From the blog "Josh's Dev Blog"

In order to get the camera frustum space dividing up correctly, I first implemented a tiled forward renderer, which just divides the screen up into a 2D grid. After working out the math with this, I was then able to add the third dimension and make an actual volumetric data structure to hold the lighting information. It took a lot of trial and error, but I finally got it working. This screenshot shows the way the camera frustum is divided up into a cubic grid of 16x16x16 cells. Red an