JP2008232972A - Image analysis system, image analysis method, and computer program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily correct tremor of an image of a measurement object due to the refractive index of the atmosphere. <P>SOLUTION: An imaging means 2 images a laser beam emitted from a laser beam irradiation device, together with a measurement object. The laser beam and the measurement object tremble together when the image trembles according to the refractive index of the atmosphere. In contrast, when vibration, a flow, or the like is generated, although the measurement object is vibrated, moved, or the like by an arbitrary distance in an arbitrary direction, the laser beam does not fluctuate due to vibration or the like of the measurement object. Thus, the differences (movement amount and movement direction) in the position of the laser beam among respective images are acquired, and are used as correction values to be added to the movement amount and the movement direction of the measurement object so that the effect of the refractive index of the atmosphere is easily removed. Accordingly, the accuracy in the analysis of the behavior of the remote measurement object at a long distance is improved. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention is a technique for analyzing various behaviors such as a vibration state and a moving direction of a measurement target by comparing time-series images captured at a predetermined imaging time interval, and is particularly separated by a long distance. The present invention relates to a long-distance image analysis system that images and analyzes a measurement target, and a computer program used in the image analysis system.

For example, as a technique for measuring vibrations of a transmission line tower or a transmission line in a non-contact manner, the present applicant adopts an imaging means including a long focal point optical system as Patent Document 1, and is tens to hundreds of meters, Alternatively, a vibration measurement technique based on image processing applying a particle image flow velocity measurement method (hereinafter referred to as “PIV”) capable of measuring vibration of a measurement object from a position several kilometers away is proposed. Similarly, Patent Document 2 discloses a system for observing smoke, water vapor, volcanic ash, yellow sand, and the like discharged from a chimney of a power generation facility from a distance using an imaging unit and a PIV analysis unit having a long focal point optical system. Has proposed.
PCT / JP2006 / 321369 Specification WO2005 / 095993A1 publication

  In Patent Document 1 and Patent Document 2, there is a difference between whether the object to be measured is a rigid body or a fluid, but in any case, the vibration and flow of the object to be measured using the PIV analysis based on the cross-correlation method and the image correlation method. This is common in the point of analyzing the behavior such as the direction of the lens, and also in that it can be applied to a measurement object separated by a long distance by adopting a long focal point optical system. Therefore, the longer the measurement distance, the greater the influence of the atmospheric refractive index due to changes in temperature, humidity, etc. during measurement, and the more the image shakes during imaging. For this reason, the position of the captured image may not match the position of the original image.

  The present invention has been made in view of the above, and in analyzing the behavior of a measurement object that is separated by a long distance using a long-focus optical system, image analysis that can easily correct the fluctuation of the measurement object image due to the atmospheric refractive index. It is an object of the present invention to provide a system and a computer program used for the image analysis system.

In order to solve the above problems, the image analysis system of the present invention images a measurement object at a predetermined imaging time interval by an imaging unit installed at a position away from the measurement object by a predetermined distance, and obtains a time series obtained A long-distance image analysis system including an image processing unit in which a PIV analysis unit that analyzes the behavior of the measurement object is obtained from the image of
A laser beam irradiation device for irradiating a laser beam at a certain position within an imaging field by the imaging unit;
The image processing means obtains a difference in position of the laser light between the images based on a time-series image of the measurement object and laser light imaged by the imaging means, and uses the difference as a correction value. A correction means for correcting the position of the measurement object in each image is set.

Further, the image analysis method of the present invention images a measurement object at a predetermined imaging time interval by an imaging unit installed at a position away from the measurement object by a predetermined distance, and from the obtained time-series images, PIV An image analysis method for obtaining velocity data between images related to a measurement object by an analysis means and analyzing the behavior of the measurement object,
Irradiating a laser beam at a certain position within an imaging field of view by the imaging means;
The imaging means also images the laser beam together with the measurement object,
Based on the time-series images of the measurement object and laser light imaged by the imaging means, a difference in position of the laser light between the images is obtained, and the difference is used as a correction value to determine the measurement object in each image. The position is corrected.

In addition, the computer program of the present invention images a measurement target at a predetermined imaging time interval by an imaging unit installed at a predetermined distance from the measurement target, and performs PIV analysis from the obtained time-series images. A computer program constituting image processing means in a long-distance type image analysis system for obtaining velocity data between images related to a measurement object by means and analyzing behavior of the measurement object,
The image processing means includes the position of the laser light between the images based on the time-series images of the measurement object picked up by the image pickup means together with the laser light irradiated to a certain position in the imaging field of view. A correction means is provided for calculating a difference and correcting the position of the measurement target in each image using the difference as a correction value.

  According to the present invention, the laser beam irradiated from the laser beam irradiation apparatus together with the measurement object is imaged by the imaging unit. The laser beam and the measurement object are shaken together when the image is shaken according to the atmospheric refractive index. On the other hand, when vibration, flow, etc. occur, the object to be measured vibrates or moves by an arbitrary distance in any direction, but the laser beam varies depending on the vibration of the object to be measured. do not do. Therefore, if the difference (movement amount and movement direction) of the position of the laser light between each image is obtained and taken as the correction value and taken into account the movement amount and movement direction of the measurement object, the influence of the atmospheric refractive index can be easily removed. This improves the accuracy in analyzing the behavior of a measurement object that is separated by a long distance.

  Hereinafter, embodiments of the present invention will be described in more detail with reference to the drawings. FIG. 1 shows an image analysis system 1 according to an embodiment of the present invention, which includes a CCD camera 2 having a long-focus optical system 3, a computer 4, a laser light irradiation device 5, etc. as imaging means. Is done.

  A long-focus optical system 3 is attached to the CCD camera 2, and it is preferable to use a single-focus lens (hereinafter referred to as “single lens”) as the long-focus optical system 3. In this case, it is more preferable to provide a turret so that a plurality of types of single lenses can be selected. By using the turret, a single lens can be automatically selected. In the case of a lens having a zoom function, it is generally disadvantageous that the curvature of field is large. However, any lens that can provide a stable image with a high refractive index glass can be used. In this embodiment, a camera (CCD camera) provided with a CCD image pickup device is used as the image pickup means, but a camera provided with a CMOS image pickup device may be used instead.

  As shown in FIGS. 1 and 2, the computer 4 is connected to the CCD camera 2 and receives a control means 41 for controlling the driving of the CCD camera 2 and an image signal photographed by the CCD camera 2 to receive a predetermined value. An image capturing means 42 and an image processing means 43 for performing processing are provided. The CCD camera 2 continuously captures images to be measured at minute time intervals. The control means 41 adjusts the focal length of the CCD camera 2 and the like. The image capturing means 42 includes a frame grabber board for digitizing the marker image signal from the CCD camera 2. The image processing means 43 comprises a computer program and analyzes the digital image signal output from the frame grabber board, details of which will be described later. Note that a circuit for correcting distortion aberration of an image or the like may be provided in the preceding stage of the image processing means 43.

  The laser beam irradiation device 5 is provided so as to be able to irradiate a laser beam at a certain position near the measurement target. For example, it is attached integrally to the upper part or the side part of the main body of the CCD camera 2, and when the image is taken by the CCD camera 2, the laser light irradiation device 5 is driven by the control means 41 and irradiated with laser light. Further, when the measurement object is imaged by the CCD camera 2, the orientation of the CCD camera 2, the irradiation direction of the laser light of the laser light irradiation device 5, or the like is included so that the irradiated laser light is included in the imaging field of view. It is adjusted by the control means 41. Thereby, when the measurement object is imaged, the laser beam is simultaneously imaged. In particular, as the laser beam irradiation device 5, it is advantageous for long-distance measurement to use a beam spot (pointer portion of a laser pointer) having a cross or circle shape instead of a dot.

  In the image processing means 43 set in the computer 4 described above, a PIV analysis means 431 and a correction means 432 are set as computer programs. The PIV analysis means performs comparative analysis of two-time images captured at a minute time interval by the CCD camera 2 using a PIV method such as a cross-correlation method, an image correlation method, or a spatiotemporal differentiation method.

  The correction unit 432 is a program for using the captured laser beam as a ground control point. That is, when the CCD camera 2 captures an image of the measurement target, if the position of the CCD camera 2 is constant, the atmospheric refractive index does not change, and the measurement target is stationary, the measurement target has a minute time interval. The position in each image to be picked up should be the same. However, even if the position of the CCD camera 2 is constant and the measurement target is stationary, the atmospheric refractive index changes every moment, so that the position of the measurement target in the image captured by the CCD camera 2 is between the images. It changes with. In particular, when the distance is long, such as several tens of meters to several kilometers, the image shakes greatly due to changes in the atmospheric refractive index. For this reason, when the position of the measurement object moves due to vibration or the like, the amount of movement (movement direction) includes the amount of image fluctuation (the direction of fluctuation) due to the change in the atmospheric refractive index, which affects the measurement accuracy. Out. However, in this embodiment, the laser beam is imaged together with the measurement target. The laser beam shakes with the measurement object due to the change in the refractive index of the atmosphere, but is not affected by the movement of the measurement object itself such as vibration. Therefore, if such laser light is used as a control point and the movement amount and movement direction of the laser light (control point) between the images are used as correction values, this is added to the movement amount and movement direction between the images to be measured. Thus, it is possible to remove the influence due to the change in the atmospheric refractive index.

  Specifically, the movement amount and movement direction of the measurement object are obtained by the PIV analysis means 431, and the movement amount and movement direction of the laser beam as the orientation point are also obtained. For example, as shown in FIG. 3, it is assumed that the measurement object indicated by the solid line is located at point A at the first time, and the measurement object moves to point B at the second time. The difference between point A and point B is ΔM. Further, the difference between the position of the laser beam at the first time and the position of the laser beam at the second time corresponding to this is ΔL. Then, ΔL is the amount of shaking of the image (the amount of shaking, the shaking direction) accompanying the change in the refractive index of the atmosphere, and ΔM includes the amount of shaking of the atmosphere ΔL in the actual amount and direction of movement of the measurement target. Size. Therefore, if the value of ΔL in the X direction and Y direction is subtracted from the value of ΔM in the X direction and Y direction, the moving direction and amount of movement of the measurement object from which the influence of the image shake due to the change in the atmospheric refractive index is removed can be obtained. Desired.

  In the above-described embodiment, the PIV analyzing unit 431 obtains each position of the measurement target and each position of the laser beam, and then performs correction by the correcting unit 432. However, the correcting unit 432 changes the atmospheric refractive index. After correcting the amount of fluctuation due to, the position of the measurement target may be obtained by applying the PIV analysis means 431. In this case, for example, the position of the laser beam at the first time is set as a known point (for example, the coordinate origin), and the difference (movement amount, moving direction) from the position of the laser beam at the second time is obtained as a correction value. If the value is added to the position of the measurement target at each time, the influence of the atmospheric refractive index can be removed, and thereafter, the PIV analysis means 431 may be applied using the corrected data.

  From the above, in the present invention, it is possible to remove the influence of the change in the atmospheric refractive index, which is a problem when imaging and analyzing a measurement object separated by a long distance. For this reason, it is suitable for analyzing the behavior of various remote objects to be measured that are difficult to access. In addition to non-fluid behavior such as transmission towers and transmission line vibrations, smoke emitted from chimneys of power generation facilities, etc. It is also suitable for analyzing fluid flows such as water vapor, volcanic ash, and yellow sand. Note that the distance from the long-focus optical system to the object to be measured differs depending on the accuracy of the long-focus optical system and the imaging device used and the irradiation distance of the laser light irradiation device, and is not particularly limited. Considering the performance of the focusing optical system and the like, it is practically preferable to use the optical fiber at 10 m or more and 20 km or less.

FIG. 1 is a diagram showing an overview of an image analysis system according to an embodiment of the present invention. FIG. 2 is a block diagram illustrating a schematic configuration of a computer of the image analysis system according to the embodiment. FIG. 3 is a diagram for explaining the operation of the image analysis system in the embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image analysis system 2 CCD camera 3 Long focus optical system 4 Computer 41 Control means 42 Image capture means 43 Image processing means 431 PIV analysis means 432 Correction means 5 Laser beam irradiation apparatus

Claims (3)

Imaging the measurement target at a predetermined imaging time interval by an imaging means installed at a position away from the measurement target by a predetermined distance, and obtaining velocity data between the images related to the measurement target from the obtained time-series images, A long-distance image analysis system including an image processing unit in which a PIV analysis unit for analyzing a behavior of a measurement target is set,
A laser beam irradiation device for irradiating a laser beam at a certain position within an imaging field by the imaging unit;
The image processing means obtains a difference in position of the laser light between the images based on a time-series image of the measurement object and laser light imaged by the imaging means, and uses the difference as a correction value. An image analysis system in which correction means for correcting the position of the measurement target in each image is set. The measurement object is imaged at a predetermined imaging time interval by an imaging unit installed at a position away from the measurement object by a predetermined distance, and from the obtained time-series images, each image related to the measurement object is detected by the PIV analysis unit. An image analysis method for obtaining the velocity data of and analyzing the behavior of the measurement object,
Irradiating a laser beam at a certain position within an imaging field of view by the imaging means;
The imaging means also images the laser beam together with the measurement object,
Based on the time-series images of the measurement object and laser light imaged by the imaging means, a difference in position of the laser light between the images is obtained, and the difference is used as a correction value to determine the measurement object in each image. An image analysis method characterized by correcting a position. The measurement object is imaged at a predetermined imaging time interval by an imaging unit installed at a position away from the measurement object by a predetermined distance, and from the obtained time-series images, each image related to the measurement object is detected by the PIV analysis unit. Is a computer program that constitutes image processing means in a long-distance image analysis system that obtains velocity data and analyzes the behavior of a measurement object,
The image processing means includes the position of the laser light between the images based on the time-series images of the measurement object picked up by the image pickup means together with the laser light irradiated to a certain position in the imaging field of view. A computer program characterized in that correction means for determining a difference and correcting the position of a measurement object in each image is set using the difference as a correction value.

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