Radiance is a set of tools which provide an advanced lighting simulation software package. It allows very detailed definition of materials' and light sources' properties through the use of advanced techniques like brdf and ies files, as well as a powerful mathematical scripting language, resulting in accurate renderings of scenes which are usually imported from CAD and 3D modelers. It uses the hybrid approach of Monte Carlo and deterministic ray tracing to achieve a reasonably accurate result in a reasonable time.
Moonlight|3D is a modeling and animation tool for three-dimensional art. It currently supports mesh-based modeling. It's a redesign of Moonlight Atelier, formed after Moonlight Atelier/Creator died in 1999/2000. Rendering is done through pluggable backends. It currently supports Sunflow, with support for RenderMan and others in planning.
K-3D is a 3D modeling, animation, and rendering system for GNU/Linux & Win32. Features include creation and editing of geometry in multiple realtime OpenGL solid, shaded, and texture-mapped views; unlimited undos and redos; complete extensibility at runtime through third-party plugins; animated procedural geometric effects; all parameters animatable through a consistent control-spline based interface; rendering pipeline to Renderman Interface compliant rendering engines; optimization for use with the Aqsis rendering engine, which features solid modelling, true displacement, and user programmable shaders; and support for background and batch rendering.