**6.1 Stereoscopic matching algorithms**

The stereoscopic matching algorithm reproduce the human stereopsis process so that a machine, for instance a robot, can perceive the depth of each point in the observed scene and thus is able to manipulate objects, avoid or recreate three-dimensional models. For a pair of stereoscopic images the main goal of these algorithms is to find for each pixel in an image its corresponding pixel in the other image (mating), in order to obtain a disparity map that contains the position difference for each pixel between two images which is proportional to the depth map. To determine the actual depth of the scene it is necessary to take into account the geometry of the stereoscopic system to obtain a metric map. As mating a single pixel is almost impossible, each pixel is represented by a small region that contains it, a socalled window correlation, thereby realizing the correlation between the windows of one image and the other, using the colour of pixels within. Once the disparity map is obtained, then the histogram of this map is the region of interest.
