Depth sensing using optical pulses and fixed coded aperature
View Patent ↗In a system and method for reconstructing a scene, a light source transmits an optical pulse unto the scene, and a set of sensors receive a reflected pulse to acquire sensed signals corresponding to the optical pulse. There is a fixed coded aperture in an optical path between the light source and set of sensors. Then, a processor performs a method to reconstruct the scene as a three-dimensional (3D) depth map using a scene model.
1. A system for reconstructing a scene, comprising:
a light source configured to transmit an optical pulse unto the scene;
a set of sensors configured to receive a reflected pulse to acquire sensed signals according to a time profile of the reflected pulse, corresponding to the optical pulse;
a fixed coded aperture in an optical path between the scene and set of sensors; and
a processor, connected to the light source and the set of sensors, configured to perform a method to reconstruct the scene, from the sensed signals, as a three-dimensional (3D) depth map using a scene model.
2. The system of claim 1 , wherein the fixed coded aperture is between the light source and the scene.
3. The system of claim 1 , wherein the fixed coded aperture is between the scene and the set of sensors, such that the set of sensors are light-based time-of-flight (TOF) depth sensors.
4. The system of claim 1 , wherein there is one optical pulse for each 3D depth map in a sequence of depth maps.
5. The system of claim 1 , wherein the optical pulse is a wide beam optical pulse.
6. The system of claim 1 , wherein the optical pulse is Gaussian shaped in time.
7. The system of claim 1 , wherein the optical pulse includes a coded sequence of pulses.
8. The system of claim 1 , wherein an arrangement of the set of sensors is random and coplanar with the light source.
9. The system of claim 1 , wherein an arrangement of the set of sensors forms a uniform array.
10. The system of claim 1 , wherein the processing uses a sparse reconstruction system.
11. The system of claim 1 , wherein the processing uses a model-based sparse reconstruction system.
12. The system of claim 1 , wherein the light source is nonstationary, and the nonstationary light source scans the scene.
13. The system of claim 1 , wherein the sensors in the set are nonstationary and the set of sensors scan the scene.
14. The system of claim 1 , wherein a pattern of the fixed code aperture is random.
15. The system of claim 11 , wherein the pattern has binary values.
16. The system of claim 11 , wherein the pattern has continuous values.
17. The system of claim 1 , wherein a signal received at each sensor is a linear combination of a 3D representation of the scene.
18. The system of claim 17 , wherein the linear combination is decomposed to a sequence of simpler linear combinations.
19. The system of claim 18 , wherein some of the simpler linear combinations are implemented in a discrete time using fast Fourier transform (FFT) based convolution systems.
20. The system of claim 17 , wherein some the linear combinations are rearranged.
21. The system of claim 1 , wherein the scene model imposes a constraint on the 3D depth map.
22. The system of claim 21 , wherein the constraint on the 3D depth map is a total variation (TV) constraint.
23. The system of claim 22 , wherein a projection onto the TV constraint is determined by solving a network flow problem.
24. The system of claim 1 , wherein the scene model imposes a constraint that there is at most a single reflector along any direction.
25. A method for reconstructing a scene, comprising steps of:
transmitting, by a light source, an optical pulse unto the scene;
receiving a reflected pulse at a set of sensors to acquire sensed signals according to a time profile of the reflected pulse, corresponding to the optical pulse, wherein there is a fixed coded aperture in an optical path between the scene and the set of sensors; and
processing the sensed signals to reconstruct the scene as a three-dimensional (3D) depth map using a scene model.
26. The system of claim 1 , wherein a distance the optical pulse travels from the light source to the scene and back to the set of sensors is a pulse delay or a light-based time-of-flight (TOF), such that the TOF is configured to have a time equivalent to a distance from a sensor plane or a sensor depth.
27. A method for reconstaiding a scene, comprising;
transmitting, by a light source, an optical pulse for each frame sequenced in time unto the scene, wherein a processor controls a timing of the pulses transmitted by the light source;
receiving a reflected pulse at a set of time-of-flight (TOF) sensors arranged in a plane with the light source to acquire sensed signals according to a time profile of the reflected pulse, corresponding to the optical pulse, wherein there is a fixed coded aperture in an optical path between the scene and the set of TOF sensors; and
processing the sensed signals to reconstruct the scene as a three-dimensional (3D) depth map using a scene model.