Assessing the Performance of a Structured Light Scanner

An alternative to the mostly known and market dominating laser scanners are Structured Light scanners. Structured light 3D scanners project a pattern of light on the object and detect the deformation of the pattern on the object. They are basically non-contact optical systems, based almost entirely on the principles of photogrammetry in order to transform image pairs to surface information. They are able to achieve information of very high density and of very high accuracy. For assessing the capabilities of such a system under real working conditions some tests were performed and their results are analysed and presented in this paper. Among others, industrial prototype gauges served as test objects, with their dimensions known at very high accuracy. Suitable mesh densities were implemented for deriving the objects’ surface. They were measured and compared to the nominal values. In addition, the system was put to test under several ambient conditions, i.e. natural sunlight and indoor lighting, and using various object materials, like marble, wood, stone etc., in order to assess its qualitative performance. Reference is also made in the paper to several practical applications of the system, in order to demonstrate its range of applicability. Special interest is given in processing aspects for the creation and visualization of detailed photorealistic 3D models. Various well known open issues in the related processes are identified and the respective solutions/significant improvements in the workflow pipeline brought by the employment of new technologies are highlighted. The software used is described and high resolution visualizations of sub-millimeter accuracy for each case study are presented and assessed based on completeness, accuracy and ease of processing. Finally, conclusions are drawn concerning the usage of the hardware and software components of the system, but also its performance characteristics. The practical results are discussed and evaluated based on the experience gained through these applications.