Method for measuring variable-frequency fringe projection structured light on basis of depth-of-field feedback

Abstract

The invention provides a method for measuring variable-frequency fringe projection structured light on the basis of depth-of-field feedback, and belongs to the field of non-contact optical three-dimensional measurement. The method includes calibrating change relations between defocusing cores and depths-of-field of cameras and projectors; primarily measuring workpieces with variable depths-of-field by the aid of uniform sine fringe image sequences to obtain the depths-of-field of the cameras and the projectors, and computing the sizes of comprehensive defocusing cores of the surfaces of the workpieces according to calibrated change relations between the defocusing cores and the depths-of-field; optimally designing N transverse variable-frequency sine phase-shift fringe image sequences andN longitudinal variable-frequency sine phase-shift fringe image sequences on the basis of the sizes of the defocusing cores in public visual fields of the projectors and the cameras; projecting and acquiring variable-frequency fringe image sequences, and acquiring projector pixel coordinates by the aid of variable-frequency decoding processes; rebuilding three-dimensional coordinate point cloud according to reacquired matched pixel coordinates of the projectors and the cameras. The projector pixel coordinates are matched with camera pixel coordinates in the public visual fields. The method hasthe advantages that the comprehensive measurement accuracy of the workpieces with the variable depths-of-field can be effectively improved, and accordingly the robustness of the method for measuringthe fringe projection structured light can be advantageously improved.

Description

technical field [0001] The invention belongs to the field of non-contact optical three-dimensional measurement, in particular to the field of three-dimensional measurement of fringe projection structured light by time phase shift method, and proposes a frequency conversion fringe projection structured light measurement method based on depth of field feedback. Background technique [0002] The fringe projection structured light measurement method is a measurement system composed of a camera, a projector and a computer. The projector is used to actively project the coded image to the surface of the measured object, and then the camera is used to collect the corresponding coded image projected on the surface of the measured object. The method of matching the pixel with the camera, and then obtaining the three-dimensional coordinates of the surface of the measured object according to the principle of triangulation. The fringe projection structured light three-dimensional measure...

AI Technical Summary

Problems solved by technology

[0006] For objects with varying depth of field, such as curved surfaces or steps, the degree of defocus varies with the depth of field. Therefore, when measuring the surface of an object with varying depth of field, if a sinusoidal fringe image with a uniform and constant frequency is used, the frequency fringe image will only The measurement accuracy of the area that can meet the specific depth of field position is high, while other positions do not reach the optimal frequency, and the measurement accuracy is not optimal, so the robustness of this method is poor

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