# How to use UDIMs without having seams?

So, something I've never quite been able to understand are UDIMs. I mean, I get it, you use multiple tiles and thus multiple textures instead of having one giant one which may save up on resources.

I have a character that has a lot of exposed skin and I want it to all have equal detail, so i created three tiles.

1- Body and clothing 2- Legs, feet, arms and hands 3- Head

I decided to give 4k to the first one and 2k to the other two, however, this method creates horrible seams. So what am I doing wrong? Do all the tiles need to be the same resolution? Is this really a better way compared to just using a 10k or 12k texture?

The tiles don't need to be all same resolution. But the so-called Texel Density needs to be the same across all tiles if you want to avoid seams. Texel density is the area occupied by a UV island relative to the resolution of the image.

Also, UV islands should not cross the tile borders.

Here's an example of a UDIM texture with three different tile sizes:

• 1024 x 1024px = 1k texture
• 512 x 512px = 1/4th of the 1k texture
• 256 x 256px = 1/4th of the 512 texture and = 1/16th of the 1k texture

If you UV unwrap it, Blender will make all UV islands the same size which results in a different texel density and seams. Crossing the tile borders also creates seams:

If you scale the UV islands according to the image size, they will all have the same density.

The left UV is not scaled at all, the middle is scaled up 2 times, and the right one is scaled up 4 times.

Or in other words: Make the island(s) on the image with the lowerest resolution fit the image and scale down the island(s) on the other tiles accordingly. From right to left is: not scaled, 0.5, 0.25.

Now the cube has no visible seams and all squares have the same size:

• Thank you. This is exactly the type of information that I was looking for. For some reason, videos talking about UDIMS never even mention this. So, thank you! Nov 10, 2021 at 14:21