Verification and Acceptance Tests for High Definition 3D Surface Scanners

Abstract

High definition three-dimensional (3D) surface scanners, based on structured light or laser light section techniques, have found a wide range of applications, especially for technical and industrial applications (mostly for measuring and inspection tasks). Since about 10 years, systems adapted for the requirements of arts and Cultural Heritage (CH) support 3D digitization of art objects. Although the use of digital 3D models in CH is rapidly growing, many of the users are not yet completely familiar with terminology and all details of technical specifications. As most of the users are practitioners there is sometimes only little experience with terms as data quality, accuracy, resolution, measurement uncertainty, especially because these terms are used in very different ways, in manuals and brochures of scanner manufacturers as well as by authors of scientific papers. Moreover, the objective of many applications is digitization instead of measurement; therefore, many users are not even aware, that they nevertheless have to care about metrology issues such as verification and acceptance tests of the used equipment to get a reliable scanning result. In its first part, the paper will give an overview the fundamentals of data acquisition and data processing, presenting also advantages and benefits, limitations and drawbacks as well as correlations between different performance parameters of high definition 3D surface scanners. Our goal is also to rectify a number of typical misunderstandings and to clarify related terms and definitions. In its second part, the paper will concentrate on verification and acceptance tests of high definition 3D scanners, reviewing the German guidelines VDI/VDE 2634/2 and proposing some preliminary extensions required to cope better with the CH domain.