Real-Time Rendering of Water Surfaces with Cartography-Oriented Design

Abstract

More than 70 percent of the Earth's surface is covered by oceans, seas, and lakes, making water surfaces one of the primary elements in geospatial visualization. Traditional approaches in computer graphics simulate and animate water surfaces in the most realistic ways. However, to improve orientation, navigation, and analysis tasks within 3D virtual environments, these surfaces need to be carefully designed to enhance shape perception and land-water distinction. We present an interactive system that renders water surfaces with cartography-oriented design using the conventions of mapmakers. Our approach is based on the observation that hand-drawn maps utilize and align texture features to shorelines with non-linear distance to improve figure-ground perception and express motion. To obtain local orientation and principal curvature directions, first, our system computes distance and feature-aligned distance maps. Given these maps, waterlining, water stippling, contour-hatching, and labeling are applied in real-time with spatial and temporal coherence. The presented methods can be useful for map exploration, landscaping, urban planning, and disaster management, which is demonstrated by various real-world virtual 3D city and landscape models.