Fig. 3. (a) Uncorrected reflection image of the sand tank; (b) estimated material map; (c) designed filling pattern. Coarse sand is indicated as dark gray, fine sand as white, and very fine sand as medium gray. Areas not classified in (b), or with no sand or a mixture of all sands in (c), are black. The white frames show the inner sections that were analyzed for averages. Note the slight horizontal stretching and vertical offset of the realized as compared to the designed pattern.