Traditional backlighting vision systems are unable to measure the
height dimensions of an object. It can then be more convenient to
use a 3D scanner, based for example on the projection of
structured light. Despite the high potential of this technique and
the growing demand of the industry for performing quality vision
control, 3D measurement systems are still often considered as
unusual solutions. This proceeding presents our 3D measurement laboratory setup based on the projection of structured light by means of a LCD beamer. This system is intended to be used in automated assembly line. The height information comes from a phase map obtained through temporal phase unwrapping. This phase always contain noise. Part of this noise brings a random phase error. A simple estimator of
the random phase error is presented. It gives two parameters to which it is necessary to pay attention in order to predict measurement repeatability and thus to improve it. The estimator is experimentally validated on our setup.