UDIM in UE4?

I have made a katana in maya, and I can’t fit the blade so that I get good texel density in 0-1. I really don’t want to cut it anywhere else than the edge, so I have 2 questions:

  1. Can a UV shell occupy more than 1 UV space, ie a shell spanning from u1v1 to u3v1?

  2. Does UE4 recognise more than 1 UV space?

I’ve tried extending the shell of the blade, on import the UV’s in the asset viewer only the 1st tile is shown, while the zone where it leaves the shell is red. I’ve also tried separating pieces, and even though UE4 shows only U1V1, it still recognises some things in U2V1 Like shell orientation. I tested this with the wooden material and depending on shell rotation the wooden stripes follow. So can I use multiple uv spaces with unreal, and if not, is there any other way to increase texel density without further cutting up the shell.


In maya assign it another material (select faces, then go to material browser and right click assign to faces) also in the UV editor make a new UV set and set it up how you need it for the second material. Import and it will set up two materials assigned, go to the second material and make a texture coordinate node and select which UV set it is using (0 for first one then usually 1 will be the one you need as 2 will be the lightmap coord) and plug that into your second UV set texture and then apply like normal. I can throw up a video of how to get it done if you need further help.

I wouldn’t recommend it though. a) the texel density will look off which can cause things too look a bit odd unless you are using repeating textures with blown up UV maps to scale it down and b) I believe it’s quite memory and instructions intensive, but if this is a first person weapon then you might get away with it.

So essentially I have to have 2 separate UV’s for 1 object. I still don’t understand how that will increase the texel density on the blade since I’m having trouble fitting it in.

Here’s a picture

As you can see there’s quite a difference between the blade and the handle. Now yes I could just scale them down to match, but I’d rather scale the blade up to match.

This is a third person weapon and really it wouldn’t really matter, as the current stretch on the blade texture isn’t noticeable. But I would still like to know how to export bigger objects with better texel density to unreal, although I suspect usually it would be easy enough to cut things and hide the seams.

Hint: textures don’t have to be square. 1024 x 512 (or equivalent) might be a better fit in this case.

It actually does.
Although I havent used it in the “UDIM” context, (but will do this soon enough as Im transitioning from Max to Modo, which provides a nice UDIM system).
In Max however, just add UVWUnwrap modifiers (in maya it should be simmilar) and assign different channel IDs.

It just becomes a bit of a pain in the behind when using textures and lightmap settings.
Unreal uses always the first channel (0) for etxtures and channel (1) for lightmaps.
Say you create 6 UV maps; 5 textures and a 6th for the lightmap.
In every material you would need to set all TextureSample nodes manually as they default to 0.
The same with Lightmap Channel IDS on static mesh import.

So you’re telling me that UE4 will have no problem with this:


If they have all unique map channel IDs, then yes :slight_smile:

So essentially if I import them as separate UV sets it’s all good? I’m sorry it seems that only Max has these channel ID’s, or maybe I just can’t find the maya equivalent in their documentation.

Not only Max, Modo has them too :smiley:
I hardly use Maya but it should work if you go under “Create UVs” tab, whenever doing a projection, just create a new UV set intead of using the same. Say you want to create “automatic mapping” for lightmap, go in the automatic mapping and in the “Create New UV set” create a new name for it.
After you did this, and lets say you want to edit that, you go to your object, press RMB and hold, under “uvsets” you select the set that you want.

When exporting to UE, it should be recognized as individual channels… fingerscrossed :slight_smile:

Right right, I’ve done the uv sets before just never imported them. Imma give it a shot friday and report back. Very helpful thanks.

P.S: I have one more question not related to the topic, but it’s kinda basic/noob and seeing how you guys are seasoned you’d probably answer easily. Do I need to have objects combined? Like if I made the blade and the handle separately, and didn’t weld them together, but just had them positioned close enough and defined them as 1 object in the outliner, would that be a problem for collision and physix and such? Cuz sometimes the shapes are super annoying to weld, and too complex to extrude from 1 primitive.

You don’t need to weld the parts, no.
You can have them be separate objects or one object that is multiple shells. You do want to combine as many meshes together as possible, as it will reduce draw calls. Having more individual objects means more draw calls; which drops performance. For your purposes won’t make any diff though, I’m almost positive about that.

As for texel density, why don’t you use tiling maps?
For that sword, since it’s a “hero” mesh, I would make the blade have it’s own texture, it’s thin and long so I would make like a 2kx512 texture for it (this res would work fine for normal maps, cavity masks, other one-off maps, etc.), then I would create a detail map that tiles over and over to get high frequency close up detail in the material. That should solve your problem.

Reason for that is that I want to use Substance to paint the textures onto the sword. I’m proficient with photoshop, i just hate the workflow it provides, since frankly it’s made for photos and not textures. And as far as I know, Substance works best when texel density is universal across the mesh, I’m still dealing with mechanics so I don’t need this sword to be textured just yet, but once I get around to it I don’t want to find out that there’s a problem with the normals.

Anyway, thank you for all the information, this has been plenty of valuable info for me, I’ll take another crack at this once the weekend hits. I’ll be sure to let you guys know how it went.
[MENTION=13213]Jak Carver[/MENTION] thanks man, couldn’t find any info about the objects being separate or not. Truth be told it’s not long ago I started Maya and I’m still wrapping my head around the proper workflow. Don’t want to pick back practices habits. So while being a trivial question I’m glad someone took the time to answer it.

There’s no trivial questions, whenever you get stuck or are unsure of something, jump online and ask.