PLURAL DETECTOR TIME-OF-FLIGHT DEPTH MAPPING

• US 20120154542A1
• Filed: 12/20/2010
• Published: 06/21/2012
• Est. Priority Date: 12/20/2010
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Katz, Sagi, Adler, Avishai, Yahav, Giora, Tardif, John
• Granted Patent: US 8,803,952 B2
• Time in Patent Office: Days
• US Class Current: 348/47
• CPC Class Codes: A63F 13/213 comprising photodetecting means, e.g. cameras, photodiodes or infrared cells A63F13/219, A63F13/655 take precedence
• CPC Class Codes: A63F 13/235 using a wireless connection, e.g. infrared or piconet
• CPC Class Codes: A63F 13/52 involving aspects of the displayed game scene
• CPC Class Codes: A63F 2300/1031 using a wireless connection, e.g. Bluetooth, infrared connections
• CPC Class Codes: A63F 2300/1087 comprising photodetecting means, e.g. a camera
• CPC Class Codes: A63F 2300/66 for rendering three dimensional images
• CPC Class Codes: G01S 17/87 Combinations of systems using electromagnetic waves other than radio waves
• CPC Class Codes: G01S 17/894 3D imaging with simultaneous measurement of time-of-flight at a 2D array of receiver pixels, e.g. time-of-flight cameras or flash lidar

Abstract

A depth-mapping method comprises exposing first and second detectors oriented along different optical axes to light dispersed from a scene, and furnishing an output responsive to a depth coordinate of a locus of the scene. The output increases with an increasing first amount of light received by the first detector during a first period, and decreases with an increasing second amount of light received by the second detector during a second period different than the first.

Claims

1. A depth-mapping method comprising:

exposing first and second detectors oriented along different optical axes to light dispersed from a scene; and

furnishing an output that increases with an increasing first amount of light received by the first detector during a first period, and decreases with an increasing second amount of light received by the second detector during a second period.

2. The method of claim 1, wherein the scene includes a plurality of loci, and wherein the output is one of a plurality of outputs corresponding to the plurality of loci, each output indicating a depth of a corresponding locus.

3. The method of claim 2, wherein the first detector forms a first image of the scene and the second detector forms a second image of the scene, wherein the first and second images each comprise a rectangular array of pixels, and wherein the first and second periods overlap and differ in duration.

4. The method of claim 3, wherein the first amount of light is a brightness integrated at a first pixel of the first image, wherein the second amount of light is a brightness integrated at a second pixel of the second image, the method further comprising:

enumerating a series of candidate pixels of the second image; and

selecting the second pixel from the series of candidate pixels so that the output indicates a depth of a locus most closely mappable to the first and second pixels.

5. The method of claim 4, wherein enumerating the series of candidate pixels comprises, for each of a corresponding series of candidate depths spanning the scene:

projecting the first pixel to 3D coordinates based on first-detector geometry; and

collapsing the 3D coordinates to define a candidate pixel of the second image based on second-detector geometry.

6. The method of claim 4 further comprising:

for the depth indicated by the output;

projecting the first pixel to 3D coordinates based on first-detector geometry; and

collapsing the 3D coordinates to define a refined second pixel of the second image based on second-detector geometry; and

recomputing the output, using, as the second amount of light, a brightness integrated at the refined second pixel of the second image.

7. The method of claim 6 further comprising repeating said projecting, collapsing, and recomputing for a finite number of iterations, or until the output has converged.

8. The method of claim 7 further comprising invalidating the output if the output does not converge in the finite number of iterations.

9. The method of claim 4, wherein the output varies substantially linearly with a ratio of the first amount of light to the second amount of light.

10. The method of claim 4 further comprising directing pulsed illumination to the scene.

11. The method of claim 4 further comprising invalidating the output when the locus most closely mappable to the first and second pixels is outside of a predefined range.

12. The method of claim 11, wherein the predefined range is defined based in part on an indicated depth of a neighboring locus of the scene.

13. The method of claim 3 further comprising aligning the second image to the first image.

14. The method of claim 2, wherein a shallowest locus of the scene is more than one meter from the first detector, and a deepest locus of the scene is less than ten meters from the first detector.

15. A vision system comprising:

a modulated illumination source configured to illuminate a scene;

first and second detectors oriented along different optical axes and arranged to detect light dispersed from the scene;

a controller operatively coupled to the first and second detectors and to the source, and configured to furnish an output that increases with an increasing first amount of light received by the first detector during a first period, and decreases with an increasing second amount of light received by the second detector during a second period.

16. The system of claim 15, wherein the source is pulse-modulated with a pulse-width of fifteen to twenty nanoseconds.

17. The system of claim 15, wherein the source comprises one or more of an infrared or near-infrared light-emitting diode and a laser.

18. The system of claim 15, wherein the first and second detectors are adjacent or separated by two to twenty centimeters.

19. A depth-mapping method comprising:

directing pulsed illumination to a scene, the scene including a plurality of loci;

exposing first and second detectors oriented along different optical axes to light dispersed from the scene;

forming a first image of the scene at a first detector and a second image of the scene at a second detector, the first and second images each comprising a rectangular array of pixels.

furnishing an output indicating a depth of one locus of the scene, the output increasing with an increasing brightness integrated at a first pixel of the first image during a first period, and decreasing with an increasing brightness integrated at a second pixel of the second image during an overlapping second period longer than the first,

wherein the second pixel is selected from a series of candidate pixels of the second image so that the output indicates a depth of a locus most closely mappable to the first and second pixels, and

wherein the series of candidate pixels is derived from a corresponding series of candidate depths spanning the scene by projecting the first pixel to 3D coordinates based on first-detector geometry and collapsing the 3D coordinates to define a candidate pixel of the second image based on second-detector geometry.

20. The method of claim 19, wherein the first and second images are formed from light of the same illumination pulse.