What is a UV Map and How to Create One

What is a UV Map

It is likely when you first start 3d modelling you are going to hear and read a lot of odd terminology and this can quickly make you feel in over your head. The term UV Map is something you will hear used quite often but what exactly is it?

A UV map is a 2d representation of a 3d model. The purpose of a UV Map is to have a standardized base to interact with the appearance of the model regardless of what render engine is used.

In this article we will cover in more detail what a UV Map is, what they can be used for and how you can create one.

What is a UV Map

As I have mentioned a UV map is a 2d representation of a model. The best way to visualise this is if you had a cube and you cut along several of the edges you would be able to lay it out flat also known as Unwrapping

This new flat shape can still be reassembled into the cube however you now have a base which you can apply color or various textures to. This is particularly useful as this means you don’t need a 3d application to paint the cube. You can use any program capable of editing images.

Because UV’s are a standardized process throughout the 3d industry this means some render engines and 3d software require them in order to render the 3d model.

While this may sound intimidating especially to create it is actually a lot easier than it sounds.

What Do UV Maps Do

The main use for UV’s are primarily to create what are referred to as Texture Maps. Having a UV alone won’t change the appearance of your model. It is equivalent to just having the wire frame of your model.

Texture Maps come in various forms and can have various functions. These can include coloring your model, dictating how shiny it is and even to alter the geometry of the model through maps known as Normal Maps

These are only a small portion or the types of texture maps. If you are interested in the various Texture Maps I encourage you to check out this article I wrote outlining them. You would be surprised what you can achieve with them.

Is UV Mapping Necessary

UV Maps are not necessary. Programs such as Zbrush allow you to paint on your model without first having a UV Map. However if you are planning on using the model outside of Zbrush you may have trouble.

This means if you wish to take your model into a game engine for instance you will not be able to utilize Texture Maps such as Normal Maps or Color Maps at all!!

If you plan is to simply sculpt, texture and render within a program such as Zbrush there is no need for a UV Map.

How to Create a UV Map

Creating a UV map is actually quite simple. In this example we will cover a manual method in Blender.

There are 3 main steps.

  1. Placing the Seams
  2. Unwrapping 
  3. Arranging the Islands

Placing the Seams

At this stage you will place the seams on your model. These seams will dictate how the model is cut up and placed on the 2d UV. Anywhere where the seams meet will create what are referred to as Islands. 

Islands are isolated pieces of geometry when pieced together can form the model again. Creating islands can be especially useful when you are trying to isolate parts of your model that need more detail or cover a larger surface area.

Unwrapping

This step is extremely easy now that you have the seam you simply hit an unwarp and you have your UV.

Arranging the Islands

Once you have your UV you can now arrange the islands of your model, scale them and put them in the place you want them on your UV.

It’s that easy there are also automatic ways to do this in most modelling programs, But typically you always get the best results by manually doing it.

What Software Can Create UV Maps

A lot of the big 3d modelling applications allow for UV Mapping this includes Blender, Maya, Zbrush and even as of late Substance Painter.

The less specialized software such as Blender and Maya give the best results as you have the ability to place each individual seam. Programs such as Zbrush and Substance Painter have automatic tools which give ok results but are usually no match to manually placing the seams yourself.

How to Create a Good UV Map

There are a few basic considerations you need to think about when creating a UV Map. These include:

  1. Seam Placement
  2. Island Size
  3. Overlapping

Seam Placement

When creating a map, seam placement is important. Where the seams are visible can cause inconsistencies in the texture. The best practice is to place seams in places that are not going to be noticeable or on hard edges.

For example if you are unwrapping a character. Placing seams in areas such as under the arms or inside of the legs is great as they are less likely to be seen. If you’re unwrapping a sword, place the seam on the edge of the blade as it won’t be noticeable when it’s textured.

Island Size

When creating the UV Map the size of the islands are important. The more room the island takes up on a UV Map the more detail that can be added. This is useful because once a texture map is created from a UV depending on the Texture Resolution you have less individual pixels to edit.

If you have a part of the model that is going to take up a large surface area ensure that it has a larger island. Similarly if there is a really intricately detailed part of your model give it a bigger island so you have more room to add in the detail.

Overlapping

Generally it is not recommended to overlap UV’s at all. However there is an exception if you have a repetitive texture you are going to apply to your model. 

For example a plank of wood. It would be time consuming to texture 50 planks of wood and would take up a lot of UV space. Overlapping the UV’s in this case can save a lot of time 

What to Avoid When Creating a UV Map

What to avoid when creating a UV map is almost the opposite to my points above.

Avoid placing seams in noticeable places as it will cause noticeable inconsistencies in your textures.

Utilize as much of the UV as possible. There is no value only using a small corner of the UV and leaving the rest of the UV blank. This may result in you having to considerably up the resolution of your textures in order to get the same results you could have at a lower resolution.

Do not overlap islands unintentionally this will result in visible artifacts appearing on your model.

Conclusion

You should now have a basic understanding of what a UV is and the principles in creating one yourself. I highly recommend you come to grips with the concept of UV’s as they are one of the most widely used processes in the industry.

I hope you have found this article helpful and the prospect of creating your own UV’s at least somewhat less daunting. Good luck and have fun!!