Specifically I want to make a collage of many pictures. For that purpose the software should be able to handle many large pictures, and align them relative to each other (snap center to center, etc)

I'd like to avoid having to do it in libre office if at all possible.

Is there anything like that?

This picture was taken back in September from the top of the Großer Aber mountain in the Bavarian Forrest. Just minutes before there was fog everywhere and soon after it returned.