Spatially self-similar patterned illumination for depth imaging
Methods, systems, and devices involving patterned radiation are provided in accordance with various embodiments. Some embodiments include a device for projecting pattern radiation. Some embodiments include a method for estimating coordinates of a location on an object in a 3D scene. Some embodiments include a system for estimating the coordinates of a location on an object in a 3D scene. A variety of radiation patterns are provided in accordance with various embodiments. Some embodiments may relate to the use of patterned illumination to identify the angular information that may be utilized to measure depth by triangulation.
1. A device for projecting patterned radiation, comprising:
a pattern-generating element configured to produce a radiation pattern, wherein the radiation pattern includes:
a plurality of spatial symbols, wherein each spatial symbol from the plurality of spatial symbols comprises a radiation distribution such that at least one characteristic of the radiation distribution varies spatially and wherein the plurality of spatial symbols are configured such that:
each respective spatial symbol from the plurality of spatial symbols is distinguishable from the other spatial symbols from the plurality of spatial symbols; and
each respective spatial symbol from the plurality of spatial symbols is related to a master spatial symbol through a transformation operation.
2. The device of claim 1 , wherein one or more of the spatial symbols from the plurality of spatial symbols is related to the master symbol through the transformation operation that includes a spatial modulation.
3. The device of claim 2 , wherein the plurality of spatial symbols include spatially modulated copies of an amplitude of the master spatial symbol.
4. The device of claim 1 , wherein one or more of the spatial symbols from the plurality of spatial symbols is related to the master symbol through the transformation operation that includes at least a rotation operation or a scaling operation.
5. The device of claim 1 , wherein the plurality of spatial symbols are further configured such that:
the plurality of spatial symbols are arranged in a spatial arrangement of spatial symbols; and
an operation taking the spatial arrangement of spatial symbols and the master spatial symbol as inputs and operating over a domain of locations within the spatial arrangement of spatial symbols yields an output with values corresponding to locations of the spatial symbols from the plurality of spatial symbols that are distinct from values corresponding to locations that are offset from the locations of the spatial symbols from the plurality of spatial symbols.
6. The device of claim 5 , wherein the operation taking the spatial arrangement of spatial symbols and the master spatial symbol as inputs and operating over the domain of locations within the spatial arrangement of spatial symbols is a spatial cross correlation operation.
7. The device of claim 6 , wherein the plurality of spatial symbols are further configured such that:
an output of the spatial cross correlation operation at locations within the domain of locations within the spatial arrangement of spatial symbols corresponding to the locations of the spatial symbols from the plurality of spatial symbols exceed a first threshold; and
an output of the spatial cross correlation operation at locations within the domain of locations within the spatial arrangement of spatial symbols corresponding to locations offset from the locations of the spatial symbols from the plurality of spatial symbols are less than a second threshold.
8. The device of claim 1 , wherein the master spatial symbol includes a plurality of discrete pattern elements.
9. The device of claim 8 , wherein the plurality of spatial symbols are produced by modulating at least an amplitude, a frequency, a phase, a position, a size, or a polarization of one or more of the discrete pattern elements comprised by the master spatial symbol.
10. The device of claim 1 , wherein the plurality of spatial symbols are two-dimensional radiation distributions.
11. The device of claim 1 , wherein one or more of the spatial symbols from the plurality of spatial symbols is repeated within the radiation pattern.