1. A method of providing a volumetric representation of a three dimensional object, comprising: defining a plurality of voxels in a three dimensional space, categorizing voxels as foreground or background according to at least one silhouette image of the object, foreground voxels being assigned a first binary value, and background voxels being assigned a second binary value, and assigning to at least some voxels a value intermediate to the first and second binary values.