8. The system of claim 4 , wherein the model processing engine comprises: an image generator, to extract a plurality of images from a 3D model; an image feature extractor, to extract a plurality of features from the images; a vector generator, to generate a feature vector from the features; and a transform calculator, to calculate at least a spherical Fourier transform using the features to generate a representation of the 3D model.
9. The system of claim 8 , wherein the images are silhouette images obtained from a plurality of viewpoints surrounding the 3D model.