Improved Computation of Attenuated Light with Application in Scenes with Multiple Light Sources

This paper presents and investigates methods for reducing illumination error in scenes illuminated with many light sources with limited spatial influence. Tiled shading and Clustered deferred and forward shading use the assumption, that light sources has limited spatial influence and can be represented as bounding spheres. Illumination of surface point is only computed, if it lies within bounding sphere of the light source. We explore difference in illumination between scenes illuminated with use of this assumption and scenes illuminated without use of this assumption. We show that difference can be decreased, if we add ambient lighting. We propose method for fast estimation of ambient lighting in scenes illuminated with many light sources with limited spatial influence. We also propose method for elimination of discontinuities on surface points on the edge of bounding spheres of light sources. Our methods are tested on two different scenes: procedurally generated city and cathedral of Sibenik. Our approach can be applied in various systems without any structural modifications.