Interactive, Multiresolution Image‐Space Rendering for Dynamic Area Lighting

Abstract

Area lights add tremendous realism, but rendering them interactively proves challenging. Integrating visibility is costly, even with current shadowing techniques, and existing methods frequently ignore illumination variations at unoccluded points due to changing radiance over the light's surface. We extend recent image-space work that reduces costs by gathering illumination in a multiresolution fashion, rendering varying frequencies at corresponding resolutions. To compute visibility, we eschew shadow maps and instead rely on a coarse screen-space voxelization, which effectively provides a cheap layered depth image for binary visibility queries via ray marching. Our technique requires no precomputation and runs at interactive rates, allowing scenes with large area lights, including dynamic content such as video screens.

Voxel-Space Ambient Occlusion

“…Higher detail is required in such areas as ambient occlusion may vary significantly from point to point. We take advantage of this fact and use a stencil based screen-space multi-resolution approach similar to Nichols and Wyman [NW09] and Nichols et al [NPW10], where we selectively render higher detail areas and lower detail areas with different precision. Ambient occlusion varies smoothly across a scene, allowing lower detail areas to be rendered at lower precision.…”

“…We sample depth values from the G-buffer and compute depth discontinuities similar to Nichols and Wyman [NW09] and Nichols et al [NPW10]. We use the computed curvature buffer and depth buffer for stencil refinement, which is discussed in the following section.…”

“…We use a stencil based multi-resolution rendering approach similar to Nichols and Wyman [NW09] and Nichols et al [NPW10]. We start by constructing a mipmap structure in a multiresolution buffer.…”

“…Reinbothe et al [RBA09] computed ambient occlusion by tracing rays in a voxel grid and filtering the occlusion result in screen space. Nichols et al [NPW10] use voxelization of screen-space geometry to render dynamic area lighting.…”

“…We extend the stencil based multi-resolution technique by Nichols et al [NPW10] by using curvature and depth discontinuities, as opposed to normal and depth discontinuites.…”