude across the entire screen. Therefore, the entire planar displacement measuring unit 25 adds a plus or minus sign to the displacement (δx _ij , δy _ij ) calculated at each coordinate of a specific region centered on the imaging center according to the direction of displacement, and this is used as a displacement vector. Then, the displacement vectors at each target coordinate are all added together, and the average is calculated to calculate the displacement (δx, δy) associated with the movement (Δx, Δy) in the planar direction.

Next, a method for calculating a displacement vector (δzx _ij , δzy _ij ) associated with a movement (Δz) in the normal direction will be described. First, consider a state in which only a displacement vector (δzx _ij , δzy _ij ) associated with a movement (Δz) in the normal direction occurs. If the amount of movement Δz of a specific region is constant within the specific region, the magnitude R(i,j) of that vector will be a value proportional to the distance from the center of imaging, as shown in the following equation 5. Furthermore, if a proportionality constant is set to k as shown in the following equation 6, equation 5 can also be expressed as equation 7.

Meanwhile, the displacements (δx _ij , δy _ij ) actually calculated first by the entire-plane displacement measuring unit 25 are composed of a resultant vector (FIG. 4: extra-thick solid arrows), as shown in Fig. 4. As can be seen from Fig. 4, this resultant vector (δx _ij , δy _ij ) includes a displacement vector (δzx _ij , δzy _ij ) (FIGS. 3 and 4: solid arrows) accompanying the movement in the normal direction (Δz), a displacement vector (δx, δy) (FIGS. 3 and 4: thick solid arrows) accompanying the movement in the in-plane direction (Δx, Δy), and an in-plane displacement (δδx _ij , δδy _ij ) (FIGS. 3 and 4: thin solid arrows) accompanying the deformation and displacement of the surface of the measurement target region.

Therefore, the vector obtained by subtracting the displacement vector (δx, δy) associated with the in-plane movement (Δx, Δy) from this resultant vector (δx _ij , δy _ij ) corresponds to the resultant vector of the displacement vector (δzx _ij , δzy _ij ) associated with the movement in the normal direction (Δz) and the in-plane displacement (δδx _ij , δδy _ij ).

Therefore, if the resultant vector of the displacement vector (δzx _ij , δzy _ijj ) and the in-plane displacement (δδx _ij , δδy _ij ) associated with a movement (Δz) in the normal direction at a certain coordinate (i, j) is defined as R _mes (i, j), these can be expressed by the following equation 8.

Incidentally, the in-plane displacement (δδx _ij , δδy _ij ) can be considered to be sufficiently small compared to the displacement vector (δx, δy) associated with the in-plane movement (Δx, Δy) and the displacement vector (δzx _ij , δzy _ij ) associated with the normal movement (Δz). Therefore, when focusing on the displacement vector (δx, δy) associated with the in-plane movement (Δx, Δy) and the displacement vector (δzx _ij , δzy _ij ) associated with the normal movement (Δz), which are the dominant components, the above equation 8 can be expressed as the following equation 9.

In this case, R _mes (i, j) at coordinates (i, j) can be treated as being approximately equal to the displacement vector components (δzx _ij , δzy _ij ) associated with the movement (Δz) in the normal direction. In this case, the displacement vector when a movement amount Δz in the normal direction is given is expressed by R(i, j) shown in Equations 6 to 8.

For this reason, the entire surface displacement measuring unit 25 estimates the rate of expansion/contraction of the displacement vector _magnitude R(i,j) due to the displacement vector (δzx _ij , δzy _ij ) accompanying the movement (Δz) in the normal direction, using the displacement vector magnitude R mes (i,j) calculated by equation 9. Specifically, the entire surface displacement measuring unit 25 estimates the magnification of R(i,j) by calculating a proportionality constant k that minimizes the evaluation function E(k) shown in equation 10 below.

Therefore, the entire surface displacement measuring unit 25 calculates the proportionality constant k by applying the least squares method to the above equation 10. Also, as the evaluation function E(k), in addition to the sum of squares of the difference between R _mes (i, j) and R(i, j) shown in the above equation 10, the sum of absolute values, the sum of other powers, etc. may be used.

Then, the entire surface displacement measurement unit 25 applies the calculated proportional constant k as a constant indicating the ratio of enlargement/reduction to the above equation 7 to calculate the movement amount Δz. The entire surface displacement measurement unit then applies the calculated Δz, the displacement (δx, δy) associated with the movement in the surface direction (Δx, Δy), and the shooting information to the above equation 3 to calculate the movement amounts Δx and Δy.

Furthermore, the entire surface displacement measurement unit 25 calculates the amount of movement of the measurement target area in the surface direction and the amount of movement of the measurement target area in the normal direction for each image captured by the imaging device 50, i.e., for each frame of the time-series image. The entire surface displacement measurement unit 25 then stores the amount of movement calculated for each frame of the time-series image in the memory unit 27 as entire surface displacement information. In this case, the entire surface displacement information can be treated as a time-series signal with the time interval between images captured as the sampling interval.

The in-plane displacement measuring unit 26 measures the in-plane displacement on a specific surface of the object from the entire surface displacement and the time-series images of the object. In this embodiment, the in-plane displacement measuring unit 26 calculates the in-plane displacement (δδx ij , δδy ij ) of the measurement target area from the initially calculated displacement (displacement vector (δx _ij , δy _{ij )} ) using the amount of movement (Δx, Δy) in the surface direction of the measurement target area and the amount of movement (Δz) in the normal direction of the measurement target area calculated by the entire surface displacement measuring unit 25. The calculation of the in-plane displacement is performed for _each frame of the time-series images.

4, it can be seen that in order to calculate the in-plane displacement (δδx _ij , δδy _ij ), it is sufficient to subtract the displacement component generated by the movement amount (Δx, Δy, Δz) of the measurement target region from the displacement vector (δx _ij , δy _ij ) calculated by the in-plane displacement measuring unit 26. That is, the in-plane displacement measuring unit 26 calculates the in-plane displacement (δδx _ij , δδy _ij ) by using the following equations 11 and 12.

Furthermore, the in-plane displacement measuring unit 26 calculates the in-plane displacement (δδx _ij , δδy _ij ) each time an image is captured by the imaging device 50, that is, along a time series. The in-plane displacement measuring unit 26 then stores the in-plane displacement calculated for each frame of the time series images in the storage unit 27 as in-plane displacement information. In this case, the in-plane displacement information can be treated as a time series signal with the time interval between captures as a sampling interval. In this specification, the in-plane displacement information is also referred to as an "in-plane displacement signal."

In this embodiment, the reference signal generating unit 21 calculates the time series change in distortion ε(t) in a specific direction of a point of interest from the in-plane displacement in a specific direction of the point of interest on a specific surface of an object, and generates a signal indicating the calculated time series change in distortion ε(t) as a reference signal.

Specifically, a point of interest is specified in advance in a measurement target area on a specific surface by an operator of the data communication system 10, etc. As shown in FIG. 2, if the target object is a bridge 60 and the measurement target area is a deck, a point on the deck is specified as the point of interest.

When a point of interest is specified, the reference signal generation unit 21 determines a number of points (for example, four points) surrounding the point of interest. Here, the area surrounded by each point is called a "local area." Next, the reference signal generation unit 21 obtains in-plane displacement information at each of the determined points from the storage unit 27.

As for the specific direction, if it has been specified in advance, like the focus point, the reference signal generator 21 uses the acquired in-plane displacement information of each point to determine the rate of change in length of the local region in the specific direction, and regards the determined rate of change as the time series change in distortion ε(t).

On the other hand, if a specific direction is not specified in advance, the reference signal generator 21 performs singular value decomposition using the acquired in-plane displacement information of each point to identify the direction in which the local region changes the most. The reference signal generator 21 then calculates the rate of change of the length of the local region in the identified direction, and regards the calculated rate of change as the time series change in distortion ε(t).

Then, the reference signal generating unit 21 stores the reference signal obtained from the calculated time series change in the distortion in the memory unit 27 as reference signal information.

In this embodiment, the regression coefficient calculation unit 22 calculates a regression coefficient for each point (i, j) in the measurement target area on the specific surface. The regression coefficient calculation unit 22 first identifies the time series change in the in-plane displacement from the in-plane displacement information stored in the memory unit 27, and identifies the time series change in the level of the reference signal from the reference signal information stored in the memory unit 27. The regression coefficient calculation unit 22 then calculates a regression coefficient indicating the degree of correlation between the time series change in the level of the identified reference signal and the time series change in the in-plane displacement, both of which are identified, for each point (i, j) in the measurement target area on the specific surface.

Here, the processing by the regression coefficient calculation unit 22 will be described with reference to FIG. 5. Each of FIG. 5(a) to FIG. 5(c) is a diagram for explaining the processing performed by the regression coefficient calculation unit in an embodiment of the present invention.

Specifically, the regression coefficient calculation unit 22 first identifies a time series change in the level of the reference signal and a time series change in the in-plane displacement (δδx _ij , δδy _ij ) at a specific point (i, j) as shown in Fig. 5(a). The in-plane displacement identified at this time may be either one of the in-plane displacement δδx _ij in the x direction and the in-plane displacement δδy _ij in the y direction, or both. In the former case, if the object is a bridge 60, for example, one of the in-plane displacements may be the in-plane displacement in the longitudinal direction of the bridge 60. In the latter case, an average in-plane displacement of the in-plane displacement δδx _ij in the x direction and the in-plane displacement δδy _ij in the y direction may be identified.

Next, as shown in FIG. 5(b), the regression coefficient calculation unit 22 compares the reference signal and the in-plane displacement along the time series for each point (i,j), i.e., for each frame of the time series image. Then, as shown in FIG. 5(c), the regression coefficient calculation unit 22 obtains a regression line that indicates the relationship between the time series change in the level of the reference signal and the time series change in the in-plane displacement for each point (i,j), and further calculates the slope as the regression coefficient. The calculation of the regression line and the calculation of the regression coefficient are performed for each of the x direction and the y direction, and in reality, the regression coefficient in the x direction and the regression coefficient in the y direction are calculated.

In this embodiment, the data output unit 23 outputs the reference signal information stored in the memory unit 27 and the regression coefficients calculated for each point (i, j) as data indicating in-plane displacement to the data decoding device 30 via the network 40.

In this embodiment, the data decoding device 30 is constructed by a program on the operating system of a terminal device, such as a PC (Personal Computer), a smartphone, or a tablet terminal. The data decoding device 30 is connected to the display device 33 of the terminal device.

In the data decoding device 30, the data acquisition unit 31 acquires the reference signal information and the regression coefficients calculated for each point (i, j) output from the data output unit 23 of the data encoding device 20.

In this embodiment, the data decoding unit 32 reconstructs the in-plane displacement in the measurement target area of the bridge 60 by multiplying the level of the reference signal identified by the reference signal information by a regression coefficient along a time series for each point (i, j). The data decoding unit 32 also generates image data for displaying the reconstructed in-plane displacement, and outputs the generated image data to the display device 33 to display the in-plane displacement on the screen.

[Device Operation]
Next, the operation of the data communication system 10 in the embodiment of the present invention will be described with reference to Figures 6 and 7. In the following, the operation of each of the data encoding device 20 and the data decoding device 30 will be described with reference to Figures 1 to 5 as appropriate. Also, in the present embodiment 1, a data communication method is implemented by operating the data communication system 10, that is, the data encoding device 20 and the data decoding device 30. Therefore, the description of the data communication method in the present embodiment will be replaced by the following description of the operation of the data encoding device 20 and the data decoding device 30.

First, the operation of the data encoding device 20 will be described using FIG. 6. FIG. 6 is a flow diagram showing the operation of the data encoding device in an embodiment of the present invention.

As shown in FIG. 6, first, when image data of a time-series image is output from the imaging device 50, the image data acquisition unit 24 acquires the output image data, and outputs the acquired image data for each frame to the entire-plane displacement measurement unit 25 and the in-plane displacement measurement unit 26 (step A1).

Next, when the image data of the time-series image is output by step A1, the entire surface displacement measuring unit 25 measures the entire surface displacement of the measurement target area of the target object, the bridge 60, for each frame (step A2). The entire surface displacement measuring unit 25 also stores the measurement results in the memory unit 27 as entire surface displacement information.

Next, the in-plane displacement measuring unit 26 uses the image data of the time-series images output in step A1 and the entire surface displacement measured in step A2 to measure the in-plane displacement in the measurement target area of the target object, the bridge 60, for each frame (step A3). The in-plane displacement measuring unit 26 also stores the measurement results in the memory unit 27 as in-plane displacement information.

Next, the reference signal generating unit 21 generates a reference signal whose level changes according to the stress generated on the specific surface of the object from the entire surface displacement measured in step A2 and the in-plane displacement measured in step A3 (step A4). The reference signal generating unit 21 also stores the generated reference signal in the memory unit 27 as reference signal information.

Next, the regression coefficient calculation unit 22 uses the reference signal generated in step A4 and the in-plane displacement measured in step A3 to calculate a regression coefficient indicating the degree of correlation between the time series change in the level of the reference signal and the time series change in the in-plane displacement for each point (i, j) in the measurement target area on the specific surface (step A5).

Next, the data output unit 23 transmits the reference signal generated in step A4 and the regression coefficient for each point (i, j) calculated in step A5 as data indicating the in-plane displacement to the data decoding device 30 via the network 40 (step A6). Execution of step A6 ends the processing in the data encoding device 20.

Next, the operation of the data decoding device 30 will be described with reference to FIG. 7. FIG. 7 is a flow diagram showing the operation of the data decoding device in an embodiment of the present invention.

As shown in FIG. 7, first, in the data decoding device 30, the data acquisition unit 31 acquires data indicating in-plane displacement, i.e., the reference signal and the regression coefficient for each point (i, j), transmitted from the data encoding device 20 (step B1).

Next, the data decoding unit 32 uses the reference signal acquired in step B1 and the regression coefficients for each point (i, j) to reconstruct the in-plane displacement on the specific surface of the object (step B2).

Then, the data decoding unit 32 generates image data for displaying the restored in-plane displacement, and outputs the generated image data to the display device 33 to display the in-plane displacement on the screen (step B3). Execution of step B3 ends the processing in the data decoding device 30.

(Effects of the embodiment)
As described above, according to the first embodiment, it is possible to reduce the amount of data indicating in-plane displacement without reducing the data itself. According to the present embodiment, it is possible to reduce the cost of transmission and storage while maintaining sufficient spatial resolution in encoding or decoding data indicating in-plane displacement extracted from an image.

In addition, in this embodiment, the regression coefficients for each point (i, j) transmitted as data indicating in-plane displacement can be compressed using an image compression method (JPEC-XR, etc.) that supports floating-point pixel representation. In this case, the data indicating in-plane displacement can be further compressed.

In addition, the reference signal transmitted as data indicating the in-plane displacement can be compressed using an audio compression method that supports floating point (such as MPEG4-ALS). In this case, the data indicating the in-plane displacement can be further compressed.

[Modification 1]
Next, modified examples 1 to 4 of the embodiment of the present invention will be described. First, in this modified example 1, the condition is that the entire surface displacement measuring unit 25 measures the entire surface displacement in the in-plane direction of the specific surface of the object and in the application direction of the external force applied to the object. Note that in the above-mentioned embodiment, the object is a bridge 60, and the application direction of the external force is the normal direction, so the above condition is satisfied.

In this first modified example, the reference signal generating unit 21 calculates the time series change D(t) of the entire surface displacement in the direction of the external force application, and generates a signal indicating the calculated time series change of the entire surface displacement as a reference signal. Specifically, the signal generating unit 13 identifies the time series change of the movement amount (Δz) in the normal direction measured by the entire surface displacement measuring unit 25 from the entire surface displacement information, and uses the time series change D(t) of this identified movement amount (Δz) as the reference signal.

In this modified example 1, unlike the above-described embodiment, there is no need to specify a point of interest, or even a specific direction, which reduces the burden on the inspector of the bridge 60. Note that this modified example 1 is useful in cases where the imaging device 50 is sufficiently fixed in a location that is unlikely to be affected by external forces, and where stress fluctuations due to external forces are linked to the overall displacement of the surface in the direction in which the external force is applied.

[Modification 2]
In the present modified example 2, the reference signal generating unit 21 first calculates a local distortion on the specific surface of the object using the in-plane displacement, and then integrates the local distortion over the entire specific surface to calculate a time series change in distortion over the entire specific surface of the object. The reference signal generating unit 21 then generates a signal indicating the time series change in the calculated distortion as a reference signal.

Specifically, in order to obtain the local strain ε(t,i,j) from the local deformation state at the coordinate (i,j) of the measurement target region for each frame of image data, the reference signal generator 21 first determines multiple points (e.g., four points) surrounding the coordinate (i,j). The region surrounded by these points here is also referred to as a "local region."

Then, the reference signal generating unit 21 acquires in-plane displacement information for each of the determined points from the storage unit 17, and identifies the direction in which the local region changes most by performing singular value decomposition using the acquired in-plane displacement information for each point. The reference signal generating unit 21 then calculates the rate of change of the length of the local region in the identified direction, and sets the calculated rate of change as the local distortion s(t, i, j).

Then, the reference signal generating unit 21 integrates the local distortion s(t,i,j) over the entire measurement target area to calculate the distortion amount S(t) over the entire measurement target area, and uses the calculated distortion amount S(t) as the reference signal. In this modification 2, since the reference signal is found from the local distortion, this modification 2 is also useful when the imaging device 50 is not sufficiently fixed, or when there is low correlation between the stress fluctuation due to the external force and the overall surface displacement in the direction of the application of the external force.

[Modification 3]
In this modification 3, similarly to the modification 2, the reference signal generating unit 21 determines a plurality of points (for example, four points) surrounding the coordinates (i, j), and acquires in-plane displacement information at each of the determined points from the storage unit 17. However, unlike the modification 2, in this modification 3, the reference signal generating unit 21 uses the acquired in-plane displacement information at each point to obtain singular values _σ1 , _σ2 ( _σ1 ≧ _σ2 ) and a singular vector _v1 indicating local deformation in a local region. Note that the singular vector _v1 here is the left singular vector corresponding to the singular value σ1, but in this modification 3, it may be determined that a singular vector other than the singular vector is selected.

Next, the reference signal generating unit 21 uses Equation 13 to calculate a local aperture vector v _op (t, i, j) that indicates the direction and size of a local aperture in a local region.

Next, the reference signal generating unit 21 performs a principal component analysis of the calculated local aperture vector to identify the first principal component. Specifically, the reference signal generating unit 21 receives the distribution of the point cloud by v _op (t, i, j) at time t as an input, and derives the maximum spreading direction of the point cloud by the principal component analysis. Furthermore, the reference signal generating unit 21 sets the standard deviation of the first principal component axis obtained by the principal component analysis as S(t), and sets this as a reference signal. In this modification example 3, by using the principal component analysis, it is possible to obtain a reference signal that is more robust against noise contained in the in-plane displacement.

[Modification 4]
In this modification 4, similarly to modification 2, the reference signal generating unit 21 first calculates the local strain s(t,i,j) for each coordinate (i,j). In addition, similarly to modification 1, the reference signal generating unit 21 also calculates the time series change D(t) of the entire surface displacement in the external force application direction. Next, the reference signal generating unit 21 calculates the regression coefficient w(i,j) between the local strain s(t,i,j) and the time series change D(t) for each coordinate (i,j).

Next, the reference signal generating unit 21 calculates a local aperture vector v _op (t, i, j) representing the local aperture direction and size in the local region using the above equation 1, as in the third modification.

Next, the reference signal generating unit 21 multiplies each of the local opening vectors v _op (t, i, j) that are the first principal components by a regression coefficient w(i, j) as a weight. Furthermore, the reference signal generating unit 21 performs the same principal component analysis as in the third modification on the local opening vector v _op (t, i, j) after weight multiplication at time t. The standard deviation of the first principal component axis obtained by the principal component analysis is set as S(t), and this is used as a reference signal. In the fourth modification, by lowering the contribution of the local opening vector to the principal component analysis at points with a low degree of linkage with the external force, it is possible to obtain a reference signal that is more robust against noise contained in the in-plane displacement.

[program]
The first program in this embodiment may be a program that causes a computer to execute steps A1 to A6 shown in Fig. 6. By installing and executing this program in a computer, the data encoding device 20 in this embodiment can be realized. In this case, the processor of the computer functions as a reference signal generating unit 21, a regression coefficient calculating unit 22, a data output unit 23, an image data acquiring unit 24, an entire surface displacement measuring unit 25, and an in-plane displacement measuring unit 26, and performs processing.

The first program in this embodiment may be executed by a computer system constructed by multiple computers. In this case, for example, each computer may function as any one of the reference signal generating unit 21, the regression coefficient calculating unit 22, the data output unit 23, the image data acquiring unit 24, the entire surface displacement measuring unit 25, and the in-plane displacement measuring unit 26.

The second program in this embodiment may be a program that causes a computer to execute steps B1 to B3 shown in FIG. 7. By installing this program in a computer and executing it, the data decoding device 30 in this embodiment can be realized. In this case, the computer's processor functions as the data acquisition unit 31 and the data decoding unit 32 and performs the processing.

The second program in this embodiment may be executed by a computer system constructed by multiple computers. In this case, for example, each computer may function as either the data acquisition unit 31 or the data decryption unit 32.

Here, a computer that realizes the data encoding device 20 by executing the first program in this embodiment, and a computer that realizes the data decoding device 30 by executing the second program in this embodiment will be described with reference to FIG. 8.

Figure 8 is a block diagram showing an example of a computer that realizes a data encoding device or a data decoding device according to an embodiment of the present invention. As shown in Figure 8, the computer 110 includes a CPU (Central Processing Unit) 111, a main memory 112, a storage device 113, an input interface 114, a display controller 115, a data reader/writer 116, and a communication interface 117. These components are connected to each other via a bus 121 so as to be able to communicate data with each other. The computer 110 may also include a GPU (Graphics Processing Unit) or an FPGA (Field-Programmable Gate Array) in addition to or instead of the CPU 111.

The CPU 111 loads the program (code) in this embodiment stored in the storage device 113 into the main memory 112 and executes it in a predetermined order to perform various calculations. The main memory 112 is typically a volatile storage device such as a DRAM (Dynamic Random Access Memory). The program in this embodiment is provided in a state stored in a computer-readable recording medium 120. The program in this embodiment may be distributed over the Internet connected via the communication interface 117.

Specific examples of the storage device 113 include a hard disk drive and a semiconductor storage device such as a flash memory. The input interface 114 mediates data transmission between the CPU 111 and input devices 118 such as a keyboard and a mouse. The display controller 115 is connected to the display device 119 and controls the display on the display device 119.

The data reader/writer 116 mediates data transmission between the CPU 111 and the recording medium 120, reads programs from the recording medium 120, and writes the results of processing in the computer 110 to the recording medium 120. The communication interface 117 mediates data transmission between the CPU 111 and other computers.

Specific examples of the recording medium 120 include general-purpose semiconductor storage devices such as CF (Compact Flash (registered trademark)) and SD (Secure Digital), magnetic recording media such as flexible disks, and optical recording media such as CD-ROMs (Compact Disk Read Only Memory).

In addition, the data encoding device 20 and the data decoding device 30 in this embodiment can be realized by using hardware corresponding to each part, rather than a computer on which a program is installed. Furthermore, the data encoding device 20 and the data decoding device 30 may be realized in part by a program and the remaining part by hardware.

A part or all of the above-described embodiment can be expressed by (Appendix 1) to (Appendix 21) described below, but is not limited to the following description.

(Appendix 1)
a reference signal generating unit that generates a reference signal whose level changes according to a stress generated on the specific surface of the object, based on an overall surface displacement on the specific surface of the object measured from time-series images of the object and an in-plane displacement on the specific surface of the object measured from the overall surface displacement and the time-series images;
a regression coefficient calculation unit that calculates a regression coefficient indicating a degree of correlation between a time series change in a level of the reference signal and a time series change in the in-plane displacement, using the reference signal and the in-plane displacement;
a data output unit that outputs the reference signal and the regression coefficient as data indicating the in-plane displacement;
A data encoding device comprising:

(Appendix 2)
2. A data encoding device according to claim 1, comprising:
an entire surface displacement measuring unit that measures the entire surface displacement from the time-series images of the object;
an in-plane displacement measuring unit that measures the in-plane displacement from the entire-plane displacement and the time-series images;
The device further comprises:
2. A data encoding device comprising:

(Appendix 3)
3. A data encoding device according to claim 1, further comprising:
When the in-plane displacement is measured for each point on a particular surface of the object,
the regression coefficient calculation unit calculates, for each of the points, the regression coefficient by using the reference signal and the in-plane displacement at the point;
the data output unit outputs, for each of the points, the reference signal and the regression coefficient at that point.
A data encoding device comprising:

(Appendix 4)
A data encoding device according to any one of claims 1 to 3,
the reference signal generating unit calculates a time series change in distortion of the point of interest in the specific direction from the in-plane displacement of the point of interest on the specific surface in the specific direction, and generates a signal indicating the calculated time series change in distortion as the reference signal.
2. A data encoding device comprising:

(Appendix 5)
A data encoding device according to any one of claims 1 to 3,
When the entire surface displacement is measured in an in-plane direction of the specific surface of the object and in an application direction of an external force applied to the object,
the reference signal generation unit calculates a time series change of the entire surface displacement in the application direction, and generates, as the reference signal, a signal indicating the calculated time series change of the entire surface displacement.
2. A data encoding device comprising:

(Appendix 6)
A data encoding device according to any one of claims 1 to 3,
the reference signal generating unit calculates a local strain on the specific surface of the object using the in-plane displacement, and further calculates a time series change in strain on the entire specific surface of the object by integrating the local strain over the entire specific surface, and generates a signal indicating the calculated time series change in strain as the reference signal.
2. A data encoding device comprising:

(Appendix 7)
a data acquisition unit that acquires a reference signal whose level changes in accordance with stress generated on a specific surface of the object, and a regression coefficient that indicates a degree of correlation between a time series change in the level of the reference signal and a time series change in an in-plane displacement on the specific surface of the object;
a data decoding unit that reconstructs an in-plane displacement on a specific surface of the object using the acquired reference signal and the regression coefficients;
Equipped with
A data decoding device comprising:

(Appendix 8)
A data encoding device and a data decoding device are provided,
The data encoding device comprises:
a reference signal generating unit that generates a reference signal whose level changes according to a stress generated on the specific surface of the object, based on an overall surface displacement on the specific surface of the object measured from time-series images of the object and an in-plane displacement on the specific surface of the object measured from the overall surface displacement and the time-series images;
a regression coefficient calculation unit that calculates a regression coefficient indicating a degree of correlation between a time series change in a level of the reference signal and a time series change in the in-plane displacement, using the reference signal and the in-plane displacement;
a data output unit that outputs the reference signal and the regression coefficient as data indicating the in-plane displacement;
The data decoding device comprises:
a data acquisition unit that acquires a reference signal whose level changes in accordance with stress generated on a specific surface of the object, and a regression coefficient that indicates a degree of correlation between a time series change in the level of the reference signal and a time series change in an in-plane displacement on the specific surface of the object;
and a data decoding unit that uses the acquired reference signal and the regression coefficients to reconstruct an in-plane displacement on the specific surface of the object.
A data communication system comprising:

(Appendix 9)
A data communication method using a data encoding device and a data decoding device, comprising:
(a) generating, by the data encoding device, a reference signal whose level changes in accordance with a stress generated on the specific surface of the object, from an overall surface displacement on the specific surface of the object measured from time-series images of the object, and an in-plane displacement on the specific surface of the object measured from the overall surface displacement and the time-series images;
(b) calculating, by the data encoding device, a regression coefficient indicating a degree of correlation between a time series change in a level of the reference signal and a time series change in the in-plane displacement, using the reference signal and the in-plane displacement;
(c) outputting, by the data encoding device, the reference signal and the regression coefficients as data indicating the in-plane displacement;
(d) acquiring, by the data decoding device, a reference signal whose level changes in accordance with the stress generated on the specific surface of the object, and a regression coefficient indicating a degree of correlation between a time series change in the level of the reference signal and a time series change in the in-plane displacement on the specific surface of the object;
(e) recovering, by the data decoding device, an in-plane displacement on a specific surface of the object using the acquired reference signal and the regression coefficients;
A data communication method comprising the steps of:

(Appendix 10)
10. The data communication method according to claim 9, further comprising:
(f) measuring the overall surface displacement from the time series images of the object by the data encoding device;
(g) measuring the in-plane displacement from the entire-plane displacement and the time-series images by the data encoding device;
Further comprising
A data communication method comprising:

(Appendix 11)
11. The data communication method according to claim 9, further comprising:
When the in-plane displacement is measured for each point on a particular surface of the object,
In the step (b), the regression coefficient is calculated for each of the points using the reference signal and the in-plane displacement at the point;
In the step (c), the reference signal and the regression coefficient at each point are output.
A data communication method comprising:

(Appendix 12)
A data communication method according to any one of Supplementary Notes 9 to 11,
In the step (a), a time series change in distortion of the point of interest in the specific direction is calculated from the in-plane displacement of the point of interest on the specific surface in the specific direction, and a signal indicating the calculated time series change in distortion is generated as the reference signal.
A data communication method comprising:

(Appendix 13)
A data communication method according to any one of Supplementary Notes 9 to 11,
When the entire surface displacement is measured in an in-plane direction of the specific surface of the object and in an application direction of an external force applied to the object,
In the step (a), a time series change of the entire surface displacement in the application direction is calculated, and a signal indicating the calculated time series change of the entire surface displacement is generated as the reference signal.
A data communication method comprising:

(Appendix 14)
A data communication method according to any one of Supplementary Notes 9 to 11,
In the step (a), a local strain on the specific surface of the object is calculated using the in-plane displacement, and the local strain is further integrated over the entire specific surface to calculate a time series change in strain on the entire specific surface of the object, and a signal indicating the calculated time series change in strain is generated as the reference signal.
A data communication method comprising:

(Appendix 15)
On the computer,
(a) generating a reference signal whose level changes in accordance with a stress generated on a specific surface of the object from an overall surface displacement on the specific surface of the object measured from time-series images of the object and an in-plane displacement on the specific surface of the object measured from the overall surface displacement and the time-series images;
(b) calculating a regression coefficient indicating a degree of correlation between a time series change in a level of the reference signal and a time series change in the in-plane displacement, using the reference signal and the in-plane displacement;
(c) outputting the reference signal and the regression coefficients as data indicative of the in-plane displacement;
A program to execute.

(Appendix 16)
16. The program according to claim 15,
The computer includes:
(d) measuring the overall surface displacement from the time series images of the object;
(e) measuring the in-plane displacement from the entire-plane displacement and the time-series images;
Further execute
A program characterized by:

(Appendix 17)
17. The program according to claim 15 or 16,
When the in-plane displacement is measured for each point on a particular surface of the object,
In the step (b), the regression coefficient is calculated for each of the points using the reference signal and the in-plane displacement at the point;
In the step (c), the reference signal and the regression coefficient at each point are output.
A program characterized by:

(Appendix 18)
The program according to any one of appendices 15 to 17,
In the step (a), a time series change in distortion of the point of interest in the specific direction is calculated from the in-plane displacement of the point of interest on the specific surface in the specific direction, and a signal indicating the calculated time series change in distortion is generated as the reference signal.
A program characterized by:

(Appendix 19)
The program according to any one of appendices 15 to 17,
When the entire surface displacement is measured in an in-plane direction of the specific surface of the object and in an application direction of an external force applied to the object,
In the step (a), a time series change of the entire surface displacement in the application direction is calculated, and a signal indicating the calculated time series change of the entire surface displacement is generated as the reference signal.
A program characterized by:

(Appendix 20)
The program according to any one of appendices 15 to 17,
In the step (a), a local strain on the specific surface of the object is calculated using the in-plane displacement, and the local strain is further integrated over the entire specific surface to calculate a time series change in strain on the entire specific surface of the object, and a signal indicating the calculated time series change in strain is generated as the reference signal.
A program characterized by:

(Appendix 21)
On the computer,
(a) acquiring a reference signal whose level changes in accordance with stress generated on a specific surface of an object, and a regression coefficient indicating a degree of correlation between a time series change in the level of the reference signal and a time series change in an in-plane displacement on the specific surface of the object;
(b) recovering an in-plane displacement of a particular surface of the object using the acquired reference signal and the regression coefficients;
A program to execute.

The present invention has been described above with reference to the embodiment, but the present invention is not limited to the above embodiment. Various modifications that can be understood by a person skilled in the art can be made to the configuration and details of the present invention within the scope of the present invention.

As described above, according to the present invention, in encoding or decoding data indicating in-plane displacement extracted from an image, it is possible to reduce the costs of transmission and storage while maintaining sufficient spatial resolution. The present invention is useful for systems that determine the condition of structures such as bridges from images.

REFERENCE SIGNS LIST 10 Data communication system 20 Data encoding device 21 Reference signal generation unit 22 Regression coefficient calculation unit 23 Data output unit 24 Image data acquisition unit 25 Whole surface displacement measurement unit 26 In-plane displacement measurement unit 27 Storage unit 30 Data decoding device 31 Data acquisition unit 32 Data decoding unit 33 Display device 40 Network 50 Imaging device 60 Bridge 110 Computer 111 CPU
112 Main memory 113 Storage device 114 Input interface 115 Display controller 116 Data reader/writer 117 Communication interface 118 Input device 119 Display device 120 Recording medium 121 Bus

Claims (10)

One or more computers,
a means for measuring a displacement of an entire surface of a specific surface of the object in a direction of application of an external force to the object based on time-series images of the object;
a means for calculating an in-plane displacement on a specific surface of the object based on time-series images of the object and an overall surface displacement in an application direction of an external force applied to the object;
a means for calculating a time series change in an overall surface displacement in an application direction of an external force applied to the object based on the overall surface displacement in the application direction;
means for calculating a correlation between the time series change of the entire-surface displacement in the application direction and the time series change of the in-plane displacement based on the time series change of the entire-surface displacement in the application direction and the in-plane displacement;
a data encoding program that operates as a means for outputting a value based on a time series change in the overall surface displacement in the application direction and the correlation. The computer further comprises:
a means for calculating a time series change in distortion at a pre-specified attention point from an in-plane displacement at a specific surface of the object, the in-plane displacement being calculated using an entire surface displacement at the specific surface of the object measured from time series images of the object and the time series images, and calculating a signal indicating the calculated time series change in distortion at the attention point as a reference signal;
2. The data encoding program according to claim 1, which is operated. the means for calculating a correlation between the time series change in the entire surface displacement in the application direction and the time series change in the in-plane displacement calculates a correlation between the time series change in the level of the reference signal based on the time series change in the entire surface displacement in the application direction and the time series change in the in-plane displacement;
3. The data encoding program according to claim 2 . the means for outputting a value based on the time series change of the entire surface displacement in the application direction and the correlation outputs the value based on the time series change of the entire surface displacement in the application direction and the correlation to a decoding device that decodes the value into an in-plane displacement on the specific surface of the object.
2. The data encoding program according to claim 1. The correlation-based value is a regression coefficient.
2. The data encoding program according to claim 1. a means for measuring a displacement of an entire surface of a specific surface of the object in a direction of application of an external force to the object based on time-series images of the object;
a means for calculating an in-plane displacement on a specific surface of the object based on time-series images of the object and an overall surface displacement in an application direction of an external force applied to the object;
a means for calculating a time series change in an overall surface displacement in an application direction of an external force applied to the object based on the overall surface displacement in the application direction;
means for calculating a correlation between the time series change of the entire-surface displacement in the application direction and the time series change of the in-plane displacement based on the time series change of the entire-surface displacement in the application direction and the in-plane displacement;
a means for outputting a value based on a time series change in the overall surface displacement in the application direction and the correlation;
A data encoding device comprising: a means for calculating a time series change in distortion at a pre-specified attention point from an in-plane displacement at a specific surface of the object, the in-plane displacement being calculated using a whole surface displacement at the specific surface of the object measured from time series images of the object and the time series images, and calculating a signal indicating the calculated time series change in distortion at the attention point as a reference signal;
The data encoding device of claim 6 further comprising: the means for calculating a correlation between the time series change in the entire surface displacement in the application direction and the time series change in the in-plane displacement calculates a correlation between the time series change in the level of the reference signal based on the time series change in the entire surface displacement in the application direction and the time series change in the in-plane displacement;
8. A data encoding device according to claim 7 . the means for outputting a value based on the time series change of the entire surface displacement in the application direction and the correlation outputs the value based on the time series change of the entire surface displacement in the application direction and the correlation to a decoding device that decodes the value into an in-plane displacement on the specific surface of the object.
7. A data encoding device according to claim 6. The correlation-based value is a regression coefficient.
7. A data encoding device according to claim 6.

Images