Essentially all computer graphics rendering assumes that the reflectance and texture of surfaces is a static phenomenon. Yet, there is an abundance of materials in nature whose appearance varies dramatically with time, such as cracking paint, growing grass, or ripening banana skins. In this paper, we take a significant step towards addressing this problem, investigating a new class of time-varying textures. We make three contributions. First, we describe the carefully controlled acquisition of

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... atasets of a variety of natural processes including the growth of grass, the accumulation of snow, and the oxidation of copper. Second, we show how to adapt quilting-based methods to time-varying texture synthesis, addressing the important challenges of maintaining temporal coherence, efficient synthesis on large time-varying datasets, and reducing visual artifacts specific to time-varying textures. Finally, we show how simple procedural techniques can be used to control the evolution of the results, such as allowing for a faster growth of grass in well lit (as opposed to shadowed) areas.