Large-depth-of-field binary defocus three-dimensional measurement method based on multi-focal projection system

Abstract

The invention discloses a large-depth-of-field binary defocus three-dimensional measurement method based on a multi-focal projection system. The method comprises the following steps: constructing themulti-focal stripe projection system which is based on an optical projection system, and realizing separation of different axial binary stripe focusing surfaces by introducing a cylindrical lens; building an anisotropic filtering model of the multi-focal stripe projection system; optimizing a binary stripe projection method on the basis of the anisotropic filtering model, and according to an optimized stripe projection algorithm, generating and projecting a plurality of phase shift binary stripe patterns; based on a binary stripe image sequence In, analyzing and calculating phase information,and obtaining continuous absolute phases through phase unwrapping; and determining system parameters of the multi-focal stripe projection system through system calibration, and restoring a three-dimensional morphology of a large-depth-of-field object on the basis of the system parameters. According to the method, the problem of failure of a focal zone of a traditional binary defocus measurement method can be effectively avoided, so that the depth-of-field measuring performance is greatly improved.

Description

technical field [0001] The invention belongs to the technical field of optical measurement, and in particular relates to a three-dimensional measurement method for a large depth of field based on a multi-focus projection system, which can eliminate the limitation of the focus area in the binary defocusing technology, thereby effectively realizing the expansion of the measured depth of field. Background technique [0002] The structured light three-dimensional measurement method based on the binary defocus projection system belongs to the active optical measurement technology, which has the characteristics of simple structure, convenient measurement, high speed, and high precision. And cultural heritage protection and other fields have broad application prospects. The binary out-of-focus projection system combined with the advanced digital projection platform can realize kHz-level fringe projection and three-dimensional measurement. This method replaces the traditional 8-bit...

AI Technical Summary

Problems solved by technology

However, with the deepening of research, people found that this method also has a big flaw: the binary fringes can only have good measurement accuracy when they are moderately defocused, and the corresponding depth of field range is very limited

However, this method has limitations in improving the measurement performance and cannot completely eliminate the problem of the focal area of ​​the fringe projection system; the method based on the optimization of the defocus system parameters realizes the optimization of the defocus system parameters by establishing a quantitative model of the defocus degree of the projector Adjustment, although this method can effectively adjust the parameters of the defocused projection system to make it in the optimal working state, it still cannot completely overcome the problem of the fringe focus area; the method based on phase error compensation mainly uses a mathematical model to fit the phase error and The relationship between the depth of field, this method can effectively eliminate the phase error, but this method needs to introduce an additional projection fringe sequence, so it is not very robust

Images