Depth mapping using multi-beam illumination

• US 8,350,847 B2
• Filed: 01/21/2008
• Issued: 01/08/2013
• Est. Priority Date: 01/21/2007
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: PrimeSense Ltd (Apple Inc.)
• Inventors: Shpunt, Alexander
• Primary Examiner(s): Nguyen, Hau
• Assistant Examiner(s): Cain, II, Leon T
• Application Number:
  US12/522,172
• Publication Number:
  US 20100020078A1
• Time in Patent Office: 1,814 Days
• Field of Search: None
• US Class Current: 345/419
• 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: G06T 7/521 from laser ranging, e.g. using interferometry; from the projection of structured light
• CPC Class Codes: G06V 10/145 Illumination specially adapted for pattern recognition, e.g. using gratings
• CPC Class Codes: G06V 2201/12 Acquisition of 3D measurements of objects

Abstract

A method for mapping an object (28) includes illuminating the object with at least two beams (37, 38) of radiation having different beam characteristics. At least one image of the object is captured under illumination with each of the at least two beams. The at least one image is processed to detect local differences in an intensity of the illumination cast on the object by the at least two beams, and the local differences are analyzed in order to generate a three-dimensional (3D) map of the object.

Claims

1. A method for mapping an object, comprising:

illuminating the object with at least first and second beams of radiation having different beam divergence characteristics, wherein an intensity of the first beam as a function of distance from an imaging device drops at a different rate from the second beam;

capturing, using the imaging device, at least one image of the object under illumination with each of the at least first and second beams;

processing the at least one image to detect local differences in an intensity of the illumination cast on the object by the at least first and second beams; and

analyzing the local differences in order to generate a three-dimensional (3D) map of the object.

2. The method according to claim 1, wherein the at least first and second beams have different geometrical shapes.

3. The method according to claim 1, wherein the at least first and second beams have different wavelengths.

4. The method according to claim 1, wherein the at least first and second beams are configured so as to project different patterns on the object.

5. The method according to claim 1, wherein illuminating the object comprises generating the at least first and second beams using light originating from a single source.

6. The method according to claim 1, wherein illuminating the object comprises generating the at least first and second beams using light originating from different sources in different respective positions.

7. The method according to claim 6, wherein the different respective positions of the different sources are located at equal respective distances from a plane of the object.

8. The method according to claim 1, wherein capturing the at least one image comprises capturing a single image under the illumination of the at least first and second beams.

9. The method according to claim 1, wherein capturing the at least one image comprises capturing first and second images under illumination of the object by the first and second beams, respectively.

10. The method according to claim 1, wherein the first and second beams have known, respective intensity distributions I₁ (x, y, z) and I₂ (x, y, z), and wherein capturing the image comprises detecting first and second intensity patterns on the object D₁ (x, y, z) and D₂ (x, y, z) using an image capture device, wherein z is a distance from the image capture device to each point (x,y) on the object, and wherein analyzing the local differences comprises inverting an equation of a form

11. The method according to claim 1, wherein analyzing the local differences comprises processing the local differences in the intensity of the illumination cast on the object by the at least first and second beams in order to generate the 3D map while canceling ambiguity due to ambient light reflected from the object.

12. The method according to claim 11, wherein the at least first and second beams comprise three beams, and wherein canceling the ambiguity comprises using the at least one image captured under the illumination with each of the three beams to cancel the ambiguity.

13. The method according to claim 1, wherein capturing the at least one image comprises capturing a succession of images while the object is moving, and wherein analyzing the local differences comprises mapping a 3D movement of the object.

14. The method according to claim 13, wherein the object is a part of a human body, and wherein the 3D movement comprises a gesture made by the part of the human body, and wherein mapping the 3D movement comprises providing an input to a computer application responsively to the gesture.

29. The method according to claim 1, wherein illuminating the object comprises generating at least one of the beams by illuminating a diffractive optical element with a laser.

30. The method according to claim 1, wherein illuminating the object comprises generating the at least first and second beams using respective sources having different, respective areas.

31. The method according to claim 1, wherein illuminating the object comprises generating multiple first diverging beams at different angles, which together define a summed second beam, and wherein processing the at least one image comprises comparing the intensity of the illumination due to the first diverging beams to a mean intensity due to the summed second beam.

15. Apparatus for mapping an object, comprising:

an illumination assembly, which is configured to illuminate the object with at least first and second beams of radiation having different beam divergence characteristics, wherein an intensity of the first beam as a function of distance from the apparatus drops at a different rate from the second beam;

an image capture assembly, which is configured to capture at least one image of the object under illumination with each of the at least first and second beams; and

an image processor, which is configured to process the at least one image to detect local differences in an intensity of the illumination cast on the object by the at least first and second beams, and to analyze the local differences in order to generate a three-dimensional (3D) map of the object.

16. The apparatus according to claim 15, wherein the at least first and second beams have different geometrical shapes.

17. The apparatus according to claim 15, wherein the at least first and second beams have different wavelengths.

18. The apparatus according to claim 15, wherein the at least first and second beams are configured so as to project different patterns on the object.

19. The apparatus according to claim 15, wherein the illumination assembly comprises a single light source for generating the at least first and second beams.

20. The apparatus according to claim 15, wherein the illumination assembly comprises at least two different light sources in different, respective positions for respectively generating the at least first and second beams.

21. The apparatus according to claim 20, wherein the different respective positions of the different sources are located at equal respective distances from a plane of the object.

22. The apparatus according to claim 15, wherein the image capture assembly is configured to capture a single image under the illumination of the at least first and second beams, and wherein the image processor is configured to process the single image in order to generate the 3D map.

23. The apparatus according to claim 15, wherein the image capture assembly is configured to capture first and second images under illumination of the object by the first and second beams, respectively, and wherein the image processor is configured to generate the 3D map by processing the first and second images.

24. The apparatus according to claim 15, wherein the at least first and second beams have known, respective intensity distributions I₁ (x, y, z) and I₂ (x, y, z), and wherein the image capture device is configured to detect first and second intensity patterns on the object D₁ (x, y, z) and D₂ (x, y, z), wherein z is a distance from the image capture device to each point (x,y) on the object, and wherein the image processor is configured to invert an equation of a form

25. The apparatus according to claim 15, wherein the image processor is configured to analyze the local differences in the intensity of the illumination cast on the object by the at least first and second beams in order to generate the 3D map while canceling ambiguities due to ambient light reflected from the object.

26. The apparatus according to claim 25, wherein the at least first and second beams comprise three beams, and wherein the image processor is configured to use the at least one image captured under the illumination with each of the three beams to cancel the ambiguity.

27. The apparatus according to claim 15, wherein the image processor is configured to process a succession of images captured while the object is moving so as to map a 3D movement of the object.

28. The apparatus according to claim 27, wherein the object is a part of a human body, and wherein the 3D movement comprises a gesture made by the part of the human body, and wherein the image processor is coupled to provide an input to a computer application responsively to the gesture.

32. The apparatus according to claim 15, wherein the illumination assembly comprises a diffractive optical element and a laser, which is configured to generate at least one of the beams by illuminating the diffractive optical element.

33. The apparatus according to claim 15, wherein the illumination assembly comprises at least two sources having different, respective areas, which respectively generate the at least first and second beams.

34. The apparatus according to claim 15, wherein the illumination assembly is configured to generate multiple first diverging beams at different angles, which together define a summed second beam, and wherein the image processor is configured to compare the intensity of the illumination due to the first diverging beams to a mean intensity due to the summed second beam.