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R. Fizimayer:
"A Real-Time Cloud Animation and Illumination Method";
Supervisor: W. Purgathofer, M. Wimmer; Institut für Computergraphik und Algorithmen, TU Wien, 2007; final examination: 2007-10.

Over the last years, real-time rendering, especially for virtual environments as can be seen in most computer games, became more and more important. As the capabilities of graphics hardware continuously increases, the expectations of users regarding to visual quality are also increasing relativly fast.

Compared to the rapid development in many fields of computer graphics, a very important element for real-time outdoor scene rendering has been almost completely disregarded. Clouds can highly improve the visual quality of a scene due to their complex structure, the beautiful colors as well as their formation and movement. Because of the computational effort to render animated and dynamically lit clouds, it has been impossible for consumer graphics adapters to draw them and simultaneously keep the framerate high enough. Although there are many methods which allow drawing clouds in outdoor environments fast enough, all of them have some restrictions eighter in movement, lighting or formation.

This thesis will examine how plausible cloud animation can be done in real time on consumer graphics hardware and how the animation results can be used to render high-quality, dynamically lit, volumetric clouds with relativly high frame rates. Since high-quality solutions already exist for non-real-time rendering applications and they are almost completely computed on the CPU, which is not acceptable for most games since the CPU is very often already at peak load, methods will be discussed to adapt those algorithms to be performed on the GPU, while also some new improvements will be presented.

The thesis first gives an overview of state-of-the-art of cloud rendering algorithms for real-time as well as for non-real-time rendering. Then, we will try to adapt parts of these techniques to work in interactive environments at high framerates while all significant characteristics of the non-real-time methods like cloud formation, extinction, movement and dynamic lighting will still be preserved.