Is there a behind the scenes texture atlas?

Hi there. To further elaborate, I'd like to know if there's a larger 'atlas' texture compiled of all of the singular textures you import into unity as a part of it's compression process.

Our team is working on an RTS that will run on iOS and we would like to reduce as many texture calls as possible by combining textures for assets into larger texture maps rather than many small. This would reduce the calls a lot and improve the performance. However if this is taken care of by unity behind the scenes then we'd rather not spend time doing so!

I've looked high and low and can't find any documentation on the matter.

Help much appreciated.

No; if you want a texture atlas you make one yourself. There is a Texture2D.PackTextures function which you can potentially use.

What unity does do on iOS devices (for Pro versions at least) is combine geometry that share the same materials. This is called batching and works on both dynamic and static geometry. If you can apply texture atlasing and get more of your assets sharing the same material, then your title ought to get some great performance!