Interference mitigation for light detection and ranging

1. A light detection and ranging apparatus, comprising:

a light emitter configured to generate, according to a first electrical pulse signal, a pulse light signal that is directed toward an object in an external environment, the first electrical pulse signal comprising a first set of non-uniformly spaced pulses;

a receiver configured to receive one or more returned light signals reflected by the object and convert the returned light signals into electrical signals; and

a filtering subsystem in communication with the receiver, configured to:

receive the electrical signals from the receiver, and

remove a point from a set of points representing at least a partial surface of the object as noise by determining whether there is a coherence between the point and corresponding neighboring points of the point along at least a first direction and a second direction of the set of points.

2. The apparatus of claim 1 , wherein two adjacent pulses of the first set of pulses are separated by a randomized distance in time domain.

3. The apparatus of claim 1 , wherein the light emitter is configured to generate a second pulse light signal according to a second electrical pulse signal, wherein the second electrical pulse signal comprises a second set of non-uniformly spaced pulses, and wherein at least one pulse in the second set of pulses is positioned at a different time-domain location than a corresponding pulse in the first set of pulses.

4. The apparatus of claim 1 , wherein the light emitter is configured to generate a third pulse light signal according to a third electrical pulse signal, wherein the third electrical pulse signal comprises a third set of non-uniformly spaced pulses, and wherein no pulse in the third set of pulses shares a same time-domain location as any pulse in the first set of pulses.

5. The apparatus of claim 4 , wherein each of the first, second, and third electrical pulse signal comprises a pulse signature.

6. The apparatus of claim 5 , wherein the pulse signature is unique for each of the first, second, and third electrical pulse signal.

7. The apparatus of claim 1 , wherein each point carries information about a vector that indicates an estimated surface normal of the object, and wherein the first direction and the second direction are determined based on the vector.

8. The apparatus of claim 1 , wherein the first direction and the second direction are two directions in a Cartesian coordinate system.

9. The apparatus of claim 1 , wherein determining the coherence between the point and the corresponding neighboring points comprises:

examining information carried in the neighboring points of the point; and

determining whether the point and the neighboring points both represent the surface of the same object.

10. The apparatus of claim 1 , wherein the information carried in a neighboring point includes at least a location of the neighboring point or a color of the neighboring point.

11. A method for sensing an object in an external environment using a light detection and ranging device, comprising:

emitting, by a light emitter of the light detection and range device, a pulse light signal towards the object according to an electrical pulse signal, the electrical pulse signal comprising a first set of non-uniformly spaced pulses;

receiving, by a receiver of the light detection and range device, one or more returned light signals reflected by the object;

converting, by the receiver, the one or more return light signals into electrical signals; and

filtering a target point from a set of points representing at least a partial surface of the object as noise by determining whether there is a coherence between the target point and corresponding neighboring points of the target point along a first direction and a second direction of the model.

12. The method of claim 11 , wherein two adjacent pulses of the first set of pulses are separated by a randomized distance in time domain.

13. The method of claim 11 , comprising:

emitting a second pulse light signal according to a second electrical pulse signal, wherein the second electrical pulse signal comprises a second set of non-uniformly spaced pulses, and wherein at least one pulse in the second set of pulses is positioned at a different time-domain location than a corresponding pulse in the first set of pulses.

14. The method of claim 11 , comprising:

emitting a third pulse light signal according to a third electrical pulse signal, wherein the third electrical pulse signal comprises a third set of non-uniformly spaced pulses, and wherein no pulse in the third set of pulses shares a same time-domain location as any pulse in the first set of pulse.

15. The method of claim 14 , wherein each of the first, second, and third electrical pulse signal comprises a pulse signature.

16. The method of claim 15 , wherein the pulse signature is unique for each of the first, second, and third electrical pulse signal.

17. The method of claim 11 , wherein each point carries information about a vector that indicates an estimated surface normal of the object, and wherein the method comprises:

determining two orthogonal directions as the first direction and the second direction based on the vector.

18. The method of claim 11 , comprising:

selecting two orthogonal directions in a Cartesian coordinate system as the first direction and the second direction.

19. The method of claim 11 , wherein determining the coherence between the target point and the corresponding neighboring points comprises:

examining information carried in the neighboring points of the target point; and

determining whether the target point and the neighboring points both represent the surface of the same object.

20. The method of claim 11 , wherein the information carried in a neighboring point includes a location of the neighboring point.

21. The method of claim 20 , comprising:

filtering out the target point upon determining that a distance between the neighboring point and the target point exceeds a predefined threshold.

22. The method of claim 11 , wherein the information carried in a neighboring point includes a color of the neighboring point.

23. The method of claim 22 , comprising:

filtering out the target point upon determining that a color difference between the neighboring point and the target point exceeds a predefined threshold.

24. The method of claim 11 , wherein filtering the target point comprises:

constructing a bounding box for the target point;

determining a number of neighboring points that are coherent with the target point; and

filtering out the target point upon determining that the number of coherent neighboring points is equal to or smaller than a predefined threshold.

25. A non-transitory computer readable medium having processor code stored thereon including program code for performing a method that comprises:

emitting, by a light emitter of the light detection and range device, a pulse light signal towards the object according to an electrical pulse signal, the electrical pulse signal comprising a first set of non-uniformly spaced pulses;

receiving, by a receiver of the light detection and range device, one or more returned light signals reflected by the object;

converting, by the receiver, the one or more return light signals into electrical signals; and

filtering a target point from a set of points representing at least a partial surface of the object as noise by determining whether there is a coherence between the target point and corresponding neighboring points of the target point along a first direction and a second direction of the model.

26. The non-transitory computer readable medium of claim 25 , wherein two adjacent pulses of the first set of pulses are separated by a randomized distance in time domain.

27. The non-transitory computer readable medium of claim 25 , wherein determining the coherence between the target point and the corresponding neighboring points comprises:

examining information carried in the neighboring points of the target point; and

determining whether the target point and the neighboring points both represent the surface of the same object.

28. The non-transitory computer readable medium of claim 25 , wherein the information carried in a neighboring point includes at least a location of the neighboring point or a color of the neighboring point.

29. The non-transitory computer readable medium of claim 25 , wherein filtering the target point comprises:

constructing a bounding box for the target point;

determining a number of neighboring points that are coherent with the target point; and

filtering out the target point upon determining that the number of coherent neighboring points is equal to or smaller than a predefined threshold.