System calibration method for grating projection three-dimensional measurement

Abstract

The invention relates to a system calibration method for grating stripe projection-based three-dimensional measurement. A calibration object is a system consisting of a projector and a video camera. The method is implemented by the following steps: (1) adjusting the relative positions of the projector and the video camera, so that the projector is parallel with a lens longitudinal axis of the video camera; (2) calculating the absolute phase position of a reference plane by combining a sinusoidal grating phase-shifting algorithm and a Gray code; (3) placing at least two standard blocks, of which the heights are known and different, on the reference plane and calculating the absolute phase position distribution; (4) calibrating a three-dimensional measuring system: establishing projection and imaging models, deducing an object point height-phase position relational expression of an object to be measured, and fitting the coefficients of the height-phase position relational expression by utilizing the standard blocks with known heights and the absolute phase position distribution thereof and through a least square method; (5) calculating the absolute phase position value of the object to be measured and obtaining the height distribution from a calibrated expression so as to realize height measurement of the object. The method has the advantages of high operability and high measuring precision.

Description

technical field [0001] The invention uses a gray-scale sinusoidal grating phase-shift algorithm to obtain the main value phase, and then uses a Gray code method to obtain the fringe order to obtain the absolute phase distribution of the reference plane and the object respectively. Then, the height-phase relationship of the object point is obtained from the positional constraints of the projector and the camera, and then the system is calibrated using a calibration block with a known height, and the coefficients of the height-phase relationship are fitted. Finally, by substituting the pixel coordinates and absolute phase values ​​of each point of the object to be measured into the relational expression, the three-dimensional contour of the object can be measured and the three-dimensional shape of the object can be reconstructed. It belongs to the field of three-dimensional information reconstruction. Background technique [0002] Optical three-dimensional measurement technol...

AI Technical Summary

Problems solved by technology

However, the optical axis and the optical center are imaginary space straight lines and points respectively, which cannot be accurately positioned in practice, and the above conditions are very difficult to meet, so the measurement system is greatly limited in practical applications, and its operability is not strong

At the same time, due to the complicated position calibration process, there will inevitably be errors, so the accuracy of the traditional three-dimensional measurement system is not high

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