Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
  • G01B11/00—Measuring arrangements characterised by the use of optical techniques
  • G01B11/24—Measuring arrangements characterised by the use of optical techniques for measuring contours or curvatures
  • G01B11/25—Measuring arrangements characterised by the use of optical techniques for measuring contours or curvatures by projecting a pattern, e.g. one or more lines, moiré fringes on the object
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
  • G01B11/00—Measuring arrangements characterised by the use of optical techniques
  • G01B11/002—Measuring arrangements characterised by the use of optical techniques for measuring two or more coordinates
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
  • G01B11/00—Measuring arrangements characterised by the use of optical techniques
  • G01B11/24—Measuring arrangements characterised by the use of optical techniques for measuring contours or curvatures
• • G—PHYSICS
  • G06—COMPUTING OR CALCULATING; COUNTING
  • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
  • G06T7/00—Image analysis
  • G06T7/50—Depth or shape recovery
  • G06T7/521—Depth or shape recovery from laser ranging, e.g. using interferometry; from the projection of structured light

Definitions

• the present invention relates to a three-dimensional shape measuring apparatus that acquires distance information to a elephant object using laser light by the principle of triangulation, and in particular, to acquire distance information with high accuracy using a single imaging device.
• the present invention relates to a three-dimensional shape measuring device capable of performing the measurement.
• An active method pattern projection, spot projection
• triangulation is known as one of the methods for measuring the three-dimensional shape of a target object. They consist of light sources such as laser light and halogen lamps, and imaging devices such as cameras and CCDs. The acquisition of three-dimensional shapes is performed based on triangulation. Therefore, the positional relationship between the light source and the camera had to be precisely known in advance, and the equipment tended to be large and complicated.
• the 3D shape acquisition device can be simplified. Therefore, a method for easily acquiring the positional relationship between the camera and the light source by attaching a marker to the light source and simultaneously shooting the marker with the camera is described in Reference 1 (Masahiro Takatsuka, Geoff A.W.West,
• the present invention provides a method for simplifying the apparatus by attaching a marker to a light source and simultaneously photographing the marker with a camera, among the active three-dimensional shape measurement methods based on triangulation. It aims to shorten and improve accuracy. Disclosure of the invention
• the present invention realizes simultaneous acquisition of many three-dimensional points from one image by using line laser light as a light source. This makes it possible to acquire a three-dimensional shape efficiently in a short time. In addition, by arranging the markers in a three-dimensional manner, it is possible to accurately acquire the position of the light source, thereby improving the accuracy of the acquired three-dimensional shape.
• FIG. 1 is a diagram showing a configuration of an image data measuring device as a first embodiment according to the present invention
• FIG. 2 is a configuration of an image data measuring device as a second embodiment according to the present invention
• FIG. 3 is a diagram showing an example of a marker arranging method using a light emitting diode according to the present invention.
• FIG. 4 is a diagram showing a marker coordinate system with a line laser light source and a camera coordinate system.
• FIG. 5 is a diagram showing a system relationship
• FIG. 5 is a diagram showing a method of estimating rotation of marker coordinates
• FIG. 6 is a diagram showing a method of estimating a three-dimensional point according to the present invention
• FIG. 7 is a diagram showing a method for estimating a deviation between the marker plane and the laser plane.
• the imaging device (1-2) is set so that the device (1-1) and the target object (114) are simultaneously within the angle of view.
• the aperture and shutter speed of the imaging device are also set at the same time so that the laser beam and the light emitting diode can be easily and accurately detected by image processing.
• the positional relationship between the device (111) and the light beam plane generated by the line laser beam is measured in advance.
• Examples of the imaging device include a video camera CCD.
• the user holds the device (1-1) in his hand and irradiates the target freely with line laser light.
• the positional relationship between the device (1-1) and the camera can be obtained by detecting the position of the light emitting diode on the captured image. At that time, improve the accuracy by nonlinear solution method Aim.
• the irradiation line laser detected by using the obtained positional relationship between the device (1-1) and the camera The great separation of the light (115) from the camera can be calculated by the principle of triangulation.
• a series of processing is displayed in real time on a display monitor (2-5), as shown in Fig. 2, the user can check the part of the laser that has not yet been measured on the spot. Therefore, the 3D shape of the target object can be obtained efficiently.
• Fig. 3 shows an example of the shape of a marker using a light emitting diode.
• the marker can be of any shape as long as it has four or more points, but it can be arranged in a square (3-1), arranged in a three-dimensional X-yz axis (3-2), or arranged in a cube ( In the case of 3-3), there are advantages such as easy manufacturing and simple calculation for obtaining the positional relationship between the device (1-1) and the camera.
• the system consists of a video camera and a line laser light source. See FIG.
• the line laser light source is manually operated, and the user irradiates the object with the line laser and scans the object.
• the shape of the surface of the target object is obtained by taking an image of the stripe irradiated by the laser beam with a camera and analyzing it.
• a light emitting diode marker is attached to the line laser light source to identify the position and direction of the line laser light source.
• the markers are placed on the laser plane so as to form square vertices.
• Marker position and direction Define the local coordinate system of the car (4-1). This is called the marker coordinate system.
• the origin of the marker coordinate system, placed in the center of gravity of the marker, base click Honoré ei, the unit in the direction of each coordinate axis, e 2,, e 3, represented by. ei 'and e 2 ' are taken in the direction parallel to the square side of the marker.
• e 3 (Ei 'is the direction of a side line laser light source for projecting laser light, e 2' is the corresponding to a direction of the side perpendicular therewith)
• e 3 ' take the form a square perpendicular direction of the marker.
• the camera coordinate system is a lens centered at the origin, to, ei, represented by e 2, e 3, ei, e 2 is the horizontal axis of the image plane, parallel to the longitudinal axis, e 3 is a vertical image plane Take from the origin in the opposite direction to the subject
• a plane laser beam is projected light and laser plane.
• the transformation between the marker coordinate system and the camera coordinate system is represented by a rotation matrix R and a translation vector t. This transformation is a representation of the position of the marker relative to the camera. See FIG.
• the laser light emitted by these markers is captured with a video force camera.
• the positions of the four light emitting diodes are extracted. Specifically, the position can be calculated by taking the center of gravity of the connected region after simple threshold processing. From the extracted positions of the light emitting diodes, calculate the straight line passing through them and calculate the intersection. These intersections are called Focus Of Expansion (FOE) (5-2a) (5_2b). If the lines are parallel, FOE is the point at infinity in the direction of the line.
• FOE Focus Of Expansion
• ⁇ is the 3D position of the ⁇ th marker in the marker coordinate system
• proj Represents the projection transformation to the image plane.
• a simplex descent method or the like is used as a method of nonlinear optimization.
• the estimated value of the laser plane is obtained from the estimated value of the marker coordinate system.
• the measurement of the relational expression between the marker coordinate system and the laser plane will be described later.
• pixels illuminated by a laser beam are extracted from an image (6-5) (6-1). This is also possible after simple thresholding, but in practice, the extraction accuracy is then increased using thinning and morphological filters.
• the three-dimensional position of the surface to be measured and the straight line (6-4) passing through the lens center corresponding to those pixels can be obtained from the camera's internal parameters. As the intersection of this straight line and the laser plane (6-2), the three-dimensional position (6-13) of the surface to be measured corresponding to the pixel is determined. See FIG.
• This relationship is expressed as a parameter of the laser beam surface expressed in the marker's local coordinate system.
• the following measurements are made in preparation for estimating the relational expression between the marker coordinates and the laser plane.
• a rectangular parallelepiped (7-5) of known size is photographed, and the external parameters of the camera are estimated using a normal camera calibration. Based on the estimated external parameters and the known size, the equation of the surface constituting the rectangular parallelepiped is estimated.
• the laser beam is projected on the rectangular parallelepiped, and the position and direction of the marker coordinate system are estimated from the position of the light emitting diode by the method described above. Then, from the current estimated value of (a, b, c, d), an estimated value of the laser plane represented by the camera coordinates is obtained. Further, From the estimated value of the laser plane, the estimated value of the line of intersection between the laser plane and the rectangular parallelepiped is calculated, and the projection position (7-2) on the image plane is calculated.
• an evaluation function is defined by adding the sum of the squares of the error between the known distance at those points and the estimated distance by the above method to the error evaluation value (6), and minimizing this. , Correct the estimation of the marker coordinate system based on the known 3D points.
• the present invention when acquiring a three-dimensional shape by an active method based on triangulation, there is no need for any complicated device that has been required in the past, and a highly accurate device can be obtained in a short time.
• a dimensional shape can be obtained.
• the user by displaying the measured 3D shape data on the display monitor in real time, the user can check the spot where the measurement has not yet been completed on the spot, and efficiently perform the 3D measurement of the target object. The shape can be obtained.

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• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Engineering & Computer Science (AREA)
• Computer Vision & Pattern Recognition (AREA)
• Optics & Photonics (AREA)
• Theoretical Computer Science (AREA)
• Length Measuring Devices By Optical Means (AREA)
• Image Input (AREA)
• Image Processing (AREA)
• Image Analysis (AREA)

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Citations (6)

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• 2002
  • 2002-11-14 JP JP2002330582A patent/JP3624353B2/ja not_active Expired - Fee Related
• 2003
  • 2003-11-13 EP EP03772747A patent/EP1580523A4/en not_active Withdrawn
  • 2003-11-13 WO PCT/JP2003/014469 patent/WO2004044522A1/ja not_active Ceased
  • 2003-11-13 US US10/534,393 patent/US7342669B2/en not_active Expired - Fee Related
  • 2003-11-13 AU AU2003280776A patent/AU2003280776A1/en not_active Abandoned

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Non-Patent Citations (2)

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