True Dimensionality: Nonlinear nonlinear MDS: 10-15 all intermediate points possible categorizable by people red, green, blue, specular, diffuse, glossy, metallic, plastic-y, roughness, rubbery, greasiness, dustiness... [A Data-Driven Reflectance Model, SIGGRAPH 2003, W Matusik, H. Pfister M. Brand and L. McMillan, graphics.lcs.mit.edu/~wojciech/pubs/sig2003.pdf] 18