Authors:
M. D. Robles-Ortega
;
J. R. Jiménez
and
L. Ortega
Affiliation:
University of Jaén, Spain
Keyword(s):
Polar diagrams; large $2.5D$ urban models; hard shadows; ray-shooting
Related
Ontology
Subjects/Areas/Topics:
Animation and Simulation
;
Computer Vision, Visualization and Computer Graphics
;
Geometry and Modeling
;
Interactive Environments
;
Lighting and Appearance
;
Modeling and Algorithms
;
Real-Time Visual Simulation
;
Rendering
;
Shadows, Translucency and Visibility
;
Virtual Tours
Abstract:
Illumination and shadows are essential to obtain realistic virtual environments. Nevertheless, large scenes like urban cities demand a huge amount of geometry that must somehow be structured or reduced in order to be manageable. In this paper we propose a novel real-time method to determine the shadowed and illuminated areas in large scenes, specially suitable for urban environments. Our approach uses the polar diagram as a tessellation plane, and a ray-casting process to obtain the visible areas. This solution derives the exact illuminated area with a high performance. Moreover, our approach is also used to determine the visible portion of the scene from a pedestrian viewpoint. As a result, we only have to render the visible part of the scene, which is considerably lower than the global scene.