extract multiple directories using git-filter-branch

Question

I have a big repository which currently contains multiple projects in top level subfolders, say /a, /b, /c, and /d.

Answer 1

I'm not aware of any better way than tree-filter for this. So you already have all the information you need. Now just do it!

Start by creating your two branches:

git branch br1
git branch br2

Now for each branch, check it out, then filter it using the tree-filter.

You could then split them out to separate directories either by pushing them out, or by cloning or pulling them in.