Optimal pitch map generation for scanning pitch design in selective sampling

The reverse engineering process represents one of the best known methodologies for creating threedimensional (3D) virtual models starting from physical ones. Even if in the last few years its usage has significantly increased, the remarkable involvement of the operator has until now represented a significant constraint for its growth. Having regard to the fact that this process, and in particular its first step (that is the acquisition phase), strongly depends on the operator’s ability and expertise, this paper aims at proposing a strategy for automatically supporting an ‘‘optimal’’ acquisition phase. Moreover, the acquisition phase represents the onlymoment inwhich there is a direct contact between the virtualmodel and the physical model. For this reason, designing an ‘‘optimal’’ acquisition phase will provide as output an efficient set of morphological data, whichwill turn out to be extremely useful for the following reverse engineering passages (pre-processing, segmentation, fitting, . . . ). This scenario drives the researcher to use a selective sampling plan, whose grid dimensions are correlated with the complexity of the local surface region analyzed, instead of a constant one. As a consequence, this work proposes a complete operative strategy which, starting from a first raw preliminary acquisition, will provide a new selective sampling plan during the acquisition phase, in order to allow a deeper and more efficient new scansion. The proposed solution does not require the creation of any intermediate model and relies exclusively on the analysis of the metrological performances of the 3D scanner device and of the morphological behaviour of the surface acquired. © 2009 Elsevier B.V. All rights reserved.