A novel approach is presented for the location of discrete targets images with subpixel accuracy. It can be adopted as
first stage of any method that uses planar and no-planar grids with circular, square or cross shaped targets in order to
calibrate close range cameras. The approach has been performed on several calibration sessions each of them followed
by the three-dimensional reconstruction of a reference object that was previously measured through a coordinate
measuring machine. The performance of the proposed approach has been expressed in terms of deviation between the
reference coordinates and the corresponding ones provided by triangulation. The results obtained have also been
compared with those achieved through ShapeCapture<sup>TM</sup>, a software widely used in photogrammetry for camera
calibration and 3D model reconstruction from images.
The paper deals with the metrological characterization of 3D scanners, and proposes a procedure for their experimental
verification in accord with the suggestions of the ISO GUM. The procedure is based on the application of a statistical
method for the evaluation of the standard uncertainty to the results of a comparison with a Coordinate Measuring
Machine (CMM). Finally the results of the experimental verification of a fringe pattern system are reported and
discussed in detail.