This image was rendered in Radiance by Ole Lemming, the author of the ConRad tool. Optimized Monte Carlo Raytracing with Importance Sampling was used to calculate the global illumination. Bilinear texture filtering of the very low resolution checker map causes some blur here. Rendering time was appr. 5h30min.
I am very curious what other global illumination renderers are doing with this test case. I would be very pleased if someone could render it with Mental Ray, Brazil, etc. and send me the results. Visit the Download Section and get the scene file in various formats for importing it into your favourite renderer.
Another comparison with this test scene can be found at www.buildart.com/render_comparison.htm.
Currently it shows renderings of Truespace, Bryce, Art*lantis and Archicad with AV-Works.