Stereo-Vision

Structure from Stereo- A Review

Stereopsis is a passive technique, the triangulation needs to be achived with the help of only the existing ambient illumination.
Hence a correspondence needs to be established between features from two images that correspond to some physical feature in space.
Then, provided the position of centers of projection, the effective focal length, the orientation of the optical axis, and the sampling interval of each camera are known, the depth can be reconstructed using triangulation.

The principal steps are: Preprocesing, establishing correspondence and recovering depth.

Preprocesing: in this step image locations satisfying certain well-defined feature characteristics are identified in each image.

Establishing correspondence - Matching: Given two or more views of a scene, correspondence needs to be established among homologous features(features that are projections of the same physical identity in each view).

Recovering depth: using trigonometric functions to obtain the depth.

They present diferents techniques for recovering the 3-D structure of a scene from analysis of stereo images.

A problem in Stereo is resolve the correspondence problem due to occlusion, most scenes contain regions which appear in only one of the two images. We call these regions half-occluded, or unmatched.

Aplication of stereo: cartography, aircraft navigation, autonomus land rovers, robotics, industrial automation and steromicroscopy.