A better class of shadow

A newly-developed algorithm can create computer generated shadows of a much better quality than ever.

Shadows are extremely important in making the graphics in 3D games and Virtual Reality applications more natural. Soft shadows in real-time applications have largely been an unsolved problem, according to Ulf Assarsson, of Chalmers University of Technology in Göteborg, Sweden.

But the new algorithm, which he presented last week in his doctoral dissertain, will open many possibilities, he says.

Sources of light that have some kind of area or volume, create gradual transitions on shadow edges from no shadow to full shadow. Graphics usually produce shadows with knife-sharp transitions from no-shadow to shadow - so-called hard shadows - since they don’t require as much time to calculate.

The larger the light source is, the more diffuse the transition becomes, and it is therefore highly desirable to be able to simulate these soft shadows even for real-time applications that only allow some 20 milliseconds to calculate a whole image, if the goal is to produce 50 images per second.

The algorithm solves the problem by utilising the new programming capacity offered by the latest graphics cards, which are now available even in cheap game cards. ®