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2006

Mechanical Engineering

Song Zhang

Structured light

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High-Resolution, Real-Time Three-Dimensional Shape Measurement, Song Zhang, Peisen S. Huang Dec 2006

High-Resolution, Real-Time Three-Dimensional Shape Measurement, Song Zhang, Peisen S. Huang

Song Zhang

We describe a high-resolution, real-time 3-D shape measurement system based on a digital fringe projection and phase-shifting technique. It utilizes a single-chip digital light processing projector to project computer-generated fringe patterns onto the object, and a high-speed CCD camera synchronized with the projector to acquire the fringe images at a frame rate of 120frames∕s. A color CCD camera is also used to capture images for texture mapping. Based on a three-step phase-shifting technique, each frame of the 3-D shape is reconstructed using three consecutive fringe images. Therefore the 3-D data acquisition speed of the system is 40frames∕s. With ...


Generic Nonsinusoidal Phase Error Correction For 3d Shape Measurement Using A Digital Video Projector, Song Zhang, Shing-Tung Yau Aug 2006

Generic Nonsinusoidal Phase Error Correction For 3d Shape Measurement Using A Digital Video Projector, Song Zhang, Shing-Tung Yau

Song Zhang

Structured light system using a digital video projector is increasingly used for a 3-D shape measurement because of its digital nature. However, the nonlinear gamma of the projector causes the projected fringe patterns to be non-sinusoidal, which results in phase error therefore shape measurement error. Previous work showed that, by using a small look-up-table (LUT), this type of phase error can be reduced significantly for a three-step phase-shifting algorithm. In this research, we prove that this type of phase error compensation method is not limited to a three-step phase-shifting algorithm. It is generic for any phase-shifting algorithm. The phase error ...


Trapezoidal Phase-Shifting Method For Three-Dimensional Shape Measurement, Peisen S. Huang, Song Zhang, Fu-Pen Chiang Jan 2006

Trapezoidal Phase-Shifting Method For Three-Dimensional Shape Measurement, Peisen S. Huang, Song Zhang, Fu-Pen Chiang

Song Zhang

We propose a novel structured light method, namely a trapezoidal phase-shifting method, for 3-D shape measurement. This method uses three patterns coded with phase-shifted, trapezoidal-shaped gray levels. The 3-D information of the object is extracted by direct calculation of an intensity ratio. Compared to traditional intensity-ratio-based methods, the vertical or depth resolution is six times better. Also, this new method is significantly less sensitive to the defocusing effect of the captured images, which makes large-depth 3-D shape measurement possible. If compared to sinusoidal phase-shifting methods, the resolution is similar, but the data processing speed is at least 4.5 times ...