What does this do?

This mod adds a panoramic screenshot feature which produces 6 files for each face of a cube.

How does it output?

The filename format is directly compatible with resource packs (as in panorama_X.png where X is a number from 0-5).

Can I modify the size?

Yes, pass it as an argument to the /panoramod command. Default is 1024, sizes above 2000 may cause lag/high resource usage.