Depth mapping using projected patterns

1. Apparatus for mapping an object, comprising: an illumination assembly, comprising: a transparency containing a plurality of micro-lenses arranged in a non-uniform pattern; a light source, which is configured to transilluminate the transparency with optical radiation, wherein the micro-lenses are configured to focus the optical radiation to form, at a focal plane, respective focal spots in the non-uniform pattern; and optics configured to project the non-uniform pattern of the focal spots from the focal plane onto the object; an image capture assembly, which is configured to capture an image of the pattern that is projected onto the object using the transparency; and a processor, which is coupled to process the image captured by the image capture assembly so as to reconstruct a three-dimensional (3D) map of the object, wherein the processor is arranged to derive the 3D map by finding respective offsets between the pattern of the spots on multiple areas of the object captured in the image of the pattern that is projected onto the object and another image of the pattern, wherein the respective offsets are indicative of respective distances between the areas and the image capture assembly.

2. The apparatus according to claim 1 , wherein at least some of the micro-lenses have non-uniform focal lengths, and wherein the light source comprises optics for projecting the non-uniform pattern of the focal spots so that the pattern that is projected on the object varies with distance from the illumination assembly.

3. The apparatus according to claim 1 , wherein the projected pattern has a duty cycle that is less than 1/e.

4. A method for mapping an object, comprising: using a light source, transilluminating a transparency containing a plurality of micro-lenses arranged in a non-uniform pattern, wherein the micro-lenses are configured to focus the optical radiation to form, at a focal plane, respective focal spots in the non-uniform pattern; projecting the non-uniform pattern of the focal spots from the focal plane onto the object; capturing an image of the non-uniform pattern that is projected onto the object; and processing the captured image so as to reconstruct a three-dimensional (3D) map of the object, wherein processing the captured image comprises finding respective offsets between the pattern of the spots on multiple areas of the object captured in the image of the pattern that is projected onto the object and another image of the pattern, and determining respective distances to the areas responsively to the respective offsets.

5. The method according to claim 4 , wherein at least some of the micro-lenses have non-uniform focal lengths, and wherein transilluminating the transparency comprises projecting the non-uniform pattern of the focal spots so that the pattern that is projected on the object varies with distance from the transparency.

6. The method according to claim 4 , wherein the projected pattern has a duty cycle that is less than 1/e.

7. Apparatus for mapping an object, comprising: an illumination assembly, comprising: a diffuser; a light source, which is configured to transilluminate the diffuser with optical radiation; a transparency containing an array of micro-lenses arranged in a non-uniform pattern, which are arranged to focus the optical radiation transmitted through the diffuser, thereby generating a non-uniform pattern of spots; and projection optics, which are arranged to project the pattern onto the object; an image capture assembly, which is configured to capture an image of the pattern that is projected onto the object using the transparency; and a processor, which is coupled to process the image captured by the image capture assembly so as to reconstruct a three-dimensional (3D) map of the object, wherein the processor is arranged to derive the 3D map by finding respective offsets between the pattern of the spots on multiple areas of the object captured in the image of the pattern that is projected onto the object and another image of the pattern, wherein the respective offsets are indicative of respective distances between the areas and the image capture assembly.

8. The apparatus according to claim 7 , wherein the illumination assembly is configured to project the pattern so that the pattern varies with distance from the illumination assembly.

9. The apparatus according to claim 7 , wherein the projected pattern has a duty cycle that is less than 1/e.

10. A method for mapping an object, comprising: using a light source, transilluminating a diffuser with optical radiation; focusing the optical radiation transmitted through the diffuser using an array of micro-lenses arranged in a non-uniform pattern, thereby generating a non-uniform pattern of spots; projecting the pattern onto the object; capturing an image of the pattern that is projected onto the object; and processing the captured image so as to reconstruct a three-dimensional (3D) map of the object, wherein processing the captured image comprises finding respective offsets between the pattern of the spots on multiple areas of the object captured in the image of the pattern that is projected onto the object and another image of the pattern, and determining respective distances to the areas responsively to the respective offsets.

11. The method according to claim 10 , wherein the projected pattern varies with distance from the array of micro-lenses.

12. The method according to claim 10 , wherein the projected pattern has a duty cycle that is less than 1/e.