JP2006064556A - Three-dimensional shape measuring device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an easily-portable and inexpensive three-dimensional shape measuring device. <P>SOLUTION: This three-dimensional shape measuring device is controlled by a PC body 1 executing an application software 4 for displaying a pattern projected onto a specimen 7 as a GUI image 11 on a PC monitor 2. A projector device 5 is a projector on the market for projecting a display on the PC monitor 2, and projects the pattern displayed on the PC monitor 2 by the application software 4 as it is onto the specimen 7, when operated as the three-dimensional shape measuring device. The application software 4 is required to have only an ability for displaying the pattern on a PC monitor screen 2, and a projector on the market for projecting the display on the PC monitor screen is sufficiently useful as the projector device 5. The pattern projected onto the specimen 7 is imaged by an imaging device 6 and processed by the PC body 1, to thereby measure the three-dimensional shape. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a three-dimensional shape measuring apparatus.

  One method for measuring the three-dimensional shape of the subject surface is a lattice pattern projection method. The grid pattern projection method is a technique for projecting a fringe pattern on the object surface and obtaining the object surface shape from the deformation amount of the projection pattern image, that is, the lateral shift amount, by the principle of triangulation.

  In order to make measurement using this principle easier, a phase shift method is used (for example, as disclosed in Patent Document 1). This is a method of obtaining the initial phase distribution by calculation based on image data picked up by sequentially changing the phase of the projected grating pattern.

  When a deformed image of the obtained pattern is expressed by an equation, I (x, y) = a (x, y) + b (x, y) cos (2πfx + φ (x, y)). Here, I (x, y) represents the luminance of the image at the coordinates (x, y). a (x, y) is a bias component, and b (x, y) is an amplitude component of the pattern. f is a spatial frequency of the pattern, and φ (x, y) is a phase to be obtained. An image obtained by shifting the pattern by π / 2 in the X direction is Ii (x, y) = a (x, y) + b (x, y) cos (2πfx + φ (x, y) + πi / 2) ( i = 0, 1, 2, 3). From these equations, the phase is obtained as φ (x, y) = Arctan ((I1 (x, y) −I3 (x, y)) / (I0 (x, y) −I2 (x, y))). Can do.

  Since the phase φ (x, y) is obtained using the Arctan function, the phase φ (x, y) is a discontinuous value folded to a value of −π to π. Therefore, a process for smoothly changing the phase distribution by adding or subtracting 2nπ (n is an integer) to the value of φ (x, y), that is, a phase connection process (unwrapping process) is performed, and a continuous initial process is performed. A phase distribution φ ′ (x, y) is obtained. As a prior art of the phase connection process, for example, there is Patent Document 2. The continuous phase distribution φ ′ (x, y) obtained in this way is converted into height using the principle of triangulation, and the height shape distribution H (x, y) of the measurement object is obtained. It is calculated | required (refer patent document 1).

  As a method of changing the phase of the grating pattern, a method of projecting a pattern to be projected while being shifted in the horizontal direction by a mechanical drive (single-axis moving stage or the like) is generally used. There is also proposed a method using a liquid crystal device as disclosed in the above. In this example, the pattern stored in the pattern memory is displayed on the liquid crystal inside the projection projector via the liquid crystal driver and projected onto the subject. Since the phase of the pattern to be projected is changed by changing the pattern to be displayed on the liquid crystal, the phase shift can be performed at a higher speed and the tact time of measurement can be improved as compared with the case of performing the phase shift by mechanical driving.

In addition, there are Patent Documents 4 and 5 as prior arts that disclose a phase shift technique using liquid crystal.
JP 2000-9444 A JP 2000-161908 A Japanese Patent Laid-Open No. 9-21620 Japanese Patent Laid-Open No. 11-83454 JP 2000-146543 A

In the apparatus for pattern projection by the liquid crystal projector as described above, a dedicated liquid crystal driver for displaying a pattern or dedicated firmware in the driver is required.
In the dedicated hardware or firmware configuration specialized for such a device, there is a problem that the device becomes large and the device price becomes expensive.

  An object of the present invention is to provide an inexpensive three-dimensional shape measuring apparatus that is easy to carry.

  A three-dimensional shape measuring apparatus of the present invention is a three-dimensional shape measuring apparatus that projects a pattern onto a subject and measures the three-dimensional shape of the subject from the deformation amount of the pattern, a display screen for displaying an image, Control means for displaying a pattern on the display screen and changing the pattern to be displayed as necessary, projection means for projecting the pattern displayed on the display screen by the control means onto the subject, and the projected An image pickup means for picking up an image of the pattern is provided.

  According to the present invention, an inexpensive three-dimensional shape measuring apparatus can be provided.

FIG. 1 is a diagram showing a schematic configuration of a three-dimensional shape measuring apparatus according to an embodiment of the present invention.
The three-dimensional shape measuring apparatus includes a personal computer (hereinafter referred to as PC) main body 1, a PC monitor 2 that displays a screen output from the PC main body 1, an instruction device 3 such as a keyboard and a mouse for issuing instructions to the PC main body 1, and the like. The application software 4 that is stored in the memory unit inside the PC main body 1 and performs various arithmetic processes, the projector device 5 that displays the same screen as the PC monitor 2 that displays the screen and is output from the PC main body 1, And an imaging device 6 for imaging the specimen 7.

The projector device 5 includes a light source for projection, a liquid crystal driver, a liquid crystal, and a projection optical system.
The monitor output terminal of the PC main body 1 and the PC monitor 2 are electrically connected, and the GUI screen 11 of the application software 4 executed on the PC main body 1 is displayed on the screen of the PC monitor 2.

  Furthermore, the monitor output terminal of the PC main body 1 is also electrically connected to the projector device 5, and the pattern displayed on the GUI screen 11 of the application software 4 executed on the PC main body 1 is applied to the subject 7 by the projector device 5. Projected towards. The projector device 5 is arranged so that the pattern projection area 10 is equal to or wider than the measurement target area of the subject 7.

The imaging device 6 is electrically connected to the image input terminal of the PC main body 1, and image data obtained by the imaging device 6 is taken into a memory unit inside the PC main body 1.
FIG. 2 is a diagram showing a display example of the GUI screen 11 according to the embodiment of the present invention.

The main GUI screen is displayed as shown in (A-1), and the buttons and numerical value input unit on the GUI screen 11 are operated by the pointing device 3 such as a mouse and a keyboard.
The measurement parameter input unit 22 is supplied with measurement parameter setting values required by the pattern projection method and the phase shift method, such as the pattern pitch, projection angle, and phase shift condition of the projection pattern.

  The measurement of the subject is started by pressing the measurement start button 20. When this button is pressed, the GUI screen 11 is switched to a screen such as (B-1). On this screen, the stripe pattern of the pitch set by the measurement parameter input unit 22 is displayed over the entire screen of the PC monitor 2.

  Further, the stripe pattern is also projected onto the subject 7 by the projector device 5. At this time, the application software 4 issues an image capture instruction to the imaging device 6, and the captured image data I 0 (x, y) is captured and stored in the memory unit inside the PC body 1. Here, the imaged stripe pattern is deformed by the uneven shape on the surface of the subject 7.

  Next, the GUI screen 11 is switched to (B-2). This screen is a stripe pattern in which the phase is shifted from the screen (B-1) by a predetermined amount (1 / 2π rad in this example) in accordance with the phase shift amount set by the measurement parameter input unit 22. This pattern is also projected onto the subject 7 by the projector device 5 in the same manner as described above, and the imaging data I1 (x, y) is taken into the memory unit inside the PC main body 1 and stored in accordance with an instruction from the application software 4.

  Hereinafter, this operation is repeated, and each time the GUI screen 11 is switched to (B-3) or (B-4), the imaging data I2 (X, y) and I3 (x, y) are sequentially stored in the memory of the PC main body 1. Stored in the department.

Based on I0 (x, y), I1 (x, y), I2 (x, y), and I3 (x, y) stored in the memory unit in the CPU unit inside the PC main body 1,
φ (x, y) = Atan ((I1 (x, y) −I3 (x, y)) / (I0 (x, y) −I2 (x, y))),
The phase is calculated according to the following formula. The obtained phase distribution φ (x, y) is subjected to a phase connection process and converted into a height to obtain a height distribution H (x, y) on the subject surface.

  The height distribution H (x, y) is displayed on the result display unit 23 as shown in (A-2). The display format in the result display section 23 can be selected by a display format selection button 21 such as contour line display, gray scale display, bird's eye view display, or the like. Various three-dimensional shapes can be measured based on the display data of H (x, y).

  The monitor output terminal of the PC main body is a built-in standard in a normal personal computer, and the projection projector used in this embodiment is of a type that projects the screen of the PC. Since this is generally commercially available, there is no need for special customization for the pattern projection apparatus. Since the pattern projection can be performed on the subject simply by displaying the phase shift projection pattern on the GUI screen of the software, it is easy to carry and a three-dimensional shape measuring apparatus can be provided with an inexpensive configuration.

  In the above embodiment, a projector using liquid crystal is used. However, a PC screen projector using a micromirror device such as a DMD (Digital Micromirror Device) may be used, and similarly, the display is performed on a PC monitor. Any pattern can be used as long as the pattern to be projected onto the subject can be projected.

  In this embodiment, a stripe pattern is projected, but the present invention is not limited to this, and a three-dimensional shape is measured by the principle of triangulation from the degree of deformation of the projected pattern, such as a matrix pattern or a concentric circle pattern. Anything is possible.

Furthermore, although the phase shift method is used in the present embodiment, the measurement may be performed based on the principle of triangulation from the degree of deformation of one projection pattern without phase shift.
Further, the projection optical system of the projector may be a reduction projection system or an enlargement projection system. Furthermore, the imaging optical system of the imaging apparatus may be a reduced imaging system or an enlarged imaging system.

Furthermore, a shutter or the like may be provided in the projection optical path so that the PC monitor screen is not projected onto the subject during non-measurement.
In the present embodiment, a method using a desktop personal computer using a PC main body and a PC monitor has been described. However, if a notebook personal computer in which the PC main body and the PC monitor are integrated is used, it becomes even easier to carry.

It is a figure which shows schematic structure of the three-dimensional shape measuring apparatus according to embodiment of this invention. It is a figure which shows the example of a display of the GUI screen according to embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 PC main body 2 PC monitor 3 Instruction apparatus 4 Application software 5 Projector apparatus 6 Imaging apparatus 7 Subject

Claims (6)

A three-dimensional shape measuring apparatus that projects a pattern onto a subject and measures the three-dimensional shape of the subject from the deformation amount of the pattern,
A display screen for displaying images;
Control means for displaying a pattern on the display screen and changing the pattern to be displayed as necessary;
Projection means for projecting the pattern displayed on the display screen by the control means onto the subject;
Imaging means for imaging the projected pattern;
A three-dimensional shape measuring apparatus comprising:   The three-dimensional shape measuring apparatus according to claim 1, wherein the pattern displayed on the display screen is a stripe pattern whose density changes periodically.   The three-dimensional shape measuring apparatus according to claim 2, wherein imaging is sequentially performed in each phase while shifting the phase of the stripe pattern. The control means is a computer that operates according to predetermined application software,
The three-dimensional shape measuring apparatus according to claim 1, wherein the projection unit is a projector that projects the display content of the display screen of the computer. A three-dimensional shape measuring method for projecting a pattern onto a subject and measuring the three-dimensional shape of the subject from the deformation amount of the pattern,
A control step for displaying the pattern on the display screen and changing the displayed pattern as necessary;
A projection step of projecting the pattern displayed on the display screen in the control step onto the subject;
An imaging step for imaging the projected pattern;
A three-dimensional shape measuring method comprising: A three-dimensional shape measuring method for projecting a pattern onto a subject and measuring the three-dimensional shape of the subject from the deformation amount of the pattern,
A control step for displaying the pattern on the display screen and changing the displayed pattern as necessary;
A projection step of projecting the pattern displayed on the display screen in the control step onto the subject;
An imaging step for imaging the projected pattern;
A program for causing a computer to realize a three-dimensional shape measuring method.

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