Spatio-temporal BRDF: Modeling and synthesis

We propose a generalization of example-based texture synthesis to spatio-temporal BRDFs. A key com-ponent of our method is a novel representation of time-varying materials using polynomials describing time-varying BRDF parameters. Our representation allows efficient fitting of measured data into a com-pact spatio-temporal BRDF representation, and it allows an efficient analytical evaluation of distances be-tween spatio-temporal BRDF parameters. We show that even polynomials of low degree are sufficient to represent various time-varying phenomena and provide more accurate results than the previously proposed representation. We are the first who applied the example-based texture synthesis on abstract structures such as polynomial functions. We present two applications of synthesizing spatio-temporal BRDFs using our method: material enlargement and transfer of time-varying phenomenon from an ex-ample to a given static material. We evaluated the synthesized BRDFs in the context of realistic rendering and real-time rendering. (c) 2021 Elsevier Ltd. All rights reserved.