Raster scanning for depth detection

• US 9,147,253 B2
• Filed: 06/19/2012
• Issued: 09/29/2015
• Est. Priority Date: 03/17/2010
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Inventors: Yee, Dawson, Lutian, John
• Primary Examiner(s): RATCLIFFE, LUKE D
• Application Number:
  US13/527,203
• Publication Number:
  US 20120257020A1
• Time in Patent Office: 1,197 Days
• Field of Search: 356 301- 315, 356 401- 41, 356 501- 515, 356 6- 22, 356/28, 356/28.5, 35613901-1391
• US Class Current: 1/1
• CPC Class Codes: G01C 3/08 Use of electric radiation detectors
• CPC Class Codes: G01S 17/10 using transmission of interrupted, pulse-modulated waves determination of distance by phase measurements G01S17/32
• CPC Class Codes: G01S 17/36 with phase comparison between the received signal and the contemporaneously transmitted signal
• CPC Class Codes: G01S 17/42 Simultaneous measurement of distance and other co-ordinates indirect measurement G01S17/46
• CPC Class Codes: G01S 17/48 Active triangulation systems, i.e. using the transmission and reflection of electromagnetic waves other than radio waves
• CPC Class Codes: G01S 17/66 Tracking systems using electromagnetic waves other than radio waves
• CPC Class Codes: G01S 17/88 Lidar systems specially adapted for specific applications
• CPC Class Codes: G01S 17/89 for mapping or imaging
• CPC Class Codes: G01S 7/4817 relating to scanning
• CPC Class Codes: G06T 2207/30196 Human being; Person
• CPC Class Codes: G06T 7/521 from laser ranging, e.g. using interferometry; from the projection of structured light

Abstract

Techniques are provided for determining distance to an object in a depth camera'"'"'s field of view. The techniques may include raster scanning light over the object and detecting reflected light from the object. One or more distances to the object may be determined based on the reflected image. A 3D mapping of the object may be generated. The distance(s) to the object may be determined based on times-of-flight between transmitting the light from a light source in the camera to receiving the reflected image from the object. Raster scanning the light may include raster scanning a pattern into the field of view. Determining the distance(s) to the object may include determining spatial differences between a reflected image of the pattern that is received at the camera and a reference pattern.

Claims

1. A depth camera, comprising:

a point light source configured to emit a point of light;

a raster scanning element configured to optically communicate with the point light source;

logic configured to control the raster scanning element to raster scan the point of light from the point light source in a raster scanned pattern over a field of view of the depth camera, wherein only one point of the raster scanned pattern is projected in the field of view at any one time by the point light source;

a light detector configured to receive reflected images of the raster scanned light from an object within the field of view, the reflected images including at least a portion of the raster scanned pattern; and

logic configured to determine a distance from the depth camera to the object based on apparent deformation in the raster scanned pattern in the reflected images.

2. The depth camera of claim 1, wherein the deformation is a warping in the raster scanned pattern.

3. The depth camera of claim 1, wherein the pattern is a grid or stripe pattern, the logic that is configured to determine a distance is configured to determine a distance to the object by comparing spatial differences between received images of the grid or stripe pattern and a plurality of reference images, each of the reference images is an image that would result by raster scanning the grid or stripe pattern over a reference object at different known distances from the depth camera, each reference image contains an amount and a nature of deformation for the respective distance.

4. The depth camera of claim 1, wherein the light detector is off axis from the scanning element such that a parallax effect causes the apparent deformation of the raster scanned pattern from the vantage point of the light detector.

5. The depth camera of claim 1, wherein the logic is configured to scan the raster scanned pattern across the field of view such that all energy of the point of light is concentrated on a small point in the field of view.

6. The depth camera of claim 1, wherein an axis of illumination of the scanned light is aligned with an image axis of the reflected image.

7. The depth camera of claim 1, wherein the pattern is a grid or stripe pattern, the logic that is configured to determine a distance is configured to determine a distance to the object by determining spatial differences between a received image of the grid or stripe pattern and a reference image, the reference image is an image that would result by raster scanning the grid or stripe pattern over a reference object at a known distance from the camera.

8. The depth camera of claim 1, wherein the distance determination logic is configured to determine a depth image of the object in the field of view.

9. A method of scanning to determine depth information, the method comprising:

transmitting light from a point light source in a camera;

controlling a scanning element while transmitting the light to scan the light in a field of view of the camera, including raster scanning a raster scanned pattern in the field of view, wherein only one point of the raster scanned pattern is projected in the field of view at any one time by the point light source;

receiving reflected images from an object in the field of view of the camera while controlling the scanning element, the reflected images include at least a portion of the raster scanned pattern;

analyzing spatial properties of the received images, the spatial properties including warping in the raster scanned pattern; and

determining a distance from the camera to the object based on the warping in the raster scanned pattern.

10. The method of claim 9, wherein the receiving reflected images is at a linear array detector.

11. The method of claim 9, wherein an axis of illumination of the scanned light is aligned with an image axis of the reflected image.

12. The method of claim 9, wherein the controlling a scanning element includes determining how far to raster scan a line based on whether the object has been fully scanned.

13. The depth camera of claim 9, wherein the controlling a scanning element includes rotating the scanning element to raster scan the light into the field of view.

14. The method of claim 9, wherein:

the determining a distance from the camera to the object comprises determining the distance to the object based on differences between spatial properties of the reflected images and a plurality of reference patterns, the reference patterns are each an image that would result by raster scanning the pattern over a reference object at a known distance from the camera, each reference image contains an amount and a nature of deformation for the respective known distances.

15. The method of claim 9, wherein raster scanning the raster scanned pattern in the field of view comprises:

scanning the raster scanned pattern across the field of view such that all energy of the light from the point light source is concentrated on a small point in the field of view, wherein the received reflected images from the object have a high signal/noise ratio (S/N).

16. A depth camera, comprising:

a point light source configured to emit collimated light;

a scanning element configured to optically communicate with the point light source;

logic configured to raster scan lines of the collimated light from the point light source in a raster scanned pattern over a field of view of the depth camera, wherein only one point of the raster scanned pattern is projected in the field of view at any one time by the point light source;

a light detector configured to receive reflected images of the raster scanned light from an object within the field of view, the reflected images include at least a portion of the raster scanned pattern;

logic configured to determine multiple distances from the depth camera to the object based on spatial properties of the reflected images, the logic configured to determine is configured to compare the raster scanned pattern in the reflected images with a plurality of reference images, each of the plurality of reference images is an image that would result by raster scanning the pattern over a reference object at different distances from the depth camera, each reference image contains an amount and a nature of deformation for the respective different distances; and

logic configured to generate a 3D mapping of the object based on the multiple distances.

17. The depth camera of claim 16, wherein the logic is configured to determine an amount of deformation in the raster scanned pattern to determine the multiple distances.

18. The depth camera of claim 16, wherein the raster scanned pattern is a grid pattern.

19. The depth camera of claim 16, wherein the raster scanned pattern is a stripe pattern.