Regional Gamma precorrection phase error compensation method in large view field structured light vision measurement

A visual measurement, phase error technology, applied in the field of phase error compensation, adaptive subregional Gamma pre-correction phase error compensation

Active Publication Date: 2016-03-16
HUAQIAO UNIVERSITY
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0005] The purpose of the invention is to overcome the deficiencies of the prior art, and provide a sub-regional Gamma pre-correction phase error compensat

Method used

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  • Regional Gamma precorrection phase error compensation method in large view field structured light vision measurement
  • Regional Gamma precorrection phase error compensation method in large view field structured light vision measurement
  • Regional Gamma precorrection phase error compensation method in large view field structured light vision measurement

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Embodiment 1

[0037] see Figure 1 to Figure 8 As shown, a sub-area Gamma pre-correction phase error compensation method in a large field of view structured light vision measurement of the present invention includes: first, counting the distribution of Gamma values ​​​​in the entire measurement field of view, and according to the required measurement accuracy, Set the allowable Gamma value change threshold to automatically divide the measurement area, and use different Gamma values ​​to pre-correct each area after division.

[0038] Preferably, the following steps are included:

[0039] A1. The computer generates a set of ideal grayscale images. The range of grayscale changes is [80,230]. The grayscale value of any two adjacent grayscale images differs by 5 steps. After projection, the grayscale images are collected by the camera and extracted separately. Get the gray value of each pixel position in each gray image;

[0040] A2, adopt the least squares fitting method to respectively fit t...

Embodiment 2

[0055] Taking the structured light binocular vision measurement system as an example, the four-step phase shift method is used for measurement. The overall process flow chart is as follows figure 1 As shown, the specific steps are as follows:

[0056] Step 1. The computer generates a set of ideal grayscale images. The range of grayscale changes is [80,230]. The grayscale value of any two adjacent grayscale images differs by 5 steps. After projection, the grayscale images are collected by the left and right cameras, and Extract the gray value of each pixel position in each gray image respectively;

[0057] Step 2. Fit the grayscale input and output response curves of each pixel using the least squares fitting method to determine the Gamma value of each pixel position on the left and right images. The resolutions of the projector and the camera are both: 1600×1200 pixels. Consistent with the resolution of the camera and projector, construct two Gamma value matrices respectivel...

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Abstract

The invention discloses a phase error compensation method for large view field adaptive regional Gamma precorrection. A standard N-step phase shift sinusoidal grating image is projected through a projector on the surface of a measured object; a camera is adopted to acquire the projected image; through carrying out phase demodulation on the phase shift image, the phase value of each pixel point is calculated and acquired, and thus, the three-dimensional surface information of the measured object is obtained reversely. In a large view field condition, Gamma values have large differences in a measurement range, residual errors exist when a single Gamma value is adopted for precorrection compensation, a least square fitting method is adopted to acquire the actual Gamma value at each pixel point position, the allowable maximal Gamma value change range deltaG is set to be a threshold according to the Gamma value distribution condition, the measurement region is divided, and thus, multiple Gamma values are adopted to carry out pre-coding correction on the ideal phase shift sinusoidal grating image, and phase errors caused by Gamma nonlinear distortion can be compensated.

Description

technical field [0001] The invention relates to a phase error compensation technology in structured light vision measurement based on a phase shift method, in particular to a phase error compensation method for self-adaptive sub-area Gamma pre-correction in the case of a large field of view, and belongs to the technical field of machine vision. Background technique [0002] A structured light vision measurement method based on phase shift technology, including a monocular structured light vision measurement method and a binocular structured light vision measurement method. No matter what method is used to obtain the three-dimensional data of the measured object, it is necessary to extract the phase, and the accuracy of phase extraction directly affects the final measurement accuracy of the system. In the measurement system, the Gamma nonlinear distortion of the camera and projector is one of the main factors affecting the high-precision phase extraction. Gamma nonlinear dis...

Claims

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Application Information

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IPC IPC(8): G01B11/25
CPCG01B11/2527
Inventor 林俊义江开勇黄剑清黄常标刘斌
Owner HUAQIAO UNIVERSITY
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