JP2008216158A - Displacement measuring device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a displacement measuring device capable of accurately calculating displacement of a measuring point. <P>SOLUTION: This displacement measuring device 1 calculates a displacement quantity of an optional measuring point 3a from an image before and after displacement of a plurality of measuring objects 10 photographed by an imaging element, and has an image processing part 13 processing the image photographed by the imaging element. The image processing part 13 has a reference point selecting means 24 for selecting optional one measuring point as a reference point 12 from a plurality of measuring points 3a of the image, and a displacement quantity calculating means 25 for calculating the displacement quantity of the respective measuring points 3a based on the reference point 12. The reference point selecting means 24 selects the reference point 12 from a variation in a coordinate value of the measuring point 3a of the image photographed first and a coordinate value of the optional measuring point 3a of the image photographed later, and sets such a measuring point 3a as the reference point 12 when determining that the variation in the coordinate value of the optional measuring point 3a is smaller than a predetermined quantity. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a displacement measuring device.

  In Patent Document 1, in a displacement measuring apparatus that measures the displacement of a measurement object, a photographic image is taken so as to include a plurality of fixed points that are not displaced before and after the displacement, and the displacement of the measurement object is determined using the fixed points as reference points. The required technology is disclosed.

JP 2004-77377 A

  However, in the prior art described in Patent Document 1, it is necessary to install a fixed reference point on the measurement object. Therefore, when the measurement object itself is displaced, it is difficult to install the reference point. There was a problem that the displacement of the measurement point could not be calculated accurately.

  An object of this invention is to obtain the displacement measuring apparatus which can calculate the displacement of a measurement point accurately.

  In order to solve the above-mentioned problem, the invention described in claim 1 is a displacement measurement device that calculates a displacement amount at an arbitrary measurement point from images before and after displacement of a plurality of measurement objects photographed on an image sensor. The image processing unit includes an image processing unit that processes an image photographed on the element, and the image processing unit selects a reference point from a plurality of measurement points of the image as a reference point, and performs each measurement based on the reference point. A displacement amount calculating means for calculating a displacement amount of the point, and the reference point selecting means obtains the reference point from the change amount of the coordinate value of the measurement point of the previously captured image and the coordinate value of the measurement point of the image captured later. When it is determined that the amount of change in the coordinate value of an arbitrary measurement point is smaller than a predetermined amount, the measurement point is used as a reference point.

  According to a second aspect of the present invention, in the first aspect of the present invention, the photographing unit is installed at two or more points having different photographing directions with respect to the measurement object, and is photographed by one photographing unit. A three-dimensional image is obtained by synthesizing an image and an image photographed by the other photographing unit.

  The invention described in claim 3 is characterized in that, in the invention described in claim 1 or 2, the target to be measured is provided with a target set in advance, and the target is used as a measurement point.

  The invention described in claim 4 is characterized in that, in the invention described in any one of claims 1 to 3, the target includes a reflecting portion.

  The invention described in claim 5 is characterized in that, in the invention described in claim 4, the reflecting part changes the area according to the distance between the imaging part and the target.

  According to a sixth aspect of the invention, in the first aspect of the invention, the image processing unit includes a centroid position calculating unit that calculates a centroid position of the reflecting unit, and the image processing unit obtains the centroid obtained by the centroid position calculating unit. It is characterized by specifying the coordinates of the measurement point from the position.

  The invention described in claim 7 is the invention according to claim 6, wherein the image processing unit includes a sub-pixel calculating unit that calculates the coordinates of the measurement point in units of sub-pixels of one pixel or less of the image sensor. And

  According to the first aspect of the present invention, when the reference point selection unit determines that the change amount of the coordinate value before and after the change of the arbitrary measurement point is smaller than the predetermined amount, the measurement point is the reference point, and the reference Since the displacement amount of each measurement point is calculated based on the point, it is not necessary to install a fixed reference point. Therefore, even if the measurement object is difficult to set a fixed reference point, the displacement amount of the measurement point can be easily calculated.

  Since the displacement of the measurement point is calculated by processing the image captured by the imaging unit, a measuring instrument such as a staff is not required, and the measurement time at the site can be shortened.

  According to the invention described in claim 2, the same effect as that of the invention described in claim 1 can be obtained, and a three-dimensional image can be obtained by synthesizing images obtained by shooting the measurement object from two or more points having different shooting directions. Therefore, the displacement in three dimensions of the measurement point can be easily calculated.

  According to the invention described in claim 3, the same effect as that of the invention described in claim 1 or 2 can be obtained, and the measurement point can be easily displayed on the image because the target provided on the measurement object is used as the measurement point. Thus, the displacement amount of the measurement point can be calculated with high accuracy.

  According to the invention described in claim 4, the same effect as in the invention described in any one of claims 1 to 3 can be obtained, and the target includes the reflecting portion. Indicates a higher luminance value than other regions, so that the position of the measurement point can be specified with high accuracy.

  According to the invention described in claim 5, the same effect as that of the invention described in claim 4 is achieved, and the area of the reflection part is changed according to the distance between the imaging part and the measurement point. When the distance between the imaging unit and the measurement point is long, by increasing the area of the reflection plate, the number of pixels of the reflection unit displayed on the display unit increases, and the coordinates of the measurement point can be measured with high accuracy.

  According to the invention described in claim 6, the same effect as that of the invention described in claim 1 is obtained, and the center of gravity position of the reflecting part is calculated by the center of gravity position calculating part to specify the coordinates of the measurement point. Therefore, the displacement amount of the measurement point can be calculated with high accuracy.

  According to the invention described in claim 7, since the same effect as that of the invention described in claim 6 is obtained and the coordinates of the measurement point are calculated in units of subpixels by the subpixel calculation unit, the coordinates of the measurement point are calculated. Further, it can be calculated with high accuracy, and the displacement amount of the measurement point can be calculated with higher accuracy.

  Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a control block diagram showing the entire displacement measuring apparatus according to an embodiment of the present invention, FIG. 2 is a perspective view showing a situation where a measurement object is photographed, and FIG. 3 is a photograph of the measurement object shown in FIG. FIG. 4 is a diagram for explaining the superposition of the first captured image and the second captured image, and FIG. 4A is extracted and shown by a two-dot chain line. The figure explaining the position of the reference point before and after the displacement, (b) is the figure explaining the position of the measurement point before and after the displacement, FIG. 5 is an enlarged front view of the target shown in FIG. 2, FIG. 6 is the outside of the digital camera 7 is a schematic diagram for explaining the orientation method, FIG. 7 is a diagram for explaining a method for calculating three-dimensional coordinates from a plurality of captured images, FIG. 8 is a diagram for explaining a method for calculating the center-of-gravity point coordinates of the reflective seal, and FIG. It is a figure explaining the image recognition of a target object, (a) is the image by a normal pixel. FIG. 10B is a diagram illustrating image recognition by subpixels, FIG. 10 is a diagram illustrating selection of a reference point using an error ellipse, and FIG. 11 is a diagram illustrating measurement by the displacement measuring apparatus according to the present invention. FIG. 12 is a flow chart for explaining the flow, FIG. 12 is a graph showing the measurement result of the displacement measuring apparatus according to the present invention, showing the correlation between the measured value of the movement amount in the depth direction, and FIG. 13 is the displacement measurement according to the present invention. It is a graph which shows the measurement result of an apparatus, and shows the correlation with the measured value and measured value of the movement amount of a horizontal / vertical direction.

  A displacement measuring apparatus 1 according to the present embodiment measures a displacement of a measuring object 10 such as a retaining wall, and as shown in FIG. 1, a digital camera (imaging unit) that photographs the measuring object 10 on an image sensor. ) 7 and a computer 9 that has been photographed by the digital camera 7 and that processes the image. As shown in FIG. 2, the measurement object 10 is imaged a plurality of times using a digital camera (imaging unit) 7, the three-dimensional coordinates of the measurement points provided at the same point before and after the displacement are calculated, and the coordinate value is moved. The amount of displacement is calculated from the amount.

  A plurality of targets 3 are installed on the measurement object 10, and as shown in FIG. 5, a reflective seal (reflecting part) 3b is attached to a black target substrate 3c (210 mm long × 210 mm wide). The reflective seal 3b has a circular shape, and the center of the circle is a measurement point 3a for measuring the displacement.

  The area of the reflective sticker 3b is changed according to the distance between the digital camera 7 and the target 3 so that the diameter of the image taken by the digital camera 7 is 5 pixels or more. Table 1 below shows the criteria for the diameter D of the reflective seal 3b to be 5 pixels or more.

  The digital camera 7 can be connected to the computer 9 through a USB cable or the like, and image data captured by the digital camera 7 is taken into the computer 9 and stored in the storage unit 17.

  The computer 9 is processed by the image processing unit 13 that analyzes the image captured by the digital camera 7, the display unit 15 that displays the captured image on the screen, and the image captured by the digital camera 7 and the image processing unit 13. And a storage unit 17 for storing each data.

  The image processing unit 13 combines an image combining unit 21 that combines the images before and after the displacement photographed by the digital camera 7, and calculates a three-dimensional coordinate of the measurement point 3a by combining a plurality of images photographed by the digital camera 7. A dimensional coordinate calculation unit 23, a reference point selection unit (reference point selection means) 24 for selecting any one measurement point 3a as a reference point 4 from a plurality of measurement points 3a in the image, and a displacement amount of the measurement point 3a is calculated. A displacement amount calculating unit 25, a center-of-gravity position calculating unit 27 for calculating the center of gravity position of the reflective sticker 3b, and a sub-pixel calculating unit 29 for calculating the coordinates of the measurement point 3a in sub-pixel units of one pixel or less.

  The image composition unit 19 superimposes the first captured image captured by the digital camera 7 and the second captured image captured by the same digital camera 7 by affine transformation. By superimposing the first captured image and the second captured image by affine transformation, based on the reference point 4 shown in FIG. 4A, the measurement points 3a before and after displacement shown in FIG. 4B are extracted. The coordinate value of is calculated.

The shooting positions (O ₁ , O ₂ ) of the digital camera 7 are calculated with reference points provided at positions other than the measurement object 10 as a reference, as shown in FIG. The shooting direction of the digital camera 7 (tilt with respect to the three axes (X, Y, Z) of the digital camera 7) is set by arbitrarily setting a reference line of three axes (X, Y, Z) and using an angle measuring instrument. Calculated. The shooting position of the digital camera 7 may be calculated using GPS.

As shown in FIG. 3, the three-dimensional coordinate calculation unit 23 captures the first image 31 obtained by photographing the measurement object 10 from the left side, the second image 33 obtained by photographing the measurement object 10 from the right side, and the digital camera 7. The three-dimensional coordinates P (X, Y, Z) of the measurement point 3a are calculated from the position (lens center position (O ₁ , O ₂ )) and information on the shooting direction.

That is, as shown in FIG. 7, the first image 31 obtained by photographing the measurement object 10 from the left side shows the two-dimensional coordinate value p ₁ (x ₁ , y ₁ ) of the measurement point 3a, and the measurement object 10 is taken from the right side. The photographed second image 33 shows the two-dimensional coordinate value p ₂ (x ₂ , y ₂ ) of the measurement point 3a. Then, the two-dimensional coordinate value p ₁ (x ₁ , y ₁ ) of the first image 31, the two-dimensional coordinate value p ₂ (x ₂ , y ₂ ) of the second image 33, the digital of the first image 31 taken from the left side. The measurement point 3a 3 is measured using a free network adjustment method from the lens center position O ₁ and the shooting direction of the camera 7 and the lens center position O ₂ and the shooting direction of the digital camera 7 of the second image 33 taken from the right side. Dimensional coordinates P (X, Y, Z) are calculated.

In the free network adjustment method, when the measurement point j appears in the two-dimensional image i, the three-dimensional coordinate P of the measurement point j is obtained by solving the conditional expression of the following equation (1). In the following formula (1), (x ₀ , y _0, z ₀ ) are parameters indicating camera coordinate values, and (ω, φ, κ) are parameters indicating angles at the time of photographing. Δx _i and Δy _i represent systematic errors, which are factors that hinder the center projection condition, and are composed of a coefficient representing lens aberration and a correction value representing deviation of the principal point position.

・・・（１）
上記式（１）は非線形であるため、各未知数をテーラー展開することで方程式を線形化する。線形化した方程式を下記式（２）に示す。

... (1)
Since the above equation (1) is non-linear, the equation is linearized by Taylor expansion of each unknown. The linearized equation is shown in the following formula (2).

・・・（２）

... (2)

As shown in FIG. 4, the displacement amount calculation unit 25 displays the three-dimensional coordinates P ₁ (X ₁₎ of the measurement point 3a before displacement, which is displayed when the first captured image and the second captured image are superimposed. , Y ₁ , Z ₁ ) and the difference between the three-dimensional coordinates P ₂ (X ₂ , Y ₂ , Z ₂ ) of the measurement point 3a after displacement are calculated to calculate the displacement amount of the measurement point 3a.

The centroid position calculation unit 27 calculates the centroid position of the measurement point 3a. As shown in FIG. 8, in calculating the position of the center of gravity, first, the calculation area is designated by surrounding the reflective seal 3b with a frame 3d. Then, luminance values in the calculation area are generated as a histogram, and pixels having high luminance values are specified in the histogram. Thereafter, a threshold value is set using a well-known Otsu model equation, and a barycentric point is calculated by multiplying a pixel indicating a luminance value equal to or higher than the threshold value by a gray scale value. When the gray scale value of an arbitrary point (x, y) in the calculation area is W and the number of pixels is n, the center of gravity (x ₀ , y ₀ ) is x ₀ = Σ (x × W) / n , Y ₀ = Σ (y × W) / n, respectively.

  The subpixel calculation unit 29 calculates the coordinates of the measurement target in units of subpixels of 1 pixel or less. For example, when the measurement object S as shown in FIG. 9A is reflected in the image, the measurement object S is recognized by the four pixels T1, T2, T3, and T4 as a whole. That is, all the four pixels T1, T2, T3, and T4 in which the measurement target S exists are recognized as “1”.

  The sub-pixel calculating unit 29 can divide the pixel into a plurality of sub-pixels (divide into four), and the measurement target S is recognized by the four sub-pixels T13, T24, T31, and T42 as shown in FIG. 9B. . That is, the four subpixels T13, T24, T31, T42 are recognized as “1”, and the other subpixels (T11, T12, T14, T21, T22, T23, T32, T33, T34, T41, T43, T44). Is recognized as “0”.

In the reference point selection unit 24, the three-dimensional coordinates P ₁ (X ₁ , Y ₁ , Z ₁ ) of the measurement point 3a before the displacement and the three-dimensional coordinates P ₂ (X ₂ , Y ₂ , When the movement amount of Z ₂ ) is calculated and the movement amount is smaller than the predetermined amount, the measurement point is used as a reference point for calculating the displacement amount.

The reference point selection unit 24 determines whether or not to select a measurement point as a reference point by a statistical method using a displacement error ellipse as shown in FIG. That is, in FIG. 10, 40a, 41a, 42a, 43a, 44a indicate the coordinate positions of the measurement points before displacement, and 40b, 41b, 42b, 43b, 44b indicate the coordinate positions of the measurement points after displacement. Yes. Displacement error ellipsoids W _{1 to} W ₅ are generated at each measurement point. The displacement error ellipse indicates whether or not the measurement point 3a exists within a predetermined region with a predetermined probability. First, a reference point is detected, and when the measurement point with respect to the detected reference point is outside the area of the displacement error ellipse (40b in FIG. 10), the reference point selection unit 24 does not select the reference point. On the other hand, when the measurement point after displacement with respect to the reference point is within the area of the displacement error ellipse (41b, 42b, 43b, 44b in FIG. 10), the reference point is selected by the reference point selection unit 24. To do.

  Next, based on the above-described configuration, the operation of the present embodiment will be described based on the flowchart shown in FIG. At the site, first, the targets 3 are installed at a plurality of locations of the measurement object 10. Next, the digital camera 7 shoots images from two shooting positions that are separated from the measurement object 10 by a predetermined distance and have different shooting directions with respect to the measurement object 10. Each photographed image is stored in the storage unit 17 of the computer 9. In order to improve the calibration accuracy of the digital camera 7, a total of four images are photographed by shifting the camera direction by about 90 degrees in the circumferential direction of the lens at each photographing position (step S1).

  From the first image 31 taken from the left side stored in the storage unit 17 and the second image 33 taken from the right side, the three-dimensional coordinates of each measurement point 3a are obtained using the free network adjustment method ( Step S2). The coordinates of the measurement point 3a are obtained by the center of gravity position calculation unit 27 calculating the center of gravity of the reflective seal 3b of the target 3 using the image displayed on the display unit 15 of the computer 9. The first shooting is completed by the above steps.

  Next, the second shooting is performed. In the second shooting, the left and right images are shot in the same manner as described in the first step, and the shot images are stored in the storage unit 17. Then, the three-dimensional coordinates of each measurement point 3a are obtained from the left and right images using a free network adjustment method.

  In the next step S3, it is determined whether or not the photographed image is the first (epoch I). If not, the process proceeds to the next step S4, and the measurement accuracy of the second photographed image is photographed for the first time. It is determined whether or not the measurement accuracy is the same as the measured image. Whether or not the measurement accuracy is the same is determined, for example, by whether or not the calibration accuracy of the digital camera 7 is the same in the first shooting and the second shooting.

  In the next step S5, the first image and the second image are compared to determine whether or not the measurement object 10 has been displaced as a whole. Whether or not the measurement object 10 has been displaced as a whole is determined by whether or not the coordinates of all the measurement points are expressed in a vector format and whether there is a significant difference between the coordinate vector values in the two measurements. If it is determined that the measurement object 10 has an overall displacement, the process proceeds to the next step S6, and if it is determined that the measurement object 10 has no overall displacement, the process proceeds to step S11.

  In step S6, the center-of-gravity coordinates of all the measurement points obtained in Epoch 1 and the center-of-gravity coordinates of all the measurement points obtained in Epoch 2 are overlapped to determine whether the center-of-gravity coordinates have the same value (equal probability displacement). Judge whether or not. When the barycentric coordinates of all the measurement points are not the same value, the process proceeds to the next step S7. In step S7, it is determined whether or not the measurement point 3a is selected as the reference point in the reference point selection unit 24. When the measurement point 3a is used as the reference point, the process proceeds to the next step S8. The calculated coordinate value is converted into a relative reference point coordinate system based on the reference point. In step S9, a displacement difference is calculated from the three-dimensional coordinate value of each measurement point obtained in epoch 1 and the three-dimensional coordinate value of each measurement point obtained in epoch 2, and whether or not each measurement point has moved in step S10. In step S11, the calculation result is output. If the measurement is continued in the next step S12, the process returns to step S1. If the measurement is not continued, the step ends.

  In the present embodiment, when the reference point selection unit 24 determines that the movement amount of the coordinate value of an arbitrary measurement point 3a is smaller than a predetermined amount, the measurement point 3a is used as a reference point, and each measurement point 3a is set based on the reference point. Since the displacement amount of the measurement point is calculated, the displacement amount of the measurement point 3a can be easily calculated even for the measurement object 10 in which it is difficult to set a fixed reference point.

  Since the displacement amount of the measurement point 3a is calculated by processing the image photographed by the digital camera 7, a measuring instrument such as a staff is not required, and the on-site measurement time can be shortened.

  Since a three-dimensional image is obtained by combining images obtained by photographing the measurement object 10 at two points different from the photographing direction, it is possible to easily calculate the three-dimensional displacement amount of the measurement point 3a.

  Since the target 3 provided on the measurement object 10 is the measurement point 3a, the measurement point 3a can be easily grasped on the image, and the displacement amount of the measurement point 3a can be calculated with high accuracy.

  Since the target 3 includes the reflective sticker 3b, in the image displayed on the display unit 15 of the computer 9, the area of the reflective sticker 3b shows a higher luminance value than the other areas, so that the position of the measurement point 3a Can be specified with high accuracy.

  Since the area of the reflective sticker 3b is changed according to the distance between the position of the digital camera 7 and the measurement point 3a, for example, when the distance between the position of the digital camera 7 and the measurement point 3a is long, the area of the reflective sticker 3b is changed. By enlarging, the number of pixels of the reflective sticker 3b displayed on the display unit 15 increases, and the coordinates of the measurement point 3a can be measured with high accuracy.

  Since the barycentric position calculation unit 27 calculates the barycentric position of the reflective seal 3b and specifies the coordinates of the measuring point 3a, the displacement amount of the measuring point 3a can be calculated with high accuracy.

  Since the subpixel calculation unit 29 calculates the coordinates of the measurement point 3a in subpixel units, the coordinates of the measurement point 3a can be calculated with higher accuracy, and the displacement amount of the measurement point 3a can be calculated with higher accuracy.

  Next, since the experiment was conducted on the accuracy of the displacement amount of the displacement measuring apparatus according to the present embodiment, the result will be described.

(Experimental example)
In this experimental example, the target 2 placed on the measurement object 10 was actually moved, and an experiment was conducted on the correlation between the actual measurement value and the displacement measurement value calculated by the displacement measurement device 1 of the present invention. The results are shown in the table of FIG. FIG. 14 is a table showing measured values of the movement amount and measured values obtained by the displacement measuring device. FIG. 12 is a graph showing the correlation between the measured value of the movement amount in the depth (Z) direction based on the table of FIG. 14, and FIG. 13 is the actual measurement of the movement amount in the horizontal and vertical directions based on the table of FIG. It is a graph which shows the correlation of a value and a measured value.

  As shown in FIG. 12, the measured values of the movement amount in the depth (Z) direction (□, ○, ×, ◇, Δ, ●, and ■ shown in FIG. A high correlation was found between the measured value and the measured value of the displacement calculated by the displacement measuring device 1 of the present invention.

  As shown in FIG. 13, the measured values of the movement amount in the horizontal and vertical (XY) directions (□, ○, ×, ◇, Δ, ●, and ■ shown in FIG. 13) are measured values ( A high correlation was found between the measured value and the measured value of the displacement calculated by the displacement measuring device 1 of the present invention.

  The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the invention. For example, in the present embodiment, the measurement object 10 is photographed from two directions, but the measurement object 10 may be photographed from three or more directions.

  In the present embodiment, the measurement point 3a is provided in the target 3. However, the present invention is not limited to this, and the feature point of the measurement object 10 may be used as the measurement point without providing the target.

  Further, the target 3 is not limited to being provided with the reflective seal 3b, but may be one in which the density of the portion is clear in relation to the surroundings. The measurement point may be a characteristic part such as a protrusion.

  The measurement object 10 may be a dam, a bridge, a tunnel, a viaduct, or may measure a landslide by observing a slope of a mountain.

  The photographing unit 7 is not limited to a digital camera but may be a single lens reflex camera.

It is a control block diagram which shows the whole displacement measuring device which concerns on embodiment of this invention. It is a perspective view which shows the appearance which image | photographs the measurement object. It is a figure which shows each the image which image | photographed the measurement object shown in FIG. 2 by changing the position of an imaging | photography part. FIG. 4 is a diagram for explaining superposition of a first captured image and a second captured image, where (a) is a diagram illustrating the position of a reference point before and after displacement, and (b) is a displacement. It is a figure explaining the measurement point position before and behind. It is a front view which expands and shows the target shown in FIG. It is the schematic explaining the external orientation method of a digital camera. It is a figure explaining the method of calculating a three-dimensional coordinate from several picked-up images. It is a figure explaining the method of calculating the barycentric point coordinate of a reflective sticker. It is a figure explaining the image recognition of a measurement target object, (a) is a figure explaining the image recognition by a normal pixel, (b) is a figure explaining the image recognition by a sub pixel. It is a figure which shows selection of the reference point using an error ellipse. It is a flowchart explaining the flow of measurement of the displacement measuring device which concerns on this invention. It is a graph which shows the measurement result of the displacement measuring device which concerns on this invention, and shows the correlation with the measured value and measured value of the moving amount | distance in a depth (Z) direction. It is a graph which shows the measurement result of the displacement measuring device which concerns on this invention, and shows the correlation with the measured value and measured value of the moving amount | distance in a horizontal-vertical (XY) direction. It is the figure which showed the measured value of the displacement measuring device which concerns on this invention, and the measured value of movement amount in the table | surface.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Displacement measuring device 3 Target 3a Measurement point 3b Reflective sticker 7 Digital camera (imaging part)
DESCRIPTION OF SYMBOLS 10 Measurement object 12 Reference point 13 Image processing part 21 Image composition part 23 Three-dimensional coordinate calculation part 24 Reference point selection part 25 Displacement amount calculation part 27 Center of gravity position calculation part 29 Sub pixel calculation part

Claims (7)

  In a displacement measurement device that calculates the displacement amount of an arbitrary measurement point from images before and after displacement of a plurality of measurement objects photographed on an image sensor, the image processing unit includes an image processing unit that processes an image photographed on the image sensor. Reference point selection means comprising a reference point selection means for selecting any one measurement point as a reference point from a plurality of measurement points of the image, and a displacement amount calculation means for calculating the displacement amount of each measurement point based on the reference point The means selects the reference point from the coordinate value of the measurement point of the image taken first and the change amount of the coordinate value of the measurement point of the image taken later, and the change amount of the coordinate value of the arbitrary measurement point is a predetermined amount. A displacement measuring device characterized in that, when it is determined that it is smaller, the measurement point is set as a reference point.   The photographing unit is installed at two or more points with different photographing directions with respect to the measurement object, and a three-dimensional image is synthesized by combining an image photographed by one photographing unit and an image photographed by the other photographing unit. The displacement measuring apparatus according to claim 1, wherein:   The displacement measuring apparatus according to claim 1, wherein a target set in advance is provided on the measurement object, and the target is a measurement point.   The displacement measuring apparatus according to claim 1, wherein the target includes a reflecting portion.   The displacement measuring apparatus according to claim 4, wherein the reflection unit changes an area according to a distance between the imaging unit and the target.   The image processing unit includes a centroid position calculation unit that calculates a centroid position of the reflection unit, and the image processing unit specifies the coordinates of the measurement point from the centroid position obtained by the centroid position calculation unit. Displacement measuring device.   The displacement measurement apparatus according to claim 6, wherein the image processing unit includes a sub-pixel calculation unit that calculates the coordinates of the measurement point in units of sub-pixels of one pixel or less of the image sensor.

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