Obtaining polyp size and shape is important for precise diagnosis. The 3-D shape reconstruction technology of computer vision is tried to be used in the medical diagnosis for this reason. Some approaches based on Shape from Shading are proposed for polyp shape recovery from endoscope image. These approaches need some parameters such as surface reflectance coefficient parameter C. It is important to obtain those parameters for accurate polyp shape recovery. This paper proposed a method to extract corresponding blood vessel regions from two endoscope images based on blood vessel structure analysis. Parameters for polyp shape recovery are calculated from geometric constraint equations of the pair of extracted regions.