Spatially self-similar patterned illumination for depth imaging

Patent metadata

Field	Value
Publication number	US-9562760-B2
Application number	US-201514643966-A
Country	US
Kind code	B2
Filing date	Mar 10, 2015
Priority date	Mar 10, 2014
Publication date	Feb 7, 2017
Grant date	Feb 7, 2017

Abstract

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.

First claim

What is claimed is:

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 arranged in a spatial arrangement, wherein each spatial symbol 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 of the plurality of spatial symbols is distinguishable from the other spatial symbols of the plurality of spatial symbols; and
each respective spatial symbol of the plurality of spatial symbols is similar to a master spatial symbol such that:

a normalized spatial cross correlation between the master spatial symbol and the plurality of spatial symbols arranged in the spatial arrangement, having a domain of relative offsets between the master spatial symbol and the spatial arrangement of spatial symbols, and producing a normalized spatial cross correlation value for each point in the domain, produces values that form peaks exceeding a first predetermined threshold at regions in the domain representing zero relative offset between the master spatial symbol and each of the spatial symbols in the spatial arrangement; and
the values of the normalized spatial cross correlation between the master spatial symbol and the plurality of spatial symbols arranged in the spatial arrangement are each side lobe, from a plurality of side lobes, of the normalized spatial cross correlation of the master spatial symbol and each respective spatial symbol is less than a second predetermined threshold at all regions of the domain other than the peaks.

2. The device of claim 1 , further comprising a radiation source.

3. The device of claim 2 , wherein the radiation source includes at least a laser diode, an array of vertical-cavity surface-emitting lasers, a light-emitting diode, or a lamp.

4. The device of claim 1 , wherein the at least one characteristic of the radiation distribution includes an amplitude of the radiation distribution.

5. The device of claim 1 , wherein the at least one characteristic of the radiation distribution includes at least a frequency, a phase, or a polarization of the radiation distribution.

6. The device of claim 1 , wherein the pattern-generating element includes at least a mask, a diffractive optical element, or a hologram.

7. The device of claim 1 , wherein the plurality of spatial symbols include spatially modulated copies of an amplitude of the master spatial symbol.

8. The device of claim 1 , wherein the plurality of spatial symbols include spatially modulated copies of at least a frequency, a phase, or a polarization of the master spatial symbol.

9. The device of claim 1 , wherein the master spatial symbol includes a plurality of discrete pattern elements.

10. The device of claim 9 , 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.

11. The device of claim 10 , wherein at least one of the discrete pattern elements is absent from at least one of the plurality of spatial symbols.

12. The device of claim 9 , wherein at least one of the plurality of spatial symbols includes one or more discrete pattern elements that are absent in the master spatial symbol.

13. The device of claim 1 , wherein the plurality of spatial symbols are two-dimensional radiation distributions.

14. The device of claim 1 , wherein one or more of the plurality of spatial symbols is repeated within the radiation pattern.

15. A method for estimating coordinates of a location on an object in a 3D scene, the method comprising:
illuminating at least a portion of the 3D scene with a radiation pattern, wherein the radiation pattern includes:
a plurality of spatial symbols, wherein each spatial symbol 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 of the plurality of spatial symbols is distinguishable from the other spatial symbols of the plurality of spatial symbols; and
each respective spatial symbol of the plurality of spatial symbols is similar to a master spatial symbol such that:
a peak of a normalized spatial cross correlation of the master spatial symbol and each respective spatial symbol exceeds a first predetermined threshold; and
each side lobe, from a plurality of side lobes, of the normalized spatial cross correlation of the master spatial symbol and each respective spatial symbol is less than a second predetermined threshold;

detecting the radiation pattern illuminating at least the portion of the illuminated 3D scene using one or more radiation detectors; and
estimating the coordinates of the location on the object based on the detected radiation pattern.

16. The method of claim 15 , wherein the detected radiation pattern forms an image of the 3D scene.

17. The method of claim 16 , wherein estimating the coordinates of the location on the object based on the formed image of the 3D scene comprises:
detecting one or more spatial symbols from the plurality of spatial symbols within the formed image of the 3D scene;
locating the one or more detected spatial symbols within the formed image of the 3D scene; and
identifying one or more of the detected spatial symbols.

18. The method of claim 17 , further comprising identifying one or more pattern elements within the identified spatial symbols.

19. The method of claim 18 , wherein estimating the coordinates of the location on the object utilizes a location of the one or more identified pattern elements within the formed image.

20. The method of claim 17 , wherein detecting the one or more spatial symbols includes comparing two or more regions within the formed image to the master spatial symbol.

21. The method of claim 20 , wherein comparing the two or more regions includes using a cross correlation operation.

22. The method of claim 15 , wherein the one or more radiation detectors comprises at least a CMOS or a CCD detector array.

23. The method of claim 20 , further comprising identifying one or more pattern elements within the identified spatial symbols based on a location of the one or more pattern elements within the identified spatial symbol.

24. The method of claim 15 , wherein the radiation pattern further comprises one or more additional spatial symbols.

25. The method of claim 15 , wherein the plurality of spatial symbols are further configured such that:
a normalized spatial cross correlation between the master spatial symbol and the plurality of spatial symbols arranged in a spatial arrangement, having a domain of relative offsets between the master spatial symbol and the arrangement of spatial symbols, is calculated to produce a normalized spatial cross correlation value for each point in the domain;
values of the normalized spatial cross correlation form peaks at regions in the domain representing zero relative offset between the master spatial symbol and each of the spatial symbols in the spatial arrangement exceeds a third predetermined threshold; and
the normalized spatial cross correlation value

Assignees

• Chiaro Tech Llc
• Cognex Corp

Inventors

• Braker Benjamin
• Wegner Aaron
• Zimmerman Ronald
• Moore Eric
• Mcdonald Trevor

Classifications

• G01B11/002 Primary

  for measuring two or more coordinates · CPC title

• G06T7/521

  from laser ranging, e.g. using interferometry; from the projection of structured light · CPC title

• G06T2207/20056

  Discrete and fast Fourier transform, [DFT, FFT] · CPC title

• G01S17/42

  Simultaneous measurement of distance and other co-ordinates (indirect measurement G01S17/46) · CPC title

• G01B11/2531 Primary

  using several gratings, projected with variable angle of incidence on the object, and one detection device · CPC title