UV unwrapping is not the most exciting part of 3D modeling and can be time consuming. Alongside this if you are new to 3D modelling it can be wearing on your mental health! However, once the task is completed it is a rewarding feeling to have a tidy ready to use unwrap. When new to unwrapping it can be a bit of a mystery for how an unwrap should be done, but following a few simple steps you will be able to pull together great UV unwraps.
UV Unwrapping Key Pillars:
Remove any faces that are not visible or required from the model (before starting the UV Unwrap).
Make sure the scale (on all the axis) of the model is all set to 1.
Use a UV grid texture so it’s easy to see the direction, pixel density and any stretching in the model (also turn on any view stretching options).
When unwrapping create as few UV faces as possible.
Keep adjacent or similar parts as near to each other as possible.
This is why smart UV (in blender) or any auto unwrap does not always offer the best output.
Consider Smart UV as a quick unwrap.
An approach I use – is to start with a smart UV unwrap > Mark islands with seams > Then remove or add seams where required > Finally manually position UV faces where and if required.
So smart UV is very useful as a starting point.
Seems should be hidden or placed in as true to life locations as possible.
Remove any stretching.
Keep pixel density consistent across the model.
This rule does vary a lot! Many models may have low density pixel resolution in some areas, such as a part that is not important or perhaps is hidden away (such as the underside of a shoe) But a part that is important may have a higher pixel density.
Keep some space between UV faces so that the texture does not bleed from one face into another.
Make sure the faces are orientated the same or intended direction.
When I first learnt unwrapping I was taught the UV faces must always be within the UV box, but this is not always the case.
This is more a grey area and specifically when you are tiling textures you can have UV faces going outside of the UV box, but for atlas wraps, texture painting, or creating specific texturing for a model then you should keep the UVs within the UV box.
I started with a smart UV project on this low poly boat. Although it wasn’t too bad in this case, but the smart UV project does not give control over the position and separation of the UV faces.
Next I marked the islands with seams.
Then I went through the islands removing or creating new seems to tidy up and create the UV faces that I was looking for.
There was an element of trial and error for some of the faces, but I pulled together this unwrap in a short period of time.
The low poly boat below has been ‘smart (auto) UV project’ unwrapped
The same boat below has been marked with seams, the UV islands are organised and with similar faces as near each other as possible. This model is much easier to texture and to work with, thus resulting in a better final output.
I’ve also used a UV grid texture to see the direction, density and any stretching in the model. There was a little bit of stretching in the bottom of the flag area (although this wasn’t noticeable with a texture used) but overall this model is ready for texturing and a good UV unwrap.