Efficient rendering of semi-transparent geometry in real-time
Licentiatavhandling, 2010

Rendering images of semi-transparent geometry representing e.g. windows, transparent cloth or architectural models made transparent for visualization purposes presents a difficult problem in interactive applications due to the limitation of the ubiquitous zbuffer of only storing one object per pixel, whereas correctly resolving the color of transparent geometry requires considering the color of all fragments within a pixel in the correct order. Very fine geometry, representing e.g. hair, fur or foliage that has triangles to thin to be correctly captured by anti-aliasing hardware must often be treated as semi-transparent and so suffer from the same limitations. Casting shadows from either of these types of geometry presents an analogous problem as standard real-time shadowing techniques do not take into account the opacity of materials. This thesis presents a number of novel solutions to the problem of rendering and casting shadows from semi-transparent and fine geometry. First, we present a method for simply sorting camera-facing billboards efficiently on the GPU. Second, the specific problem of rendering alpha-composited self-shadowing hair or fur, where the geometry is typically a large number of short line-segments is addressed. Third, we present a method that handles any type of transparent geometry under the assumption that alpha can be considered constant for all fragments and finally, we present a general algorithm that is able on current hardware to render any type of fine or transparent geometry which is equivalent to backwards Monte Carlo raytracing (with no changes in ray direction). For each new method introduced, comparisons to previous work are made considering performance as well as quality of the rendered images.

Opponent: Michael Doggett


Erik Sintorn

Chalmers, Data- och informationsteknik, Datorteknik

Hair Self Shadowing and Transparency Depth Ordering Using Occupancy maps

Proceedings of the Symposium on Interactive 3D Graphics and Games (I3D 2009),; (2009)

Paper i proceeding

Fast Parallel GPU-Sorting Using a Hybrid Algorithm

Journal of Parallel and Distributed Computing,; Vol. 68(2008)p. 1381-1388

Artikel i vetenskaplig tidskrift

Stochastic Transparency

Proceedings of the 2010 ACM SIGGRAPH symposium on Interactive 3D Graphics and Games,; (2010)p. 157-164

Paper i proceeding

Real-Time Approximate Sorting for Self Shadowing and Transparency in Hair Rendering

Proceedings of the Symposium on Interactive 3D Graphics and Games (I3D 2008),; (2008)p. 157-162

Paper i proceeding



Technical report L - Department of Computer Science and Engineering, Chalmers University of Technology and Göteborg University: 1652-876X


Opponent: Michael Doggett

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