Since Yafray development seems to be frozen anyone got interested in finding a good external GI renderer to be used as a real alternative; actually there are a few options, most of them are in a early stage of development, only two of them are good for production level: the first is Pov-Ray, which can be used with Blender 2.41 thanks to RCRuiz's custom builds, the second one, which I'm using in my daily workflow, is Kerkythea, a commercial quality renderer which boasts a straightforward standalone GUI and different GI solvers.
I hope that Kerkythea will become a powerful renderer in the future, among the other popular freeware ray tracers. My intention is to add things and improve along with user interaction, so feedback is always welcomed.
Those are the words of Ioannis Pantazopoulos, the guy behind the project, and looking and the full Kerkythea's feature-set it seems that he is a few steps from achieving his goal:
- Easy and fast rendering - Optimized ray tracing kernel
- Easy and consistent XML configuration for a scene
- Standalone application, navigation and scene setup with integrated OpenGL viewer (GUI based on Fox toolkit)
- Material library - Reusing your saved materials
- Material editor - Materials supported (Phong, Ward, Lafortune, Dielectric, Thin Glass, Layered)
- Bump Mapping, Clip Mapping, Edge Outlining
- Support for many image formats (based on FreeImage library)
- HDRI support - image based rendering
- Real depth of field (using stratified ray tracing)
- Camera projection models: planar, cylindrical, spherical
- Importing 3DS and OBJ files
- Exporters for Blender, 3dsMax and SketchUp
- Basic/Iterative antialiasing based on brightness difference
- Texture filtering (based on ray differentials)
- GI support based on various methods (Path Tracing, Photon Maps/Mesh Maps + Irradiance Caching, Diffuse Interreflection)
- Light sources (Point, Spot) + Self-Luminant area lights
- Soft/Area shadows
- Caustics (based on Photon Maps or quick heuristics)
- Basic Chromatic Dispersion
- Material (BSDF) SDK and plugin support upon initialization
- Thin Glass physically accurate material
- Script support and execution (kst batch files)
- Real field of view (thin lens model extension)
- Irradiance gradients
- Secondary/arbitrary gathering depth
- Available on both Win32 and Linux platforms
Actually the Python exporter for Blender suffers from a couple minor issues which will be fixed soon (a new major version is on the way too) but it will work good in most cases, exporting to 3ds/obj is an option if you'll find any problem using it.
Give it a try and post your thoughts on the project's forums.