A while back I covered how to move your Blender scene into Nuke, and this is sort of the reverse of that. Hope it helps!
I realize Nuke is not free or open source, but I post these workflows to help artists who are trying to use Blender in a studio pipeline in conjunction with commercial tools. If you’re a compositor wanting to add some 3D elements to your shot, getting your 3D scene out of Nuke and into Blender will be necessary.
At the studio where I work, our matchmoving department creates a camera and scene for almost every shot (usually in Syntheyes), then passes it on to the compositors. Often I find myself wanting to add CG elements I can only create in Blender, like smoke or rigid body sims, and the easiest way to make sure it perfectly matches my Nuke setup is to use the exact same camera and layout.