Three-dimensional measurement method and related apparatus

A three-dimensional measurement system, comprising:

• a processor, a projector and a camera;
• wherein:
• the processor is used for converting a total number of levels of sawtooth fringes in a sawtooth fringe image of n sawtooth fringe images into a Gray code, and acquiring a sawtooth slope coefficient of each sawtooth fringe according to each bit code value in the Gray code;
• and fusing the sawtooth slope coefficient into the sawtooth fringe image to generate a plurality of target sawtooth fringe patterns fused with the Gray code, wherein the target sawtooth fringe pattern is:
• In(u,v)=A(u,v)+B(u,v)×{gn(u,v)×kn(u,v)×φ(u,v)+bn(u,v)};
• wherein In(u, v) is an nth target sawtooth fringe pattern, n=0, 1, 2, . . . , N-1, N is a total number of the target sawtooth fringe patterns, (u, v) is pixel point coordinates, A(u, v) is an average intensity, B(u, v) is a modulation intensity, gn(u, v) is a sawtooth slope coefficient of a sawtooth fringe of an nth sawtooth fringe image, kn(u, v) is a slope of a sawtooth fringe of the nth target sawtooth fringe pattern,
• φ
• ⁡
• (
• u
• ,
• v
• )
• =
• [
• mod
• ⁡
• (
• u
• ,
• T
• )
• -
• T
• 2
• ]
• is a modulated phase of the target sawtooth fringe pattern, mod(u, T) is a complementary function, T is a number of pixels of a single-period fringe of the sawtooth fringe image, and bn(u, v) is a basic offset of the sawtooth fringe of the nth target sawtooth fringe pattern;
• the projector is used for projecting each target sawtooth fringe pattern to a surface of a to-be-measured object;
• the camera is used for collecting a deformed target sawtooth fringe pattern on the surface of the to-be-measured object, so as to obtain a sawtooth fringe collection pattern;
• the processor is further used for solving a Gray code of each sawtooth fringe collection pattern at each pixel point according to a differential property of adjacent pixels in each sawtooth fringe collection pattern;
• solving a fringe level and a wrapped phase at each pixel point through the Gray code of each sawtooth fringe collection pattern at each pixel point and each sawtooth fringe collection pattern;
• calculating an absolute phase at each pixel point according to the fringe level and the wrapped phase at each pixel point;
• and reconstructing a three-dimensional point cloud through triangulation ranging based on the absolute phase at each pixel point, so as to obtain a three-dimensional model of the to-be-measured object;
• wherein the acquiring the sawtooth slope coefficient of the sawtooth fringe according to each bit code value in the Gray code, comprises:
• acquiring the sawtooth slope coefficient of the sawtooth fringe through a conversion formula according to each bit code value in the Gray code, wherein the conversion formula is:
• g
• n
• (
• u
• ,
• v
• )
• =
• {
• 1
• ,
• DtoG
• [
• Floor
• (
• u
• T
• )
• ,
• n
• ]
• =
• 0
• -
• 1
• ,
• DtoG
• [
• Floor
• (
• u
• T
• )
• ,
• n
• ]
• =
• 1
• ;
• wherein (u, v) is pixel point coordinates, gn(u, v) is the sawtooth slope coefficient of the sawtooth fringe of the nth sawtooth fringe image,
• DtoG
• [
• Floor
• (
• u
• T
• )
• ,
• n
• ]
• is an nth bit code value in the Gray code of the total number of levels converted from a decimal number, n=0, 1, 2, . . . , N-1, and
• Floor
• (
• u
• T
• )
• is a rounding function.