Distance measurement using a longitudinal grid pattern
A projection pattern is projected onto a surface of an object from a projection point of a distance by projecting a plurality of beams of light from the projection point. The plurality of beams of light creates a plurality of projection artifacts that is arranged in a grid on the surface of the object. A center projection artifact lies at an intersection of a grid longitude line and a grid latitude line. A projection of the plurality of beams is adjusted so that the longitude line and/or the latitude line is rotated by a predetermined amount from an original position to a new position, resulting in an adjusted projection pattern on the surface of the object. An image of the object, including at least a portion of the adjusted projection pattern, is captured. A distance from the distance sensor to the object is calculated using information from the image.
1. A method, comprising:
projecting a projection pattern onto a surface of an object from a projection point of a distance sensor, wherein the projection pattern is created by a plurality of beams of light projected from the projection point, wherein the plurality of beams of light creates a plurality of projection artifacts that is arranged in a grid on the surface of the object, wherein a center projection artifact of the plurality of projection artifacts lies at an intersection of a longitude line of the grid and a latitude line of the grid, wherein each projection artifact of the plurality of projection artifacts has a trajectory, and wherein the trajectory of a given projection artifact of the plurality of projection artifacts describes a movement of the given projection artifact on the surface of the object as the distance from a baseline of the distance sensor to the object changes;
adjusting a projection of the plurality of beams so that at least one of the longitude line and the latitude line is rotated by a predetermined amount from an original position to a new position, resulting in an adjusted projection pattern being projected onto the surface of the object, wherein an overlap of the trajectory of the given projection artifact with a trajectory of another projection artifact of the plurality of projection artifacts is minimized by the adjusted projection pattern;
capturing an image of the object, including at least a portion of the adjusted projection pattern; and
calculating a distance from the distance sensor to the object using information from the image.
2. The method of claim 1 , wherein the grid comprises a plurality of rows and a plurality of columns.
3. The method of claim 2 , wherein the plurality of columns is arranged in a staggered pattern, such that those projection artifacts of the plurality of artifacts that reside in a common row are non-collinear.
4. The method of claim 1 , wherein the distance corresponds to a radius of a spherical surface centered on a principal point of a lens of the distance sensor.
5. The method of claim 1 , wherein a plane of the projection pattern is parallel to the baseline of the distance sensor, and wherein the baseline is defined as a lateral distance between a central axis of the projection point and a central axis of a lens of the distance sensor.
6. The method of claim 1 , wherein the adjusting comprises:
rotating the longitude line by a first angle; and
rotating the latitude line by a second angle.
7. The method of claim 6 , wherein the first angle and the second angle are equal.
8. The method of claim 6 , wherein the first angle and the second angle are unequal.
9. The method of claim 1 , wherein the projection point and a lens of the distance sensor are mounted in a common plane, so that the projection point is level with a principal point of an imaging capturing device to which the lens is connected in a direction of an optical axis of the image capturing device.
10. The method of claim 9 , wherein the principal point is a front nodal point of the lens.
11. The method of claim 1 , wherein a field of view of an image device used to capture the image is hemispherical.
12. A non-transitory machine-readable storage medium encoded with instructions executable by a processor, wherein, when executed, the instructions cause the processor to perform operations comprising:
projecting a projection pattern onto a surface of an object from a projection point of a distance sensor, wherein the projection pattern is created by a plurality of beams of light projected from the projection point, wherein the plurality of beams of light creates a plurality of projection artifacts that is arranged in a grid on the surface of the object, wherein a center projection artifact of the plurality of projection artifacts lies at an intersection of a longitude line of the grid and a latitude line of the grid, wherein each projection artifact of the plurality of projection artifacts has a trajectory, and wherein the trajectory of a given projection artifact of the plurality of projection artifacts describes a movement of the given projection artifact on the surface of the object as the distance from a baseline of the distance sensor to the object changes;
adjusting a projection of the plurality of beams so that at least one of the longitude line and the latitude line is rotated by a predetermined amount from an original position to a new position, resulting in an adjusted projection pattern being projected onto the surface of the object, wherein an overlap of the trajectory of the given projection artifact with a trajectory of another projection artifact of the plurality of projection artifacts is minimized by the adjusted projection pattern;
capturing an image of the object, including at least a portion of the adjusted projection pattern; and
calculating a distance from the distance sensor to the object using information from the image.
13. The non-transitory machine-readable storage medium of claim 12 , wherein a plane of the projection pattern is parallel to the baseline of the distance sensor, and wherein the baseline is defined as a lateral distance between a central axis of the projection point and a central axis of a lens of the distance sensor.
14. The non-transitory machine-readable storage medium of claim 12 , wherein the adjusting comprises:
rotating the longitude line by a first angle; and
rotating the latitude line by a second angle.
15. The non-transitory machine-readable storage medium of claim 12 , wherein the projection point and a lens of the distance sensor are mounted in a common plane, so that the projection point is level with a principal point of an imaging capturing device to which the lens is connected in a direction of an optical axis of the image capturing device.
16. The non-transitory machine-readable storage medium of claim 15 , wherein the principal point is a front nodal point of the lens.
17. The method of claim 1 , wherein a source of all projection artifacts of the plurality of projection artifacts is the projection point.
18. The method of claim 1 , wherein the adjusting rotates the at least one of the longitude line and the latitude line without rotating all lines of the grid.