Seamless Integration of Labels into Interactive Virtual 3D Environments Using Parameterized Hulls

Abstract

This paper presents an approach for the automated, dynamic placement of labels attached to objects of 3D scenes. These labels are seamlessly integrated into the 3D scene by textured polygons aligned to parameterized hulls, which generalize an object's geometry. This way, the labels follow the principle shape of the annotated objects, emphasize the label-object relationship, reduce ambiguities of interpretation, and achieve visual concise and aesthetic results. The algorithm first sets up candidate positions across the hull. Cascaded filtering and presorting steps reject early improper placement candidates and order the remaining ones according to their quality. Then, they are iteratively tested to find positions that allow for a visible and legible label placement. If more than one position exists, the selection is controlled by a layout strategy, for which we present efficient evaluation techniques and discuss the impact on the aesthetic appearance. As proof of concept, we have implemented a 3D viewer that annotates building models of 3D city models. Compared to view plane-based labeling approaches, our approach achieves a strong visual relation between label and annotated object, treats labels as first-class objects of virtual 3D environments, and offers a high degree of customization and stylization.