3-D measurement of human face by stereophotogrammetry

At present several methods are adapted for optical characterization of 3-D surface profiles and forms, which differ in accuracy, measurement as well as computation time or its constructional complexity. In this work we show a possibility for a rapid measurement of the shape of a human face for medical applications (e. g. jaw-measurement) by stereophotogrammetry. The surface structure of the human face is too homogenous to find homologous points by an ordinary illumination; therefore special statistical patterns are projected on the face. About 20 pictures are taken by each camera of the convergent stereo system. To find the corresponding points in the pictures we use an enhanced correlation technique, which takes all pictures into account in one step. Depending on imaging hardware (cameras and interfaces) it is possible to realise a time of measurement less than one second. The reachable accuracy is +/- 0.1mm, which is sufficient for medical and other applications.