Unwrapping highly-detailed 3D meshes of rotationally symmetric man-made objects

In: Proc. of the XXIV. CIPA 2013 Symposium Recording, Documentation and Cooperation for Cultural Heritage. ISPRS - International Society for Photogrammetry and Remote Sensing 2013, pp. 259-264 (SPRS Ann. Photogramm. Remote Sens. Spatial Inf. Sci. ; II-5/W)

Online-Ressource, English http://www.ub.uni-heidelberg.de/archiv/15488

Abstract

Rotationally symmetric objects commonly occur at archæological finds. Instead of creating 2D images for documentation purposes by manual drawing or photographic methods, we propose a method based on digitally colored surface models that are acquired by 3D scanners, thereby including color information. We then transform these highly-detailed meshes using simple geometrical objects such as cones and spheres and unwrap the objects onto a plane. Our method can handle curved vessel profiles by dividing the surface into multiple segments and approximating each segment with a cone frustum that serves as an auxiliary surface. In order to minimize distortions, we introduce a simple quality measure based on distances of points to a fitted cone. We then extend our method to approximately spherical objects by fitting a sphere on the surface of the object and applying a map projection, namely the equirectangular projection known from cartography. Our implementation generates true-to-scale images from triangular meshes. Exemplary results demonstrate our methods on real objects, ranging from small and medium-sized objects such as clay cones from the Ancient Orient and figural friezes of Greek vessels to extremely large objects such as the remains of a cylindrical tower of Heidelberg Castle.