Our aim is to produce a tessellation of space into small voxels and, based on only a few tomographic projections of an object, assign to each voxel a label that indicates one of the components of interest constituting the object. Traditional methods are not reliable in applications, such as electron microscopy in which (due to the damage by radiation) only a few projections are available. We postulate a low level prior knowledge regarding the underlying distribution of label images, and then directly estimate the label image based on the prior and the projections. We use a relatively efficient approximation to a global search for the optimal estimate.