1. A method for modeling a time-variant appearance of a material sample, comprising: employing a processor that executes instructions retained in a computer-memory, the instructions when executed by the processor implement at least the following operations: performing a sample analysis of the material sample, wherein the sample analysis orders surface points of the material sample with respect to weathering from data captured at a single instant in time; and performing an appearance synthesis using the sample analysis, wherein the appearance synthesis generates a time-variant sequence of frames for weathering an object.