DEPTH MEASUREMENT USING MULTIPLE PULSED STRUCTURED LIGHT PROJECTORS
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.
1 . A depth measurement assembly (DMA) comprising:
a pulsed illuminator assembly comprising at least two structured light projectors, wherein each of the structured light projectors are configured to project pulses of structured light at a pulse rate into a local area at different times 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 and, 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 structure light source, 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 structured light projectors illuminate at least two objects in the local area, the depth camera captures image data for each of the objects, and the controller determines depth information for each of the objects.
3 . The DMA of claim 3 , wherein the captured image data comprises separate image data for each structured light projector.
4 . The DMA of claim 3 , wherein the captured image data comprises combined image data for all the structured light projectors.
5 . 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.
6 . The DMA of claim 5 , wherein the detector comprises a plurality of photodiodes, each photodiodes comprising at least two storage regions.
7 . The DMA of claim 5 , 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.
8 . The DMA of claim 7 , wherein the detector comprises a tunable filter that is inactive during each exposure duration and active outside exposure durations of the detector.
9 . The DMA of claim 7 , wherein the exposure duration is 20% longer than the duration of the pulse.
10 . The DMA of claim 1 , wherein each structured light projector includes a pulsed illuminator, a diffractive optical element, and a projection assembly.
11 . The DMA of claim 7 , wherein the pulses of structured light projected by each structured light projector are formed by interference of two or more beams of pulsed light.
12 . The DMA of claim 1 , wherein the structured light projectors alternatively projects pulses of structured light.
13 . 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.
14 . 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.
15 . 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.
16 . 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.
17 . The DMA of claim 1 , wherein the controller is further configured to use triangulation calculation to obtain a depth map of the local area.
18 . The DMA of claim 1 , wherein the depth instructions comprise one or more pulse parameters for the structured light projector.
19 . 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
20 . The DMA of claim 1 , wherein the depth instructions comprise an exposure rate and an exposure duration.
21 . The DMA of claim 19 , wherein the exposure rate equals the pulse rate of the pulsed illuminator assembly.