WO2022249321A1 - ひび割れ画像点検システムおよび方法 - Google Patents

ひび割れ画像点検システムおよび方法 Download PDF

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Publication number
WO2022249321A1
WO2022249321A1 PCT/JP2021/019974 JP2021019974W WO2022249321A1 WO 2022249321 A1 WO2022249321 A1 WO 2022249321A1 JP 2021019974 W JP2021019974 W JP 2021019974W WO 2022249321 A1 WO2022249321 A1 WO 2022249321A1
Authority
WO
WIPO (PCT)
Prior art keywords
digital camera
image inspection
crack
laser
pixels
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/JP2021/019974
Other languages
English (en)
French (fr)
Japanese (ja)
Inventor
優理奈 田中
勇一 赤毛
宗一 岡
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
NTT Inc
Original Assignee
Nippon Telegraph and Telephone Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Nippon Telegraph and Telephone Corp filed Critical Nippon Telegraph and Telephone Corp
Priority to JP2023523794A priority Critical patent/JPWO2022249321A1/ja
Priority to US18/561,959 priority patent/US20240223878A1/en
Priority to PCT/JP2021/019974 priority patent/WO2022249321A1/ja
Publication of WO2022249321A1 publication Critical patent/WO2022249321A1/ja
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N23/00—Cameras or camera modules comprising electronic image sensors; Control thereof
    • H04N23/56—Cameras or camera modules comprising electronic image sensors; Control thereof provided with illuminating means
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/84—Systems specially adapted for particular applications
    • G01N21/88—Investigating the presence of flaws or contamination
    • G—PHYSICS
    • G06—COMPUTING OR CALCULATING; COUNTING
    • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T7/00—Image analysis
    • G06T7/0002—Inspection of images, e.g. flaw detection
    • G—PHYSICS
    • G06—COMPUTING OR CALCULATING; COUNTING
    • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T7/00—Image analysis
    • G06T7/60—Analysis of geometric attributes
    • G—PHYSICS
    • G06—COMPUTING OR CALCULATING; COUNTING
    • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T2207/00—Indexing scheme for image analysis or image enhancement
    • G06T2207/30—Subject of image; Context of image processing
    • G06T2207/30181—Earth observation
    • G06T2207/30184—Infrastructure
    • G—PHYSICS
    • G06—COMPUTING OR CALCULATING; COUNTING
    • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T2207/00—Indexing scheme for image analysis or image enhancement
    • G06T2207/30—Subject of image; Context of image processing
    • G06T2207/30242—Counting objects in image

Definitions

  • the present invention relates to a crack image inspection system and method.
  • crack width is one of the survey items related to cracks on the concrete surface. Crack width is measured by comparison with the crack scale. Conventionally, since this measurement is performed manually, there is a problem that a lot of inspection time is required and variations occur depending on the operator.
  • a ruler is often added as a reference, and adding a reference every time a huge area is photographed is a lot of work and takes time.
  • Parts included in the structure may also be used as references. In this case, you don't need to shoot with a reference, but you do need to shoot from the front.
  • the adjustment of the shooting angle of the camera often depends on the photographer, and if the shooting is not perpendicular to the reference, the actual distance may differ from pixel to pixel.
  • the present invention has been made to solve the above-described problems, and aims to make it possible to capture crack images so that the correspondence between pixels and actual distances is constant.
  • a crack image inspection system includes a digital camera, a projection lens with a known focal length, and a laser, fixed to the digital camera, and irradiates a laser beam condensed by the projection lens in the photographing direction of the digital camera. and a counting device for counting the number of pixels of the projected image in the projection image obtained by capturing the projected image of the laser light irradiated by the laser irradiation device and projected on the target surface with a digital camera,
  • the focal length of the lens is a value obtained from the relationship between the dimension of one pixel of the imaging device of the digital camera and the length above the image captured by the digital camera.
  • the crack image inspection method is a laser irradiation device equipped with a projection lens and a laser having a known focal length and fixed to a digital camera, and a laser beam focused by the projection lens in the photographing direction of the digital camera.
  • a first step of irradiating light; a second step of capturing, with a digital camera, a projected image of the laser light irradiated by the laser irradiation device and projected onto the target surface; and a third step of counting the number of pixels in the part, and the focal length of the projection lens is obtained from the relationship between the dimension of one pixel of the imaging device of the digital camera and the length above the image captured by the digital camera. value.
  • the number of pixels in the projected image portion of the projected image captured by the digital camera is counted.
  • a crack image can be captured.
  • FIG. 1 is a configuration diagram showing the configuration of a crack image inspection system according to an embodiment of the present invention.
  • FIG. 2 is a flow chart explaining a crack image inspection method according to an embodiment of the present invention.
  • FIG. 3 is a configuration diagram showing the hardware configuration of the crack image inspection system according to the embodiment of the present invention.
  • This crack image inspection system comprises a digital camera 101 , a laser irradiation device 102 , a counting device 103 and a display device 104 .
  • the digital camera 101 has an area image sensor (solid-state imaging device) as a light receiving unit.
  • the laser irradiation device 102 has a projection lens (objective lens) with a known focal length and a laser, and is fixed to the digital camera 101 .
  • the laser irradiation device 102 is fixed to the digital camera 101 so that the reference point of the focal length of the projection lens coincides with the light receiving surface of the imaging element of the digital camera 101 .
  • the focal length of the projection lens is a value obtained from the relationship between the dimension of one pixel of the imaging element of the digital camera 101 and the length above the image captured by the digital camera 101 .
  • the counting device 103 counts the number of pixels in the projection image portion of the projection image captured by the digital camera 101 with the laser light irradiated by the laser irradiation device 102 and projected onto the target surface.
  • the number of pixels counted by the counting device 103 is displayed on the display device 104, for example.
  • the size (e.g., beam diameter) of the projected image of the laser light irradiated by the laser irradiation device 102 and projected onto the target plane varies depending on the difference from the focal length of the projection lens.
  • the beam diameter is minimized when the distance of the projection plane on which the projected image is formed is equal to the focal length of the projection lens.
  • the number of pixels displayed on the display device 104 changes when the distance of the digital camera 101 (laser irradiation device 102) to the target surface is changed.
  • the distance between the target surface and the digital camera 101 (laser irradiation device 102) is equal to the focal length of the projection lens described above, the number of displayed pixels is minimized.
  • ⁇ is the wavelength of the laser light.
  • a beam spot of size d appears at a distance f from the lens (projection lens), and the beam diameter and distance from the lens are constant unless the lens is changed.
  • This can be used as an image for calibration, and the number of pixels of the beam spot of this image for calibration can be counted and used as a reference number of pixels.
  • the resolution coefficient for converting one pixel into length
  • the resolution can be calculated from the reference number of pixels and the beam diameter of the beam spot.
  • the crack image inspection system can be provided with a determination device 105 that determines whether the number of pixels counted by the counting device 103 falls within the reference range and outputs the determination result.
  • the determination device 105 determines that the number of pixels counted by the counting device 103 falls within the reference range, the determination device 105 stores the image captured by the digital camera 101 in the storage device 106 .
  • the lens of the active digital camera 101 is pointed at the inspection point, and the inspection point is set to be within the imaging range using the liquid crystal monitor of the digital camera 101 or the like.
  • a laser irradiation device 102 equipped with a projection lens and a laser having a known focal length and fixed to a digital camera 101 emits laser light condensed by the projection lens in the shooting direction of the digital camera 101. to irradiate.
  • the focal length of the projection lens is a value obtained from the relationship between the dimension of one pixel of the imaging element of the digital camera 101 and the length above the image captured by the digital camera 101 .
  • a second step S102 the digital camera 101 captures a projected image of the laser light irradiated by the laser irradiation device 102 and projected onto the target surface.
  • a third step S103 the number of pixels in the projection image portion of the projection image captured by the digital camera 101 is counted. The counted number of pixels is displayed on the display device 104 and can be visually recognized by the inspector.
  • the fourth step S104 it is determined whether or not the number of pixels counted in the third step S103 falls within the reference range. If it is determined that the number of pixels counted in the fourth step S104 is within the reference range (yes in the fourth step S104), the image captured by the digital camera 101 is stored in the fifth step S105. Store in device 106 . For example, by pressing the shutter button (release the shutter) of the digital camera 101 in the state determined as described above, the image displayed on the liquid crystal monitor is stored in the storage device 106 . The determination described above is performed by the determination device 105, and the determination device 105 can release the shutter of the digital camera 101 when the counted number of pixels reaches the reference value.
  • the laser irradiation device 102 is fixed to the digital camera 101, and according to the movement of the digital camera 101, the laser irradiation device 102 also moves simultaneously.
  • the beam diameter of the laser light irradiated onto the target surface varies depending on the difference from the focal length of the projection lens.
  • the laser irradiation device 102 is also adjusted to the focal length of the projection lens, and the beam diameter of the beam projected onto the target plane is minimized.
  • the positions of the digital camera 101 and the object to be measured are adjusted so that the beam diameter is minimized.
  • the digital camera 101 is arranged so that the number of pixels of the projected image of the laser beam projected onto the target surface falls within the reference range when picking up crack images for inspection.
  • the captured image is stored in the storage device 106 .
  • the captured image can be stored in the storage device 106 by pressing the shutter button by the inspector. Further, the shutter of the digital camera 101 can be automatically released by the operation of the determination device 105 described above.
  • the inspector can acquire an inspection image simply by adjusting the position of the digital camera 101 back and forth with respect to the target surface.
  • the inspection work can be completed by performing these operations on the entire inspection location.
  • the projection shape can be made into an arbitrary shape such as a rectangle or a character. can also This makes it possible to use not only the number of pixels but also the shape of the projected image (pixel arrangement) to adjust the shooting position, so that the shooting position can be adjusted more easily.
  • DOE diffractive optical element
  • a spatial light modulator etc.
  • the laser irradiation device 102 (first step S101) can irradiate a plurality of laser beams.
  • the ground is irradiated with two upper and lower laser beams, and two projection images are projected onto the target surface for crack measurement (inspection).
  • the two projection images projected in this manner are captured by the digital camera 101, and the number of pixels of each projection image is counted.
  • the shooting angle of the digital camera 101 is a so-called low angle or high angle
  • the number of pixels of the upper and lower projected images will be different. In this state, even if one pixel count falls within the reference range, the other pixel count deviates from the reference.
  • the angle is horizontal, the number of pixels of both of them can be simultaneously within the reference range.
  • the counting device, judging device, and storage device of the crack image inspection system include a CPU (Central Processing Unit) 301, a main storage device 302, and an external A computer device having a storage device 303, a network connection device 304, etc., and a program developed in the main storage device 302 causes the CPU 301 to operate (execute the program) to perform each function (crack image inspection method).
  • the above program is a program for a computer to execute the crack image inspection method shown in the above embodiment.
  • a network connection device 304 connects to a network 305 . Also, functions may be distributed among multiple computing devices.
  • the present invention since the number of pixels in the projected image portion of the projected image captured by the digital camera is counted, the correspondence between the pixels and the actual distance becomes constant. Thus, crack images can be captured. According to the present invention, inspection can be performed without requiring much inspection time and without causing variations among operators. According to the present invention, there is no need to attach a ruler or the like as a reference, and no great effort or time is required.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Theoretical Computer Science (AREA)
  • Computer Vision & Pattern Recognition (AREA)
  • Signal Processing (AREA)
  • Quality & Reliability (AREA)
  • Multimedia (AREA)
  • Geometry (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Length Measuring Devices By Optical Means (AREA)
PCT/JP2021/019974 2021-05-26 2021-05-26 ひび割れ画像点検システムおよび方法 Ceased WO2022249321A1 (ja)

Priority Applications (3)

Application Number Priority Date Filing Date Title
JP2023523794A JPWO2022249321A1 (https=) 2021-05-26 2021-05-26
US18/561,959 US20240223878A1 (en) 2021-05-26 2021-05-26 Cracking image inspection system and method
PCT/JP2021/019974 WO2022249321A1 (ja) 2021-05-26 2021-05-26 ひび割れ画像点検システムおよび方法

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Citations (5)

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WO2011118065A1 (ja) * 2010-03-23 2011-09-29 富士フイルム株式会社 撮影装置及びその制御方法、並びに三次元情報測定装置
JP2015184056A (ja) * 2014-03-20 2015-10-22 株式会社東芝 計測装置、方法及びプログラム
US20150323449A1 (en) * 2014-05-09 2015-11-12 Kairos Aerospace Inc. Systems and methods for detecting gas leaks
JP2019144191A (ja) * 2018-02-23 2019-08-29 株式会社市川工務店 橋梁などの構造物を検査するための画像処理システム、画像処理方法及びプログラム

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JP5820365B2 (ja) * 2012-12-28 2015-11-24 トキコーポレーション株式会社 発光装置および光照射装置
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Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2010121992A (ja) * 2008-11-18 2010-06-03 Taisei Corp ひび割れ検出方法
WO2011118065A1 (ja) * 2010-03-23 2011-09-29 富士フイルム株式会社 撮影装置及びその制御方法、並びに三次元情報測定装置
JP2015184056A (ja) * 2014-03-20 2015-10-22 株式会社東芝 計測装置、方法及びプログラム
US20150323449A1 (en) * 2014-05-09 2015-11-12 Kairos Aerospace Inc. Systems and methods for detecting gas leaks
JP2019144191A (ja) * 2018-02-23 2019-08-29 株式会社市川工務店 橋梁などの構造物を検査するための画像処理システム、画像処理方法及びプログラム

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US20240223878A1 (en) 2024-07-04

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