From LuxRender Wiki
LuxRender's texture support is very powerful and flexible and supports image textures and a large number of 2D and 3D procedural textures. Textures can be used to modulate most material properties, including bump mapping and displacement - see the LuxRender_Materials page for details.
Color, Float, and Fresnel Textures
In LuxRender, all textures output one of 3 kinds of values: colors, floats (numerical data) or fresnel data (optical properties). Some can be switched to output either color or float values. It is important that you pay attention to which one is which. Numerical fields need float textures, colors need color textures. Fresnel textures are used on special numerical fields that accept optical data, such as for volumes or the metal2 material.
If you apply the wrong kind, LuxRender will give an error that it couldn't find the specified texture. If you need a float-only texture to output a color, you can use it on the "mix amount" channel of the mix or band texture. The color values for the mix/band texture will become the colors of the texture. NOTE: Some exporters will set this up for you if try and set a float texture type on a color field.
Image Textures are two dimensional images that are projected on 3d objects. These textures can be used in a variety of material channels, for example colour, bump and displacement. Typically, the UV mapping of images on 3d objects is handled by the 3d application.
The following formats can be used as textures:
- BMP (uncompressed)
- HDR (Analyze 7.5)
- RAW (consisting of a very simple header (in ascii), then the image data)
- ASC (Ascii)
- INR (Inrimage)
- PPM/PGM (Portable Pixmap)
- PAN (Pandore-5)
- DLM (Matlab ASCII)
Tif images and Photoshop files (.psd) may work on some platforms.
In most cases, PNG files work best for texturing in LuxRender.
Image Texture Parameters
When using an image as a texture in any material channel, a couple of parameters are available:
- gamma - The gamma correction value for the texture. 1.0 will not affect the texture, which is what you want when you need to use the actual RGB values encoded into the texture, such as for a bump map or specular map. If you want a color image texture to appear as the image did on screen, you will want to set this to the screen gamma it was built using, which is probably 2.2
- gain - A scaling factor that will be applied to the image. This is the same as piping it through a scale texture
- filter - This determines how LuxRender will filter the image when sampling it. In most cases, the default of "bilinear" works best.
Procedural textures are defined mathematically, which means that the texture value (or color) at any given point is calculated by the program instead of being defined by an existing bitmap image. By combining various textures, very complex materials can be created. At the same time, using procedural textures can be very time effective since mapping is not required.
The downside of having LuxRender calculate the texture's values is that your 3d application may not be able to show previews for all textures. As many of LuxRender's procedural texture types have been taken from Blender, this program is very suitable for working with Luxrender's procedural materials. However, all textures can be assigned using any exporter.
Many of the procedural textures are fully three dimensional, which means that regardless of the shape of an object, they will always fit perfectly at edges.
Procedural textures are not filtered or anti-aliased. This is hardly ever a problem as the user can keep the specified frequencies within acceptable limits.
Procedural Texture Types - Blender Procedurals
LuxRender includes an implementation of most of Blender's procedural texture options.
For more information, see LuxRender Textures Blender
Procedural Texture Types - LuxRender Procedurals
In addition to the Blender procedural textures, LuxRender has many procedural textures of its own. These also include special textures for mixing or altering other textures, namely the mix, scale, band, and multi mix textures.
For more information, see LuxRender Textures Lux
The spectrum textures are a set of color textures that define an actual light spectrum rather than an RGB color (which is converted to a spectrum later). They are mainly used for absorption and emission, but can be used on any color field if desired.
For more information, see LuxRender Textures Spectrum
The fresnel textures are special textures for defining optical properties. For more information, see LuxRender Textures Fresnel