In this scene, glass skylights on the ceiling obscure all direct light paths to the sun and sky lamp outside. Light must first pass through these skylights before reaching the camera, which creates a challenging lighting scenario. The scene also includes highly specular metallic and glossy materials on the lamps, windows, and floor, in addition to rough glass on the lamps.

      For the final render, I made use of LuxRender's Bidirectional Path Tracing (BDPT) integrator to more efficiently resolve the challenging light paths. Bidirectional path tracing improves upon simple path tracing by creating light paths at both the camera and the light source. These paths are able to "meet in the middle" so to speak, greatly improving the renderer's light-finding ability.

      Additionally, the scene makes use of the Lanczos-Sinc reconstruction filter which tends to create very sharp results at the cost of increased render times. The negative and positive lobes of the filter also have the possibility to create artifacts around bright spots or "hot pixels," however no such artifacts are shown in this image.

      With over 19,000,000 triangles, the image at left was rendered to 50,000 Samples Per Pixel (SPP) inLuxRender 1.6.