The r_wobj, θ_wobj, φ_wobj coordinates computed from the mechanical signals at the whisker base can reconstruct the shape of the peg.

The data in this figure exclude small angle deflections, i.e., any point that lay less than sclosest*tan(2°) from the whisker, where sclosest is the arc length of the point on the whisker closest to the contact point. (A) The rwobj, θwobj, φwobj coordinates computed from the mechanical signals are plotted in whisker-centered coordinates. The whisker is the black tapered, dotted line. Each magenta dot represents a 3D contact point on the peg with respect to the whisker. Each dot is computed based on mechanical data obtained from a single video frame (1 ms resolution). These are the identical points as were plotted in Fig 4D, but are now plotted in their correct 3D spatial locations relative to the whisker. (B) Diagrams of the rat whisking into the peg show where reconstructed contact points are expected. The rat first whisks forward against the back of the peg, and then whisks backwards against the front of the peg. We therefore expect to see reconstructions of both the front and the back of the peg. (C) The same view of the rat head as in B, now including contact points. Tracked (“ground truth”) contact points are shown as black dots. Contact points computed from mechanical signals are shown as transparent magenta dots. Two expanded views of the reconstructed peg are shown to the right. In the side view, the points create two vertical lines: one indicating contact with the back of the peg, and the other indicating contact with the front of the peg. The top view reveals that the largest errors are found in the estimate of radial distance, rather than in estimates of the angles of contact.