Simulation and Rendering of Pitting Corrosion

Simulation and rendering of material weathering is of great interest in computer graphics as it facilitates modeling of realistic objects in virtual scenes. We present a physio-chemically based methodology to model pitting corrosion. Our simulation has two components. The first models pit nucleation on the surface of the object. It is implemented as a stochastic process, exponentially deteriorating with time. The second component models pit growth using another stochastic process influenced by pit characteristics (geometry, neighborhood and exposure). We validate our model with measurements published in the corrosion literature and then demonstrate its effectiveness in generating realistic images. Our corrosion model leads to shape degradation. Color degradation is less tractable. Hence we instead learn that directly from acquired images of corroded models. We present an efficient rendering algorithm that generates color, normal and depth textures to display the corrosion of any object of interest. This is an important step in linking the appearance to structural damage.