Reconstructing shape from shading with a point light source at the projection center: Shape reconstruction from an endoscope image

A new method for reconstructing three dimensional object from an endoscope image is presented. The proposed method uses image shading generated by a light source at the endoscope head. In this case, the light source is near to the object surface so that the image brightness depends on not only the surface gradients but also the distance from the light source to the surface point. To deal with this difficulty, we consider the imaging system of the endoscope as the system having a point light source at the projection center. The object surface is reconstructed by propagating equal-distance contours, spatial curves composed of points at an equal distance from the light source. The propagation is controlled by the image shading. We use the level-sets method for numerical computation. Experimental results for real medical images show feasibility of this method.