Creating and Baking Alpha layers for Cinnamon and Chai using UDIM Tiles

In this article I will show you step by step how to create and bake alpha layers for Cinnamon and Chai using UDIM Tiles. Bonus, you can also create alphas for the SLUV using this particular kit if you want! 3 birds, one stone 🙂

Don’t be put off by the term UDIM. It is really not as scary as it seems. It’s simply that the UV Islands of Head, Upper and Lower body are laid out over 3 horizontal tiles, instead of stacked on top of one another and separated by material face. UDIM tiles make painting seamlessly over the 3 zones simple and accessible, and baking to the other body UV’s is trivial with this method. You can make your alpha layers for all 3 body UV’s (SLUV, Chai and Cinnamon) in a matter of minutes!

After you have completed your mesh clothing build and textures, and checked that it is moving and properly fitted in Second Life is a really good time to make your alpha layers.

First time setup – Preparing Blender

If you have done this previously, you do not need to do it again.

This article goes into detail on how to install Blender and add the UDIM Baker Plugin

  • Install the latest version of Blender
  • Add the UDIM Baker Plugin
  • Open the file in your Skinmakers Files – UDIM – Cinnamon Chai Skin Kit 2.93 with SLUV_UDIM TILES
The 3d scene as opened
  • Go to the Render properties tab and scroll all the way to the top
  • Ensure the engine is set to Cycles, not Eevee
  • Ensure the device is set to GPU Compute, not CPU
Setting the engine and device defaults
  • Go to the top image view and in the right side menu click the image tab. Select 1001 and then scroll down to “Fill Tile
  • Fill with 512×512 black texture.
  • Repeat with tile 1002 and 1003. Once you do the first tile, blender remembers the settings for the next ones. You must fill each tile even if they appear filled.
Filling tiles on the SLUV panel
  • In the menu at the top of that panel, select Image, Save As Image and save the tileset wherever you want your alpha textures to live. Save them as name_SLUV.1001.png and Blender will take care of the other 2 images in the tileset.
Saving the SLUV.1001 texture
  • Repeat the fill tile steps in the middle Image panel. Remember to save them as ChaiUV.1001
  • Repeat in the lowest image panel. Remember to save them as CinnUV.1001
  • You must save the tilesets before Blender will bake to them. When you want to make a new alpha, you do not need to repeat these steps, simply save each tileset out with a new name or in a different folder, and Blender will take care of the rest.
All the new textures saved and ready for painting/baking
  • Make sure you save before each new bake, or you will override your previous bakes.
  • Alternatively, keep the one single bake texture set, and move/rename them after each bake into their own folders.

Painting alpha maps

  • Export your mesh clothing as an obj. You don’t need any armature or materials for this process, just the clothing obj
  • Import your mesh item into the “Cinnamon Chai Skin Kit 2.93 with SLUV_UDIM TILES” scene.
    • If you are working in Blender/avastar, it should import correctly to scale.
    • If you are working in another 3d program, you may need to scale your clothing down. Select it, press “S .01” and it should scale down to the exact right size for the body meshes in the blender scene
    • (most 3d software works on a scale 10 times larger than Blender so scaling by .01 should work.}
  • Now that you have your clothing in the scene and your body tilesets filled with black colour, it’s time to paint the alpha maps!
Dress imported into scene ready for painting

Painting the first alpha map.

  • Turn off visibility of the objects Chai for Skin Painting and Cinnamon for Skin Painting
  • Select the object “aaChai for Skin Conversion Kit SLUV LOAD TEXTURES HERE”
  • At the top of the 3d scene, where it says “Object Mode” select that dropdown and choose “Texture Paint”
Putting the SLUV body into texture paint mode
  • This will bring up the texture paint tools on the right side of the 3d scene and allow you to paint on the body.
  • You can just paint with the default brush that is set when you choose texture paint mode.
  • Make sure your brush colour is set to white and strength is set to 100.
  • If your clothing is symmetrical, turn on x symmetry.
  • Paint everything outside your clothing white! Any bit of skin you can see, paint it pure white! I see some skin there and I want to paint it white…
Painting the white part of the map
  • You can turn on Xray mode so you can see through your clothing and paint through it. This will help you catch any bits you might not be able to see.
  • remember anything that is on your alpha map that is black will be invisible in SL, Anything that is white will be visible. If you have a greyscale gradient, you will be able to use the alpha mask sliders on the Cinnamon and Slink HUDs to move the edges of the alpha layer!
  • You can also paint directly onto the image tiles! on the image tileset which now shows you some white and black maps, select the View Menu and change it to paint. Now you can just paint directly onto the 2d image.
Painting on the 2d images
  • When you are happy with the first alpha map on the SLUV version, save your SLUV Image tileset (image, save as image), and your blender scene. It is time to start baking.
  • It is important to save your painted tiles AFTER painting, as they do not automatically update the textures in your folder the way baking does.
SLUV Maps ready for baking

Baking Chai and Cinnamon

  • Make sure you set your SLUV model from texture paint mode to object mode
  • Turn on the visibility of Chai and Cinnamon
  • Select the “aaChai for Skin Conversion Kit SLUV LOAD TEXTURES HERE” in the outliner and then hold down CTRL (or Command) and select Chai for Skin Painting
  • Go to the render properties tab and find the button “Bake to UDIM Tiles” and press it.
Baking Chai
  • Go make a cuppa
  • Come back to the Chai version of the alpha map baked.
Chai baked from SLUV
  • deselect everything
  • Select “aaChai for Skin Conversion Kit SLUV LOAD TEXTURES HERE” in the outliner, hold down CTRL or Command and select Cinnamon for Skin Painting.
  • Find that Bake to UDIM Tiles button again. Press it.
Baking Cinnamon
  • Drink a few sips of your cuppa
  • Come back a couple of minutes later to find your Cinnamon UV texture baked.
Cinnamon UV Maps baked from SLUV
  • Save your blender file. That is it for Blender, now onto Photoshop.

Putting it together in Photoshop

  • Open Photoshop
  • Navigate to where your images were saved. You will have 12 new images. They are
    • SLUV.1001, SLUV.1002 SLUV.1003
    • ChaiUV.1001, ChaiUV.1002, ChaiUV.1003
    • CinnUV.1001, CinnUV.1002, CinnUV.1003,
  • You will likely not need 1001 for any of them unless your alpha covers the head.
  • Open the 1002 and 1003 images for each set.
All 6 relevant file open in Photoshop

Once you have them open, you have 2 options for creating the actual alpha that you will upload into SL;

PNG Method

  • Double click any that are layer locked. You can tell by looking at the layer selection and if there is a padlock, and the layer is called Background, it needs to be unlocked
This layer is locked. Double click and select OK on the prompt to unlock it
  • Go to Select – Select by Colour
  • Eyedropper the black section of your image
  • Once selected, delete it.
Deleting the black section to prepare the texture to be saved as .png
  • Save the file as a .png. It’s ready for upload.

TGA Method

  • When you have the image open, press Ctrl or Command A to select the whole Image, Press Ctrl C to copy it.
  • Open the channels view (window – Channels)
  • Make a new channel
  • Ctrl V to paste the image into the new channel
  • Save the file as Targa .tga and make sure you select 32 bit on the popup box.
Copy/paste the layer onto the alpha channel to prepare the texture to be saved as 32 bit .tga
  • It is now ready for upload.
  • Make your alpha layers the usual way for Second Life. Right click the clothing folder where your mesh clothing lives, select New Clothes – New Alpha Mask. Name it Your Brand – Name of Clothing – SLUV
  • Copy it twice and name them Your Brand – Name of Clothing – Chai and Your Brand, Name of Clothing – Cinnamon
  • Wear and edit the new alpha layers
  • Place the appropriate .1002 texture into the upper body slot and the appropriate 1003 texture into the lower body slot.
  • Save and pack everything up!