Accurate 3D Shape Measurement Research Articles

5-9 間接反射成分の抑制による高精度三次元形状計測手法の提案(第5部門 立体映像技術)

5-9 間接反射成分の抑制による高精度三次元形状計測手法の提案(第5部門 立体映像技術)

Accurate 3D shape measurement of multiple separate objects with stereo vision

3D shape measurement has emerged as a very useful tool in numerous fields because of its wide and ever-increasing applications. In this paper, we present a passive, fast and accurate 3D shape measurement technique using stereo vision approach. The technique first employs a scale-invariant feature transform algorithm to detect point matches at a number of discrete locations despite the discontinuities in the images. Then an automated image registration algorithm is applied to find full-field point matches with subpixel accuracy. After that, the 3D shapes of the objects can be reconstructed according to the obtained point matching and the camera information. The proposed technique is capable of performing a full-field 3D shape measurement with high accuracy even in the presence of discontinuities and multiple separate regions. The validity is verified by experiments.

Unambiguous 3D measurement from speckle-embedded fringe

This paper proposes a novel phase-shifting method for fast, accurate, and unambiguous 3D shape measurement. The basic idea is embedding a speckle-like signal in three sinusoidal fringe patterns to eliminate the phase ambiguity, but without reducing the fringe amplitude or frequency. The absolute depth is then recovered through a robust region-wise voting strategy relying on the embedded signal. Using the theoretical minimum of only three images, the proposed method greatly facilitates the application of phase shifting in time-critical conditions. Moreover, the proposed method is resistant to the global illumination effects, as the fringe patterns used are with a single high frequency. Based on the proposed method, we further demonstrate a real-time, high-precision 3D scanning system with an off-the-shelf projector and a commodity camera.

Research and development of an accurate 3D shape measurement system based on fringe projection: Model analysis and performance evaluation

In this paper, the research and development of an accurate 3D shape measurement system based on fringe projection is presented. This system utilizes a sliding projection unit to project the desired encoding fringe patterns onto the object and the object shape can be obtained by analyzing the images captured with a camera for each projection. The sliding projection unit uses a high precision grating element fabricated by electron beam lithography to produce the accurate encoding fringe patterns thus to reduce the projection error. And a method based on gray-code and phase-period edge detection is developed to align the grating element with its sliding direction to guarantee the alignment between the projected patterns. The influence of the lens distortion of both the projection unit and the camera is also studied and an improved nonlinear system model is developed based on triangulation. This model gives a more accurate mathematical representation of the shape measurement system and thus improves the system measurement accuracy. The experimental results show that an overall measurement error of 0.04 mm with a variability of ±0.035 mm can be obtained for the developed system.