PointWorks: Abstraction and Rendering of Sparsely Scanned Outdoor Environments

This paper describes a system, dubbed PointWorks, for rendering three-dimensionally digitized outdoor environments in non-photorealistic rendering styles. The difficulty in rendering outdoor environments is accommodating their inaccuracy, incompleteness, and large size to deliver a smooth animation without suggesting the underlying data deficiency. The key method discussed in this paper is employing artistic drawing techniques to illustrate features of varying importance and accuracy. We employ a point-based representation of the scanned environment and operate directly on point-based models for abstraction and rendering. We develop a framework for producing mainly two artistic styles: painterly and profile lines. The framework first analyzes the input point models and performs a fuzzy classification. These points are then taken as stroke candidates during the rendering. At run time, a subset of points are selected viewdependently and strokes of various geometry and styles are placed at these points’ screen positions. By varying the run-time stroke selection scheme and individual stroke rendering, various looks can be achieved. Strategies have also been employed to leverage modern graphics hardware for achieving interactive rendering of large scenes.