# US 11,029,399 B2 · System and method for calibrating light intensity > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,029,399 B2 - Document ID: US11029399B2 - Status: Granted - Kind: B2 - Application number: 15/886,206 - Filed: 2018-02-01 - Published: 2019-08-01 - Granted: 2021-06-08 - Earliest claimed: 2018-02-01 - Assignees: Beijing Voyager Technology Co., Ltd. - Applicants: Beijing Voyager Technology Co., Ltd. - Inventors: Xufeng Han; Tingbo Hou - Web page: https://patentgrep.com/patent/US11029399B2 ## CPC - G01S 7/4972: {Alignment of sensor} - G01C 21/005: {with correlation of navigation data from several sources, e.g. map or contour matching (G01C21/30 takes precedence)} - G01S 7/497: Means for monitoring or calibrating - G01S 17/42: Simultaneous measurement of distance and other co-ordinates (indirect measurement G01S17/46) - G01S 17/89: for mapping or imaging - G01S: RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES - G01C: MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY (measuring liquid level G01F; radio navigation, determining distance or velocity by use of propagation effects, e.g. Doppler effects, propagation time, of radio waves, analogous arrangements using other waves G01S) ## Abstract Systems and methods are provided for calibrating light intensity. An exemplary method for light intensity calibration may comprise: obtaining a plurality of intensity distributions of reflected light from an area, wherein each of the intensity distributions is associated with a beam; determining a reference intensity distribution from the plurality of intensity distributions, wherein the reference intensity distribution is associated with a reference beam, the plurality of intensity distributions excluding the reference intensity distribution are non-reference intensity distributions, and the non-reference intensity distributions are each associated with a non-reference beam; and aligning each of the non-reference intensity distributions to the reference distribution to calibrate the non-reference intensity distributions against the reference distribution. ## Claims ### Claim 1 A method for light intensity calibration, comprising: emitting a plurality of light beams from a plurality of light emitters of a LIDAR (Light Detection And Ranging) device, receiving reflected light of the plurality of light beams by a plurality of light detectors of the LIDAR device, wherein the reflected light comprises a reference intensity distribution associated with a reference beam of the plurality of light beams, and one or more non-reference intensity distributions associated with one or more non-reference beams of the plurality of light beams; and calibrating the one or more non-reference intensity distributions to the reference intensity distribution. ### Claim 2 (depends on 1) The method of claim 1, wherein calibrating the one or more non-reference intensity distribution to the reference intensity distribution comprises: applying a Dynamic Time Warping (DTW) algorithm to align the one or more non-reference intensity distributions to the reference intensity distribution. ### Claim 3 (depends on 1) The method of claim 1, wherein calibrating the one or more non-reference intensity distributions to the reference intensity distribution comprises: ordering the light beams based on a physical proximity among intersections of the light beams with an area of the reflected light, wherein the physical proximity among the intersections of the light beams with the area corresponds to another physical proximity among the light emitters of the LIDAR device, wherein the reference beam is in the center of the ordered light beams. ### Claim 4 (depends on 1) The method of claim 1, wherein: the plurality of light emitters and the plurality of light detectors are movable relative to an area of the reflected light and configured to obtain an intensity reading at various time points to obtain the corresponding intensity distribution over the area. ### Claim 5 (depends on 4) The method of claim 4, wherein: the LIDAR device is disposed on a vehicle; the plurality of light emitters and the plurality of light detectors are configured to rotate relative to the vehicle as the vehicle moves relative to the area; and the reference intensity distribution and the non-reference intensity distributions comprise a plurality of the intensity readings caused by the rotation and the vehicle movement. ### Claim 6 (depends on 1) The method of claim 1, wherein: the reference intensity distribution and the non-reference intensity distributions are representable in histograms associating light intensity readings and frequency of occurrence of the light intensity readings in an area of the reflected light; the area comprises a marker corresponding to one or more intensity peaks in one or more histograms of the intensity distributions; and the reference intensity distribution is representative of the marker in a background. ### Claim 7 (depends on 1) The method of claim 1, further comprising: obtaining an intensity mapping that maps any raw non-reference beam intensity reading to a calibrated intensity reading. ### Claim 8 A system for light intensity calibration, comprising one or more processors and one or more non-transitory computer-readable memories coupled to the one or more processors and configured with instructions executable by the one or more processors to cause the system to perform operations comprising: emitting a plurality of light beams from a plurality of light emitters of a LIDAR (Light Detection And Ranging) device, receiving reflected light of the plurality of light beams by a plurality of light detectors of the LIDAR device, wherein the reflected light comprises a reference intensity distribution associated with a reference beam of the plurality of light beams, and one or more non-reference intensity distributions associated with one or more non-reference beams of the plurality of light beams; and calibrating the one or more non-reference intensity distribution to the reference intensity distribution. ### Claim 9 (depends on 8) The system of claim 8, wherein calibrating the one or more non-reference intensity distribution to the reference intensity distribution comprises: applying a Dynamic Time Warping (DTW) algorithm to align the one or more non-reference intensity distributions to the reference intensity distribution. ### Claim 10 (depends on 8) The system of claim 8, wherein the plurality of light emitters and the plurality of light detectors are rotatable light emitters and detectors mountable on a movable vehicle, the each light emitter emitting the each light beam of the plurality of light beams and the each light detector detecting the each corresponding light intensity while in rotation as the vehicle moves relative to the area, wherein calibrating the plurality of non-reference intensity distribution to the reference intensity distribution comprises: ordering the plurality of light beams based on a physical proximity among intersections of the beams with an area of the reflected light at the same time; and recursively aligning the each non-reference beam to a physically closest beam towards the reference beam until aligning to the reference beam. ### Claim 11 (depends on 10) The system of claim 10, wherein recursively aligning the each non-reference beam to the physically closest beam towards the reference beam comprises: aligning closest light beams of the plurality of light beams to the reference beam; aligning next closest light beams of the plurality of light beams to the closest light beams; repeating the alignments until each of the non-reference beams is aligned to another beam towards the reference beam; and propagating the alignments throughout the non-reference beams to align each of the non-reference beams to the reference beam. ### Claim 12 (depends on 10) The system of claim 10, wherein: the physical proximity among the intersections of the beams with the area corresponds to another physical proximity among the light emitters on the LIDAR device. ### Claim 13 (depends on 8) The system of claim 8, wherein: the plurality of light emitters and the plurality of light detectors are movable relative to an area of the reflected light and configured to obtain an intensity reading at various time points to obtain the corresponding intensity distribution over the area. ### Claim 14 (depends on 13) The system of claim 13, wherein: the LIDAR device is disposed on a vehicle; the plurality of light emitters and the plurality of light detectors are configured to rotate relative to the vehicle as the vehicle moves relative to the area; and the reference intensity distribution and the non-reference intensity distributions comprise a plurality of the intensity readings caused by the rotation and the vehicle movement. ### Claim 15 (depends on 8) The system of claim 8, wherein: the reference intensity distribution and the non-reference intensity distributions are representable in histograms associating light intensity readings and frequency of occurrence of the light intensity readings in an area of the reflected light; the area comprises a marker corresponding to one or more intensity peaks in one or more histograms of the intensity distributions; and the reference intensity distribution is representative of the marker in a background. ### Claim 16 (depends on 8) The system of claim 8, wherein the processor is further configured to: obtain an intensity mapping that maps any raw non-reference beam intensity reading to a calibrated intensity reading. ### Claim 17 A non-transitory computer-readable storage medium coupled to a processor and comprising instructions that, when executed by the processor, cause the processor to perform a method for light intensity calibration, the method comprising: emitting a plurality of light beams from a plurality of light emitters of a LIDAR (Light Detection And Ranging) device; receiving reflected light of the plurality of light beams by a plurality of light detectors of the LIDAR device, wherein the reflected light comprises a reference intensity distribution associated with a reference beam of the plurality of light beams, and one or more non-reference intensity distributions associated with one or more non-reference beams of the plurality of light beams; and calibrating the one or more non-reference intensity distribution to the reference intensity distribution. ### Claim 18 (depends on 17) The non-transitory computer-readable storage medium of claim 17, wherein calibrating the one or more non-reference intensity distribution to the reference intensity distribution comprises: applying a Dynamic Time Warping (DTW) algorithm to align each of the non-reference intensity distributions to the reference intensity distribution. ### Claim 19 A system for light intensity calibration, implementable on a LIDAR (Light Detection And Ranging) device, the system comprising: a plurality of rotatable light emitters and detectors mountable on a movable vehicle, the each light emitter emitting a beam and the each light detector detecting an reflection of the corresponding beam while in rotation as the vehicle moves relative to an area; and a processor coupled to the detectors and configured to: obtain a plurality of intensity distributions of the reflected light from the area; determine a reference intensity distribution from the plurality of intensity distributions, wherein the reference intensity distribution is associated with a reference beam, the plurality of intensity distributions excluding the reference intensity distribution are one or more non-reference intensity distributions, and the one or more non-reference intensity distributions are associated with one or more non-reference beams; and align the one or more non-reference intensity distributions to the reference intensity distribution to calibrate the one or more non-reference intensity distributions against the reference intensity distribution. ### Claim 20 (depends on 19) The system of claim 19, wherein: to align the one or more non-reference intensity distribution to the reference intensity distribution, the processor is configured to recursively align the one or more non-reference intensity distribution to a neighboring non-reference intensity distribution towards the reference intensity distribution until aligned with the reference intensity distribution.