Not sure if the right place to ask. I have downloaded a model from the store. The texture was a bit low res for my liking so decided to reskin it, when I opened it discovered the .dds file seems to have 4 textures in one 2048x file. (see image attached for in game vs just texture) So the model only loads 1024x of the whole 2048x file. Seems to be made so the one model can be assigned different textures from a single file.

If I want to make the texture itself 2048x, I have to make the entire image 4096x. Is this bound to the model or is there a .fpe type of file setting that tells this particular model to look for an XYZ in the texture so I can just throw in the one new texture that takes up the whole 2048x and the model will use it all without the unused and space wasting textures? Or would I have to import this into blender or something and unwrap it and make a new texture map?

Any assistance with this would be greatly appreciated.

The best way to solve this would be to re-layout the UV co-ordinates in the model and paint a new texture to the size you want, this would be the most efficient method for the game engine. I do believe that there are a number of software packages out there for free that would enable you to do this, unfortunately I don't use them myself but a quick google and you should be able to find them along with a video tutorial. Its a really simple shape to do and shouldn't take more than an hour for you to do and work it out.

Try this
http://www.uvlayout.com/index.php?option=com_wrapper&Itemid=72

Tutorial
https://www.youtube.com/watch?v=bkk8GoQ7g6A

Its all looks more complicated than it actually is, once you have cracked that you will be well on your way to creating your own models.

Hope that helps

Thanks for the suggestions Frap. I had a feeling an unwrap and making the texture from scratch would be in order. I generally unwrap in programs like blender. Must admit I am being a bit lazy and was hoping to just be able to just swap out the texture. Thought it might of been some sort of co-ordinate based thing seeing as it has 4 textures in one. Seemed kind of weird to have the texture like this otherwise. I cannot recall ever seeing things like it in game assets, only one I can recall recently is StarMade which uses a single sheet for it's textures, including animations with the games engine just shift the sheet around to the right texture as needed. But yeah just odd and seems wasteful to have a 2048x texture when all you ever see is 1/4 of it.

Seems to be common as I open more and more textures for GG assets I've purchased and find they they have a great deal of empty space going to waste with say 2048px square and say only 512px worth of actual texture being used.
I think I am just going to have to start focusing more on making my own models from scratch when it comes to such simple shapes.

I'm kind of concerned about if the model is loading the entire texture into memory or just the part it shows when it is done like this.

To be honest, this looks like a simple floor tile am I right? If so you're better off just making your own in blender, all you need to do is make a single mesh plane, size it up to 100x100x1 (that's the size of a standard 8x8 tile in GG) and then texture it, create an fpe, bmp and the dds files and job done.

Sorry Rabid, I had assumed you had not modeled before.

I hope this makes sense to you or at least shines some light on the way texturing and UV's work. I the model file somewhere it will contain all the co-ordinates for each poly and where they relate to on the texture, this I believe is done from a point horizontally and vertically on a percentage basis. Therefore increasing and decreasing the actual texture should have no bearing on how the model reads this data. However that being said with numeric rounding you will often see missing edges when the texture is shrunk down.

Its a perhaps a simplified explanation but essentially that is kind of the way it works.

You will probably find that whoever made that model has multiple identical models that use the same texture file, it's a way of reducing the amount of textures you need to load, you bake UV's for four models in different locations on the image then merge them together afterwards, that way you can have four models using the same texture to save space and load.