Optional 3D digitizer, system and method for digitizing an object

• US 6,493,095 B1
• Filed: 04/12/2000
• Issued: 12/10/2002
• Est. Priority Date: 04/13/1999
• Status: Expired due to Term

• Current Assignee: Creaform, Inc. (Ametek Incorporated)
• Original Assignee: InSpeck, Inc. (Ametek Incorporated)
• Inventors: Bourassa, Yvan, Song, Li, Beauchamp, Dominique, Lemelin, Guylain
• Primary Examiner(s): Pham, Hoa Q.
• Application Number:
  US09/548,232
• Time in Patent Office: 972 Days
• Field of Search: 356/601, 356/602, 356/603, 356/604, 356/605, 356/607, 356/608, 356/611, 356/613, 356/2, 250/237.G, 382/154
• US Class Current: 356/603
• CPC Class Codes: G01B 11/25 by projecting a pattern, e.g. one or more lines, moiré fringes on the object G01B11/255 takes precedence ; image analysis for depth or shape recovery G06T7/50
• CPC Class Codes: H04N 13/239 using two 2D image sensors having a relative position equal to or related to the interocular distance H04N13/243 takes precedence
• CPC Class Codes: H04N 13/254 in combination with electromagnetic radiation sources for illuminating objects

Abstract

An optical 3D digitizer for digitizing an object, comprises a white light source producing white light, a projection lens projecting the white light toward the object whereby the object has a fully illuminated side, a grating device producing a fringe pattern in the light projected by the projection lens, and first and second cameras positioned aside from the projection lens and aligned in angled directions with respect to each other so that the cameras have complementary fields of view directed on the illuminated side of the object and partially overlapping with each other over a depth of measurement of the object. The cameras have respective video outputs to produce video signals representing complementary images of the object with a common image portion as a result of the fields of view being partially overlapping.

Claims

1. An optical 3D digitizer for digitizing an object, comprising:

a white light source adapted to produce white light;

a projection lens optically coupled to the white light source and arranged to project the white light toward the object whereby the object has a fully illuminated side;

grating means optically coupled between the white light source and the projection lens, for controllably producing a fringe pattern in the light projected by the projection lens; and

first and second cameras positioned aside from the projection lens and aligned in angled directions with respect to each other so that the cameras have complementary fields of view directed on the illuminated side of the object and partially overlapping with each other over a depth of measurement of the object, the cameras having respective video outputs to produce video signals representing complementary images of the object with a common image portion as a result of the fields of view being partially overlapping.

2. The optical 3D digitizer according to claim 1, wherein the cameras are mounted on opposite sides of the projection lens.

3. The optical 3D digitizer according to claim 1, wherein the cameras are monochrome cameras.

4. The optical 3D digitizer according to claim 1, wherein the cameras are color cameras.

5. The optical 3D digitizer according to claim 1, wherein the grating means comprises a grating slide extending across the white light produced by the source, and an actuating unit arranged to controllably move the slide transversely with respect to the white light to shift the fringe pattern produced in the light projected by the projection lens.

6. The optical 3D digitizer according to claim 1, further comprising a multi-functional rotatable disk having circumferentially distributed optical elements selectively moveable in optical registry with the grating means and the projection lens by controlled rotation of the disk, and an actuating unit arranged to controllably rotate the disk, the optical elements including at least one defocusing element suppressing the fringe pattern produced by the grating means and providing uniform illumination by the white light projected on the object.

7. The optical 3D digitizer according to claim 6, wherein the optical elements further include an aperture, at least one shutter, and at least one filter filtering out a predetermined range of colors.

8. The optical 3D digitizer according to claim 1, wherein the fringe pattern includes a set of encoding points having absolute 3D positions determinable in the images captured by the cameras using experimentally predefined functions, the encoding points being positioned so that each one of the cameras captures at least one of the encoding points.

9. The optical 3D digitizer according to claim 1, further comprising a main control board having a peripheral interface, and a control unit connected to the peripheral interface, the grating means and the white light source, the control unit controlling use of the grating means and operation of the white light source in response to commands received through the peripheral interface.

10. The optical 3D digitizer according to claim 9, wherein the grating means comprises a grating slide extending across the white light produced by the source, and an actuating unit arranged to controllably move the slide transversely with respect to the white light to shift the fringe pattern produced in the light projected by the projection lens, the device further comprising:

a multi-functional rotatable disk having circumferentially distributed optical elements selectively moveable in optical registry with the grating means and the projection lens by controlled rotation of the disk, and an actuating unit arranged to controllably rotate the disk, the optical elements including an aperture, at least one shutter, at least one filter, and at least one defocusing element suppressing the fringe pattern produced by the grating means and providing uniform illumination by the white light projected on the object;

a motor driver board connected between the control unit and the motorized rotatable disks and driving the actuating units thereof in response to selective control signals produced by the control unit; and

a lamp driver board connected between the control unit and the white light source and driving the white light source in response to an operation control signal produced by the control unit.

11. The optical 3D digitizer according to claim 10, further comprising a casing enclosing the cameras, the projection lens, the white light source, the grating means, the multi-functional disk, the driver boards, the control unit, and power supply means for producing power supply signals compatible with electronics of the boards, the white light source and the cameras, the casing having external connectors connected to the cameras, the peripheral interface and the power supply means.

12. An optical 3D digitizer system for digitizing an object, comprising:

an optical 3D digitizer including;

a white light source adapted to produce white light;

a projection lens optically coupled to the white light source and arranged to project the white light toward the object whereby the object has a fully illuminated side;

grating means optically coupled between the white light source and the projection lens, for selectively producing a fringe pattern in the light projected by the projection lens;

first and second cameras positioned aside from the projection lens and aligned in angled directions with respect to each other so that the cameras have complementary fields of view directed on the illuminated side of the object and partially overlapping with each other over a depth of measurement of the object, the cameras having respective video outputs to produce video signals representing complementary images of the object with a common image portion as a result of the fields of view being partially overlapping; and

a control circuit connected to the white light source and the grating means;

a computer including a frame grabber having inputs for receiving the video signals from the cameras, the computer having a communication link with the control circuit of the digitizer.

13. The optical 3D digitizer system according to claim 12, wherein the computer comprises means for:

extracting a 3D data set per pixel from the images with structured light projection as a result of the fringe pattern being produced by the grating means in the light projected on the object, the 3D data set representing a relative 3D position of each pixel in the images;

detecting encoding points laid at specific locations in the fringe pattern, the encoding points having absolute 3D positions determinable in the images captured by the cameras using experimentally predefined functions;

converting the relative 3D position of each pixel into a real 3D position using the absolute 3D position of a detected one of the encoding points;

producing texture images associated to the images captured by the cameras based on an optical intensity of the pixels defining the images; and

generating a single full digitized image of the object as a function of a predefined spatial relationship between the cameras and the real 3D position of each pixel, the texture images being integrated into the digitized image.

14. The optical 3D digitizer system according to claim 13, wherein the computer further comprises means for:

determining a mean intensity value based on the intensity of the pixels in the common image portion captured by the cameras;

determining a gain factor for each complementary image based on the mean intensity value with respect to the

intensity of the pixels in the common image portion; and

applying the gain factor on a corresponding one of the texture images.

15. The optical 3D digitizer system according to claim 14, wherein the mean intensity value and the gain factor are determined for each one of R, G and B channels, while the gain factors are respectively applied on each one of the R, G and B channels.

16. The optical 3D digitizer system according to claim 13, further comprising a defocusing device optically coupled between the grating means and the projection lens, the defocusing device being adapted to suppress the fringe pattern produced by the grating means and to provide uniform illumination by the white light projected on the object, the defocusing device operating when acquiring the images used to produce the texture images.

17. An optical 3D digitizing method for digitizing an object, comprising the steps of:

projecting white light toward the object using a single white light source, whereby the object has a fully illuminated side;

controllably producing a fringe pattern in the light projected on the object; and

capturing complementary images of the object illuminated by the white light using first and second cameras positioned aside from the white light source and aligned in angled directions with respect to each other so that the cameras have complementary fields of view directed on the illuminated side of the object and partially overlapping with each other over a depth of measurement of the object, the cameras having respective video outputs to produce video signals representing the complementary images of the object with a common image portion as a result of the fields of view being partially overlapping.

18. The optical 3D digitizing method according to claim 17, further comprising the steps of:

extracting a 3D data set per pixel from the images with structured light projection as a result of the fringe pattern being produced in the light projected on the object, the 3D data set representing a relative 3D position of each pixel in the images;

detecting encoding points laid at specific locations in the fringe pattern, the encoding points having absolute 3D positions determinable in the images captured by the cameras using experimentally predefined functions;

converting the relative 3D position of each pixel into a real 3D position using the absolute 3D position of a detected one of the encoding points;

producing texture images associated to the images captured by the cameras based on an optical intensity of the pixels defining the images; and

generating a single full digitized image of the object as a function of a predefined spatial relationship between the cameras and the real 3D position of each pixel, the texture images being integrated into the digitized image.

19. The optical 3D digitizing method according to claim 18, further comprising the steps of:

determining a mean intensity value based on the intensity of the pixels in the common image portion captured by the cameras;

determining a gain factor for each complementary image based on the mean intensity value with respect to the intensity of the pixels in the common image portion; and

applying the gain factor on a corresponding one of the texture images.

20. The optical 3D digitizing method according to claim 19, further comprising the steps of:

defocusing the white light projected on the object when acquiring the images used to produce the texture images, to suppress the fringe pattern and to provide uniform illumination by the white light projected on the object.