Processed Patches

We collected 3D representations of 96 natural objects such as rocks, leaves, bark, fruits, vegetables, etc., as well as 41 human-made objects including scissors, knifes, purses, mugs, etc. To quantify the local shape of these data, we randomly sampled 100-150 circular surface patches with a radius of 6 mm, similar to the size of a human fingertip. This procedure resulted in a total of 12,309 and 5,788 patches for natural and human-made objects, respectively. For each surface patch we computed maps of distance, slope, and curvature. Briefly, the distance of the surface points was computed with respect to a reference plane yielding a circular distance map P(D) with a total of 448 points for each patch. From P(D) we computed a 421-dimensional slope map P(S) using first-order forward difference, and a 384-dimensional curvature map P(C) using second-order central difference.