Campus Event Calendar
Event Entry
What and Who
Walking the Dog Fast in Practice: Algorithm Engineering of the Fréchet Distance
André Nusser
Max-Planck-Institut für Informatik - D1
AG1 Mittagsseminar (own work)
AG 1
AG Audience
English
Note: We use this to send email in the morning.
Date, Time and Location
Thursday, 6 June 2019
13:00
30 Minutes
E1 4
024
Saarbrücken
Abstract
The Fréchet distance provides a natural and intuitive measure for the popular task of computing the similarity of two (polygonal) curves. While a simple algorithm computes it in near-quadratic time, a strongly subquadratic algorithm cannot exist unless the Strong Exponential Time Hypothesis fails. Still, fast practical implementations of the Fréchet distance, in particular for realistic input curves, are highly desirable. This has even lead to a designated competition, the ACM SIGSPATIAL GIS Cup 2017: Here, the challenge was to implement a near-neighbor data structure under the Fréchet distance. The bottleneck of the top three implementations turned out to be precisely the decision procedure for the Fréchet distance.
In this work, we present a fast, certifying implementation for deciding the Fréchet distance, in order to (1) complement its pessimistic worst-case hardness by an empirical analysis on realistic input data and to (2) improve the state of the art for the GIS Cup challenge. We experimentally evaluate our implementation on a large benchmark consisting of several data sets (including handwritten characters and GPS trajectories). Compared to the winning implementation of the GIS Cup, we obtain running time improvements of up to more than two orders of magnitude for the decision procedure and of up to a factor of 30 for queries to the near-neighbor data structure.
This is a practice talk for SoCG 2019.
Contact
André Nusser
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André Nusser, 05/31/2019 16:42 -- Created document.