Auto range control for active illumination depth camera

Patent metadata

Field	Value
Publication number	US-9800795-B2
Application number	US-201514977140-A
Country	US
Kind code	B2
Filing date	Dec 21, 2015
Priority date	Dec 21, 2015
Publication date	Oct 24, 2017
Grant date	Oct 24, 2017

Abstract

A method and apparatus for auto range control are described. In one embodiment, the apparatus comprises a projector configured to project a sequence of light patterns on an object; a first camera configured to capture a sequence of images of the object illuminated with the projected light patterns; a controller coupled to the projector and first camera and operable to receive the sequence of images and perform range control by controlling power of the sequence of light patterns being projected on the object and exposure time of a camera based on information obtained from the sequence of images captured by the camera.

First claim

We claim:

1. An apparatus comprising:
a projector configured to project a sequence of light patterns on an object;
a camera configured to capture a sequence of images of the object illuminated with the projected light patterns; and
a controller coupled to the projector and the camera and operable to receive the sequence of images and perform range control by controlling power of the sequence of light patterns being projected on the object and exposure time of the camera based on information obtained from the sequence of images captured by the camera.

2. The apparatus defined in claim 1 wherein the information comprises intensity information associated with the sequence of images captured by the camera.

3. The apparatus defined in claim 2 wherein the intensity information comprises an average intensity determined by averaging intensity values of one image that results from taking a difference between intensity values of images captured by the camera.

4. The apparatus defined in claim 1 wherein the controller is operable to control depth dynamic range by decreasing the projector power if average intensity between the sequence of images captured by the camera is above a first threshold and the camera exposure is set to a preset minimal value and decreasing the exposure of the camera if the average intensity between the sequence of images captured by the camera is above the first threshold and the camera exposure is not set to the preset minimal value.

5. The apparatus defined in claim 4 wherein the controller is operable to control depth dynamic range by increasing the camera exposure of the camera if average intensity between the sequence of images captured by the camera is below a second threshold and the projector power is set to a preset minimal value and increasing the projector power if average intensity between the sequence of images captured by the camera is below the second threshold and the projector power is not set to the present minimal value, wherein the first and second thresholds are not the same.

6. The apparatus defined in claim 1 wherein the controller is operable to control power of the sequence of light patterns being projected on the object and exposure time of the camera based on information obtained from the sequence of images captured by the camera by performing automatic projector gain and automatic exposure control based on object intensity.

7. The apparatus defined in claim 6 wherein performing automatic projector gain and automatic exposure control comprises activating automatic projector gain when object intensity associated with the object increases and increasing projector gain as the object intensity decreases until the object intensity reaches a preset maximum value, and when the object intensity reaches the preset maximum value, then activating the automatic exposure control until a preset minimum value is reached after which time the automatic projector gain is activated.

8. The apparatus defined in claim 1 wherein the controller reconstructs depth using triangulation.

9. The apparatus defined in claim 1 wherein the projector comprises an infrared (IR) projector and the camera comprises an IR camera.

10. A method comprising:
projecting a sequence of light patterns on an object using a projector;
capturing a sequence of images of the object illuminated with the projected light patterns using a camera; and
controlling depth dynamic range by controlling power of the sequence of light patterns being projected on the object and exposure time of the camera based on information obtained from the sequence of images captured by the camera.

11. The method defined in claim 10 wherein the information comprises intensity information associated with the sequence of images captured by the camera.

12. The method defined in claim 11 wherein the intensity information comprises an average intensity determined by averaging intensity values of one image that results from taking a difference between intensity values of images captured by the camera.

13. The method defined in claim 10 wherein controlling depth dynamic range comprises decreasing the projector laser power if average intensity between the sequence of images captured by the camera is above a first threshold and the camera exposure is set to a preset minimal value and decreasing the exposure of the camera if the average intensity between the sequence of images captured by the camera is above the first threshold and the camera exposure is not set to the preset minimal value.

14. The method defined in claim 13 wherein controlling depth dynamic range comprises increasing the camera exposure of the camera if average intensity between the sequence of images captured by the camera is below a second threshold and the projector power is set to a preset minimal value and increasing the projector power if average intensity between the sequence of images captured by the camera is below the second threshold and the projector power is not set to the present minimal value, wherein the first and second thresholds are not the same.

15. The method defined in claim 10 wherein controlling depth dynamic range by controlling power of the sequence of light patterns being projected on the object and exposure time of the camera based on information obtained from the sequence of images captured by the camera comprises performing automatic projector gain and automatic exposure control based on object intensity.

16. The method defined in claim 15 wherein performing automatic projector gain and automatic exposure control comprises activating automatic projector gain when object intensity associated with the object increases and increasing projector gain as the object intensity decreases until the object intensity reaches a preset maximum value, and when the object intensity reaches the preset maximum value, then activating the automatic exposure control until a preset minimum value is reached after which time the automatic projector gain is activated.

17. The method defined in claim 10 wherein the power of the sequence of light patterns comprises laser power and the projector comprises an infrared (IR) projector.

18. An article of manufacture having one or more non-transitory computer readable storage media storing instructions which when executed by a system perform a method comprising:
capturing, using a camera, a sequence of images of an object illuminated with projected light patterns on an object using a projector; and
controlling depth dynamic range by controlling power of the sequence of light patterns being projected on the object and exposure time of the camera based on intensity information obtained from the sequence of images captured by the camera.

19. The article of manufacture defined in claim 18 wherein the intensity information comprises an average intensity determined by averaging intensity values of one image that results from taking a difference between intensity values of images captured by the camera.

20. The article of manufacture defined in claim 18 wherein controlling depth dynamic range comprises:
decreasing the projector laser power if average intensity between the sequence of images captured by the camera is above a first threshold and the exposure of the camera is set to a preset minimal value;
decreasing the exposure of the camera if the average intensity between the sequence of images captured by the camera is above the first threshold and the exposure of the camera is not set to the preset minimal value;
increasing the exposure of

Assignees

• Intel Corp

Inventors

• Zabatani Aviad
• Sperling Erez
• Mulla Ofir
• Kimmel Ron
• Bronstein Alex
• Bronstein Michael
• Silver David H
• Menashe Ohad
• Surazhsky Vitaly

Classifications

• G01B11/25

  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 title

• H04N23/73

  by influencing the exposure time · CPC title

• H04N23/741

  by increasing the dynamic range of the image compared to the dynamic range of the electronic image sensors · CPC title

• H04N23/56

  provided with illuminating means · CPC title

• H04N23/74 Primary

  by influencing the scene brightness using illuminating means · CPC title