Texturing
Contents
Texturing
Texturing refers to the act of producing 2d images for use with 3d models. Commonly referred to as maps or sometimes as "skins" work in conjunction with materials and Shaders to produce the final rendering inside a game engine on a game model that has a UV Layout. Multiple texture types are often used to control different parameters or channels of the shader, such as Normal maps or Specular maps. A variety of techniques and Tools are used to make textures: painted by hand in a traditional 2d package, painted in 3d directly on models, created parametrically, or Baking image data from one model to another.
(a couple of 2d/newbie-friendly tutorial links should go here) See the texturing tutorial for more links.
Texture Types
Depending on the engine and visual style, different types of maps are used for different effects. Vertex colors are optionally used to control additional effects, such as blending between two images in the same model. Images are made up of Pixels and are split up into Red, Green and Blue components, also known as channels, and may additionally have an Alpha channel which can be used to store opacity or another type of map or mask. Masks are images or layers used to control "How much of What", such as Specular maps or Gloss maps, and are typically (but not always) greyscale (pixels only utilizing one channel).
For the average prop, arrangements of map types might use Diffuse/Specular/Normal for a current-gen game. Physical Based Rendering setup might be Albedo/Microsurface/Reflectivity/Normal for a next-gen shader.
Other surfaces need more specialized shaders and textures, such as Skin or water.
For an expanded list, see Texture types.
Tutorials
There are many ways to create textures for 3d models using the various tools available to us.
Technical
todo: technical info: dimensions, bit depth, channels, pixel/texel, format(and page for format types).
Often, artists need to make choices about the formatting of their textures, usually during the planning stage before creating the model/texture. Here is some technical information on 2d images.
Size: The dimensions of the image, how the model is unwrapped, the scale of the model and scene scale all equate to the resolution of the textured model when seen in-game. It is important that all objects in the scene have similar texture scaling to keep the overall look consistent; a low-resolution image looks jarring when placed next to a high-resolution one. Texture size is the first place to start for this decision, determining texel, the ratio between UV space/Texture resolution/Scene and object scale when uv unwrapping the model is the second.
Images store pixels in two dimensions, and can be square or rectangular. Most engines require dimensions to be in powers of two: 2,4,8,16,3164,128,256,512,1024,2048,4096. Other engines may not require it, but an off-sized image can potentially harm performance.
Channels refers to the color components in the image. Red, Green and Blue (RGB) are each stored as data in separate indices and some software can display each as a greyscale image. An additional channel named Alpha can also be present, but not always rendered into the composite. Some formats store other channel types, such as HSL (Hue, Saturation, Luminance), CYMK (Cyan, Yellow, Magenta, Chroma/Black), or simply luminance or alpha.
Bit depth is how much data is allotted to each pixel either in memory or in the file. More bits per pixel (bpp) increases the number of colors available for each channel. The 1 bit type has two colors, black and white (or off and on), and is often used for transparent alpha testing - a simple sorting for whether or not a pixel is visible. 8 bits gives 256 colors per channel (16.7 million RGB colors), and is often the default mode for most applications. However, higher bpp means increased file size and memory use. It's not uncommon for a format to store colors unequally: 5 bits red, 6 bits green, 5 bits blue, for an example of a total 16 bit storage. Compression is another method to decrease the file size.
Compression
(the following is the old wiki page, will clean up as pages are written)
Related Pages
- CharacterSculpting and EnvironmentSculpting have information on 3D sculpting.
- has drawing and painting fundamentals.
Texture Sizes
- How often are 4096 textures used in next-gen gaming on the Polycount Forum
