# US 7,986,321 B2 · System and method for generating structured light for 3-dimensional image rendering > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 7,986,321 B2 - Document ID: US7986321B2 - Status: Granted - Kind: B2 - Application number: 11/968,559 - Filed: 2008-01-02 - Published: 2009-07-02 - Granted: 2011-07-26 - Earliest claimed: 2008-01-02 - Assignees: Spatial Integrated Systems, Inc. - Inventors: Ping Zhuang; Leslie Ray Elkins - Web page: https://patentgrep.com/patent/US7986321B2 ## CPC - G06T 17/20: Finite element generation, e.g. wire-frame surface description, {tesselation} - G01B 11/2545: {with one projection direction and several detection directions, e.g. stereo} - G06T: IMAGE DATA PROCESSING OR GENERATION, IN GENERAL - G01B: MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS ## Abstract A system and method for illuminating an object in preparation for three-dimensional rendering includes a projection device configured to project at least three two-dimensional structured light patterns onto a 3-dimensional object. At least two cameras detect light reflected by the object in response to the at least three structured light patterns. Each structured light pattern varies in intensity in a first dimension and is constant in a second dimension. A single line along the first dimension of a given structured light pattern is created from a superposition of three or more component triangular waveforms. Each component triangular waveform has an amplitude, a periodicity (frequency), and a phase shift which is implemented as a pixel shift. Each component triangular waveform may be subject to one or more waveshaping operations prior to being summed with the remaining component triangular waveforms. The summed waveform itself may also be subject to waveshaping operations. ## Claims ### Claim 1 A method of illuminating an object in preparation for three-dimensional rendering, comprising: providing a light projector having a field of view which includes said object; creating three two-dimensional structured light patterns, each structured light pattern being derived from a corresponding aperiodic waveform replicated in a second dimension, each aperiodic waveform being derived from the same set of component triangular waveforms, wherein a given aperiodic waveform is created using a unique set of phase shifts applied to members of said same set of component triangular waveforms; and illuminating said object with each of the three two-dimensional structured light patterns, in succession. ### Claim 2 (depends on 1) The method according to claim 1, wherein: each of the component triangular waveforms has a unique periodicity, with no periodicity being an exact multiple of another periodicity. ### Claim 3 (depends on 2) The method according to claim 2, wherein: at least three component triangular waveforms are summed to form each of said aperiodic waveforms. ### Claim 4 (depends on 3) The method according to claim 3, wherein: exactly four component triangular waveforms are summed to form each of said aperiodic waveforms. ### Claim 5 (depends on 1) The method according to claim 1, wherein: each component triangular waveform comprises a train of isoceles triangles. ### Claim 6 (depends on 1) The method according to claim 1, wherein: each aperiodic waveform is subject to signal conditioning, prior to creating the three two-dimensional structured light patterns. ### Claim 7 (depends on 6) The method according to claim 6, wherein said signal conditioning includes: gamma correcting pixels of said each periodic waveform; and rescaling pixels of said each periodic waveform in accordance with a capability of the light projector. ### Claim 8 (depends on 1) The method according to claim 1, wherein said step of creating comprises: (a) obtaining four triangular waveforms, each triangular waveform having a predetermined amplitude and predetermined periodicity; (b) phase shifting each triangular waveform by a predetermined amount; (c) summing the phase shifted triangular waveforms to thereby form an aperiodic summed waveform; (d) gamma correcting each pixel in the aperiodic summed waveform; by a gamma factor to form a gamma-corrected waveform; (e) resealing the gamma-corrected waveform to conform to the pixel value range of the projection device, thereby forming a one-dimensional illuminating waveform; (f) replicating the one-dimensional illuminating waveform in a second dimension to form a two-dimensional structured light pattern; and (g) repeating steps (b)-(f) at least two more times with different combinations of phase shifts to form a total of at least three two-dimensional structured light patterns. ### Claim 9 A method of performing three-dimensional rendering of an object, comprising: providing a light projector and at least two spaced apart cameras in a known configuration relative to one another, wherein the object is within a field of view of said light projector and also said at least two spaced apart cameras; creating three two-dimensional structured light patterns, each structured light pattern being derived from a corresponding aperiodic waveform replicated in a second dimension, each aperiodic waveform being derived from the same set of component triangular waveforms, a given aperiodic waveform being created using a unique set of phase shifts applied to members of said same set of component triangular waveforms; illuminating the object with each of the three two-dimensional structured light patterns and capturing three images of illuminated object with each camera to thereby from a plurality of sets of three images, each set of three images being captured by one camera; and processing the plurality of sets of images to form a three-dimensional surface model of the object. ### Claim 10 (depends on 9) The method according to claim 9, wherein: each of the component triangular waveforms has a unique periodicity, with no periodicity being an exact multiple of another periodicity. ### Claim 11 (depends on 10) The method according to claim 10, wherein: at least three component triangular waveforms are summed to form each of said aperiodic waveforms. ### Claim 12 (depends on 11) The method according to claim 11, comprising: providing exactly two cameras; and summing exactly four component triangular waveforms to form each of said aperiodic waveforms. ### Claim 13 (depends on 9) The method according to claim 9, wherein: each component triangular waveform comprises a train of isoceles triangles. ### Claim 14 (depends on 9) The method according to claim 9, wherein: each aperiodic waveform is subject to signal conditioning, prior to creating the three two-dimensional structured light patterns. ### Claim 15 (depends on 14) The method according to claim 14, wherein said signal conditioning includes: gamma correcting pixels of said each periodic waveform; and resealing pixels of said each periodic waveform in accordance with a capability of the light projector. ### Claim 16 (depends on 9) The method according to claim 9, wherein said step of creating comprises: (a) obtaining four triangular waveforms, each triangular waveform having a predetermined amplitude and predetermined periodicity; (b) phase shifting each triangular waveform by a predetermined amount; (c) summing the phase shifted triangular waveforms to thereby form an aperiodic summed waveform; (d) gamma correcting each pixel in the aperiodic summed waveform; by a gamma factor to form a gamma-corrected waveform; (e) rescaling the gamma-corrected waveform to conform to the pixel value range of the projection device, thereby forming a one-dimensional illuminating waveform; (f) replicating the one-dimensional illuminating waveform in a second dimension to form a two-dimensional structured light pattern; and (g) repeating steps (b)-(f) at least two more times with different combinations of phase shifts to form a total of at least three two-dimensional structured light patterns. ### Claim 17 A computer memory having stored thereon a set of three two-dimensional structured light patterns, each structured light pattern comprising a plurality of pixels having pixel intensities which vary in a first dimension and are constant in a second dimension, wherein: each structured light pattern is derived from a corresponding aperiodic waveform replicated in a second dimension; each aperiodic waveform is derived from the same set of component triangular waveforms; and a given aperiodic waveform is created using a unique set of phase shifts applied to members of said same set of component triangular waveforms. ### Claim 18 (depends on 17) The two-dimensional structured light pattern according to claim 17, wherein: the pixel intensities along said first dimension comprise a distorted version of a sum of said set of component triangular waveforms. ### Claim 19 (depends on 18) The two-dimensional structured light pattern according to claim 18, wherein said distorted version comprises pixels which have been gamma corrected and then rescaled in accordance with a capability of the light projector. ### Claim 20 A structured light system capable of illuminating an object in preparation for three-dimensional rendering, comprising: a light projector; and a computer memory coupled to the light projector and having stored thereon a set of three two-dimensional structured light patterns, each structured light pattern comprising a plurality of pixels having pixel intensities which vary in a first dimension and are constant in a second dimension, wherein: each structured light pattern is derived from a corresponding aperiodic waveform replicated in a second dimension; each aperiodic waveform is derived from the same set of component triangular waveforms; and a given aperiodic waveform is created using a unique set of phase shifts applied to members of said same set of component triangular waveforms. ### Claim 21 (depends on 20) The structured light system according to claim 20, further comprising: a computer; and at least two digital cameras configured to feed output to the computer, wherein the relative positions of focal planes of the cameras are known to the computer.