Phase unwrapping method in large depth-of-field scene

Abstract

The invention relates to a phase unwrapping method in a large depth-of-field scene. The phase unwrapping method comprises the following steps: 1, setting a three-gray-level Gray code picture; 2, selecting a fringe pattern with a fixed period for unwrapping, and selecting six two-gray-level Gray code pictures and three three-gray-level Gray code pictures; 3, selecting two sub-depth-of-field in a large-depth-of-field scene, and projecting the fringe pattern, the two-gray-level gray code pattern and the three-gray-level gray code pattern to a measured object; 4, in two sub-depth-of-field scenes, obtaining a corresponding level graph and an error between the two sub-depth-of-field scenes; and 5, the level error difference between the three-gray-level Gray code method and the two-gray-level Gray code method is small, and the phase unwrapping effect difference is small. According to the method, the phase solving effect of the three-gray-level Gray code in a large-depth-of-field scene is similar to that of a two-gray-level Gray code, and compared with the two-gray-level Gray code, the three-gray-level Gray code reduces the number of projection frames, improves the measurement efficiency and meets the rapid measurement in the large-depth-of-field scene.

Description

technical field [0001] The invention relates to a phase unwrapping method in a scene with a large depth of field, and belongs to the technical field of image processing. Background technique [0002] In fringe projection profilometry FPP, according to different phase unwrapping principles, the current mainstream phase unwrapping algorithms are divided into two types: Spatial Phase Unwrapping Algorithm and Temporal Phase Unwrapping Algorithm. The spatial phase unwrapping algorithm is a very intuitive and very simple phase unwrapping method. Its process is generally to select the direction of the data row or column to truncate the phase, and analyze the phase values ​​of adjacent elements. If the phase difference value is less than , then the phase value of the latter element will add ; if the phase difference value is greater than , then the phase value of the latter element will be subtracted . Spatial phase unwrapping is a point-by-point unwrapping process of integ...

AI Technical Summary

Problems solved by technology

Although the effect of gray code method for phase unwrapping in scenes with large depth of field is acceptable, it is not suitable for fast measurement in scenes with large depth of field due to the excessive number of projected Gray code frames.

The multi-frequency heterodyne method is greatly affected by noise, and it is impossible to completely eliminate the influence of noise in scenes with large depth of field. This method is also not suitable for phase unwrapping in scenes with large depth of field.

Traditional phase unwrapping algorithms have their own defects in phase unwrapping in large depth of field scenes. Therefore, it is necessary to propose a new phase unwrapping method to ensure the accuracy of phase unwrapping in large depth of field scenes and improve the efficiency of 3D measurement.

Images