Reporting flock patterns

Data representing moving objects is rapidly getting more
available, especially in the area of wildlife GPS tracking. It is
a central belief that information is hidden in large data sets in
the form of interesting patterns. One of the most common
spatio-temporal patterns sought after is flocks. A flock is a
large enough subset of objects moving along paths close to each
other for a certain pre-defined time. We give a new definition
that we argue is more realistic than the previous ones, and by the
use of techniques from computational geometry we present fast
algorithms to detect and report flocks.
The algorithms are analysed both theoretically and experimentally.