Hybrid depth detection and movement detection

1. A method for camera-based tracking of movements of a head-mounted device (HMD) in a low light environment in conjunction with determining object depth, the method being performed by the HMD, the method comprising:

at a first selected frequency, performing at least the following:

causing a flood infrared (IR) light illuminator to emit a flood of IR light into the low light environment;

causing a head tracking stereo camera pair to obtain one or more images of reflected IR light resulting from the flood of IR light and reflected visible light reflecting off of one or more objects in the low light environment, wherein the head tracking stereo camera pair includes a first camera and a second camera; and

using the one or more images to track the movements of the HMD; and

at a second selected frequency, performing at least the following:

causing a dot-pattern IR illuminator to emit a dot-pattern IR illumination onto at least a part of the low light environment;

causing the head tracking stereo camera pair to obtain one or more images of reflected dot-pattern IR light resulting from the dot-pattern illumination; and

using the one or more images of the reflected dot-pattern IR light and the reflected visible light to construct a geometric surface for at least the part of the low light environment.

2. The method of claim 1 , wherein the HMD is a virtual reality system.

3. The method of claim 1 , wherein the HMD is an augmented reality system.

4. The method of claim 1 , wherein the first selected frequency is at least 15 frames per second.

5. The method of claim 1 , wherein the second selected frequency is at least 0.5 frames per second.

6. The method of claim 1 , wherein the method further includes one or more of:

segmenting a hand of a user within the one or more images; or

using a generated 3D depth map to calculate a size and/or a pose of the user's hand.

7. The method of claim 1 , wherein the one or more images of the reflected dot-pattern IR light include an image of a hand of a user, and wherein the method further includes:

after identifying the user's hand in the one or more images of the reflected dot-pattern IR light, adjusting the second selected frequency to a higher frequency; and

track a movement of the user's hand at the higher frequency.

8. The method of claim 7 , wherein after determining that the user's hand is no longer in the one or more images of the reflected dot-pattern IR light, adjusting the second frequency to a lower frequency.

9. A head-mounted device (HMD) comprising:

one or more processors; and

one or more computer-readable hardware storage devices having stored thereon computer executable instructions that are executable by the one or more processors to cause the HMD to perform a method for tracking movements of the HMD in a low light environment in conjunction with determining object depth, wherein the method comprises:

at a first selected frequency, performing at least the following:

causing a flood infrared (IR) light illuminator to emit a flood of IR light into the low light environment;

causing a head tracking stereo camera pair to obtain one or more images of reflected IR light resulting from the flood of IR light and reflected visible light reflecting off of one or more objects in the low light environment, wherein the head tracking stereo camera pair includes a first camera and a second camera; and

using the one or more images to track the movements of the HMD; and

at a second selected frequency, performing at least the following:

causing a dot-pattern IR illuminator to emit a dot-pattern IR illumination onto at least a part of the low light environment;

causing the head tracking stereo camera pair to capture one or more images of reflected dot-pattern IR light resulting from the dot-pattern illumination and reflected visible light; and

using the one or more images of the reflected dot-pattern IR light and the reflected visible light to construct a geometric surface for at least the part of the low light environment.

10. The HMD of claim 9 , wherein the dot-pattern IR illuminator is positioned on the HMD closer to the first camera than to the second camera.

11. The HMD of claim 9 , wherein the HMD includes a second flood IR light illuminator.

12. The HMD of claim 11 , wherein the flood IR light illuminator is mounted on the HMD proximately to the first camera and the second flood IR light illuminator is mounted on the HMD proximately to the second camera.

13. The HMD of claim 9 , wherein the method further includes:

determining that at least the part of the low light environment has low texture; and

triggering the dot-pattern IR light illuminator to emit the dot-pattern illumination onto at least the part of the low light environment in response to determining that at least the part of the low light environment has low texture.

14. One or more hardware storage device(s) having stored thereon computer executable instructions that are executable by one or more processor(s) to cause a head-mounted device (HMD) to track movements of the HMD in a low light environment in conjunction with determining object depth by causing the HMD to at least perform the following:

at a first selected frequency, performing at least the following:

causing a flood infrared (IR) light illuminator to emit a flood of IR light into the low light environment;

causing a head tracking stereo camera pair to obtain one or more images of reflected IR light resulting from the flood of IR light and reflected visible light reflecting off of one or more objects in the low light environment, wherein the head tracking stereo camera pair includes a first camera and a second camera; and

using the one or more images to track the movements of the HMD; and

at a second selected frequency, performing at least the following:

causing a dot-pattern IR illuminator to emit a dot-pattern IR illumination onto at least a part of the low light environment;

causing the head tracking stereo camera pair to capture one or more images of reflected dot-pattern IR light resulting from the dot-pattern illumination and reflected visible light; and

using the one or more images of the reflected dot-pattern IR light and the reflected visible light to construct a geometric surface for at least the part of the low light environment.

15. The one or more hardware storage device(s) of claim 14 , wherein the dot-pattern IR illuminator is positioned on the HMD closer to the first camera than to the second camera.

16. The one or more hardware storage device(s) of claim 14 , wherein the HMD includes a second flood IR light illuminator.

17. The one or more hardware storage device(s) of claim 16 , wherein the flood IR light illuminator is mounted on the HMD proximately to the first camera and the second flood IR light illuminator is mounted on the HMD proximately to the second camera.

18. The one or more hardware storage device(s) of claim 14 , wherein execution of the computer-executable instructions further causes the HMD to:

determine that at least the part of the low light environment has low texture; and

trigger the dot-pattern IR light illuminator to emit the dot-pattern illumination onto at least the part of the low light environment in response to determining that at least the part of the low light environment has low texture.

19. The one or more hardware storage device(s) of claim 14 , wherein the first selected frequency is at least 15 frames per second.

20. The one or more hardware storage device(s) of claim 14 , wherein the second selected frequency is at least 0.5 frames per second.