This is what's possible in real-time today with graphics accelerator hardware using OpenGL or DirectX. Visibility tests are performend via backface culling and a depth buffer. Shading is typically done at vertex level with a local illumination model and then gouraud-interpolated over a triangle mesh. The shadows are computed via a shadow buffer or shadow polygons without correct penumbra. A mirrored copy of the complete scene is used for the reflection on the floor, alpha-combined with the checker texture. The reflection in the mirror sphere can be generated using cubic environment mapping.
Note that the transparency of the glass sphere is only alpha blending without refraction or caustics. The contour edges of the spheres are not perfectly smooth, because curved surfaces have to be approximated using a triangle mesh. A constant ambient light factor instead of true global illumination doesn't show any edges, shades or color bleeding in the shadow areas on the ceiling or in the middle-back corner.
Full scene antialiasing is done by rendering the scene internally in double resolution and then average every 2x2 sub-pixels to the final pixel value.
(For walkthroughs in static scenes, it is possible to pre-compute a view-independant global illumination solution with indirect illumination and caustics and use it as a lighting map / environment map during real-time rendering later. This would produce very high image quality but without the possibility to get interactive (move objects or light sources, in a game or VR application for example), which would require a new calculation of the global illumination. - Current 3D-games often use a mixture of static illumination maps for the background and real-time calculated shadows for the actors.)
Rendering time is about 0.1 seconds.
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.