2.1. The Parallel Binocular Stereo Vision Principle
Figure 1 is the imaging schematic diagram of the simple parallel binocular 3D (Zhang,2005; Zhang,2013). B stands for the baseline of the 2 cameras.
Figure 1. Binocular 3D imaging principle
The two cameras view the same feature P(xc,yc,zc) of the space object at the same time, and respectively obtain the image coordinates, (XL,Y)and(XR,Y), from the left image and the right image. Supposing both of the two cameras’ focal distance are f,then the following formula will be gotten by the triangular geometry relationship (Xiang, Ying, Jiang,2012; Zhang,2013):
(1)In the formula, D is the optical parallax, and 
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