Trajectory Bundling
Listing One is the SAL code that performs the following computation. The steps and substeps, which correspond to the coding steps in Listing One, illustrate how you can use SAL.
Step 1. Aggregate points to trajectory curves. Given input points; Figure 6(a). Compute a neighborhood graph, constructed by a minimal spanning tree (MST) algorithm on a Delaunay triangulation, to encode spatial adjacency of points from the input field; Figure 6(b). Form equivalence classes of points from the MST by deleting inconsistent edges in the MST that are significantly longer than neighboring edges; Figure 6(c). Each of the resulting connected components in the graph forms an equivalence class of consistent points.
Step 2. Aggregate trajectory curves to trajectory bundles. Redescribe the equivalence classes of consistent points as trajectory curves; Figure 6(d). Aggregate trajectory curves into a neighborhood graph such that curves are adjacent if any of their constituent points are neighbors in the underlying minimal spanning tree; Figure 6(e). Classify connected curves into the same equivalence class if their shape is relatively similar; Figure 6(f).
Figure 7 shows an interactive interpreter session for another application.
— F.Z., C. B-K., I.O.
