What Is UV Mapping in 3D Applications?

The Prelude to Creating Great Textures with Blender

One of the fastest growing industries in the world today is the video games industry. More games are being released every year, from an ever growing list of independent developers, as a result of professional grade software being made more readily available to the general public. 

As you will no doubt have guessed 3D applications are crucial to the creation of assets for many a video game. These applications include Blender, Maya, and 3DS max. 

The process of asset creating with these applications is the same across the board. Start by modelling the object so that you get the shape, dimensions and detail, unwrap the object in a process known as UV mapping, apply textures and materials to the asset, and then rig and animate if required.

Of all the steps mentioned above, the one that confuses people the most is UV mapping.

So what is UV mapping?

UV mapping is the process in which a 3D object is cut up by its seams (marked edges of the object) and mapped out on a 2D surface known as the UV grid. This grid is used to map a 2D texture onto the object by positioning the UV map over the texture. It can be considered as sort of a reverse form of digital origami. 

This process of conversion is crucial for blender to know how to position the texture onto the object. Without it, you would not be able to control how the texture is being applied to your object.

Fortunately, UV mapping is one of those things that can be tricky to learn but easy to master. Its tricky to start off with because it's such a niche skill to learn but once you understand the basics it becomes easier to master. 

Cube Unwrap

How to set up Blender for UV mapping?

So how do you Unwrap an object in Blender?

In order to be able to map a 3D object onto a 2D plane you must first make sure that you are in edit mode for the object that you want to unwrap. Then make sure that the geometry that you want to unwrap is selected as any faces that are not a part of the active selection will not be unwrapped.

Blender is very hotkey intensive, and the hotkey for bringing up the unwrap menu is the 'u' key. This menu will provide you with all of the different methods for unwrapping your object. We won't be going though all of these in this article, but just know that each of them has their on advantages and disadvantages.

The one we are going to focus on for now is the unwrap option. This creates a UV map of the object based on the seams that have been manually created by the user.

What if you have not created any seams for the object?

If no seams have been marked then blender will unwrap the object in a way that has each face use as much of the map as possible. A four sided face for example will use up the entire UV map. This also results in all the faces overlapping each other, which is something you don't really want for your UV map.

We solve this issue by marking the seams on the object. Remember that the seams are where those imaginary scissors go to begin cutting up and folding out the object. If we want to mark a seam, then we need to select the edges of the object that we want to become seams. Then bring up the edge tool menu by using the Hotkey combination 'control + E' on windows or 'command + E' on a mac. Then select mark seam to mark those selected edges as seams.

When seams are marked they are highlighted red to distinguish them from unmarked seams.

Marked Seams on Cube with Red Highlight

What to consider when marking seams?

The following should be taken into consideration as a little cheat guide to marking seams for UV maps.

  1. Imagine as detailed as possible how your object would unwrap as an animation in your head.
  2. How many seams do you need?
  3. Where are the seams going to go?
  4. What texture is being used?
  5. What are the key areas of the object where seams need to be avoided (such as the face of a character head)?
  6. Are you looking to create islands on your UV map (Normally the case for objects with more geometry)?

Copy and paste this list and keep it safe somewhere while learning how to use the UV editing tools in Blender. Just a quick note about islands which were mentioned with point six — islands are independent sections of the UV map that can be moved, rotated and scaled separately from other parts of the map.

UV Map with Islands

Practice makes perfect and although every object has its own UV map and can be configured multiple different ways but the process will always remain the same.

Udemy Blender Course for Learning How to UV Map

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What Is UV Mapping in 3D Applications?
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