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Procedural descriptions for analyzing digitized artifacts

: Ullrich, Torsten; Schinko, Christoph; Schiffer, Thomas; Fellner, Dieter W.


Applied geomatics 5 (2013), No.3, pp.185-192
ISSN: 1866-9298 (Print)
ISSN: 1866-928X (Online)
Journal Article
Fraunhofer Austria ()
Computer Aided Design (CAD); cultural heritage; ray tracing; ray casting; reverse engineering; visualization; Forschungsgruppe Semantic Models, Immersive Systems (SMIS); Heightfield; offset geometry

Within the last few years, generative modeling techniques have gained attention especially in the context of cultural heritage. As a generative model describes a rather ideal object than a real one, generative techniques are a basis for object description and classification. This procedural knowledge differs from other kinds of knowledge, such as declarative knowledge, in a significant way: It is an algorithm, which reflects the way objects are designed. Consequently, generative models are not a replacement for established geometry descriptions (based on points, triangles, etc.) but a semantic enrichment. In combination with variance analysis techniques, generative descriptions can be used to validate reconstructions. Detailed mesh comparisons can reveal smallest changes and damages. These analysis and documentation tasks are needed not only in the context of cultural heritage but also in engineering and manufacturing.
Our contribution to this problem is a work flow, which automatically combines generative/procedural descriptions with reconstructed artifacts and performs a nominal/actual value comparison. The reference surface is a procedural model whose accuracy and systematics describe the semantic properties of an object, whereas the actual object is a real-world data set (laser scan or photogrammetric reconstruction) without any additional semantic information.