Definition of the operational parameters of a structured light system and development of an adaptive lighting algorithm

Surface 3D reconstruction a topic of great relevance and having a wide range of applications. Systems for surface contouring can be divided into two main categories: the contact systems and non-contacting systems. CMM is the most widespread contact methodology while the 3D laser scanner is the most popular without contact approach. Nowadays further systems are under study and development. One of the most promising is the Structured Light Projection (SLP) approach based upon the projection of a complex pattern of light on the object to be reconstructed. The projection determines the distortion of the projected pattern, the modulated pattern contains the information about the object geometry. If compared with laser scanning SLP is very effective to reduce the measurement time as it does not require the operation of scanning of the object. Also it becomes of great importance when the measurement has to be done on very complex shape object. In fact, in this case, proper identification of the projected sequence can allow to manage very high discontinuity. This becomes essential, for example, in the case of contouring of cultural heritage artifact. For this class of object, moreover, structuration in terms of light intensity could be adopted to compensate local variation of reflectivity. In this paper operating parameters of a structured light system are defined. In particular, the optimal frequency of the projection pattern was defined. Furthermore an algorithm is proposed that locally controls the level of illumination to compensate for the local inhomogeneities in terms of surface reflectivity.