Texture in middle of landscape

I have made a landscape with resolution 8129*8129. I have a corresponding texture (drone orto image) that I want to drape directly onto the landscape, it’s in the same resolution as the landscape. It needs to be aligned correctly, so all the corners needs to match. I want to use this orto image as a reference, to then paint on top of the landscape with other materials. Can anyone give me a hint on how to do this?