High-dynamic-range grating projection three-dimensional measurement method based on full-automatic exposure

Abstract

The invention discloses a high-dynamic-range grating projection three-dimensional measurement method based on full-automatic exposure, and the method comprises the steps: collecting a grating projected by a projector through a camera, wherein the exposure time is an initial value t1 at this moment; calculating a stripe modulation degree coefficient I' of the collected image; solving a modulation degree threshold value I't according to a noise level curve of the camera; calculating a group of exposure moments (N) required by the whole measurement process according to a threshold value; automatically carrying out the photographing of N groups of grating stripes according to the obtained N exposure moments; solving N phase diagrams through the N groups of stripe patterns via a conventional phase shift algorithm; dividing all pixels of an original image into N groups according to the stripe modulation degree coefficient I', wherein the impact on the phases of all pixels in the i-th group in the i-th phase diagram from noise is smaller; synthesizing N phase diagrams into a final phase diagram according to the rule, and solving the three-dimensional information with the high dynamic range of an object through combining with the calibration information.

Description

Technical field: [0001] The invention belongs to the field of three-dimensional reconstruction in computer vision, and in particular relates to a three-dimensional measurement method for high dynamic range grating projection based on fully automatic exposure. Background technique: [0002] FPP (fringe projection profilometry), a three-dimensional measurement technology based on grating projection, has been extensively researched and applied in recent years because of its high precision, fast speed, and less influence by ambient light. As a three-dimensional measurement method based on active light projection, FPP also has corresponding limitations. One of the more obvious ones is that the industrial cameras used in the measurement system have a small dynamic range, which leads to poor quality of the collected grating fringe images when measuring objects with complex surface textures. This affects the phase quality of the solution and the final 3D reconstruction accuracy. ...

AI Technical Summary

Problems solved by technology

Second, when the surface texture of the object is dark, the signal-to-noise ratio of the image collected by the FPP system is small, so the phase quality obtained in the dark texture image is poor

However, this method also has its obvious disadvantages: the entire measurement process is relatively cumbersome to operate, and the same scene needs to be measured several times in succession to obtain the final result

In addition, the exposure value of the camera in each measurement is difficult to quantify, and manual adjustment is required based on experience

Although some methods for calculating camera exposure time have been proposed, the calculation process is still relatively complicated and requires human intervention to complete the measurement

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