# US 2021/0344892 A1 · Method and system for determining optimal exposure time and number of exposures in structured light-based 3d camera > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2021/0344892 A1 - Document ID: US20210344892A1 - Status: Published application - Kind: A1 - Application number: 17/365,985 - Filed: 2021-07-01 - Published: 2021-11-04 - Earliest claimed: 2015-10-27 - Assignees: Research & Business Foundation Sungkyunkwan University - Applicants: Research & Business Foundation Sungkyunkwan University - Inventors: Suk-han LEE; Yun-su CHOI; In-sub SHIN - Web page: https://patentgrep.com/patent/US20210344892A1 ## CPC - H04N 13/254: in combination with electromagnetic radiation sources for illuminating objects - H04N 23/71: Circuitry for evaluating the brightness variation - H04N 23/73: by influencing the exposure time - H04N 23/743: Bracketing, i.e. taking a series of images with varying exposure conditions - H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION ## Abstract Disclosed is a method for determining the optimal exposure time and the number of exposures in a structured light-based 3D camera system. The method includes capturing a reference image onto which first and second patterns are projected, calculating a slope related to brightness and an exposure time for a pixel of the reference image and categorizing a state of the slope, creating an upper loss pixel distribution chart and an accumulation pixel distribution chart by calculating the number of upper loss pixels and the number of accumulation pixels for the exposure time of the structured light-based 3D camera system, and determining the optimal exposure time and the number of exposures of the structured light-based 3D camera system using the upper loss pixel distribution chart and the accumulation pixel distribution chart. ## Claims ### Claim 1 A method for determining an exposure parameter for a structured light-based 3D camera system, the method comprising: capturing a first reference image and a second reference image, the first reference image including a reflection of a first pattern from a target object and the second reference image including a refection of a second pattern from the target object; calculating a pixel distribution from the first reference image and the second reference image; and determining the exposure parameter using the pixel distribution. ### Claim 2 (depends on 1) The method of claim 1, wherein the calculating the pixel distribution includes calculating a plurality of slopes related to a brightness and an exposure time for selected pixels of the first reference image and the second reference image, and categorizing the plurality of slopes. ### Claim 3 (depends on 1) The method of claim 1, wherein the calculating the pixel distribution further includes calculating an upper loss pixel distribution and an accumulation pixel distribution from a number of upper loss pixels and a number of accumulation pixels. ### Claim 4 (depends on 1) The method of claim 1, wherein the exposure parameter includes at least one of an exposure time and a number of exposures. ### Claim 5 (depends on 1) The method of claim 1, wherein each of the first pattern and the second pattern includes at least one of an all-black pattern and an all-white pattern. ### Claim 6 (depends on 3) The method of claim 3, wherein the calculating the upper loss pixel distribution and the accumulation pixel distribution includes excluding states in which a brightness value of a pixel associated with the first reference image and a brightness value of a pixel associated with the second reference image are less than a predetermined threshold brightness value. ### Claim 7 (depends on 1) The method of claim 1, wherein the first pattern and the second pattern are the same. ### Claim 8 (depends on 1) The method of claim 1, wherein the first pattern and the second pattern are different. ### Claim 9 A structured light-based 3D camera system, comprising: a projection unit for projecting a first pattern and a second pattern onto a target object; a capturing unit for capturing a first reference image and a second reference image, the first reference image including a reflection of the first pattern from the target object and the second reference image including a reflection of the second pattern from the target object; and a processing unit for calculating a pixel distribution from the first reference image and the second reference image, and determining an exposure parameter for the structured light-based 3D camera system using the pixel distribution. ### Claim 10 (depends on 9) The structured light-based 3D camera system of claim 9, wherein each of the first pattern and the second pattern includes at least one of an all-black pattern and an all-white pattern. ### Claim 11 (depends on 9) The structured light-based 3D camera system of claim 9, wherein the exposure parameter includes at least one of an exposure time and a number of exposures. ### Claim 12 (depends on 9) The structured light-based 3D camera system of claim 9, wherein the processing unit calculates the pixel distribution by calculating a plurality of slopes related to a brightness and an exposure time for selected pixels of the first reference image and the second reference image, and categorizing the plurality of slopes. ### Claim 13 (depends on 9) The structured light-based 3D camera system of claim 9, wherein the processing unit calculates the pixel distribution by calculating an upper loss pixel distribution and an accumulation pixel distribution from a number of upper loss pixels and a number of accumulation pixels. ### Claim 14 (depends on 13) The structured light-based 3D camera system of claim 13, wherein the calculating the upper loss pixel distribution and the accumulation pixel distribution comprise excluding states in which a brightness value of a pixel associated with the first reference image and a brightness value of a pixel associated with the second reference image are less than a predetermined threshold brightness value. ### Claim 15 (depends on 9) The structured light-based 3D camera system of claim 9, wherein the first pattern and the second pattern are the same. ### Claim 16 (depends on 9) The structured light-based 3D camera system of claim 9, wherein the first pattern and the second pattern are different.