4 research outputs found
Defining and Computing Alternative Routes in Road Networks
Every human likes choices. But today\u27s fast route planning algorithms usually compute just a single route between source and target. There are beginnings to compute alternative routes, but this topic has not been studied thoroughly. Often, the aspect of meaningful alternative routes is neglected from a human point of view. We fill in this gap by suggesting mathematical definitions for such routes. As a second contribution we propose heuristics to compute them, as this is NP-hard in general
Compressed Transmission of Route Descriptions
We present two methods to compress the description of a route in a road
network, i.e., of a path in a directed graph. The first method represents a
path by a sequence of via edges. The subpaths between the via edges have to be
unique shortest paths. Instead of via edges also via nodes can be used, though
this requires some simple preprocessing. The second method uses contraction
hierarchies to replace subpaths of the original path by shortcuts. The two
methods can be combined with each other. Also, we propose the application to
mobile server based routing: We compute the route on a server which has access
to the latest information about congestions for example. Then we transmit the
computed route to the car using some mobile radio communication. There, we
apply the compression to save costs and transmission time. If the compression
works well, we can transmit routes even when the bandwidth is low. Although we
have not evaluated our ideas with realistic data yet, they are quite promising.Comment: 7 pages, technical repor