Color & Normal Compression Result

The screenshot below shows the result; includes specular lighting.
Octree: 115 MB , 2.88 bytes / voxel (including specular, glow, and more components),
Resolution : 4096x4096x4096 voxels

Using zip for storing the octree on disk reduces the size to ~1.44 bytes/voxel
( This includes color, normal, position and LOD data )

Comparison to common compression methods:

Color compression, DXT1: 0.5 byte / pixel
Normal compression, 3dc: 1 byte / pixel (only tangent space, no arbitrary normals!)
Linear octree: ~2.275 bit / voxel (for a surface, ~4 of 8 bit/node are used)

For CRUNCH, it provides ~1 bit/pixel for color and ~2 bit / pixel for normals.
https://www.youtube.com/watch?v=7bJ-D1xXEeg
https://code.google.com/p/crunch/

Example with 4 different specular power settings