Method and apparatus for depth-map estimation of a scene
The method of determination of a depth map of a scene comprises generation of a distance map of the scene obtained by time of flight measurements, acquisition of two images of the scene from two different viewpoints, and stereoscopic processing of the two images taking into account the distance map. The generation of the distance map includes generation of distance histograms acquisition zone by acquisition zone of the scene, and the stereoscopic processing includes, for each region of the depth map corresponding to an acquisition zone, elementary processing taking into account the corresponding histogram.
1. A device comprising:
a time of flight sensor configured to generate a distance map of a scene, the time of flight sensor being configured to generate a corresponding distance histogram for each acquisition zone of the scene; and
a stereoscopic image acquisition device configured to acquire two images of the scene at two different viewpoints, wherein the device is configured to
identify regions of a depth map to be generated from the two images that corresponds to the distance map,
identify one of the regions of the depth map as being a plane region when the identified region has a substantially planar surface that is substantially perpendicular to a measurement optical axis of the device,
assign a constant depth to the plane region of the depth map, and
extrapolate distances of the scene from disparities between the two images to generate the depth map while omitting extrapolation of the distances in the region identified as being the plane region.
2. The device of claim 1 , wherein the device comprises a stereoscopic processor and an elementary processor configured to cause the device to identify the regions, identify the one of the regions of the depth map, assign the constant depth, and extrapolate the distances.
3. The device of claim 1 , wherein identifying one of the regions of the depth map as being the plane region comprises determining that the corresponding distance histogram of the distance map includes a single group of distances, wherein a mid-height width of the single group of distances is less than a threshold width.
4. The device of claim 3 , wherein the constant depth is equal to a distance from the single group.
5. The device of claim 1 , wherein the constant depth is chosen to be a measured largest population distance, a mean value, or a median value from the histogram for that acquisition zone.
6. The device of claim 1 , wherein the depth map has a resolution that is at least one thousand times greater than a resolution of the distance map measured by time of flight, the resolution of the distance map measured by time of flight being equal to a total number of acquisition zones.
7. The device of claim 1 , wherein the distance map of the scene obtained by time of flight measurements includes from ten to one thousand acquisition zones.
8. The device of claim 1 , wherein the device comprises a camera, a mobile telephone, or a touchscreen tablet.
9. A device comprising:
a time of flight sensor configured to generate a distance map of a scene, the time of flight sensor being configured to generate a corresponding distance histogram for each acquisition zone of the scene; and
a stereoscopic image acquisition device configured to acquire two images of the scene at two different viewpoints, wherein the device is configured to
identify regions of a depth map to be generated from the two images that corresponds to the distance map,
identify an out of range region having distances out of an observable range of the stereoscopic image acquisition device by identifying regions in which the corresponding distance histogram does not include any distance between a stereoscopic range ceiling value and a stereoscopic range floor value, and
extrapolate distances of the scene from disparities between the two images to generate the depth map while omitting extrapolation of the distances in the out of range region.
10. The device of claim 9 , wherein the device comprises a stereoscopic processor and an elementary processor configured to cause the device to identify the regions, identify the out of range region, and extrapolate the distances.
11. The device of claim 9 , wherein a maximum distance measurable by the time of flight sensor is greater than the stereoscopic range ceiling value, and wherein a minimum distance measurable by the time of flight sensor is less than the stereoscopic range floor value.
12. The device of claim 9 , further comprising assigning a default depth to the out of range region, the default depth being obtained from distances of the corresponding distance histogram.
13. The device of claim 9 , wherein the depth map has a resolution that is at least one thousand times greater than a resolution of the distance map measured by time of flight, the resolution of the distance map measured by time of flight being equal to a total number of acquisition zones.
14. The device of claim 9 , wherein the distance map of the scene obtained by time of flight measurements includes from ten to one thousand acquisition zones.
15. The device of claim 9 , wherein the device comprises a camera, a mobile telephone, or a touchscreen tablet.
16. A device comprising:
a time of flight sensor configured to generate a distance map of a scene, the time of flight sensor being configured to generate a corresponding distance histogram for each acquisition zone of the scene; and
a stereoscopic image acquisition device configured to acquire two images of the scene at two different viewpoints, wherein the device is configured to
identify regions of a depth map to be generated from the two images that corresponds to the distance map,
identify one of the regions of the depth map as being a plane region when the identified region has a substantially planar surface that is substantially perpendicular to a measurement optical axis of the device,
assign a constant depth to the plane region of the depth map, and
extrapolate distances of the scene from disparities between the two images to generate the depth map while omitting extrapolation of the distances in the region identified as being the plane region, wherein the device comprises a stereoscopic processor and an elementary processor configured to cause the device to identify the regions, identify the one of the regions of the depth map, assign the constant depth, and extrapolate the distances.
17. The device of claim 16 , wherein identifying one of the regions of the depth map as being the plane region comprises determining that the corresponding distance histogram of the distance map includes a single group of distances, wherein a mid-height width of the single group of distances is less than a threshold width.
18. The device of claim 17 , wherein the constant depth is equal to a distance from the single group.
19. The device of claim 16 , wherein the constant depth is chosen to be a measured largest population distance, a mean value, or a median value from the histogram for that acquisition zone.
20. The device of claim 16 , wherein the depth map has a resolution that is at least one thousand times greater than a resolution of the distance map measured by time of flight, the resolution of the distance map measured by time of flight being equal to a total number of acquisition zones.
21. The device of claim 16 , wherein the distance map of the scene obtained by time of flight measurements includes from ten to one thousand acquisition zones.
22. The device of claim 16 , wherein the device comprises a camera, a mobile telephone, or a touchscreen tablet.
23. The device of claim 16 , wherein the device is battery powered.