JP2023103459A - Data encoding program and data encoding device - Google Patents

Abstract

To reduce the cost required for transmission and accumulation while maintaining a sufficient spatial resolution when encoding or decoding data indicating in-plane displacement extracted from an image.SOLUTION: A data encoding device 20 comprises: a reference signal generation section 21 that generates a reference signal, whose level varies in accordance with stress generated on a specific surface of an object, from whole surface displacement on the specific surface of the object, which is measured from time series images of the object, and in-plane displacement in the specific surface of the object, which is measured from the whole surface displacement and the time series images; a regression coefficient calculation section 22 that calculates, using the reference signal and the in-plane displacement, regression coefficients that indicate an interlocking degree between time series variations at a level of the reference signal and time series variations in the in-plane displacement; and a data output section 23 that outputs the reference signal and the regression coefficient as data indicating the in-plane displacement.SELECTED DRAWING: Figure 1

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 to a program for realizing these.

Conventionally, techniques have been proposed for non-contact determination of the state of a structure such as a bridge (see, for example, Patent Literature 1). According to such a determination technique, an inspector can inspect a structure without coming into contact with the structure. Such determination techniques are particularly useful for structures that are grounded in places that are not easily accessible to inspectors.

Patent Document 1 discloses an apparatus that derives an in-plane displacement component of a determination target portion from an image of a structure such as a bridge, and determines the state of the structure based on the derived in-plane displacement component.

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

Next, the apparatus disclosed in Patent Document 1 obtains an in-plane displacement distribution from the derived in-plane displacement component, and compares the obtained in-plane displacement distribution with a reference in-plane displacement distribution. At this time, if there is damage such as an opening due to a crack, a difference occurs in the two in-plane distributions, so the apparatus disclosed in Patent Document 1 detects defects such as cracks from the comparison result.

WO2016/152075

By the way, the in-plane displacement component data derived by the device disclosed in Patent Document 1 is transmitted to a data server or the like via a network for recording, and is accumulated there. However, the in-plane displacement component data obtained in this way has a characteristic that the amount of data is very large, and there is a problem that a large amount of cost is required for transmission and storage via a network.

For example, let us say that the conditions for moving image data of a structure are 2048×2048 pixels, a frame rate of 80 fps, and a time of 10 seconds. In this case, if the X-direction and Y-direction displacements (each 32-bit floating point) are obtained for each pixel coordinate, the data amount of the in-plane displacement component data is approximately 26 GB.

Also, conventionally, MPEG is known as a compression format for moving image data, and if such a compression format is used to compress data of in-plane displacement components, it may be possible to reduce costs. However, MPEG is a compression method for efficiently compressing time-series two-dimensional data, whereas in-plane displacement component data is composed of input signals in floating-point format. Therefore, even if the cost can be reduced, there is a possibility that the accuracy in determining the state by damage detection will be greatly reduced due to the distortion that occurs when the compression is performed at a high compression rate.

Although 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 size of the data to a practical level at which costs can be reduced while maintaining sufficient spatial resolution for damage detection.

It is an object of the present invention to provide a data encoding device, a data decoding device, a data communication system, a data communication method, and a program capable of solving the above-described problems and reducing transmission and storage costs while maintaining sufficient spatial resolution when encoding or decoding data representing 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 includes:
a reference signal generation unit that generates a reference signal whose level changes according to the stress generated on the specific surface of the object from the entire surface displacement on the specific surface of the object measured from the time-series images of the object and the in-plane displacement on the specific surface of the object measured from the whole surface displacement and the time-series images;
a regression coefficient calculation unit that calculates a regression coefficient that indicates the degree of interlocking between the time-series change in the level of the reference signal and the 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;
characterized by comprising

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

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 is
a reference signal generation unit that generates a reference signal whose level changes according to the stress generated on the specific surface of the object from the entire surface displacement on the specific surface of the object measured from the time-series images of the object and the in-plane displacement on the specific surface of the object measured from the whole surface displacement and the time-series images;
a regression coefficient calculation unit that calculates a regression coefficient that indicates the degree of interlocking between the time-series change in the level of the reference signal and the 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
a data acquisition unit that acquires a reference signal whose level changes according to the stress generated on a specific surface of an object, and a regression coefficient that indicates the degree of linkage between the time-series change in the level of the reference signal and the time-series change in the in-plane displacement on the specific surface of the object;
a data decoding unit that restores an in-plane displacement on a specific surface of the object using the acquired reference signal and the regression coefficient;
It is characterized by

Further, 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,
(a) generating a reference signal, the level of which changes according to the stress generated on the specific surface of the object, from the entire surface displacement of the specific surface of the object measured from the time series images of the object and the in-plane displacement of the specific surface of the object measured from the whole surface displacement and the time series images by the data encoding device;
(b) using the reference signal and the in-plane displacement by the data encoding device to calculate a regression coefficient that indicates the degree of linkage between the time-series change in the level of the reference signal and the time-series change in the in-plane displacement;
(c) outputting the reference signal and the regression coefficient as data indicative of the in-plane displacement by the data encoding device;
(d) obtaining, by the data decoding device, a reference signal whose level changes according to the stress generated on the specific surface of the object, and a regression coefficient that indicates the degree of linkage between the time-series change in the level of the reference signal and the time-series change in the in-plane displacement on the specific surface of the object;
(e) reconstructing an in-plane displacement on a specific surface of the object using the reference signal and the regression coefficients obtained by the data decoding device;
characterized by having

Furthermore, in order to achieve the above object, the first program in one aspect of the present invention is
to the computer,
(a) generating a reference signal whose level changes according to the stress generated on the specific surface of the object from the entire surface displacement on the specific surface of the object measured from the time-series images of the object and the in-plane displacement on the specific surface of the object measured from the whole surface displacement and the time-series images;
(b) using the reference signal and the in-plane displacement to calculate a regression coefficient that indicates the degree of linkage between the time-series change in the level of the reference signal and the time-series change in the in-plane displacement;
(c) outputting the reference signal and the regression coefficient as data indicative of the in-plane displacement;
is characterized by executing

Furthermore, in order to achieve the above object, a second program in one aspect of the present invention is
to the computer,
(a) acquiring a reference signal whose level changes according to the stress generated on a specific surface of an object, and a regression coefficient indicating the degree of linkage between the time-series change in the level of the reference signal and the time-series change in the in-plane displacement on the specific surface of the object;
(b) reconstructing an in-plane displacement at a particular surface of the object using the obtained reference signal and the regression coefficients;
is characterized by executing

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

FIG. 1 is a block diagram showing the configuration of a data communication system according to an embodiment of the invention. FIG. 2 is a block diagram more specifically showing 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 the measurement target region of the object is photographed. FIG. 4 is a diagram schematically showing a two-dimensional spatial distribution of displacements (δx _ij , δy _ij ) observed in a specific region on an image of the measurement target region. 5(a) to 5(c) are diagrams for explaining the processing performed by the regression coefficient calculator 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 according to the embodiment of the present invention. FIG. 8 is a block diagram showing an example of a computer that implements the data encoding device or data decoding device according to the embodiment of the present invention.

(Embodiment)
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. 1 to 8. FIG.

[System configuration]
First, using FIG. 1, configurations of a data encoding device, a data decoding device, and a data communication system according to this embodiment will be described. FIG. 1 is a block diagram showing the configuration of a data communication system according to an embodiment of the invention.

A data communication system 10 according to the present 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 . The data encoding device 20 and the data decoding device 30 are connected via a network 40 such as the Internet.

A 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 generation section 21, a regression coefficient calculation section 22, and a data output section .

Among them, the reference signal generator 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 and the in-plane displacement.

The regression coefficient calculator 22 also uses the reference signal and the in-plane displacement to calculate a regression coefficient that indicates the degree of linkage 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 in-plane displacement.

A 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 section 31 and a data decoding section 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 the regression coefficient to restore the in-plane displacement on the specific surface of the object.

As described above, in the present embodiment, the data indicating the in-plane displacement is not reduced in size but is transmitted after being converted into a reference signal and regression coefficients. Therefore, according to this embodiment, it is possible to reduce transmission and storage costs while maintaining sufficient spatial resolution in encoding or decoding data representing in-plane displacement extracted from an image.

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

As shown in FIG. 2, in the present embodiment, the object for which the in-plane displacement is measured is the bridge 60, and when the bridge 60 bends due to the weight of a vehicle 61 passing through the bridge 60, the in-plane displacement in the measurement target area set on the bridge 60 is measured. The measurement target area includes bridge girders, floor slabs, and the like.

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

Furthermore, as shown in FIG. 2, in the present embodiment, the data encoding device 20 includes an image data acquisition unit 24, an entire plane displacement measurement unit 25, an in-plane displacement measurement unit 26, and a storage 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 plane 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 the object from the time-series images of the object. In the present embodiment, the entire surface displacement measuring unit 25 acquires the time-series images output by the imaging device 50, and uses an image captured at an arbitrary time as a reference image and the other images as processed images. Then, the entire surface displacement measuring unit 25 finds the corresponding position in each processed image for each point in the region corresponding to the measurement target region on the specific surface in the reference image (hereinafter referred to as “specific region”), and calculates the displacement. The displacement with respect to the specific region for each processed image calculated in this way is the displacement distribution.

Specifically, the entire surface displacement measuring unit 25 searches for a point (coordinates) in the processed image that is most similar to a certain point (coordinates) in the specific region, and calculates the displacement of the specified point (coordinates). Examples of a method for identifying similar locations include a method of searching for the position (coordinates) with the highest correlation using a similarity correlation function such as SAD (Sum of Squared Difference), SSD (Sum of Absolute Difference), NCC (Normalized Cross-Correlation), ZNCC (Zero-means Normalized Cross-Correlation), etc., using luminance values of a certain location (coordinates) and coordinates around it.

By repeatedly performing such calculation processing for each coordinate in the specific region, it is possible to obtain the displacement distribution for the specific region in the processed image. Further, by performing the same processing for each processed image, it is possible to obtain the displacement distribution for the specific region for each processed image. Here, the specific coordinates of the measurement target area are defined as (i, j)), and the calculated displacement is expressed as (Δx _ij , Δy _ij ).

Next, from the calculated displacement (δx _ij , δy _ij ) and the imaging information, the entire surface displacement measuring unit 25 calculates the amount of movement (Δx, Δy) in the surface direction and the amount of movement (Δz) in the normal direction of the measurement target area. Further, the displacement (δx _ij , δy _ij ) and the amount of movement (Δx, Δy, Δz) calculated by the entire surface displacement measuring unit 25 become the displacement of the entire surface. Further, the entire surface displacement measuring unit 25 stores the calculated displacements (δx _ij , δy _ij ) and the movement amounts (Δx, Δy, Δz) in the storage unit 27 as the entire surface displacement information. The imaging information includes the size of one pixel of the solid-state imaging device 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 measurement unit 26 measures the in-plane displacement on the specific surface of the bridge 60 from the movement amount (Δx, Δy, Δz) calculated by the entire surface displacement measurement 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 FIGS. 3 and 4. FIG. 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 the measurement target region of the object is photographed. FIG. 3 also shows a state in which a bridge 60, which is an object, receives a load from a passing vehicle 61, and as a result, the measurement target area moves in the three-dimensional direction by the amount of movement (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 of 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 imaging device 50 . Note that the coordinates (i, j) on the imaging surface of the imaging device 50 can be replaced with the coordinates on the captured image.

In the state of FIG. 3, the measurement target area of the bridge 60 has movement amounts (Δx, Δy, Δz) in the horizontal and vertical directions (X, Y directions) and the normal direction (Z direction) on the screen. The measurement target area moves parallel to the imaging surface of the imaging device 50 by the amount (Δx, Δy) of movement in the horizontal direction and vertical direction (X, Y directions) within the screen. Also, it approaches the imaging device 50 by the amount (Δz) of movement in the normal direction (Z direction). Therefore, the imaging distance is shortened by the movement amount Δz.

As a result, as shown in FIG. 3, in addition to the displacement .delta.x caused by the movement amount .DELTA.x of the measurement target area in the horizontal direction (X direction) with respect to the imaging surface of the imaging device 50, a displacement _.delta.zxij due to the movement amount .DELTA.z is generated. Similarly, on the imaging surface of the image pickup device 50, a displacement δzy _ij due to the movement amount Δz is also generated in addition to the displacement δy caused by the movement amount Δy of the image pickup device 50 in the direction perpendicular to the screen (Y direction).

Further, when the surface of the measurement target area is deformed (ΔΔX _ij , ΔΔY _ij ) due to the load applied to the bridge 60, the in-plane displacement (δδx _ij , δδy _ij ) is also superimposed on the imaging plane of the imaging device 50 accordingly.

Here, the in-plane displacement (δδx _ij , δδy _ij ) associated with the deformation of the surface of the measurement target region changes continuously in a healthy region without defects such as cracks, but does not change continuously but changes discontinuously in a region across cracks. In this way, a healthy region without defects and a region with some defects have different surface displacement distributions.

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

Let L be the imaging distance from the principal point of the lens to the measurement target area, f be the lens focal length of the imaging device 50, and (i, j ₎ be the coordinates from _the imaging center.

Assuming that all the measurement target areas are moving in the same three-dimensional manner, the displacement (δx, δy) associated with the movement (Δx, Δy) in the plane direction shown by Equations 3 and 4 above is constant regardless of the coordinates of point A. Also, it can be seen that the displacement (δzx _ij , δzy _ij ) associated with the movement (Δz) in the normal direction increases as the coordinates of the point A move away from the origin. On the other hand, the in-plane displacement (δδx _ij , δδy _ij ) of the measurement target region shows a distribution of continuous/discontinuous displacements depending on the position of defects such as cracks on the surface, regardless of the coordinates of the point A.

FIG. 4 is a diagram schematically showing a two-dimensional spatial distribution (hereinafter referred to as a displacement distribution) of displacements (δx _ij , δy _ij ) observed in a specific region on an image of the measurement target region. As shown in FIG. 4, the displacement (δx _ij , δy _ij ) of each coordinate of the specific region calculated by the entire surface displacement measuring unit 25 is expressed as a displacement vector. In this case, the displacement vector is expressed as a composite component of displacement (δx, δy) accompanying movement in the plane direction (Δx, Δy) observed in a uniform direction and magnitude over the entire screen, displacement (δzx _ij , δzy _ij ) accompanying movement in the normal direction (Δz) observed as a vector group radially from the imaging center of the screen, and in-plane displacement (δδx _ij , δδy _ij ) accompanying 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 displacements (.delta.x, .delta.y) accompanying the movement (.DELTA.x, .DELTA.y) in the planar direction are basically observed in uniform directions and magnitudes over the entire screen. Therefore, plus or minus is added to the displacement (δx _ij , δy _ij ) calculated at each coordinate of the specific region around the imaging center by the entire surface displacement measuring unit 25 depending on the direction of displacement, and this is used as a displacement vector. Then, the displacement vectors (Δx, Δy) associated with the movement (Δx, Δy) in the plane direction are calculated by adding up all the displacement vectors at each target coordinate and calculating the average.

Next, a method for calculating the displacement vector (δzx _ij , δzy _ij ) associated with the movement (Δz) in the normal direction will be described. First, consider a state in which only displacement vectors (δzx _ij , δzy _ij ) are generated due to movement (Δz) in the normal direction. The magnitude R(i,j) of the vector becomes a value proportional to the distance from the imaging center, as shown in Equation 5 below, if the movement amount Δz of the specific region is constant within the specific region. Also, if k is a constant of proportionality as shown in Equation 6 below, Equation 5 can also be expressed as Equation 7.

On the other hand, actually, the displacements (δx _ij , δy _ij ) first calculated by the entire surface displacement measuring unit 25 are composed of composite vectors (FIG. 4: thick solid line arrows), as shown in FIG. As can be seen from FIG. 4, this combined vector (δx _ij , δy _ij ) is a displacement vector (δzx _ij , δzy _ij ) associated with movement (Δz) in the normal direction (FIGS. 3 and 4: medium solid line arrows), a displacement vector (δx, δy) associated with in-plane direction movement (Δx, Δy) (FIGS. 3 and 4: thick solid line arrows), and a displacement vector (δx, δy) associated with in-plane direction movement (Δx, Δy) (FIGS. 3 and 4: bold solid line arrows). displacements (δδx _ij , δδy _ij ) (FIGS. 3 and 4: thin solid line arrows).

Therefore, the vector obtained by subtracting the displacement vector ( _δx , _δy ) accompanying the in-plane movement (Δx, Δy) from the combined vector (δx _ij , δy ij ) corresponds to the combined vector of the displacement vector (δzx ij , δzy _ij ) accompanying the normal direction movement (Δz) and the in-plane displacement (δδx _ij , δδy _ij ).

Therefore, assuming that the combined vector of the displacement vector (δzx _ij , δzy _ij ) and the in-plane displacement (δδx _ij , δδy _ij ) associated with the normal direction movement (Δz) at the coordinates (i, j) is R _mes (i, j), these can be expressed by Equation 8 below.

By the way, the in-plane displacement (δδx _ij , δδy _ij ) can be regarded as sufficiently small compared to the displacement vector (δx, δy) associated with the in-plane direction movement (Δx, Δy) and the displacement vector (δzx _ij , δzy _ij ) associated with the normal direction movement (Δz). Therefore, focusing on the displacement vector (δx, δy) accompanying the movement (Δx, Δy) in the in-plane direction and the displacement vector (δzx _ij , δzy _ij ) accompanying the movement (Δz) in the normal direction, which are the dominant components, Equation 8 above can be expressed as Equation 9 below.

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

Therefore, the entire surface displacement measuring unit 25 uses the displacement vector magnitude R _mes (i , j) obtained by Equation 9 to estimate the expansion/reduction ratio of the displacement vector magnitude R(i, j) due to the displacement vector (δzx _ij , δzy _ij ) associated with the movement (Δz) in the normal direction. Specifically, the entire surface displacement measuring unit 25 estimates the magnification of R(i,j) by obtaining the proportional constant k that minimizes the evaluation function E(k) shown in Equation 10 below.

Therefore, the entire surface displacement measuring unit 25 applies the method of least squares to Equation 10 to calculate the constant of proportionality k. Further, 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 Equation 10, a sum of absolute values, a sum of powers, or the like may be used.

Then, the entire surface displacement measuring unit 25 applies the calculated proportionality constant k as a constant indicating the ratio of enlargement/reduction to Equation 7 to calculate the movement amount Δz. Then, the entire surface displacement measuring unit applies the calculated Δz, the displacement (δx, δy) accompanying the movement (Δx, Δy) in the surface direction, and the imaging information to Equation 3 above to calculate the movement amounts Δx and Δy.

In addition, the entire surface displacement measuring unit 25 calculates the amount of movement of the measurement target area in the planar direction and the amount of movement of the measurement target area in the normal direction for each photographing by the imaging device 50, that is, for each frame of time-series images. Then, the entire surface displacement measuring unit 25 stores the movement amount calculated for each frame of the time-series images in the storage unit 27 as the entire surface displacement information. In this case, the entire surface displacement information can be handled as a time-series signal with sampling intervals equal to the imaging time intervals.

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

According to FIG. 4, in order to calculate the in-plane displacement (δδx _ij , δδy _ij ), the displacement component generated by the movement amount (Δx, Δy, Δz) of the measurement target area can be subtracted 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 in-plane displacements (δδx _ij , δδy _ij ) by using Equations 11 and 12 below.

In addition, the in-plane displacement measuring unit 26 calculates the in-plane displacement (δδx _ij , δδy _ij ) every time the imaging device 50 takes an image, that is, along the time series. Then, the in-plane displacement measurement unit 26 stores the in-plane displacement calculated for each frame of the time-series image in the storage unit 27 as in-plane displacement information. In this case, the in-plane displacement information can be handled as a time-series signal with sampling intervals equal to the imaging time intervals. In this specification, the in-plane displacement information is also referred to as "in-plane displacement signal".

In the present embodiment, the reference signal generation unit 21 calculates the time-series change ε(t) of the strain in a specific direction of the target point from the in-plane displacement in the specific direction of the target point on the specific surface of the object, and generates a signal indicating the calculated time-series change ε(t) of the strain as the reference signal.

Specifically, the operator or the like of the data communication system 10 designates a point of interest in the measurement target area on the specific surface in advance. As shown in FIG. 2, when the object is the bridge 60 and the measurement target area is the floor slab, a point on the floor slab is specified as the point of interest.

When the point of interest is designated, the reference signal generator 21 determines a plurality 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 acquires in-plane displacement information at each determined point from the storage unit 27 .

Then, if the specific direction is also specified in advance, similarly to the point of interest, the reference signal generation unit 21 uses the in-plane displacement information of each acquired point to obtain the rate of change in the length of the local region in the specific direction, and the obtained rate of change is taken as the time-series change ε(t) of the strain.

On the other hand, if a specific direction is not specified in advance, the reference signal generation unit 21 uses the acquired in-plane displacement information of each point to perform singular value decomposition, thereby specifying the direction in which the local region changes the most. Then, the reference signal generator 21 obtains the change rate of the length of the local region in the specified direction, and sets the obtained change rate as the time-series change ε(t) of the strain.

After that, the reference signal generation unit 21 stores the reference signal obtained from the calculated time-series variation of the distortion in the storage unit 27 as reference signal information.

In this embodiment, the regression coefficient calculator 22 calculates a regression coefficient for each point (i, j) of the measurement target region on the specific surface. The regression coefficient calculator 22 first identifies the time-series change in in-plane displacement from the in-plane displacement information stored in the storage unit 27, and the time-series change in the level of the reference signal from the reference signal information stored in the storage unit 27. Then, the regression coefficient calculation unit 22 calculates a regression coefficient indicating the degree of interlocking between the specified time series change in the level of the reference signal and the similarly specified time series change in the in-plane displacement for each point (i, j) of the measurement target area on the specific surface.

Here, processing by the regression coefficient calculation unit 22 will be described using FIG. 5(a) to 5(c) are diagrams for explaining the processing performed by the regression coefficient calculator in the embodiment of the present invention.

Specifically, as shown in FIG. 5(a), the regression coefficient calculator 22 first identifies the time-series change in the level of the reference signal and the time-series change in the in-plane displacement (δδx _ij , δδy _ij ) at the specific point (i, j). Moreover, the in-plane displacement specified 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 may be both. In the former case, one example of in-plane displacement is in-plane displacement in the longitudinal direction of the bridge 60 if the object is the bridge 60 . In the latter case, the 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 specified.

Next, the regression coefficient calculator 22 compares the reference signal and the in-plane displacement for each point (i, j) along the time series, that is, for each frame of the time-series image, as shown in FIG. 5(b). Then, as shown in FIG. 5(c), the regression coefficient calculation unit 22 obtains a regression line indicating 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. Further, the calculation of the regression line and the calculation of the regression coefficient are performed in each of the x direction and the y direction. Actually, the regression coefficient in the x direction and the regression coefficient in the y direction are calculated.

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

In this embodiment, the data decryption device 30 is constructed by a program on the operating system of a terminal device such as a PC (Personal Computer), a smart phone, 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 coefficient calculated for each point (i, j) output from the data output unit 23 of the data encoding device 20 .

In the present embodiment, the data decoding unit 32 multiplies the level of the reference signal specified by the reference signal information by the regression coefficient along the time series for each point (i, j), thereby restoring the in-plane displacement in the measurement target area of the bridge 60. The data decoding unit 32 also generates image data for displaying the restored in-plane displacement, outputs the generated image data to the display device 33, and displays the in-plane displacement on its screen.

[Device operation]
Next, operations of the data communication system 10 according to the embodiment of the present invention will be described with reference to FIGS. 6 and 7. FIG. Hereinafter, operations of the data encoding device 20 and the data decoding device 30 will be described with reference to FIGS. 1 to 5 as appropriate. Further, in Embodiment 1, the 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. FIG. Therefore, the description of the data communication method in this embodiment is replaced with the description of the operations of data encoding device 20 and data decoding device 30 below.

First, the operation of the data encoding device 20 will be described with reference to FIG. FIG. 6 is a flow chart showing the operation of the data encoding device according to the embodiment of the present invention.

As shown in FIG. 6, first, when image data of time-series images 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 for each frame (step A1).

Next, when the image data of the time-series images is output in step A1, the entire surface displacement measuring unit 25 measures the entire surface displacement of the measurement target area of the bridge 60, which is the object, for each frame (step A2). Further, the entire surface displacement measuring unit 25 stores the measurement result in the storage unit 27 as the entire surface displacement information.

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

Next, the reference signal generation 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). Further, the reference signal generation unit 21 stores the generated reference signal in the storage 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 linkage 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) of the measurement target region 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 to the data decoding device 30 via the network 40 as data indicating in-plane displacement (step A6). By executing step A6, the processing in the data encoding device 20 ends.

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

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

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

After that, the data decoding unit 32 generates image data for displaying the restored in-plane displacement, outputs the generated image data to the display device 33, and displays the in-plane displacement on its screen (step B3). By executing step B3, the processing in the data decoding device 30 ends.

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

Further, in the present embodiment, the regression coefficient for each point (i, j) transmitted as data indicating in-plane displacement can be compressed using an image compression method (JPEC-XR, etc.) compatible with floating-point pixel representation. In this case, the data representing the in-plane displacement can be further compressed.

In addition, the reference signal, which is transmitted as data indicating in-plane displacement, can be compressed using a floating-point audio compression method (MPEG4-ALS, etc.). In this case also, the data representing 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 Modification 1, it is a condition 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. In the above-described embodiment, the object is the bridge 60, and the external force is applied in the normal direction, so the above conditions are satisfied.

In Modification 1, the reference signal generator 21 calculates the time-series change D(t) of the entire surface displacement in the external force application direction, and generates a signal indicating the calculated time-series change of the entire surface displacement as the reference signal. Specifically, the signal generation unit 13 identifies the time-series change in the movement amount (Δz) in the normal direction measured by the entire surface displacement measurement unit 25 from the entire surface displacement information, and uses the time-series change D(t) of the identified movement amount (Δz) as a reference signal.

According to Modification 1, unlike the above-described embodiment, it is not necessary to specify a point of interest and furthermore, to specify a specific direction, so the burden on the inspector of the bridge 60 is reduced. Note that Modification 1 is useful when the imaging device 50 is sufficiently fixed in a location that is not easily affected by external force, and stress fluctuation due to the external force and overall surface displacement in the direction in which the external force is applied are interlocked.

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

Specifically, the reference signal generation unit 21 first determines a plurality of points (for example, four points) surrounding the coordinates (i, j) in order to obtain the local strain ε(t, i, j) from the local deformation state at the coordinates (i, j) of the measurement target region for each frame of the image data. A region surrounded by each point here is also referred to as a “local region”.

Next, the reference signal generation unit 21 acquires in-plane displacement information at each of the determined points from the storage unit 17, and performs singular value decomposition using the acquired in-plane displacement information of each point, thereby identifying the direction of the largest change in the local region. Then, the reference signal generation unit 21 obtains the change rate of the length of the local region in the specified direction, and sets the obtained change rate as the local strain s(t, i, j).

Subsequently, the reference signal generation unit 21 integrates the local strain s(t, i, j) over the entire measurement target region, calculates the strain amount S(t) over the entire measurement target region, and uses the calculated strain amount S(t) as a reference signal. In Modification 2, the reference signal is obtained from the local strain. Therefore, Modification 2 is useful when the fixing of the imaging device 50 is insufficient, or when the interlocking between the stress fluctuation due to the external force and the displacement of the entire surface in the direction in which the external force is applied is low.

[Modification 3]
In Modification 3, similarly to Modification 2, the reference signal generation 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, in Modification 3, unlike Modification 2, the reference signal generation unit 21 uses the acquired in-plane displacement information of each point to obtain the singular values σ ₁ and σ ₂ (σ ₁ ≥ σ ₂ ) and the singular vector v ₁ indicating the local deformation in the local region. Note that the singular vector _v1 here is the left singular vector corresponding to the singular value σ1, but in the present modified example 3, it may be determined to select another singular vector.

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

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

[Modification 4]
In Modification 4, similarly to Modification 2, the reference signal generator 21 first calculates local strain s(t, i, j) for each coordinate (i, j). Further, the reference signal generator 21 also calculates the time-series change D(t) of the entire surface displacement in the external force application direction, as in the first modification. Subsequently, the reference signal generator 21 calculates a 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).

Subsequently, the reference signal generation unit 21 calculates the local aperture vector v _op (t, i, j) representing the local aperture direction and size in the local region using Equation 1 as in the third modification.

Next, the reference signal generation unit 21 multiplies each local aperture vector v _op (t, i, j), which is the first principal component, by the regression coefficient w(i, j) as a weight. Furthermore, the reference signal generator 21 performs the same principal component analysis as in Modification 3 on the weight-multiplied local aperture vector v _op (t, i, j) at time t. Let S(t) be the standard deviation of the first principal component axis obtained by the principal component analysis, and use this as a reference signal. In Modified Example 4, by reducing the degree of contribution of the local aperture vector to the principal component analysis at points where the degree of interlocking with the external force is low, 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 any program that causes a computer to execute steps A1 to A6 shown in FIG. By installing this program in a computer and executing it, the data encoding device 20 in this embodiment can be realized. In this case, the processor of the computer functions as a reference signal generation unit 21, a regression coefficient calculation unit 22, a data output unit 23, an image data acquisition unit 24, an entire plane displacement measurement unit 25, and an in-plane displacement measurement unit 26, and performs processing.

Also, the first program in the present embodiment may be executed by a computer system constructed by a plurality of computers. In this case, for example, each computer may function as one of the reference signal generation unit 21, the regression coefficient calculation unit 22, the data output unit 23, the image data acquisition unit 24, the entire surface displacement measurement unit 25, and the in-plane displacement measurement unit 26.

The second program in this embodiment may be any program that causes a computer to execute steps B1 to B3 shown in FIG. 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 processor of the computer functions as a data acquisition section 31 and a data decoding section 32 to perform processing.

Also, the second program in this embodiment may be executed by a computer system constructed by a plurality of computers. In this case, for example, each computer may function as either the data acquisition section 31 or the data decoding section 32 .

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

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

The CPU 111 expands the programs (codes) of the present embodiment stored in the storage device 113 into the main memory 112 and executes them 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). Also, the program in the present embodiment is provided in a state stored in computer-readable recording medium 120 . It should be noted that the program in this embodiment may be distributed on the Internet connected via communication interface 117 .

Further, as a specific example of the storage device 113, in addition to a hard disk drive, a semiconductor storage device such as a flash memory can be cited. Input interface 114 mediates data transmission between CPU 111 and input devices 118 such as a keyboard and mouse. The display controller 115 is connected to the display device 119 and controls display on the display device 119 .

Data reader/writer 116 mediates data transmission between CPU 111 and recording medium 120 , reads programs from recording medium 120 , and writes processing results in computer 110 to recording medium 120 . Communication interface 117 mediates data transmission between 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, or optical recording media such as CD-ROMs (Compact Disk Read Only Memory).

Note that the data encoding device 20 and the data decoding device 30 in the present embodiment can also be realized by using hardware corresponding to each part instead of a computer in which a program is installed. Furthermore, the data encoding device 20 and the data decoding device 30 may be partly realized by a program and the rest by hardware.

Some or all of the above-described embodiments can be expressed by (Appendix 1) to (Appendix 21) described below, but are not limited to the following descriptions.

(Appendix 1)
a reference signal generation unit that generates a reference signal whose level changes according to the stress generated on the specific surface of the object from the entire surface displacement on the specific surface of the object measured from the time-series images of the object and the in-plane displacement on the specific surface of the object measured from the whole surface displacement and the time-series images;
a regression coefficient calculation unit that calculates a regression coefficient that indicates the degree of interlocking between the time-series change in the level of the reference signal and the 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)
The data encoding device according to Supplementary Note 1,
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;
further comprising
A data encoding device characterized by:

(Appendix 3)
The data encoding device according to appendix 1 or 2,
When the in-plane displacement is measured for each point on the specific surface of the object,
wherein the regression coefficient calculation unit calculates the regression coefficient for each point using the reference signal and the in-plane displacement at the point;
The data output unit outputs the reference signal and the regression coefficient at each point,
A data encoding device characterized by:

(Appendix 4)
The data encoding device according to any one of Appendices 1 to 3,
The reference signal generation unit calculates a time series change in strain in the specific direction of the point of interest from the in-plane displacement in the specific direction of the point of interest on the specific surface, and generates a signal indicating the calculated time series change in strain as the reference signal.
A data encoding device characterized by:

(Appendix 5)
The data encoding device according to any one of Appendices 1 to 3,
When the whole-plane displacement is measured 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,
The reference signal generation unit calculates a time-series change of the entire surface displacement in the application direction, and generates a signal indicating the calculated time-series change of the entire surface displacement as the reference signal.
A data encoding device characterized by:

(Appendix 6)
The data encoding device according to any one of Appendices 1 to 3,
The reference signal generation unit uses the in-plane displacement to calculate a local strain on a specific surface of the object, further integrates the local strain over the entire specific surface, calculates a time-series change in strain on the entire specific surface of the object, and generates a signal indicating the calculated time-series change in the strain as the reference signal.
A data encoding device characterized by:

(Appendix 7)
a data acquisition unit that acquires a reference signal whose level changes according to the stress generated on a specific surface of an object, and a regression coefficient that indicates the degree of linkage between the time-series change in the level of the reference signal and the time-series change in the in-plane displacement on the specific surface of the object;
a data decoding unit that restores an in-plane displacement on a specific surface of the object using the acquired reference signal and the regression coefficient;
is equipped with
A data decoding device characterized by:

(Appendix 8)
comprising a data encoding device and a data decoding device,
The data encoding device is
a reference signal generation unit that generates a reference signal whose level changes according to the stress generated on the specific surface of the object from the entire surface displacement on the specific surface of the object measured from the time-series images of the object and the in-plane displacement on the specific surface of the object measured from the whole surface displacement and the time-series images;
a regression coefficient calculation unit that calculates a regression coefficient that indicates the degree of interlocking between the time-series change in the level of the reference signal and the 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
a data acquisition unit that acquires a reference signal whose level changes according to the stress generated on a specific surface of an object, and a regression coefficient that indicates the degree of linkage between the time-series change in the level of the reference signal and the time-series change in the in-plane displacement on the specific surface of the object;
a data decoding unit that restores an in-plane displacement on a specific surface of the object using the acquired reference signal and the regression coefficient;
A data communication system characterized by:

(Appendix 9)
A data communication method using a data encoding device and a data decoding device,
(a) generating a reference signal, the level of which changes according to the stress generated on the specific surface of the object, from the entire surface displacement of the specific surface of the object measured from the time series images of the object and the in-plane displacement of the specific surface of the object measured from the whole surface displacement and the time series images by the data encoding device;
(b) using the reference signal and the in-plane displacement by the data encoding device to calculate a regression coefficient that indicates the degree of linkage between the time-series change in the level of the reference signal and the time-series change in the in-plane displacement;
(c) outputting the reference signal and the regression coefficient as data indicative of the in-plane displacement by the data encoding device;
(d) obtaining, by the data decoding device, a reference signal whose level changes according to the stress generated on the specific surface of the object, and a regression coefficient that indicates the degree of linkage between the time-series change in the level of the reference signal and the time-series change in the in-plane displacement on the specific surface of the object;
(e) reconstructing an in-plane displacement on a specific surface of the object using the reference signal and the regression coefficients obtained by the data decoding device;
A data communication method characterized by comprising:

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

(Appendix 11)
The data communication method according to appendix 9 or 10,
When the in-plane displacement is measured for each point on the specific surface of the object,
In step (b), calculating the regression coefficient for each point using the reference signal and the in-plane displacement at the point;
In step (c), for each point, outputting the reference signal and the regression coefficient at the point;
A data communication method characterized by:

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

(Appendix 13)
The data communication method according to any one of Appendices 9 to 11,
When the whole-plane displacement is measured 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,
In step (a), calculating a time-series change in the entire surface displacement in the application direction, and generating a signal indicating the calculated time-series change in the entire surface displacement as the reference signal;
A data communication method characterized by:

(Appendix 14)
The data communication method according to any one of Appendices 9 to 11,
In the step (a), using the in-plane displacement, local strain on a specific surface of the object is calculated, and the local strain is 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 the strain is generated as the reference signal.
A data communication method characterized by:

(Appendix 15)
to the computer,
(a) generating a reference signal whose level changes according to the stress generated on the specific surface of the object from the entire surface displacement on the specific surface of the object measured from the time-series images of the object and the in-plane displacement on the specific surface of the object measured from the whole surface displacement and the time-series images;
(b) using the reference signal and the in-plane displacement to calculate a regression coefficient that indicates the degree of linkage between the time-series change in the level of the reference signal and the time-series change in the in-plane displacement;
(c) outputting the reference signal and the regression coefficient as data indicative of the in-plane displacement;
The program that causes the to run.

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

(Appendix 17)
The program according to Appendix 15 or 16,
When the in-plane displacement is measured for each point on the specific surface of the object,
In step (b), calculating the regression coefficient for each point using the reference signal and the in-plane displacement at the point;
In step (c), for each point, outputting the reference signal and the regression coefficient at the point;
A program characterized by

(Appendix 18)
The program according to any one of Appendices 15 to 17,
In the step (a), from the in-plane displacement of the point of interest on the specific surface, a time-series change in strain in the specific direction is calculated, and a signal indicating the calculated time-series change in the strain 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 whole-plane displacement is measured 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,
In step (a), calculating a time-series change in the entire surface displacement in the application direction, and generating a signal indicating the calculated time-series change in the entire surface displacement 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), using the in-plane displacement, local strain on a specific surface of the object is calculated, and the local strain is 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 the strain is generated as the reference signal.
A program characterized by

(Appendix 21)
to the computer,
(a) acquiring a reference signal whose level changes according to the stress generated on a specific surface of an object, and a regression coefficient indicating the degree of linkage between the time-series change in the level of the reference signal and the time-series change in the in-plane displacement on the specific surface of the object;
(b) reconstructing an in-plane displacement at a particular surface of the object using the obtained reference signal and the regression coefficients;
The program that causes the to run.

Although the present invention has been described with reference to the embodiments, the present invention is not limited to the above embodiments. Various changes that can be understood by those 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, it is possible to reduce transmission and storage costs while maintaining sufficient spatial resolution in encoding or decoding data representing in-plane displacement extracted from an image. INDUSTRIAL APPLICABILITY The present invention is useful for systems that determine the state 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 entire plane 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,
means for measuring the entire surface displacement of a specific surface of the object in the direction of application of the external force applied to the object, based on time-series images of the object;
means for calculating an in-plane displacement on a specific surface of the object based on the time-series images of the object and the entire surface displacement in the application direction of the external force applied to the object;
Means for calculating a time-series change of the entire surface displacement in the application direction of the external force applied to the object, based on the entire surface displacement in the application direction;
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 based on the time-series change in the entire surface displacement in the application direction and the in-plane displacement;
A data encoding program operated as means for outputting a value based on the time-series change of the entire surface displacement in the application direction and the correlation. the computer, further
As a means for calculating a reference signal whose level changes according to the stress generated on the specific surface of the object based on the time series change of the entire surface displacement in the application direction,
2. A data encoding program as claimed in claim 1, to run. The means for calculating the 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 the 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.
2. A data encoding program according to claim 1. The means for outputting a value based on the time-series variation of the entire surface displacement in the application direction and the correlation outputs the value based on the time-series variation 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 a specific surface of the object.
2. A data encoding program according to claim 1. wherein said correlation-based values are regression coefficients;
2. A data decoding program according to claim 1. means for measuring the entire surface displacement of a specific surface of the object in the direction of application of the external force applied to the object, based on time-series images of the object;
means for calculating an in-plane displacement on a specific surface of the object based on the time-series images of the object and the entire surface displacement in the application direction of the external force applied to the object;
Means for calculating a time-series change of the entire surface displacement in the application direction of the external force applied to the object, based on the entire surface displacement in the application direction;
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 based on the time-series change in the entire surface displacement in the application direction and the in-plane displacement;
means for outputting a value based on the time series change of the entire surface displacement in the application direction and the correlation;
A data encoding device comprising: Means for calculating a reference signal whose level changes according to the stress generated on the specific surface of the object based on the time series change of the entire surface displacement in the application direction,
7. The data encoding apparatus of Claim 6, further comprising: The means for calculating the 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 the 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.
7. A data encoding device according to claim 6. The means for outputting a value based on the time-series variation of the entire surface displacement in the application direction and the correlation outputs the value based on the time-series variation 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 a specific surface of the object.
7. A data encoding device according to claim 6. wherein said correlation-based values are regression coefficients;
7. A data encoding device according to claim 6.

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