Structured-light, triangulation-based three-dimensional digitizer

• US 6,549,288 B1
• Filed: 05/14/1999
• Issued: 04/15/2003
• Est. Priority Date: 05/14/1998
• Status: Expired due to Term

• Current Assignee: Andreas Acquisitions, LLC
• Original Assignee: Viewpoint Mhc
• Inventors: Petrov, Michael, Abadjev, Vadim, Lebedev, Alexei, Migdal, Alexander, Shelyekhova, Veronika, Bernstein, Vladimir, Afanassenkov, Andrei
• Primary Examiner(s): SMITH, ZANDRA V
• Application Number:
  US09/312,447
• Time in Patent Office: 1,432 Days
• Field of Search: 356/601, 356/602, 356/603, 356/604, 356/605, 382/154, 250/237.2, 250/559.23
• 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: G01B 11/2509 Color coding
• CPC Class Codes: G01B 11/30 for measuring roughness or irregularity of surfaces
• CPC Class Codes: G06T 7/521 from laser ranging, e.g. using interferometry; from the projection of structured light

Abstract

The present invention provides a system for illuminating an object with a special kind of structured light pattern, recording the shape of the reflected points of light by means of a camera, and, by a triangulation technique that does not depend on the fixed direction of the light source relative to the camera, reconstructing the 3D shape of the object through a computer using the data points collected from the reflection of the structured light pattern. The scanning system is portable and does not require data processing contemporaneous with the data collection. The portable system stores in the storage media several images of the objects with different illumination patterns. The data is subsequently processed, by a computer system which applies data processing routines, i.e., the model building algorithms which provide 3D surface generation. The data acquisition according to the present invention is simplified to acquiring of only two or, optionally, four images of the object, thereby significantly increasing the digitization speed over that of laser-based scanners. The light source projects both structured light and uniform illumination light from the same apparent source, and that allows for numerical normalization of the images.

Claims

1. A system for determining a three dimensional profile of an object comprising:

a first light-source unit configured to project a structured light pattern on the object and configured to uniformly illuminate the object; and

an image-detecting device configured to detect a sequence of images, the sequence of images including at least one structured light pattern image and at least one uniform illumination image;

wherein said structured light pattern comprises a plurality of light stripes, having a gradual variation in intensity of light, and wherein said image-capturing device is located relative to said first light-source unit at a known position, and wherein depth coordinates corresponding to two-dimensional coordinates of detected light stripes in each image are calculable by triangulation based on an angle of approach of each of said light stripes onto said object, whereby a plurality of three-dimensional coordinates representative of said three-dimensional profile of said object are determined.

2. The system according to claim 1, wherein said plurality of light stripes comprises light stripes of at least two different colors.

3. The system according to claim 2 further comprising a second light-source unit located symmetrically opposite to said first light-source unit and having a positional relationship with respect to said detector which mirrors the positional relationship between said first light-source unit and said detector.

4. The system according to claim 3, wherein said structured light pattern and light to uniformly illuminate the object are emitted from the same apparent optical source position.

5. A system for determining a three dimensional profile of an object comprising:

a first light-source unit for projecting a structured light pattern and a uniform illumination pattern for illumination of the object;

a second light-source unit located symmetrically opposite to said first light-source unit and having a positional relationship with respect to said detector which mirrors the positional relationship between said first light-source unit and said detector; and

an image-detecting device for detecting a sequence of images containing at least one of a structured light pattern image and a uniform illumination pattern image;

wherein said structured light pattern comprises a plurality of light stripes each having a gradual variation in intensity of light, and wherein said image-capturing device is located relative to said first light-source unit at a known position, and wherein depth coordinates corresponding to two-dimensional coordinates of detected light stripes in each image are calculable by triangulation based on an angle of approach of each of said light stripes onto said object, whereby a plurality of three-dimensional coordinates representative of said three-dimensional profile of said object are determined,

wherein said plurality of light stripes comprises light stripes of at least two different colors,

wherein said structured light pattern and uniform illumination pattern are emitted from the same apparent optical source position, and

wherein said first light-source unit and said second light-source unit each comprises two photographic flashes, and wherein said structured light pattern and said uniform illumination pattern are combined through a semitransparent mirror for each of said first light-source unit and said second light-source unit.

6. A system for determining a three dimensional profile of an object comprising:

a first light-source unit for projecting a structured light pattern and a uniform illumination pattern for illumination of the object;

a second light-source unit located symmetrically opposite to said first light-source unit and having a positional relationship with respect to said detector which mirrors the positional relationship between said first light-source unit and said detector; and

an image-detecting device for detecting a sequence of images containing at least one of a structured light pattern image and a uniform illumination pattern image;

wherein said structured light pattern comprises a plurality of light stripes each having a gradual variation in intensity of light, and wherein said image-capturing device is located relative to said first light-source unit at a known position, and wherein depth coordinates corresponding to two-dimensional coordinates of detected light stripes in each image are calculable by triangulation based on an angle of approach of each of said light stripes onto said object, whereby a plurality of three-dimensional coordinates representative of said three-dimensional profile of said object are determined,

wherein said plurality of light stripes comprises light stripes of at least two different colors,

wherein said structured light pattern and uniform illumination pattern are emitted from the same apparent optical source position, and

wherein the image containing the structured light pattern is normalized by using the image containing uniform illumination pattern.

7. A system for determining a three dimensional profile of an object comprising:

a first light-source unit for projecting a structured light pattern and a uniform illumination pattern for illumination of the object; and

an image-detecting device for detecting a sequence of images containing at least one of a structured light pattern image and a uniform illumination pattern image;

wherein said structured light pattern comprises a plurality of light stripes each having a gradual variation in intensity of light, and wherein said image-capturing device is located relative to said first light-source unit at a known position, and wherein depth coordinates corresponding to two-dimensional coordinates of detected light stripes in each image are calculable by triangulation based on an angle of approach of each of said light stripes onto said object, whereby a plurality of three-dimensional coordinates representative of said three-dimensional profile of said object are determined,

wherein said plurality of light stripes comprises light stripes of at least two different colors, and

wherein said first light-source unit comprises two photographic flashes, and wherein said structured light pattern and said uniform illumination pattern are combined through a semitransparent mirror.

8. A system for determining a three dimensional profile of an object comprising:

a first light-source unit for projecting a structured light pattern and a uniform illumination pattern for illumination of the object;

a second light-source unit located symmetrically opposite to said first light-source unit and having a positional relationship with respect to said detector which mirrors the positional relationship between said first light-source unit and said detector; and

an image-detecting device for detecting a sequence of images containing at least one of a structured light pattern image and a uniform illumination pattern image;

wherein depth coordinates corresponding to two-dimensional coordinates of detected light stripes in each image are calculable by triangulation based on an angle of approach of each of said light stripes onto said object, whereby a plurality of three-dimensional coordinates representative of said three-dimensional profile of said object are determined, and

wherein said first light-source unit and said second light-source unit each comprises two photographic flashes, and wherein said structured light pattern and said uniform illumination pattern are combined through a semitransparent mirror for each of said first light-source unit and said second light-source unit.

9. A system for determining a three dimensional profile of an object comprising:

a first light-source unit for projecting a structured light pattern and a uniform illumination pattern for illumination of the object;

an image-detecting device for detecting a sequence of images containing at least one of a structured light pattern image and a uniform illumination pattern image;

wherein said structured light pattern comprises a plurality of light stripes, and wherein depth coordinates corresponding to two-dimensional coordinates of detected light stripes in each image are calculable by triangulation based on an angle of approach of each of said light stripes onto said object, whereby a plurality of three-dimensional coordinates representative of said three-dimensional profile of said object are determined;

wherein the image containing the structured light pattern is normalized by using the image containing uniform illumination pattern.

10. A system for determining a three dimensional profile of an object comprising:

a first light-source unit for projecting a structured light pattern and a uniform illumination pattern for illumination of the object; and

an image-detecting device for detecting a sequence of images containing at least one of a structured light pattern image and a uniform illumination pattern image;

wherein said structured light pattern comprises a plurality of light stripes, and wherein depth coordinates corresponding to two-dimensional coordinates of detected light stripes in each image are calculable by triangulation based on an angle of approach of each of said light stripes onto said object, whereby a plurality of three-dimensional coordinates representative of said three-dimensional profile of said object are determined,

wherein said first light-source unit comprises two photographic flashes, and wherein said structured light pattern and said uniform illumination pattern are combined through a semitransparent mirror.

11. A method for determining a three dimensional profile of an object, comprising:

projecting a structured light pattern on an object, the structured light pattern including a plurality of stripes;

capturing a structured light pattern image of the object;

uniformly illuminating the object;

capturing a uniform illumination image of the object;

determining three-dimensional coordinates representative of the three-dimensional profile of the object as a function of the structured light pattern image; and

determining a texture of the object as a function of at least the uniform illumination image.

12. The method according to claim 11, further comprising:

determining a model of the object using the three-dimensional coordinates and the texture of the object.

13. The method according to claim 12, further comprising:

displaying the model on a display device.

14. The method according to claim 11, wherein each one of the light stripes has a gradual variation of light intensity within the one of the light stripes.

15. The method of claim 11, wherein said plurality of light stripes comprises light stripes of at least two different colors.

16. The method of claim 11, further comprising:

normalizing the structured light pattern image using the uniform illumination image.

17. The method of claim 11, wherein the projecting the structured light pattern step includes projecting the structured light pattern from the same apparent optical source as that which uniformly illuminates the object.

18. A method for determining a three dimensional profile of an object using an image capturing device located at a known position relative to two light sources comprising:

capturing a first image of the object while a structured light pattern including a plurality of light stripes is projected on the object from the first light source;

capturing a second image of the object while a uniform illumination pattern is projected on the object from the first light source;

capturing a third image of the object while a structured light pattern including a plurality of light stripes is projected on the object from the second light source;

capturing a fourth image of the object while a uniform illumination pattern is projected on the object from the second light source;

calculating, by triangulation based on an angle of approach of each of said light stripes, depth coordinates corresponding to two-dimensional coordinates of detected light stripes in the first and third captured images; and

determining a plurality of three-dimensional coordinates representative of said three-dimensional profile of said object based on the two-dimensional coordinates of light stripes in the first and third captured images and corresponding calculated depth coordinates.

19. The method of claim 18, wherein said plurality of light stripes comprises light stripes of at least two different colors.

20. The method of claim 18, further comprising:

normalizing the first captured image using the second captured image.

21. The method of claim 18, further comprising:

reconstructing a texture of the object based on the second and fourth captured images.

22. The method of claim 21, wherein the reconstructing step is performed using the Torrance-Sparrow model.