DEPTH MEASUREMENT USING A PULSED STRUCTURED LIGHT PROJECTOR

• US 20190072770A1
• Filed: 09/05/2017
• Published: 03/07/2019
• Est. Priority Date: 09/05/2017
• Status: Active Grant

• Current Assignee: META Platforms Technologies LLC (Meta Platforms, Inc. (f/k/a Facebook, Inc.))
• Original Assignee: Facebook Technologies, LLC (Meta Platforms, Inc. (f/k/a Facebook, Inc.))
• Inventors: Hall, Michael
• Granted Patent: US 10,962,790 B2
• Time in Patent Office: Days
• CPC Class Codes: G01B 11/22 for measuring depth
• CPC Class Codes: G01B 11/2513 with several lines being projected in more than one direction, e.g. grids, patterns
• CPC Class Codes: G01B 5/0014 due to temperature on machine tools B23Q11/0003
• CPC Class Codes: G02B 2027/0138 comprising image capture systems, e.g. camera
• CPC Class Codes: G02B 27/0176 characterised by mechanical features
• CPC Class Codes: G06T 19/006 Mixed reality object pose determination, tracking or camera calibration for mixed reality G06T7/00
• CPC Class Codes: G06T 7/507 from shading G06T7/586 takes precedence
• CPC Class Codes: H04N 13/25 using two or more image sensors with different characteristics other than in their location or field of view, e.g. having different resolutions or colour pickup characteristics; using image signals from one sensor to control the characteristics of another sensor

Abstract

A depth measurement assembly (DMA) includes a pulsed illuminator assembly, a depth camera assembly, and a controller. The pulsed illuminator assembly has a structured light projector that projects pulses of structured light at a pulse rate into a local area. The depth camera assembly captures images data of an object in the local area illuminated with the pulses of structured light. An exposure interval of the depth camera assembly is pulsed and synchronized to the pulses projected by the pulsed illuminator assembly. The controller controls the pulsed illuminator assembly and the depth camera assembly so that they are synchronized. The controller also determine depth and/or tracking information of the object based on the captured image data. In some embodiments, the pulsed illuminator assembly have a plurality of structured light projectors that projects pulses of structured light at different times.

Claims

1. A depth measurement assembly (DMA) comprising:

a pulsed illuminator assembly configured to project pulses of structured light at a pulse rate into a local area in accordance with depth instructions;

a depth camera assembly configured to capture image data of a portion of the local area illuminated with the pulses of structured light in accordance with depth instructions, wherein an exposure interval of the depth camera is pulsed and synchronized to the projected pulses;

a controller configured to;

generate the depth instructions;

provide the depth instructions to the depth camera and the structured light projector, and

determine depth information of an object in the local area based in part on the image data.

2. The DMA of claim 1, wherein the depth camera comprises a detector configured to collect pulses of structured light reflected from the object in synchronization with pulse emission of the structured light projector.

3. The DMA of claim 2, wherein the detector comprises a plurality of photodiodes, each photodiodes comprising at least two storage regions.

4. The DMA of claim 2, wherein for each pulse of structured light, the detector is configured to take one or more exposures during an exposure duration same as or longer than duration of the pulse.

5. The DMA of claim 4, wherein the detector comprises a tunable filter that is inactive during each exposure duration and active outside exposure durations of the detector.

6. The DMA of claim 4, wherein the exposure duration is longer than the duration of the pulse.

7. The DMA of claim 1, wherein the pulsed illuminator assembly comprises a single structured light projectors configured to project pulses of structured light in to the portion of the local area in accordance with depth instructions.

8. The DMA of claim 7, wherein the structured light projector includes a pulsed illuminator, a diffractive optical element, and a projection assembly.

9. The DMA of claim 7, wherein the pulses of structured light are formed by interference of two or more beams of pulsed light.

10. The DMA of claim 1, wherein the pulsed illuminator assembly comprises at least two structured light projectors configured to project pulses of structured light in to the portion of the local area at different times in accordance with depth instructions.

11. The DMA of claim 1, wherein the structured light projectors alternatively projects pulses of structured light.

12. The DMA of claim 1, wherein the pulses emitted by the pulsed illuminator assembly have a frequency in a range from 100 kHz to 200 MHz.

13. The DMA of claim 1, wherein the pulses emitted by the pulsed illuminator assembly have a pulse duration in a range from 100 ps to 100 ns.

14. The DMA of claim 1, wherein the controller is configured to determine the depth information based on phase-shifted patterns of the portions of the reflected structured light distorted by shapes of the objects in the local area.

15. The DMA of claim 1, wherein the controller is configured to determine the depth information using a ratio of charge between storage regions associated with each photodiode of the depth camera assembly.

16. The DMA of claim 1, wherein the controller is further configured to use triangulation calculation to obtain a depth map of the local area.

17. The DMA of claim 1, wherein the depth instructions comprise one or more pulse parameters for the structured light projector.

18. The DMA of claim 17, wherein the one or more pulse parameters include pulse rate, pulse length, pulse wavelength, pulse amplitude, some other parameter that controls how the pulses of structured light are projected by the pulsed illuminator assembly, or some combination thereof.

19. The DMA of claim 1, wherein the depth instructions comprise an exposure rate and an exposure duration.

20. The DMA of claim 19, wherein the exposure rate equals the pulse rate of the pulsed illuminator assembly.