Digital road maps are clearly important for both consumers and businesses. At
present, these maps are created by companies fielding fleets of specialized vehicles
equipped with GPS to drive the roads and record data. This is an expensive process,
and it is difficult to keep up with changes in the road network. An emerging
alternative is to use GPS data from regular vehicles driving their regular routes. This
has the advantage of easily scaling to the entire road network and providing much
more up-to-date data whenever roads change.
The challenge of this technique is how to process all the data into a road map. The
OpenStreetMap [1] project provides one model where volunteers manually edit GPS
traces and aerial images into digital maps. While OpenStreetMap moves away from
the use of specialized vehicles, we would like to eliminate the manual step. In this
paper, we show how to automate one important aspect of this processing: finding road
intersections. We test our process on a large amount of GPS data we gathered from
vehicles that were already driving in our metropolitan area. This data is shown in
Figure 1(a).
GIScience 2010, Sixth International Conference on Geographic Information Science, Zurich, 14-17th September, 2010
Our algorithm detects intersections in the GPS data, an example of which is shown
in Figure 1(b). It begins by using a shape descriptor trained on positive and negative
examples of intersections. Next it connects the intersections by finding vehicle traces
that move between them. Finally, the algorithm refines the locations of the
intersections based on the GPS data associated with the nearby roads. We evaluate
our algorithm by comparing it to a known road network. Specifically, we evaluate it
in terms of its ability to find intersections, the accuracy of the intersections’ computed
locations, and the accuracy of the lengths of the roads between the intersections.