I'm still a bit confused by the bricks. Crassin mentions in most of his papers that color values are written to the leaf nodes of the octree structure after its creation.
Some of his papers imply that the color values are written to a 3D texture and the octree structure just points to the texture coordinates - is this the same thing?
In his OpenGL Insights chapter he writes that color values are appended to the "voxel fragment list" during voxelization, then this is written to the 3D texture after construction of the octree.

The thing I am most confused about is, if bricks are used that are say 3x3x3, yet coordinates on the 3D-texture does not correspond to coordinates in world space; how would we write the color values so that you get voxels inside a brick that are in the correct order (i.e. the voxels within each brick would neighbour each other as they do in world space)? I am thinking the only way to get correct ordering of voxels within bricks is to generate the octree structure using morton-order interleaving.

Also, if the octree structure is sparse, meaning that every few voxels may border empty-space, how would I tell the code to detect that there are empty space voxels?