Phase error correction method for out-of-focus phenomenon of fringe projection three-dimensional measuring system

Abstract

The invention discloses a phase error correction method for an out-of-focus phenomenon of a fringe projection three-dimensional measuring system. The method comprises: a computer generates a phase-shifted fringe image and the image is collected by a camera; for the collected image, a background image I' and a phase phi' containing an error are calculated and edge extraction is carried out on the background image I'; a point spread function (PSF) of each edge pixel is calculated after edge map obtaining; a phase gradient direction and a phase density of each to-be-processed pixel are calculatedby using gradient filtering and neighborhood averaging methods in the phase map phi'; and then for the to-be-processed pixels, phase errors delta phi caused by the out of focus of the camera are calculated pixel by pixel, so that a finally corrected phase phi is obtained and the phi meets a formula: phi=phi'-delta phi. The corrected phase information can be converted into three-dimensional information of a to-be-measured object by a phase-height mapping relationship.

Description

Technical field: [0001] The invention belongs to the field of three-dimensional reconstruction in computer vision, and in particular relates to a phase error correction method for the defocus phenomenon of a fringe projection three-dimensional measurement system. Background technique: [0002] The three-dimensional measurement technology FPP (fringe projection profilometry) based on fringe projection has been extensively researched and applied in recent years because of its advantages of high precision, fast speed, and little influence from ambient light. As a three-dimensional measurement method based on active light projection, FPP also has corresponding limitations. In the active light projection technology, it is often assumed that a certain object point on the surface of the object to be measured only directly receives the illumination from the sensor of the projection device. This assumption does not hold in many practical situations. In addition to directly receivin...

AI Technical Summary

Problems solved by technology

However, industrial projectors cannot accurately project stripes with very small stripe widths. For example, for common projectors, when the projection stripe width is less than 8 pixels, the projector often cannot accurately project

Therefore, this type of method cannot be used to solve the phase error caused by camera defocus in the FPP system

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