First Look at UDIM Textures in Blender 2.82 Alpha: What They Are and How to Use Them
Dec 19th 2019
Blender 2.82 Alpha just got UDIM Texture support, and it’s a pretty big deal.
When you unwrap your objects for texturing, you do it in UV space, which is an alternate dimension to XYZ space. Images used are usually square and have a pixel resolution that is a power of 2 because that's easier for a graphics card to calculate. So you’ve got to lay out your unwrapped mesh in this square texture space. To get more resolution in one area of your mesh you scale up its corresponding UV islands to take up more of the space than the areas that need less resolution. This works great!
Sometimes though, you need really, really high resolution details in one area but don’t need them in another area. Rather than deal with massive image files with wildly different UV island scales, the fine folks at Weta Digital back in 2002 decided to place multiple UV tiles next to each other and assign them different images that can have different dimensions, but still act as one texture in a shader. UDIM is short for U-Dimension because it adds another dimension to your UV’s and W was already taken by quaternion rotations and as a variable for some render engines’ behind the scenes trickery.
It’s technically more efficient to render out one large image than many small images, but when you get to really large sizes it starts to become less practical to work with. UDIMs are useful for working on objects that need really high resolution textures. It’s standard to see them in VFX and animation productions, but unusual to see them in a game pipeline. UDIM support in Blender means that it will better work alongside other VFX software like MARI, Substance, and Maya. That’s great news for everybody!
Check out the video below for a full walk through of how to use them in Blender 2.82 Alpha. You can grab the latest experimental version of Blender here if you'd like to try it for yourself.
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mmrmugglez I think using the robot as an example was unfortunately a little misleading - you wouldn't really use UDIMs for games since it's not something that's well supported by Unity or Unreal. In your example, it would be better to make the face a separate shader with it's own regular texture that has every face laid out like a sprite sheet and animate the UV's between them. Hope that helps clear things up!
I have never used UDIMs before but might consider it. From a games perspective, using the model in the video as an example, if you wanted to have a face on the robot screen that could change based on texture/image it would make sense to use a UDIM, and have several different face images to swap between. Correct me if I'm wrong, but you could use UDIMs that way couldn't you?
UDIM makes too much sense to be real - ha. I can't wait for this to be released.
I've played with hacky methods of UDIM in the past. Sooo looking forward to trying this workflow soon. Thanks for the Intro :)
Haven't used it yet but it is great to see Blender evolves.
Thanks for the article, Jonathan.