Dynamic Update of Radiosity Simulations
[Work Package 4]


However, we believe it unlikely that true real-time feedback will be possible using such radiosity update approaches in scenes of real-world complexity. In order to achieve a high degree of interactivity, fast, approximate solutions are being developed also, which enable true realtime feedback to user interaction.

In this context, the Multipoint shading method [SM98][Sch99] has been developed. This approach has been implemented using a simplified shadow calculation on a reduced (fixed) mesh, with which real-time shadow movement can be achieved even in moderately complex scenes, taking into account that the shadow representation is poor. Time/quality trade-off can be controlled by the user. This approach recently has been improved furtheri and made more robust.

The implementation of this method has been integrated in Fraunhofer IGD's Virtual Reality system VirtualDesign2, and the benefits and shortcomings of the approach have been evaluated. One of the major shortcomings is the initialisation time requred by the approach, while the update rates achieved during the application are high. The method is adjustable to the user's needs by trading shadow quality for update speed, and thus allows application to scenes of different complexity. Some example images for different quality levels are shown below.

Low quality.
Shadow update time: 0.06 sec.

Medium quality.
Shadow update time: 0.09 sec.

High quality.
Shadow update time: 0.24 sec.

A Progressive Refinement
radiosity solution: 4.5 sec.