Method for calibrating three-dimensional imaging system

Abstract

The invention discloses a method for calibrating a three-dimensional imaging system, which comprises the following steps of: 1, designing a calibration flat plate to be white and have a diffuse reflection surface and designing black annular identifiers in a square matrix arrangement mode on the calibration flat plate simultaneously, wherein the center distance between adjacent identifiers is equal; 2, placing the calibration flat plate at different positions in a measurement field, projecting non-uniform sinusoidal grating stripes with the optimal number of stripes at each placement position onto the surface of the calibration flat plate, and acquiring and calculating the absolute phase of each white pixel point inside the black annular identifiers; 3, extracting the central point position of each identifier from a corresponding absolute phase diagram to solve the relative depths of the identifiers when the calibration flat plate is at each placement position; 4, establishing a high-order polynomial (A) to express the relationship between the absolute phases and the relative depths; and 5, converting the absolute phases into actual depth data by using the calibrated polynomial coefficients so as to finish the calibration of the three-dimensional imaging system.

Description

technical field [0001] The invention relates to a three-dimensional imaging system calibration technology, in particular to a three-dimensional imaging system calibration method based on non-uniform fringe projection technology to measure the surface phase of an object and establish the relationship between absolute phase and depth. Background technique [0002] Existing 3D imaging system calibration methods either rely on precisely moving and positioned plates to establish the relationship between phase and depth, which takes a long time to calibrate and is limited to a laboratory environment; or rely on calculating the internal and external parameters of the imaging unit and projection unit and Its relative positional relationship, this method is difficult to implement, and the obtained parameters are not accurate, so it is impossible to obtain high-precision three-dimensional shape data. Within the scope of the applicant's search, the calibration method of the 3D imaging ...

AI Technical Summary

Problems solved by technology

Therefore, the process of model-based calibration technology is cumbersome, and the accuracy of the obtained parameters is not high; polynomial-based calibration technology needs a look-up table to establish the relationship between the depth and phase of each pixel

In addition, most of the two methods require precise two-dimensional or three-dimensional calibration equipment, which is expensive, which limits the calibration of the system to be completed in the laboratory, and is not suitable for actual field use

Therefore, the calibration of 3D imaging systems, especially on-site calibration outside the laboratory, is a difficult problem that has not been well solved

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