Modified Gray-Level Coding Method for Absolute Phase Retrieval

Fringe projection systems have been widely applied in three-dimensional (3D) shape measurements. One of the important issues is how to retrieve the absolute phase. This paper presents a modified gray-level coding method for absolute phase retrieval. Specifically, two groups of fringe patterns are pr...

Full description

Saved in:
Bibliographic Details
Published in:Sensors (Basel, Switzerland) Switzerland), 2017-10, Vol.17 (10), p.2383
Main Authors: Chen, Xiangcheng, Chen, Shunping, Luo, Jie, Ma, Mengchao, Wang, Yuwei, Wang, Yajun, Chen, Lei
Format: Article
Language:English
Subjects:
Accuracy
Algorithms
Cameras
Coding
fringe projection
gray-level coding
Luminous intensity
Methods
Phase retrieval
Phase shift
Sensors
Wavelet transforms
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Fringe projection systems have been widely applied in three-dimensional (3D) shape measurements. One of the important issues is how to retrieve the absolute phase. This paper presents a modified gray-level coding method for absolute phase retrieval. Specifically, two groups of fringe patterns are projected onto the measured objects, including three phase-shift patterns for the wrapped phase, and three -ary gray-level ( GL) patterns for the fringe order. Compared with the binary gray-level ( GL) method which just uses two intensity values, the GL method can generate many more unique codewords with multiple intensity values. With assistance from the average intensity and modulation of phase-shift patterns, the intensities of GL patterns are normalized to deal with ambient light and surface contrast. To reduce the codeword detection errors caused by camera/projector defocus, GL patterns are designed as -ary gray-code ( GC) patterns to ensure that at most, one code changes at each point. Experiments verify the robustness and effectiveness of the proposed method to measure isolated objects with complex surfaces.
ISSN:1424-8220
1424-8220
DOI:10.3390/s17102383