1. A method comprising: accessing a first multi-dimensional graphical matrix representation that describes the appearance of a plurality of points of an object from a plurality of viewing directions, the appearance varying from point to point and viewing direction to viewing direction; creating a second graphical representation that approximates the first graphical representation and that includes at least one expression having a fewer dimensions than the first multi-dimensional graphical representation by decomposing the first multi-dimensional graphical representation into the second graphical representation, the decomposing including sign consistent matrix factorization to selectively represent information from the first graphical representation.