intro to Materials and UVs

Materials

In 3D computer graphics, two things define the surface quality of an object - light and materials. Think of a material as a coat of paint. Just like some paints are glossy and some are matte, Maya's materials allow you to simulate shiny, glossy or flat (matte) surfaces.

The three most common types of materials are lambert, phong and blinn.

Lambert - no specular data, ideal for flat (matte) surfaces.

Phong - glossy material, good for glass and shiny plastic

Blinn - highly specular material, good for metals and certain types of glass

When you first create and object in Maya, the default Lambert1 shader gets applied to it. You should immediately assign a new material to it, otherwise any changes you make to Lambert1 will affect all new objects created in the scene.


UVs
http://en.wikipedia.org/wiki/UV_mapping

http://wiki.polycount.com/TextureCoordinates

http://blog.machinimatrix.org/the-basics-of-texturing-i/


Overview

The best analogy for UV mapping is that you are essentially taking a 3D shape and flattening it out so it can be textured in 2D space. This is much like how a bear-skin rug works; the bear used to be a 3D creature, but once it was pelted, the furrier converted it into a flat 2D shape.

UV mapping, along with rigging, is considered to be one of the more difficult and time consuming tasks in the 3D pipeline. The secret is, it doesn't have to be! If you spend some time planning and thinking ahead, you can minimize alot of errors and rework, and in many cases, achieve good UV layout in a short amount of time. Stay positive and remember that there are PLENTY of UV mapping tools, tips and tutorials online.

Maya's UV projection functions
Maya has 4 main UV projection functions - planar, cylindrical, spherical and automatic mapping. Many times, you will have to use several of these techniques in order to completely map the object. Consider the shape you are trying to capture in 2d space, and think about what kind of projections would best capture that shape.

The three-way battle...
UV mapping is a three-way battle. You are fighting between...

1. Less distortion, meaning that you want the 2D UVs to match the shape of the 3D face they represent as closely as possible.
2. Fewer pieces, meaning that you will ideally end up with fewer UV islands and borders, potentially reducing visible seams.
3. Maximizing texture space, meaning that you are trying to utilize as much of the 0 to 1 UV space as you possible can, so you can squeeze in extra juicy texture goodness!

Mapping early on non-deformed objects

Mapping objects that have not yet been deformed or translated/rotated away from the origin will usually result in cleaner and easier UVs. Consider a curved tree branch; this could most likely be easily mapped using cylindrical projection if it was not curved, but mapping the UVs after the deformation would be more difficult.

Auto mapping

Maya's automatic mapping is okay, but there are much better options for auto-unwrap out there. Maya's bonus tools features an amazing UV unwrap tool, and zBrush has a similar tool called UV master, which allows you to paint where you want the UV seams and edges to be. Feel free to use these tools for you final project if you feel it speeds up your workflow.

Maya's select > convert selection menu

Maya's select menu (in the hotbox, far left) features an awesome convert selection tool, which lets you covert selected components into another component type. For example, if you have a set of faces selected, but you want to select the UV's associated with those faces, go to select > convert selection > to UV's.