Abstract: A procedure and an apparatus for obtaining information regarding the geometry of surfaces, for example on work pieces in mechanical industry.The procedure is based on casting a shadow on the surface by partially shielding incident light or other types of radiation. The edge of the shadow thus cast on the work piece, if viewed from a direction substantially different from that defined by the radiation source and the edge of the shield,will provide a profile of shield, will surface. Moving the shadow across the work piece will provide a continuous series of such profiles, if the edge of the shadow may be seen at all times.The apparatus may include photo-electric converters, like a TV camera, for registering the shape of the shadow by means of a display screen, and for providing signals which may be processed by a computer.