US 12,072,177 B2
Three-dimensional shape measuring apparatus, three-dimensional shape measuring method, program, and storage medium
Shizuo Sakamoto, Tokyo (JP)
Assigned to NEC CORPORATION, Tokyo (JP)
Filed by NEC Corporation, Tokyo (JP)
Filed on Feb. 2, 2022, as Appl. No. 17/591,020.
Application 17/591,020 is a continuation of application No. 16/980,978, abandoned, previously published as PCT/JP2019/010414, filed on Mar. 13, 2019.
Claims priority of application No. 2018-049546 (JP), filed on Mar. 16, 2018.
Prior Publication US 2022/0155056 A1, May 19, 2022
Int. Cl. G01B 11/25 (2006.01)
CPC G01B 11/2513 (2013.01) [G01B 11/254 (2013.01); G01B 11/2522 (2013.01)] 8 Claims
OG exemplary drawing
 
1. A three-dimensional shape measuring method comprising:
projecting, by a projector, a first light pattern having a luminance that changes at a first cycle on a measured object;
acquiring at least three first images of the measured object on which the first light pattern has been projected at different phases of the first phases;
projecting, by the projector that projected the first light pattern, a second light pattern having a luminance that changes at a second cycle that is longer than the first cycle on the measured object;
acquiring a single second image of the measured object on which the second light pattern has been projected, wherein the at least three first images and the single second image each have a corresponding plurality of pixels;
for each of the at least three first images, calculating, based on first luminance values of the first image for the pixels, relative phase values for parts of the measured object corresponding to each of the pixels;
calculating, based on the relative phase values and the first luminance values, a parameter of a relational expression representing a relationship between luminance and phase, wherein the parameter corresponds to a physical characteristic of the projector;
calculating, based on second luminance values of the single second image, based on the relative phase values calculated for the parts of the measured object corresponding to the pixels, and based on the parameter, absolute phase values for the parts of the measured object corresponding to the pixels, wherein only one image of the measured object on which the second light pattern has been projected is used in calculating the absolute phase values, the only one image being the single second image; and
calculating, based on the absolute phase values, calculating three-dimensional coordinates for each of the parts of the measured object.