Using UV Maps for Precise Edits
- Jun 25, 2015
- 4 min read
When editing the texture files for your mods, you may find yourself with the need to make very precise edits every now and then. Maybe you just want things to line up the first time without having to save your GPK file and then login just to see if things are where you want them to be. Ever open up a file and wonder what goes where?
This is when using the model's UV map will come in handy. The first 2 minutes of this video should give you a good idea of what a UV map is. It will show you which parts of the texture (e.g. the DIFF files you edit) are actually being used in the in-game 3D model and where the boundaries are for things.
In order to get the UV map, however, we're going to need to know what to look for. In your GPK viewer (e.g. UtHelper), open up your GPK file. For this guide, I will be working with the PC_Event_22 file which contains the 2014 swimsuits. Specifically, I will be working with the Angel-striped swimsuit, which is marked as PC_Event_22_Popori_F_A_01. The "01" is for the Angel-striped version of swimsuit, and "02" is for the Devil-striped version, which shares the same 3D model.
Now we need to open up the 3D model of this swimsuit in Umodel. Unreal Engine Resource Viewer also known as Umodel, Unreal Model Viewer, or UE Viewer is a program for viewing and extracting resources from various games made with Unreal Engine.
Fire up Umodel, and point it to where your GPK file is, whether it's the original in your TERA game files or somewhere else like your mods folder. Umodel will go through all the possible files in that folder, so it may take a while if you point it to your TERA game files.
After Umodel is done scanning, you will be presented with a list of the files it found. You can either select your GPK file from the list or type in the name of the file in the Filter box. Click on "Open" to open your GPK file.
When Umodel has your GPK file opened, click on "Navigate" from the menu bar, and select "Include meshes". Now press your "Page Up" or "Page Down" keys until you see the model (or skel) of the one you're working with. In my case, I am looking for PC_Event_22_Popori_F_A.
Once you've found the model you're looking for, click on "Tools" from the menu bar, and select "Export current object". You can also use the keyboard shortcut CTRL+X.
Umodel will export the 3D model to a folder called "UmodelExport" in the Umodel program folder.
Now we need to open this in a 3D modeling program and unwrap the model, which is basically just taking the 3D model and laying it out in a 2D format. I use MilkShape 3D for this step, but you're welcome to use whatever tool you feel most comfortable with so long as it is able to import PSK files.
In MS3D, we will need to import the PSK file the Umodel created. So go to the UmodelExport folder, and you now see a folder with the name of the GPK file you had open. Inside, you will open the SkeletalMesh3 folder and find the PSK file of the 3D model you exported earlier.
You could use MS3D to unwrap the model, but it can be unreliable at times. So we will use another tool called LithUnwrap to do this instead. But first, we will save the PSK file as an MS3D file so that LithUnwrap can open it. I usually just save it in the same folder the PSK file is.
Now open that MS3D file in LithUnwrap by going to the File menu and clicking Model > Open. You should now be looking at a 2D representation of the 3D model. Don't worry if the aspect ratio looks strange. LithUnwrap just scales up the display to fill the entire window. The actual map size is determined when you export it.
Keep in mind that if you see any overlapping, there are probably multiple groups enabled, so you will need to disable the ones you don't need. In the case of my file, I need to disable the group for Popori_F_BaseBody_Foot_MI, which uses a completely different file, but leave all the Popori_F_A ones active. To do this, go to Groups > Hide and select the groups you need to disable.
Now just save the UV map by going to File > UV Map > Save. I recommend saving the file using the dimensions of the diff/spec/norm/cstm files you're working with -- some of them are not square. In UtHelper, you can see this information in the "Information" tab. In my case, I am saving this UV map as 1024 x 1024.
Just a note: LithUnwrap has a limit to how many bones it can deal with. If you run into this problem, you will need to delete them in MS3D before you save the file for import into LithUnwrap.
It's really up to you how you use the UV map file in your image editor of choice. I use Adobe Photoshop, so things will most likely be different for you if you use GIMP or some other image editor.
The first thing I typically do is create an overlay to give me an idea of what goes where. I simply bring in the UV map as a layer above my texture, desaturate it, and then I change the blending mode to Screen (or invert the layer and switch the blend mode to Multiply if the colors are too light). This is usually more than enough for most edits.
If I want to create a mask, I simply use the Magic Wand tool to select all the black areas around the UV map, contract by 1px (just to have "breathing room"), and either quick-mask or create a new layer with the selection. This will help me ensure that things I want to be showing are and things that don't need to be seen aren't.
I hope you found this guide useful. If you have any questions or comments, be sure to leave them below.
Special thanks to Kitsune at Teratoday.com for reminding me that MS3D can open these PSK files.
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