3D Photography Using Shadows in Dual-Space Geometry
A simple and inexpensive approach for extracting the three-dimensional shape of objects is presented. It is based on ‘weak structured lighting’. It requires very little hardware besides the camera: a light source (a desk-lamp or the sun), a stick and a checkerboard. The object, illuminated by the light source, is placed on a stage composed of a ground plane and a back plane; the camera faces the object. The user moves the stick in front of the light source, casting a moving shadow on the scene. The 3D shape of the object is extracted from the spatial and temporal location of the observed shadow. Experimental results are presented on five different scenes (indoor with a desk lamp and outdoor with the sun) demonstrating that the error in reconstructing the surface is less than 0.5% of the size of the object. A mathematical formalism is proposed that simplifies the notation and keep the algebra compact. A real-time implementation of the system is also presented.