Offentlige arrangementer

Fluid Simulation and Control for Computer Graphics

Physically accurate computer simulations of fluids such as water, gasses and air have for many years been a valuable complement to experimental methods in examining the flow around airplanes, cars, wind turbines etc. Recently physically based simulation of fluids has also been adopted in computer graphics, where such techniques are required to faithfully reproduce the visually complex motion of fluids that is very hard to animate in a traditional sense. However, the demands are different in graphics where the visual properties of the fluid have to impose character on the fluid in addition to adhering to the vision of an artist or a director. This poses entirely new research challenges for fluid simulation in computer graphics where artistic control, low simulation cost and visual richness are in focus. In this presentation I will motivate the use of physically based fluid simulation for computer graphics, show examples of state of the art and go into more depth with a recent fluid control framework developed at Aarhus University in collaboration with DreamWorks Animation and Digital Domain. I will elaborate both on the final technique and results as well as on the process that took us there, including challenges faced and approaches that turned out not to be successful.

Title: The curse of dimensionality (somewhat) explained

Abstract:
Parameterized complexity aims to design exact algorithms whose running times depend on certain parameters of the input data that are naturally related to the problem at hand and in a way capture its complexity. A problem is called fixed-parameter tractable (FPT) with respect to a parameter k if there is an efficient algorithm to solve the problem for the cases where the parameter k is small. Another objective of this theory is to show that such algorithms are unlikely to exist for certain problems (and parameters).

Not many geometric problems have been studied from the parameterized complexity point of view. Most research has focused on special (combinatorial) parameters for geometric problems, like, e.g., the number of inner points (i.e., points in the interior of the convex hull) for the TSP problem or for the problem of computing minimum convex decompositions. Also, on the negative side, only few connections between geometric problems and known hard parameterized problems are known to date. We provide a brief tour of results from parameterized complexity theory for various geometric problems (e.g. hyperplane depth, clustering) with a focus on the dimension as the parameter. Our results indicate that all these problems are inherently difficult in higher dimensions.

Med henblik på erhvervelsen af ph.d.-graden i Informations- og Medievidenskab forsvarer cand.mag. Kasper Ostrowski sin afhandling:
Værdibasering som kommunal praksis – Et performativt blik på værdibaseret ledelse i lyset kommunalreformen
Onsdag den 7. oktober 2009 kl. 13-16 Det lille Auditorium, INCUBA SCIENCE PARK, Åbogade 15.

Få mere information her

Historien har altid været godt stof i medierne – også den kriminelle historie. I takt med, at historien breder sig i mediekulturen, forbinder den sig i stigende grad med populære genrer. Umberto Ecos metakrimi Rosens navn (1980) var ikke den første, men den gav den historiske krimi som koncept et internationalt gennembrud, og siden er der udviklet talrige varianter.

Men hvilke synsvinkler kan den historiske krimi anlægge på fortiden? Hvad er dens relation til populærkulturen? Og hvilke former for spejlfunktioner kan den have i forhold til nutiden?
I forelæsningen vil jeg diskutere disse spørgsmål i forbindelse med en mulig typologi for den historiske krimi og overvejelser over dens aktuelle funktioner. Mine eksempler stammer primært fra en britisk og skandinavisk sammenhæng – fra Philip Kerr til Kurt Aust, Ole Frøslev, Gretelise Holm, Gunnar Staalesen, Jo Nesbø og Arne Dahl.

Title: Instance-Optimal Geometric Algorithms

Abstract:
Standard worst-case analysis of algorithms has often been criticized as overly pessimistic. As a remedy, some researchers have turned towards adaptive analysis where the cost of algorithms is measured as a function of not just the input size but other parameters, such as the output size. The ultimate in adaptive algorithms is an instance-optimal algorithm, i.e., an algorithm whose cost is at most a constant factor from the cost of any other algorithm running on the same input, for every input instance. In other words, an instance-optimal algorithm cannot be beaten by any other algorithm on any input.

For many problems, this requirement is too stringent but we show that if we ignore the order of the input elements (i.e., we assume the input is given in the worst case order), then adaptive algorithms exist for many fundamental geometric problems such as convex hull. Thus, these convex hull algorithms are optimal with respect to all the measures of difficulty that are independent of the order, such as output-size, spread of the input point set or more complicated quantities like the expected size of the convex hull of a random sample.

- Fashion as character performance: The Case of WoW

This paper studies the up-to-now neglected area of clothing and fashion in computer games, particularly MMORPGs, which we claim to be an important aspect of game aesthetics and player performance. Combining knowledge from the cultural studies of fashion with a study of the function and importance of clothing in the gameworld World of Warcraft, and drawing on qualitative methods, we argue that fashion in an online gameworld like WoW is a vehicle for personal storytelling and individualisation.