jan novák

Screen-Space Bias Compensation for Interactive High-Quality Global Illumination with Virtual Point Lights

Jan Novák, Thomas Engelhardt, and Carsten Dachsbacher

ACM Siggraph Symposium on Interactive 3D Graphics and Games (I3D '11)

Our algorithm enables high quality rendering for VPL based methods by restoring the short distance illumination that is usually clamped to avoid artifacts. By employing our hierarchical integration scheme in screen space, which takes about 27 ms for these images, we can efficiently compute the missing energy (right image), and obtain results that are comparable to offline renderers at interactive frame rates (10 fps for the Dragon, and 7.2 fps for the Happy Buddha scene).


In this paper we present a method that targets high-quality global illumination at interactive frame rates. As many techniques in this context, our method is based on instant radiosity, which represents the indirect illumination in a scene with a set of virtual point lights, and therefore enables efficient GPU rendering. Instant radiosity captures light transport over larger distances well, but it requires clamping of the point lights’ contribution to avoid bright splotches on nearby surfaces. By bounding the short distance light transport, the algorithm removes some energy and thus introduces bias, that is visible as incorrect darkening near edges and corners. Our method improves the quality and correctness of the rendered images by removing bias using a hierarchical screen space approach. We show that the bias compensation can be formulated as a post-processing step and demonstrate renderings comparable to results from offline algorithms at interactive speed.








    author      = {Nov\'{a}k, Jan and Engelhardt, Thomas and Dachsbacher, Carsten},
    title       = {Screen-space bias compensation for interactive high-quality global illumination with virtual point lights},
    booktitle   = {Symposium on Interactive 3D Graphics and Games},
    series      = {I3D '11},
    year        = {2011},
    location    = {San Francisco, California},
    pages       = {119--124},
    publisher   = {ACM},
    address     = {New York, NY, USA},
    isbn        = {978-1-4503-0565-5},
    url         = {http://doi.acm.org/10.1145/1944745.1944765},
    doi         = {http://doi.acm.org/10.1145/1944745.1944765},
    acmid       = {1944765},