Merging Ground Points into Drivable Surface.

Fig. 4, right, gives the idea how we connect ground points of one scan with the ones of its neighbors: The basic observation is that points labeled ground in individual neighboring scans and denoting the same patch of path in the environment would end up very close to each other after registration. So it has proved sound to grow regions of drivable surface around areas containing sufficiently many ground points in sufficient density, disregarding from which individual scans their labels were derived. Significant differences in absolute point height are checked, as mentioned previously.

This strategy assumes that neighboring scans overlap sufficiently well, to map the drivable surface sufficiently densely. While this is no completely new requirement (registration itself also needs some minimal overlap), we are still experimenting with suitable combinations of point density requirements and efficient scan distances.