[tutorial] How to weld UVs in 3ds max?


While working on unwrap of our models we often face the situation when we need to precisely fit vertices of different UV shells. Looks at the screenshot to see what I mean:

Vertices on UV shelld do not fully coincide

Vertices here do not fully coincide and this can lead to unwanted artifacts in the final result. So you might want to weld them. There is built-in weld function in 3ds Max UVW Editor, but it works only if UV shells have common boundaries (i.e. in this case this won’t work).

Stinky workarounds for dupes

3ds Max has built-in welding function, but it will weld only common boundaries, not the internal vertices.

Vertices on UV shelld do not fully coincide

So, built-in weld does not do the trick.

There’s also function called “Copy/Paste UVs”. Sometimes it’s very good, but in some cases, especially, if you have mirrored parts, it works not correctly.

Result of 3ds max built-in function “Copy/Paste UVs” if often incorrect.

Sometimes you can use some workarounds like “First unwrap the half of the model and only then you mirror it!”. OK, this might work, but it’s not kinda convenient and you always have to keep that in mind. And what if you’ve forgotten about that, or there’s another reason to mirror model first?

Well, you could try collapsing vertices by pressing Align horizontally/vertically to pivot. It’s perfect, but it takes too much manual work. What if you have hundreds and thousands vertices to weld? Would you do each on your own?

Align horizontally/vertically to pivot buttons in 3ds Max UVW Editor

True solution for a man with big cojones

One day I faced this problem again and thought “Why the heck there is no such a simple function as just welding UV vertices by a threshold in 3ds max embedded?!”. I asked in some CG forums and chats, but I only got answers that advised me workarounds that I was already aware of.

Thus, I decided to write custom MaxScript to solve this problem. And here it is! Meet the…

ABTO Tools!

ABTO Tools v0.3 interface.
Result of using ABTO Tools v0.3

The link leads to the GitHub repository, where I always keep the latest version.
To download it press the green button “Clone or download” and then choose “Download ZIP” (in case you’re not very familiar with GitHub).
Installation process is described ibid, and also it might change as newer versions are being released so I won’t copy/paste the instruction here.

So how to solve our problem? It’s very simple with ABTO Tools. You just select vertices on the UV you want to weld, choose threshold and, hmm, click… WELD! That’s it. Simple, right?

Even more useful!

ABTO Tools v.3.0 only U and only V option
Script also have another feature: it can weld vertices only by U or V axis. This might be useful when you need to make boundaries of your UV polygons to be grid-like. It you have them like here you might encounter some artifacts while texturing especially if texture resolution is low, for example if you’re doing gamedev asset.

With such boundaries of UV polygons you’ll have texturing artifacts.

So you can weld by U or by V axis separately by choosing corresponding option.

This is how UV looks like!

Now out UVs are completely prefect!

You also can watch video, it’s short and briefly shows what is described supra:

So have a perfect unwrap and never weld manually as of this day!

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