What is UDIM?

Already know about UDIM? Skip to the setup!

Already setup? Skip to the baking!

UDIM stands for U-Dimension and is a method of working with textures in 3d models that allows you to place different UV Islands across multiple tiles in the UV space, rather than in the same UV space over different material assignments. This can be extremely useful in programs such as Substance Painter, as you are able to work on multiple separate UV maps at once without having to switch between them and manage seams. UDIM tiles make converting SL skins to Cinnamon and Chai skins very simple. UDIM tiles are easy to work with once you understand a few basics, which I will cover in this tutorial.

Watch the video tutorial on youtube or follow the steps below
Chai UV template with multiple material assignments for texturing
Chai UV Template with UDIM tiles

Installing Blender

If you don’t already have Blender 2.9x installed, you can go now to The Blender Homepage and download the latest version for free.

Getting the UDIM Baker Plugin

To bake UDIM tiles in Blender you will need to install a plugin. This is not optional. It will seriously save you a lot of time and effort as the alternative is manually moving UV islands and baking individual maps. It is very easy to install and even easier to use!

You can either purchase it from the creators BlenderMarket store for $5

Or you can download it from the creators Gumroad account for $0

  • Go to the Gumroad page for the UDIM Baker plugin
  • Enter 0 in the price panel
  • Click “I want this”
  • Enter your email address and click “Get”
  • When you see the next screen that says your purchase was successful, click the “view content” button
  • Click “Download”
  • Save the file in a directory you will be able to locate later.
Getting the free UDIM Baker plugin from Gumroad

Installing the Plugin

  • Open Blender 2.93x
  • Go to Edit-Preferences
  • Click on the Addons section and then at the top of that window, press “Install”
Installing the Plugin
  • Navigate to where you saved the downloaded addon file
  • Double click it to install it
  • When you are back in the addons window, ensure the plugin is active by checking the little box next to it in the addons list
Activate the plugin
  • Your preferences should auto save. You can check by clicking the 3 horizontal lines in the lower left. Check “autosave” if it’s not already checked.
Save the preferences
  • Close the preferences window. Your plugin is installed and you won’t have to do this step again.

Converting SL skins to Chai and Cinnamon using UDIM tiles

I have included a blend file that has UDIM tiles already setup, as well as the textures already saved. It is called “Cinnamon Chai Skin Kit 2.93 with SLUV_UDIM TILES”

  • The panels you will see when you open the file are:
    • The 3d Scene
    • The Shader Editor
    • The Usage agreement
    • Chai SLUV Tiles
    • Chai CUSTOM Tiles
    • Cinnamon Tiles
    • The Outliner
    • The Bake Tab
    • The Materials Tab

You will use the 3d scene, the 3 Tiles panels, the Outliner and the Bake tab in this tutorial

The “Cinnamon Chai Skin Kit 2.93 with SLUV_UDIM TILES” as first opened

Preparing SL skin textures for conversion

  • Find your SL texture sets. You will need Head, Upper and Lower textures for each skin tone
  • Copy them into a new folder
  • Rename each set to name.1001, name.1002 and name.1003
  • For example
    • Physique Skin REDUX HEAD Tone 1 becomes Tone1.1001.tga
    • Physique Skin REDUX TORSO tone 1 becomes Tone1.1002.tga
    • Physique Skin REDUX LEGS tone 1 becomes Tone1.1003.tga
  • This naming is important. Each file in the set must have the same name ahead of the numbers so Blender recognises them as the same texture set. It doesn’t matter what the name is before the numbers, but it must be the same for each texture in the set. The textures are differentiated by the .100x numbers
  • The head texture name must include .1001, upper body texture must include .1002 and the lower body texture must include .1003 so Blender will know which tile to assign them to.
Skin textures named and ready to bake.

Loading the textures into Blender

  • Open the blend file
  • Navigate to the Bake Tab FIRST and scroll all the way to the top of the section
  • Ensure your “Render Engine” is set to Cycles, not Eevee
  • Ensure your “Device” is set to GPU Compute, not CPU. GPU is a lot faster and won’t cause your computer to skip other tasks it might be doing.
Setting the render engine and device settings
  • In the outliner, select the mesh object called “aaChai for Skin Conversion Kit SLUV LOAD TEXTURES HERE
  • On the right side menu on the top image panel, click the button that looks like a little open folder.
Opening the texture set by double clicking on the one named *.1001.tga
  • Navigate to where you previously saved your texture files
  • Open them by double clicking on the 1001 file (you can have multiple sets of 1001, 1002 and 1003 textures provided they are named the same otherwise eg mediumskin.1001, mediumskin.1002 mediumskin.1003 and lightskin.1001, lightskin.1002 and lightskin.1003 will not clash with each other
  • Double click to open will open all 3 associated textures into their proper slots on the body you are working with.
The base SL textures loaded into the SLUV texture tileset

If you have named your texture files correctly you will see a head, upper body and lower body texture appear in the top Tiles panel.

Baking preparation

  • Once you have loaded textures into the Chai SLUV tileset. It’s time to prepare Chai Custom and Cinnamon Custom for baking.
  • Navigate to Chai_UV_UDIM tileset (the middle texture tileset and under the image menu, click the first tile 1001, scroll down on the menu, and press “Fill tile”
  • Fill it with white, 2048×2048
  • Repeat for tiles 1002 and 1003
  • Repeat the above steps with the Cinn_UV_UDIM tileset.
  • Save both of these image tilesets by selecting Image – Save as – and saving it in the same folder as you stored this blender file. Allow Blender to set the name as it will automatically append 1001, 1002, 1003 to the textures.
  • This is important as Blender will NOT bake the textures if the texture files are not saved.
  • SAVE your scene at this time with file – save.

Baking! The fun part! Woo!

  • Select the “aaChai for Skin Conversion Kit SLUV LOAD TEXTURES HERE” mesh in the outliner with left click
  • Hold down CTRL and select the “Chai for Skin Painting Kit”
  • The meshes should be highlighted with “Chai for Skin Painting Kit” having the brighter highlight
  • This is important as if you select them in the wrong order, the textures will bake incorrectly.
Selecting meshes using CTRL for correct selection order
  • Under the BAKE panel, leave all of the preset settings as they are, and press the BAKE UDIM TILES button that becomes available when you install the UDIM Baker plugin.
  • Important – Don’t change any of the preset settings. They have been carefully finetuned for the best possible results with no post processing required.
  • Blender will not show a progress bar but as you are baking 3x 2k textures to 3 other 2k textures with raytracing, it will take a little while. Go get yourself a glass of water because it won’t be long enough for you to make a cuppa!
Switching back to the Chai SLUV UDIM texture and saving the image tileset
  • Once the bake is done, one of your visible textures may flip to another one or to no texture, you can just choose it from the dropdown button with the mountain and sun over the texture editing panel
  • Save your newly baked texture into a folder. You only need to save it once, and all 3 maps will be saved out.
    • Go to the newly baked texture tileset.
    • Select Image – Save As
    • Save it in your skins folder with a new name. ie: Chai Tone 1. Blender will automatically add the 1001,1002 and 1003 and you will not override your loaded UDIM textures in Blender
  • Select the “aaChai for Skin Conversion Kit SLUV LOAD TEXTURES HERE” mesh in the outliner with left click
  • Hold down CTRL and select “Cinnamon for skin painting”
  • Navigate to the Bake tab and press Bake UDIM tiles
Starting the Cinnamon Bake process
  • Wait for the bake to complete.
  • Save out your new Cinnamon texture tileset with a new name ie: Cinnamon Tone 1
All 3 textures sets completed
Saving the texture sets
The new textures as they appear in Explorer

I have done many bakes this way and have found the texture conversion to be extremely good and completely lossless. If you keep your texture resolution at 1024 or 2048 you will have an easy time baking your details from one UV to the other with no post processing required. Simply upload your textures to SL, and place them onto your skin layers!

Chai torso (1002) goes to Upper body Slot – legs (1003) go to lower body slot

Cinnamon Trunk (1002) goes to upper body slot – limbs (1003) go to lower body slot!


Substance Painter

I have included a sps file for substance painter that has the UDIMS already setup. It has both the Chai body and the Cinnamon body ready for you to paint on. Remember that Chai is symmetrical so asymmetrical shading will result in an arm seam that you will have to fix.