STUDY OF DIFFERENT APPROACHES TO PHOTOREALISTIC MODELLING AND RENDERING OF COMPLEX SURFACES
Keywords: Heritage, Castle, 3D modelling, Historical constraints, Extraction, Realistic rendering
Abstract. Schwarzenburg Castle is one of the few Alsatian castles that can be dated with precision. The Schwarzenbourg family, taking advantage of a favourable historical and political context, built the castle in 1261 on the municipal boundary of the town of Munster. Initially intended for residential use, the castle passed through the centuries from family to family, and shortly becoming a ruin. The first major renovation was realized in the 15th century, but for military purposes rather than for housing. This was the only one, as the castle was quickly abandoned at the end of the same century. It was only during the First World War that the castle was used by the German army, which built a bunker in the upper courtyard. Schwarzenbourg castle is, therefore, an original in Alsace, both in terms of its history and its characteristics, which have no regional equal. The objective of this modelling project is twofold. On the one hand, to model the current state of the castle, i.e., an advanced state of ruin for certain elements, and, on the other hand, to model the reconstruction of the castle as it was when it was built in 1261. This double objective comes up against several problems, mainly technical. Indeed, how to move from a point cloud of a certain density and quality to a surface model allowing a realistic rendering? How to limit the influence of the noise on the quality of the surface model? How to remain faithful to the cloud while simplifying the geometric primitives to make the rendering more efficient? Or what technique should be used to reconstitute the castle as it was when it was built? The objective here was to realize the transformation from a consolidated and geo-referenced point cloud to a surface model allowing for a photo-realistic rendering.