IEEE Computer Graphics and Applications
Near real-time shadow generation using BSP trees
SIGGRAPH '89 Proceedings of the 16th annual conference on Computer graphics and interactive techniques
Discontinuity Meshing for Accurate Radiosity
IEEE Computer Graphics and Applications
A fast shadow algorithm for area light sources using backprojection
SIGGRAPH '94 Proceedings of the 21st annual conference on Computer graphics and interactive techniques
An environment for real-time urban simulation
I3D '95 Proceedings of the 1995 symposium on Interactive 3D graphics
The influence of dynamic shadows on presence in immersive virtual environments
VE '95 Selected papers of the Eurographics workshops on Virtual environments '95
Fast calculation of soft shadow textures using convolution
Proceedings of the 25th annual conference on Computer graphics and interactive techniques
Shadow volume reconstruction from depth maps
ACM Transactions on Graphics (TOG)
Shadow algorithms for computer graphics
SIGGRAPH '77 Proceedings of the 4th annual conference on Computer graphics and interactive techniques
Real-Time Rendering of Densely Populated Urban Environments
Proceedings of the Eurographics Workshop on Rendering Techniques 2000
Casting curved shadows on curved surfaces
SIGGRAPH '78 Proceedings of the 5th annual conference on Computer graphics and interactive techniques
IEEE Computer Graphics and Applications
Intuitive Crowd Behaviour in Dense Urban Environments using Local Laws
TPCG '03 Proceedings of the Theory and Practice of Computer Graphics 2003
Geopostors: a real-time geometry / impostor crowd rendering system
Proceedings of the 2005 symposium on Interactive 3D graphics and games
Adaptive crowd behaviour to aid real-time rendering of a cultural heritage environment
VAST'04 Proceedings of the 5th International conference on Virtual Reality, Archaeology and Intelligent Cultural Heritage
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In this paper, we address the problem of shadow computation for large environments including thousands of dynamic objects. The method we propose is based on the assumption that the environment is 2.5D, which is often the case for virtual cities, thus avoiding complex visibility computation. We apply our method for virtual cities populated by thousands of walking humans, which we render with impostors, allowing real time simulation.In this paper, we treat the cases of shadows cast by buildings on humans, and by humans on the ground. To avoid 3D computation, we represent the shadows cast by buildings onto the environment with a 2.5D shadow map. When humans move, we quickly access the shadow information at the current location with a 2D grid. For each new position of a human, we compute its coverage by the shadow, and we render the shadow on top of the impostor with low cost using multi-texturing hardware. We also use the property of an impostor to display the shadow of humans on the ground plane, by projecting the impostor relatively to the light source.The method is currently limited to sharp shadows and a single light source. However approximations could be made to allow non-accurate soft-shadows. We show in the results that the computation of the shadows, as well as the display is done in real time, and that the method could be easily extended to real time moving light sources.