Types Of Texture Maps for Video Games

which texture maps to use

Once you start to texture your models you will run across the different types of texture maps. It can be confusing about when and where each type should be used, and even how they are different from each other.

Based on which modeling software, renderer, or game engine you use, some map types may work better than others or not at all they also require the maps to be provided in certain formats. I will be focusing on a Maya to Unity workflow, but I will include information for 3ds Max, Blender, CryEngine, and Unreal Engine where I can. For this chart, I am going to be sticking to the types of maps commonly used with gaming, there are many many more which I will not cover. If you want to learn about those, check out the Further Reading section down at the bottom of this post.

One thing that is consistent throughout various software is how texture maps are applied:

Mesh in Maya

Mesh in Maya

  1. First a model has a mesh, the mesh is the polygonal faces that you can see (wireframe draws the edges of the mesh). The mesh is typically represented by a gray color.
  2. Materials are applied to the mesh. Common types of materials are Blinn, Lambert, and Phong. The type of material will effect the quality of the render, how much it costs (cost is how much processor time the render will consume), and which attributes can be changed.
  3. Texture map(s) are applied to the material (these can be color, specular, bump, etc.). A texture map is laid out in a UV texture space from 0-1.
    Blinn in Maya

    Blinn on mesh

    Typically texture maps are square and sized in base 2 number of pixels (ex: 64×64, 128×128, 256×256). Some engines and platforms allow odd sized maps such as a few games made for the PlayStation 2.

Color

Color is what really defines a model. These should have the base color of the model, variation in that color, and even dirt or wear that has come to the surface. Use many reference images to get it right. For the most part, these are the only required maps in a game.

Color Map (Sometimes called Diffuse (3ds Max, Unity) or texture):

blinn-color

The color map is a texture space used for the color. Shadows can be drawn into the color map to define geometry that doesn’t exist on the model through a technique known as “baking”.

It is worth noting that some software (including 3ds Max and Unity) refers to the color map as the diffuse map, however diffuse is something different. This confusion is likely due to a fast developing industry where no standards where in place at the time of naming.

Color Map Examples:

UVtemplateColor

UV Template

Color map for various tools

Color map for various tools

color map for 3d

Color map for tillable floor

Color map for a blue gas pump

Color map for a blue gas pump

Light

Maps can be used to define how light reacts to the material by controlling how much light is absorbed by the material and how reflective it is (ex: metal, wood or even cloth) as well as other emulating other elements we see in the world.

Specular Map:

blinn-color-spec

The specular map defines where in the texture space it is and is not shiny. These maps are drawn in gray scale where white is shiny and black is not.

Specular maps can be used to decrease the shine is areas with dirt or moss.

Specular Map Examples:

checkered specular map

Specular map for example

Specular map for tile floor

Specular map for tile floor

Specular map for wound

Specular map for wound

Diffuse Map:

Honestly, diffusion maps aren’t used in gaming much because of their cost but are baked into the color and specular maps. I am including it here to clear up some confusion that Autodesk’s 3ds Max caused about what a diffuse map is.

Using the word properly, diffusion determines how much of the color you can see by regulating how much light is reflected and absorbed by the material.

Diffuse maps are in shades of gray, with white causing the surface to become more diffused, and black having no effect.

For example a perfect mirror that reflects all light (and has no color) would have low diffusion and be represented by a black diffuse map. Wood has a higher diffusion and would be represented by a shade of gray on the diffusion map.

Another way of seeing how this effects your color map is to set the diffusion map to multiply in Photoshop over the color layer.

 

Gloss Map:

 

Ambient Occlusion Map:

 

Reflection:

 

Texture

Maps that add texture to the model are powerful. They allow models with a low polycount to appear to have much more geometry than they have in actuality. These types of maps do not modify the silhouette (see the rendered normal map example below) so you will need to be careful when adding them near edges.

Bump Map:

The way bump maps are represented is that white is high on the model, and black is low, gray is neutral and is inline with the mesh.

Sides of where the bump maps effects the model can look jagged since they only work in one direction; up and down. Normal maps are an attempt to improve on bump maps and should be over bump maps where they can.

Bump Map Examples:

Bump map for bark

Bump map for bark

Bump map for roof tiles

Bump map for roof tiles

Normal Map (also called bump maps):

textured mesh for 3d video game

Normal maps are an improvement over bump maps and are more commonly used in game design. They are mostly blue, rainbow colored maps.

A very common use is to model a highpoly version of a model and then bake the geometry from it onto a lowpoly version as normals. This technique can save millions of polygons and allow a complex model to be used in a game where otherwise it would cost too much.

Normal Map Examples:

square normal map

Normal map for example

Normal map for K-rail barrier

Normal map for K-rail barrier

 

Other

Alpha Map:

Opacity

 

Further Reading

Photorealistic Texturing for Dummies (mirror)

Resources

 

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