US 2017/0102228 A1 · MEASUREMENT METHOD, MEASUREMENT APPARATUS, MEASUREMENT PROGRAM AND COMPUTER READABLE RECORDING MEDIUM IN WHICH MEASUREMENT PROGRAM HAS BEEN RECORDED

Abstract

A phase of a specific frequency is found by carrying out a two-dimensional Fourier transformation on an image of a two-dimensional grid image on the surface of an object taken by a camera, and the displacement of the surface of the object is measured from the phase. As a result, measurement that is strong against noise can be carried out without projecting a grid having a brightness distribution of precise cosine waves. In addition, the process is simple and the number of pixels used for the measurement is smaller than that in the sampling moire method. The displacement can be found at a high speed.

Claims6

Dependent claims

A measurement method for measuring a displacement of a surface of an object from an image of a two-dimensional grid image on the surface of the object taken by a camera, comprising the steps of:

taking an image of a two-dimensional grid image on a surface of an object with a camera in such a state that the direction of camera pixels is adjusted towards said image of the two-dimensional grid image before displacement, and at the same time one period of said image of the two-dimensional grid image in the x direction is adjusted to Nx pixels of the camera and one period in the y direction is adjusted to Ny pixels of the camera, where Nx and Ny are integers greater than 2;
obtaining a phase from said image of the two-dimensional grid image for the frequencies in the x direction and the y direction that correspond to one period of said grid in said image of the two-dimensional grid image;
and
finding a displacement of the surface of the object from the phase.

1 more element

Dependencies are inferred from the claim text.

Measurement method, measurement apparatus, measurement program and computer readable recording medium in which measurement program has been recorded

Life of this patent

Measurement method, measurement apparatus, measurement program and computer readable recording medium in which measurement program has been recorded

Life of this patent

Abstract

Claims6