Non-Photorealistic Computer Graphics Library

Illustrating Terrains using Direction of Slope and Lighting

Author(s): Kevin Buchin, Mario Costa Sousa, Jürgen Döllner, Faramarz Samavati, Maike Walther.
Proceedings: 4th ICA Mountain Cartography Workshop, Vall de Núria, Catalunya, Spain, 30th September - 2nd. October 2004, 2004.
[BibTeX]

Abstract:
Landscape illustrations and cartographic maps depict terrain surface in a qualitatively effective way. In this paper, we present a framework for line drawing techniques for automatically reproducing traditional illustrations of terrain by means of slope lines and tonal variations. Given a digital elevation model, surface measures are computed and slope lines of the terrain are hierarchically traced and stored. At run-time slope lines are rendered by stylized procedural and texture-based strokes. The stroke density of the final image is determined according to the light intensities. Using a texture based approach, the line drawing pipeline is encapsulated from the rendering of the terrain geometry. Our system operates on terrain data at interactive rates while maintaining frame-to-frame coherence.