A portable optical measurement system, capable of measuring free form surfaces over large areas and comparing them
with reference surfaces was developed within this work. The system merges passive and active stereo vision. Data is
acquired in both modes for each partial overlapped position of the system, covering all the area of interest of the free
form surface or part being measured.
In passive stereo vision mode, circular targets are used to determine the coarse position of the system (i.e. cameras and
projector) referenced to a global coordinate system defined by the targets. In active stereo vision mode, three-dimensional
point clouds are locally measured and registered in the global coordinate system. The algorithm performs
the calculation of these point clouds into a single intrinsically structured regular mesh, allowing an efficient comparison
between different surfaces because the correspondence of points can be pre-defined. Experimental evaluations, using
different kinds of geometric patterns and calibrated free form surfaces demonstrate the feasibility and the advantages of
the proposed methods.