A Qubicle model can contain millions of voxels that are managed by matrix and compound objects.
A Voxel - short for volumetric pixel - is basically a single colored cube.
A Matrix is 3-dimensional grid of voxels. A voxel - short for volumetric pixel - is basically a single colored cube. The purpose of matrices is to sub-divided a huge voxel model into smaller objects that are easier to transform and edit. The theoretical maximum size of a Matrix is 1024x512x1024 voxels, which are a total of over 5 million voxels. That’s way more than your computer can handle. So it is strongly recommended to never ever use that maximum size. Instead, use several smaller matrices to build a big model. Any matrix larger than 128³ will decrease Qubicle’s performance.
Compounds enable you to organize your model. You can pack any amount of Matrices and other Compounds into a Compound and thus establish object hierarchies. Compounds will also speed up render performance and are useful for mesh export and modeling workarounds. If you are a Photoshop user think of Compounds as Smart Objects. Compounds are distinguished from Matrices by a dashed bounding box.
A Voxel Model is a collection of Voxel Matrices and Voxel Compounds. It does not have any other properties and just functions as the root node of a scene.