ABSTRACT
In this paper, a process for high-resolution, automated 3D digitization of unknown objects (i.e., without any digital model) is presented. The process has two stages-the first leads to a coarse 3D digital model of the object, and the second obtains the final model. A rough model, acquired by a 3D measurement head with a large working volume and relatively low resolution, is used to calculate the precise head positions required for the full digitization of the object, as well as collision detection and avoidance. We show that this approach is much more efficient than digitization with only a precise head, when its positions for subsequent measurements (so-called next-best-views) must be calculated based only on a partially recovered 3D model of the object. We also show how using a rough object representation for collision detection shortens the high-resolution digitization process.
ABSTRACT
This paper presents the outcome of research into the effects of ambient temperature changes on structured-light three-dimensional (3D) scanners. The tests were conducted in a thermal chamber and consisted of a comparison of the 3D measurement of a special reference unit (made of a carbon composite) performed at different temperatures, with measurements performed at the calibration temperature. A contact measuring arm with temperature compensation was used as a reference. Based on the results of these experiments, we propose a method that allows us to extend the existing scanner calibration method by using a temperature-correction procedure that is based on linear and nonlinear mathematical models. An exemplary application of this procedure has shown that the range of temperatures in which scanner accuracy is within declared limits can be increased 11-fold.
