Brian Wyvill,

University of Victoria


The talk will be divided into two parts. In the first part implicit blending is discussed and in the second cyclic scene
Blending is both the strength and the weakness of implicit surfaces. While it gives them the unique ability to smoothly
merge into a single, arbitrary shape, it makes implicit modelling hard to control since implicit surfaces blend at a distance,
in a way that heavily depends on the slope of the field functions that define them. We have found that to be more intuitive
and easy to control, blends should be located where two objects intersect, while enabling other parts of the objects to
come as close to each other as desired without being deformed. Our solution relies on automatically defined blending
regions around the intersection curves between two objects. Outside of these volumes, a clean union of the objects is
computed thanks to a new operator that guarantees the smoothness of the resulting field function; meanwhile, a smooth
blend is generated inside the blending regions. This talk describes joint work done with French researchers, Marie-Paule
Cani, Loic Barthe and Adrien Berhardt.

The second half of the talk describes work on scene graphs. Conventional scene graphs use directed acyclic graphs. We
investigate scene graphs with recursive cycles for defining graphical scenes. This permits both conventional scene graphs
and iterated function systems within the same framework and opens the way for other definitions not possible with either.
We explore several mechanisms for limiting the implied recursion in cyclic graphs, including both global and local limits.
This approach permits a range of possibilities, including scenes with carefully controlled and locally varying recursive
depth. It has applications in art and design, and opens up interesting avenues for future research. The second half of the
talk describes work done with Prof. Neil Dodgson, University of Cambridge.


Brian Wyvill graduated from the University of Bradford, Uk with a PhD in computer graphics in 1975. As a post-doc he
worked at the Royal College of Art and helped make some animated sequences for the Alien movie. He emigrated to
Canada in 1981 where he has been working in the area of implicit modeling, sometimes with his brother Geoff Wyvill
(University of Otago). He is also interested in sketch based modeling and NPR and enjoys combining these areas of
research. In 2007 Brian took up an appointment as Professor and Canada Research Chair at the University of Victoria,
British Columbia.


Date: 2009-Oct-15     Time: 12:00:00     Room: 336

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