# What is a UV map and how it works for 3D models

In this post you’re gonna learn what is a UV map and how it works or actually how it acts on a Mesh (tridimensional object).

## What is a UV map?

A UV map is like this one:

Actually it simply makes two things:

• Give instructions to the engine on how to apply the texture.
• Teach the engine on how to trace shadows.

There is one UV map for each of those two functions.
So generally only two UV maps are really useful: if the mesh contains more than two it’s because they are interchangeable, instead if it has just one UV map this means that the UV map related to shadows tracing is missing.

## How a UV map works?

UV maps work in strict relation with vertices of a mesh.
To understand how it works a UV map, let’s make a more practical example.

Let’s assume that you wanna apply this texture to a cube mesh.

A texture has his own coordinates that go from 0;0 to 1;1, like the picture shows.

Practically the UV map doesn’t do more than teach the engine what coordinates apply on triangles of the mesh, taking them from the texture.

Let’s enumerate conventionally vertices of a cube like in the picture, the result will be the following one if it takes the area of the texture that goes from 0;0 to 1;1: to the vertex 1 corresponds 0;0, to the vertex 4 instead 1;1.

Let’s suppose we wanna take only the area between coordinates 0,5;0,5 and 1;0.

What we’re doing is actually cutting out the texture applying to the mesh just a portion of it.

So to the vertex 1 corresponds 0,5;0, instead 1;0,5 to the vertex 4.
Then the result is the same image but enlarged.

On doing this operation, that is to instruct what coordinates to apply, the responsible is just the UV map. Now you should understand without any problem what is a UV map and how it works.

So a professional 3D modeler should follow those points accurately first than give the 3D model to the developer that will use it on the creation of his videogame:

• create the mesh
• ensure that the texture is correctly applied
• ensure that, if needed, shadows are correctly traced
• take the number of triangles the lower possible to not overcharge the GPU
• remember to export materials and UV maps

#### What you learned

1. What is a UV map
2. How a UV map works, that is in which way it applies a texture on a mesh
3. Tips for a correct operating of the mesh inside the videogame

Now you can proceed to create your models (e.g. with Blender) avoiding problems or solving them analyzing UV maps!