Rollouts of Fine Ware Pottery using High Resolution 3D Meshes

Abstract

A common part of the documentation of archaeological finds is the drawing of so-called rollouts. Rollouts provide a complete and continuous depiction of graphical elements on the surface of rotation-symmetric objects and are especially useful for the iconographic interpretation of figurative vase painting. In the past, rollouts were created either by manual drawing or photographically. We propose a new method to generate rollouts in which the tedious process of manual drawing or the disadvantage of having to decide on a specific projection in advance of any photographical process is replaced by the acquisition of a digital coloured surface model using a structured-light 3D scanner. This model is then used to generate high-quality rollouts with arbitrary projection parameters. To handle curved vessel profiles, we divide the vessel's surface into multiple segments. Each segment is then approximated with a frustum which serves as a developable auxiliary surface. In the rollout generation process, the vessel's surface is projected onto a frustum's mantle, which is then developed into the image plane. The shape of each frustum is selected in such a way that projection distortions are minimized, but interrelated graphical features like figural friezes are still unrolled in one piece. To control distortion effects in rollouts of non-developable surfaces, we investigated the use of cartographic methods. A first implementation of our method generates true-to-scale rollouts from meshes provided as PLY files and writes them to a raster image file. Our program uses off-screen OpenGL in combination with tiled rendering to generate high-resolution images which are suited for professional printing. Exemplary results from the Austrian Corpus Vasorum Antiquorum (CVA) project of the Kunsthistorisches Museum Wien (KHM - Museum of Art History in Vienna) and the Universalmuseum Joanneum Graz (UMJ) are shown.