From LuxRender Wiki
In the LuxBlend material panel properties for materials and light objects can be set.
selecting, saving and loading materials
At the top of the material panel, the name of the current material is displayed in a drop down menu. By default, this is the material of the Blender object that is currently selected. When working with objects that have multiple Blender materials applied to them, the filter button will limit the available materials in the drop down menu to the ones that are applied to the object, instead of showing all materials in the scene.
On the left of the drop down menu, there is a button with a C on it. Pressing this will convert some of Blender's material settings of the selected material to the LuxRender material. This includes colours, procedural and bitmap textures and basic material settings such as specularity level and hardness.
The Preview button will render a preview of the material within LuxBlend's material tab.
The buttons named L, S and D can be used respectively to load, save and delete materials. By saving materials, they will be available to other Blender files. Saved materials are stored in a file called luxblend_materials.cfg in .blender/scripts/bpydata/config.
LuxRender supports a variety of physically based material models, all of which have their own set of adjustable properties. For a list of available materials and their characteristics, please see LuxRender Materials.
A preview of LuxRender materials can be rendered within LuxBlend. As this takes considerable time, it is only done on demand by pressing the Update Preview button.
On the left of the preview image, the buttons with an S, P and T can be used to select the preview scene. Currently a sphere, a plane and a torus are available.
With the zoom button activated, a close up of the preview scene will be rendered, so that the surface can be studied in more detail.
When the Area button is pressed, an area light will be used instead of the default point light.
From a dropdown menu, the quality (and hence the render time) of the preview can be set. This setting is stored with the current material; if you want to change the default quality for all materials, use the preview quality setting in LuxBlend's system tab instead.
The "Large" button switches between a preview size of 110x110 and 140x140 pixels.
Each material type has a number of channels. A channel allows you to modify the base colour of material components, such as its diffuse reflection colour, specular reflection colour, transmittance colour and so on.
Additionally, each channel can be modulated by a texture. These can be simple image map textures which are loaded from image files, 2D and 3D procedural textures, or complicated hierarchical mixes of all these different types of textures. The ability to modulate each material channel with endlessly complex mixes of the different types of textures opens up the possibility to create arbitrarily complex materials.
This function is a modifier of glossy materials. A regular glossy material models a diffuse base covered with a varnish. The absorption code makes the varnish absorb light. When activated there are two parameters: A color and a Depth.
The color is the "spectral distribution" of the absorption. For example, a color of [0.9 0.5 0.0] will absorb almost all red and half of the green and no blue.
The Depth parameter is the thickness of the 'varnish'.
The bump effect on a surface is defined by a texture and a strength. LuxRender can use both procedural and bitmap images as bump maps. The strength of the effect is expressed in scene units. By default, LuxBlend assumes the scene unit to be one meter, whereas a typical bump effect is a lot smaller, for example one millimeter. Using big bump values may result in unrealistic results.
A preview image for bump maps is available, similar to the material preview described above.
Depending on the texture type, a range of parameters is available. For details, please see LuxRender_Textures.
Any mesh can operate as a light source. When the emission tab is enabled you can set light color, power, and gain just as you would with a lamp object. While very similar in effect to assigning the 'light' material to an object, the emission tab allows any material (not just matte) to emit light.
Subdivision works similar to Blender's subsurf modifier. The mesh is triangulated first, so objects using quads will look different with LuxRender's subdivision than with Blender's subsurf modifier.
Displacement will displace the mesh surface based on an image or procedural texture.
Although not strictly speaking materials, exit portals (LuxRender_Materials#portal) can be created by assigning a material to the objects that should function as an exit portal and choosing "portal" as its material type in LuxBlend.
Light objects can be created using Blender's light objects (lamp, area, spot) or using any mesh and assigning a light material. Additionally, a sun sky and other environment lights can be set up using the Cam/Env tab.
Blender lamp objects
When exporting a scene, Blender's Lamp, Area and Spot lights are converted to LuxRender light objects. Some settings will automatically be used by LuxRender, such as the width of the cone of a spot light or the size of an area light. However, intensity and colour need to be set in LuxBlend's material tab.
When a lamp object is selected, LuxBlend's material panel will show a texture dropdown menu and the relevant options for the selected textures type. Multiple options to set the spectrum (or colour) are available: blackbody, constant, equalenergy, frequency, gaussian, irregular data and regular data. Additionally, image textures and procedural textures can be used to specify the light colour.
For details on setting the spectrum, please refer to the LuxRender_Lighting page.
Emitters are meshes that emit light and hence can have any desirable shape. To create an emitter, create a material in Blender with a name of your choice (emitter might be suitable), assign this material to the mesh you want to function as a light source and go to the material tab in LuxBlend. In the material drop down menu, select the material you've just created and select light in the second drop down menu. A dropdown menu with texture types will appear, showing the same options that are available for Blender lamp objects (see above).
The number of faces of emitter has a considerable impact on render times. It is therefore advisable to keep the number of faces of emitter objects as low as possible. Emitters only emit light from the side their face normals are pointing from. If the back side of an emitter shows, it will be rendered as a surface with the default material applied.