Three-dimensional surface profile imaging method and apparatus using single spectral light condition

• US 6,556,706 B1
• Filed: 01/26/2001
• Issued: 04/29/2003
• Est. Priority Date: 01/28/2000
• Status: Expired due to Fees

• Current Assignee: Technest Holdings, Inc. (AccelPath, Inc.)
• Original Assignee: Geng Z. Jason
• Inventors: Geng, Z. Jason
• Primary Examiner(s): Johnson, Timothy M.
• Assistant Examiner(s): Tabatabai, Abolfazl
• Application Number:
  US09/770,124
• Time in Patent Office: 823 Days
• Field of Search: 382/154, 382/190, 382/163, 382/164, 382/165, 382/104, 348/47, 348/154, 356/357, 356/376, 356/606
• US Class Current: 382/154
• CPC Class Codes: G01B 11/2509 Color coding
• CPC Class Codes: G01S 17/89 for mapping or imaging

Abstract

A three-dimensional surface profile imaging method and system uses a single spectral light illumination constraint to guarantee consistent RGB values corresponding to a given light spectrum, regardless of the surface reflectance characteristics of the object being imaged. In one embodiment, each light sheet projected onto the object contains only a single wavelength. As a result, the spectral composition of the projected light at any surface point of the object will be independent of the light intensity and the reflectance characteristics of the surface.

Claims

1. A device for creating a three-dimensional profile of an object or scene being imaged, the device comprising:

a light source for illuminating said object or scene with a light pattern having at least one light plane, wherein said light pattern varies in wavelength spatially across said object or scene, and wherein said at least one light plane corresponds to at least one angle at which light of that wavelength is emitted by said light source and contains only a single spectral component;

a camera for imaging said object or scene as illuminated with said light pattern; and

a processor for calculating a distance to a point on said object or in said scene based on a baseline distance between said light source and said camera, an angle between said camera and said baseline, and an angle at which light striking the point is emitted by said light source as determined from red/green/blue (RGB) values corresponding to the wavelength of the light striking the point.

2. The device of claim 1, wherein the single spectral component is based on a light intensity value of the light source and the wavelength emitted by said light source.

3. The device of claim 2, wherein the RGB values depend on a sensitivity function of the camera and are independent of the light intensity of the light source and a surface reflectance of the object or scene.

4. The device of claim 1, wherein said light pattern varies over a visible light spectrum.

5. The device of claim 1, wherein said light pattern varies over an infrared light spectrum.

6. The device of claim 1, wherein said light pattern varies over an ultraviolet light spectrum.

7. The device of claim 1, wherein the processor calculates the distance to the point by triangulation of the baseline distance between said light source and said camera, the angle between said camera and said baseline, and the angle at which light striking the point is emitted by said light source.

8. A device for creating a three-dimensional profile of an object or scene being imaged, the device comprising:

a light source for illuminating said object or scene with a light pattern having a plurality of light planes, wherein said light pattern varies in wavelength spatially across said object or scene, and wherein each of said plurality of light planes corresponds to at least one angle at which light of that wavelength is emitted by said light source and contains only a single spectral component, the single spectral component being based on a light intensity value of the light source and the wavelength emitted by said light source for one of said light planes;

a camera for imaging said object or scene as illuminated with said light pattern; and

a processor for calculating a distance to a point on said object or in said scene using triangulation based on a baseline distance between said light source and said camera, an angle between said camera and said baseline, and an angle at which light striking the point is emitted by said light source as determined from red/green/blue (RGB) values corresponding to the wavelength of the light striking the point, wherein the RGB values depend on a sensitivity function of the camera and are independent of the light intensity of the light source and a surface reflectance of the object or scene.

9. The device of claim 8, wherein said light pattern varies over a visible light spectrum.

10. The device of claim 8, wherein said light pattern varies over an infrared light spectrum.

11. The device of claim 8, wherein said light pattern varies over an ultraviolet light spectrum.

12. A method for creating a three-dimensional profile of an object or scene being imaged, the method comprising the steps of:

illuminating the object or scene with a light pattern having a plurality of light planes, wherein said light pattern varies in wavelength spatially across said object or scene, and wherein said at least one light plane corresponds to at least one angle at which light of that wavelength is emitted and contains only a single spectral component;

imaging said object or scene as illuminated in said illuminating step;

calculating a distance to a point on said object or in said scene using triangulation based on a baseline distance between said light source and said camera, an angle between said camera and said baseline, and an angle at which light striking the point is emitted by said light source as determined from red/green/blue (RGB) values corresponding to the wavelength of the light striking the point.

13. The method of claim 12, wherein the RGB values depend on a sensitivity function of the camera and are independent of the light intensity of the light source and a surface reflectance of the object or scene.

14. The method of claim 12, wherein the illuminating step varies the light pattern over a visible light spectrum.

15. The method of claim 12, wherein the illuminating step varies the light pattern over an infrared light spectrum.

16. The method of claim 12, wherein the illuminating step varies the light pattern over an ultraviolet light spectrum.