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1. What are UV Maps and UV Textures?
1. What are UV Maps and UV Textures?
What is a UV Map?
What is a UV Map?
A UV map is a flat representation of the surface of a 3D model.
Why is it called 'UV' Map? Well, we use X,Y coordinates to identify where a pixel sits on a 2D image (e.g. a sprite), but we use U,V coordinates to represent a surface that us unfolded from a 3-dimensional polygon.
The image on the top right shows the surface of a cube and its UV.
The animation bottom right shows what this process of unwrapping theoretically looks like.
What is a UV Texture?
What is a UV Texture?
A UV Texture is an image mapped onto a 3D model using the UV Map.
The image below left shows a UV Texture (a black background with numbers) superimposed onto the UV Map (the grey lines).
The image below right shows the same UV texture mapped onto the 3D cube. This clearly shows how the UV map determines where on the object the UV texture is shown.
The image below left is the UV map of a character. The image below middle is the UV map superimposed on a UV texture map (diffuse), and the image on the right is simply the UV texture map (diffuse).
Why use UVs?
Why use UVs?
Computer games are limited in their processing power, so 3D game objects need to have a lower number of polygons. Consequently, the main reason to use UVs is:
To create the illusion of more polygons you use UVs to wrap an image that has more detail than the polygons. However it should be noted that a computer (or at least its graphics card) still has to do a lot of processing to calculate how a pixel on a UV texture wrapped around a 3D object in a 3D scene is rendered to a 2D screen.
To create the illusion of textural properties you use a mixture of different types of UV Textures, e.g.
colour maps (aka diffuse or albedo maps) for basic colour (sometimes this is the only UV Texture)
normal maps to create more subtle surface texture effects, e.g. clothing folds (now often used in place of bump maps, look purplish)
roughness or gloss maps to create the effect of shininess/wetness (predominantly black with white highlights)
metallic or reflectivity maps to create the effect of metal surfaces through sharpened reflective properties
opacity maps to allow parts of an object to remain invisible (black with white showing visible elements)
emissive maps to create glowing effects (glow colour where things)
ambient occlusion maps (aka cavity maps) to create deep shadows (mostly white with black showing the deep cavities)
displacement maps to physically deform the geometry (usually black with white gradients for raised areas).
2. UV Unwrapping in Maya
2. UV Unwrapping in Maya
The two basic pipelines for generating UVs in a game context are:
A. Photoshop method (see section 4)
Model your model in Maya;
Generate a UV map using the UV Editor;
Create a UV snapshot and export to Photoshop to create UV textures.
B. Sculpting method (see section 5)
Export your model to Mudbox (or ZBrush or another 3D paint/sculpting tool) to create UV textures;
Bring your textures back into Maya and check/set the image file associations;
Export your textured model as an .fbx (using the fbx for Unity option).;
Drag the resulting folder/files into the Assets panel of your Unity project;
Drag into your Scene!
Maya documentation:
UV Mapping Tips and Tricks (Gamasutra article):
3. Materials in Maya
3. Materials in Maya
The simplest approach to creating a textured object is simply to import a texture in Maya to either your entire object or to several faces of an object.
You can do this by:
assigning a new material (right click and choose option from the menu);
creating the file association to your image (select the appropriate material node, e.g. lambert, in the Attribute editor - see below).
4. UV Texturing in Photoshop
4. UV Texturing in Photoshop
One way to create UV Textures for your model is by exporting a UV Snapshot (an image of your UV map) into Photoshop, and then simply use Photoshop to import and align images, or create new images, that will wrap around your model. You then save the Photoshop image as .jpg or other single-layer and import into Maya.
Create futuristic weapon - texturing (the workflow for this one pager mostly focuses on Photoshop texturing).
5. Texturing Software
5. Texturing Software
Substance, Mixer, etc
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