For the TCCD project, I really would like to get a Jenkins job building things, but the problem is that everything is on GitHub and the repo is enormous due to the huge number of images. Partial checkouts with git are tricky. However, by looking at this documentation, I've figured out and tested a way to script a partial checkout using svn instead.

Say you want only the [proj]/level1/level2/level3 directory:

svn co -N https://github.com/[proj] proj
cd proj
svn up -N trunk
svn up -N trunk/level1
svn up -N trunk/level1/level2
svn up -N trunk/level1/level2/level3

That will get you a sparse checkout down to the contents of the level3 directory.