From LuxRender Wiki
Physically based rendering
LuxRender is built on physically based equations that model the transportation of light. This allows it to accurately capture a wide range of phenomena which most other rendering programs are simply unable to reproduce. This also means that it fully supports high-dynamic range (HDR) rendering.
LuxRender is written to be portable, and binaries are available for Windows, Linux and OSX.
The core of Luxrender is fully spectral. Unlike traditional rendering software, which only operates on distinct colors (such as red, green and blue), Luxrender uses individual wavelengths. This allows LuxRender to correctly deal with wavelength dependent effects, such as dispersion, or accurately capture the color of incandescent lights. It also makes the rendered images look more natural.
Optimized rendering methods
Select between regular path tracing, bi-directional path tracing and distributed path tracing to get the best performance depending on your scene.
Path tracing is excellent for scenes with primarily direct lighting, like outdoor scenes.
Bi-directional path tracing is a significant extension of the path tracing method. It is excellent for scenes with complicated lighting, like caustics or indoor scenes with indirect lighting.
Distributed path tracing is a variation of path tracing which is geared towards rendering animations. It has several additional parameters which which allows you to optimize the quality and rendering time for your scene.
In addition LuxRender offers Metropolis sampling, a sophisticated technique which will "seek out" the light. Combined with bi-directional path tracing this makes LuxRender able to deliver excellent results for scenes with very complex lighting.
True motion blur
Both camera and objects can be made to move while the camera shutter is open. The result is true motion blur. No difficult settings to tweak, just animate the camera or object, set the shutter times and you're done.
Realistic sun sky system
LuxRender has a physically based sun and sky system for realistic daylight lighting. Excellent for architectural visualizations.
LuxRender is an external rendering program. Exporters are available for several popular modelling programs.
The primary exporter is LuxBlend, which tightly integrates LuxRender with Blender. It supports all the features of LuxRender. It also features interactive material preview inside Blender, significantly reducing the time it takes to create complex, realistic materials.
Procedural and image based textures
LuxRender supports a wide variety of procedural textures, including most of Blender's internal procedural textures. It also has support for image based textures, including HDR textures. Complex textures can be created by mixing other textures recursively.
Loop subdivision and displacement mapping
Using the built-in support for Loop subdivision of meshes, with optional displacement mapping, allows you to create highly detailed models with little extra effort.
Supports HDR environment maps for realistic HDRI lighting. Latlong, vertical cross and angular ("light probe") formats supported.
Supports HDR output using the EXR file format for external tonemapping.
Optimized architectural glass
Architectural glass is optimized for windows where refraction is not necessary. This substantially increases the performance compared to using regular glass.
Built-in support for cross-platform network rendering, including co-operative rendering.
Save precious time by adjusting the light balance without having to render the scene again and again. By assigning lights to different groups, you can adjust the contribution of each one as a post-process.
In addition to the standard perspective camera, LuxRender also supports orthographic and environment cameras.
The perspective camera is based on a standard pinhole camera model. It supports Depth of Field (DoF), with the ability to specify aperture shape for realistic DoF effects.
The environment camera is ideal for making environment maps.