Three-dimensional mapping and imaging
Imaging apparatus includes an illumination subassembly, which is configured to project onto an object a pattern of monochromatic optical radiation in a given wavelength band. An imaging subassembly includes an image sensor, which is configured both to capture a first, monochromatic image of the pattern on the object by receiving the monochromatic optical radiation reflected from the object and to capture a second, color image of the object by receiving polychromatic optical radiation, and to output first and second image signals responsively to the first and second images, respectively. A processor is configured to process the first and second signals so as to generate and output a depth map of the object in registration with the color image.
1. Imaging apparatus, comprising:
an illumination subassembly, which is configured to project onto an object a pattern of monochromatic optical radiation in a given wavelength band;
an imaging subassembly comprising:
an image sensor, which comprises an array of detector elements comprising (i) first detector elements configured to capture a first, monochromatic image of the pattern on the object by receiving the monochromatic optical radiation reflected from the object, (ii) second detector elements configured to capture a second, color image of the object by receiving polychromatic optical radiation, and (iii) third detector elements configured to capture a third image by receiving a wavelength band of monochromatic optical radiation that is offset from the given wavelength band, wherein the first, second, and third detector elements are configured to output first, second, and third image signals responsively to the first, second, and third images, respectively; and
a switching circuit, configured to demultiplex the first and second image signals from the image sensor so as to simultaneously output the first and second signals in each of a sequence of frames; and
a processor, which is configured to process the first and second signals so as to generate and output a depth map of the object in registration with the color image,
wherein the processor is configured to subtract the third image signal from the first image signal in order to generate the depth map.
2. The apparatus according to claim 1 , wherein the given wavelength band of the monochromatic optical radiation comprises an infrared (IR) band.
3. The apparatus according to claim 2 , wherein the IR band has a bandwidth that is no greater than 20 nm.
4. The apparatus according to claim 2 , wherein the imaging subassembly comprises an IR bandpass filter, which is configured to inhibit IR radiation that is outside the given wavelength band from reaching the image sensor.
5. The apparatus according to claim 1 , wherein the imaging subassembly comprises a mosaic filter comprising a pattern of filter elements overlaid respectively on the detector elements.
6. The apparatus according to claim 5 , wherein the filter elements comprise second filter elements, which are overlaid on the second detector elements and are configured to pass different, respective polychromatic wavelength bands, and first filter elements, which are overlaid on the first detector elements and are configured to pass the given wavelength band of the monochromatic optical radiation.
7. The apparatus according to claim 6 , wherein the second filter elements comprise red, green and blue filter elements, and the first filter elements comprise infrared (IR) filter elements, which are interleaved with the second filter elements in a rectilinear pattern.
8. The apparatus according to claim 5 , wherein the mosaic filter comprises a set of filter elements that overlay the third detector elements and are configured to pass the wavelength band of monochromatic optical radiation that is offset from the given wavelength band.
9. A method for imaging, comprising:
projecting onto an object a pattern of monochromatic optical radiation in a given wavelength band;
capturing, using first detector elements in an image sensor, a first, monochromatic image of the pattern on the object by receiving the monochromatic optical radiation reflected from the object, and outputting a first image signal from the first detector elements responsively to the first image;
capturing, using second detector elements in the image sensor, a second, color image of the object by receiving polychromatic optical radiation, and outputting a second image signal from the second detector elements responsively to the second image;
capturing, using third detector elements in the image sensor, a third, monochromatic image by receiving a wavelength band of monochromatic optical radiation that is offset from the given wavelength band, and outputting a third image signal from the third detector elements responsively to the third image;
using a switching circuit, demultiplexing the first and second image signals so as to simultaneously output the first and second signals in each of a sequence of frames; and
processing the first and second signals so as to generate a depth map of the object in registration with the color image,
wherein processing the first and second signals comprises subtracting the third image signal from the first image signal.
10. The method according to claim 9 , wherein the given wavelength band of the monochromatic optical radiation comprises an infrared (IR) band.
11. The method according to claim 10 , wherein the IR band has a bandwidth that is no greater than 20 nm.
12. The method according to claim 10 , wherein capturing the first and second images comprises filtering the optical radiation impinging on the image sensor so as to inhibit IR radiation that is outside the given wavelength band from reaching the image sensor.
13. The method according to claim 9 , wherein capturing the first and second images comprises filtering the optical radiation impinging on the image sensor using a mosaic filter, which comprises a pattern of filter elements overlaid respectively on the detector elements.
14. The method according to claim 13 , wherein the filter elements comprise second filter elements, which are overlaid on the second detector elements and are configured to pass different, respective polychromatic wavelength bands, and first filter elements, which are overlaid on the first detector elements and are configured to pass the given wavelength band of the monochromatic optical radiation.
15. The method according to claim 14 , wherein the second filter elements comprise red, green and blue filter elements, and the first filter elements comprise infrared (IR) filter elements, which are interleaved with the second filter elements in a rectilinear pattern.
16. The method according to claim 13 , wherein the mosaic filter includes a set of filter elements that overlay the third detector elements and are configured to pass the wavelength band of monochromatic optical radiation that is offset from the given wavelength band.