Tuesday, May 4, 2010

Coded Structured light as a technique to solve the corresponding problem

This paper covers the motivation, history and different techniques regarding the Structured Light and Coded Structured light methodologies for 3D surface reconstruction.

First, a passive stereovision system with two sensor/cameras is explained and the mathematical equations and geometrical constraints are analyzed in detail. Then, structured light as an active method is covered and presented as an alternative to solve the "correspondence problem". Mathematical model is explained as well. Then, the purpose of the coded structured light is described, analyzing temporal dependence, emitted light dependence and depth surface discontinuity dependence. Finally several coded structured light techniques are covered, discussed and compared.

Active and passive techniques are covered in separate, and then, when the mathematical models are explained, the similarities are remarked.

Even though this paper is quite old (1998) it covers structured light and vision systems for 3D reconstruction from an historical perspective. That makes it a very useful source of information in order to understand structured light as a whole, and to be included, in the end, in our Sate of the Art document.

We present a survey of the most significant techniques, used in the last few years, concerning the coded structured light methods employed to get 3D information. In fact, depth perception is one of the most important subjects in computer vision. Stereovision is an attractive and widely used method, but, it is rather limited to make 3D surface maps, due to the correspondence problem. The correspondence problem can be improved using a method based on structured light concept, projecting a given pattern on the measuring surfaces. However, some relations between the projected pattern and the reflected one must be solved. This relationship can be directly found codifying the projected light, so that, each imaged region of the projected pattern carries the needed information to solve the correspondence problem.

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