One feature that is missing in SketchUp, though, is photo-realistic rendering. But don’t let that stop you… You can add high-quality rendering to the free SketchUp software even if you don’t have any of the full-featured commercial rendering programs like 3ds max, VRay, maxwell etc. Although there are some commercial rendering solutions available for SketchUp (namely Twilight, Podium, VRay for SketchUp, LightUp, IDX Renditioner – all of these integrate nicely into SketchUp and offer “one-click” rendering), I suggest you take a look at the freeware Kerkythea. For completeness, it should be mentioned that there are also the free renderers (with export plugins) Indigo and POVRAY, but I (currently) prefer Kerkythea due to its great user interface, fast and great results as well as multiprocessor support.
Kerkythea installs as a separate program and SketchUp models are converted to its XML-based scene description language with a very seamless exporter plug-in (a Ruby-plugin). The rendering engine then provides various rendering methods such as ray tracing, photon mapping, path tracing, BiPT, MLT and also presets for clay and ambient occlusion renderings. It includes a full-featured material editor and additional high-quality materials can be downloaded from the web.