Automated Extraction of Landmarks
(Raubal and Winter 2002) a formal model is proposed that allows to
compute a measure of landmarkness for features of a city. The model is
based on a classification of (Sorrows and Hirtle 1999) who distinguish
between visual, structural, and semantic aspects of landmarkness.
attributes determined in the model comprise the façade area, façade
aspect ratio, deviation from bounding rectangle, color and visibility.
Structural attraction is determined mainly by the road network. Used
measures are the grade of connectivity of a node, and a measure for
barrierness. Semantic attraction cultural, historial or economic
importance - is determined by linking external directories, for example
the Kulturgüterkataster or the Yellow Pages. The individual measures
are then weighted and combined to a global measure of landmarkness.
the given model it is possible for the first time to select features
from multipurpose data sets for their landmarkness automatically. These
could be used to enrich wayfinding instructions with these selected
features, inspired by human communication of routes (Denis et al. 1999;
Michon and Denis 2001), to improve the usability of such instructions.
thesis shall investigate the model. Specific questions to be solved are
whether the proposed model is robust to variation in the parameters,
whether the measures can be computed automatically, and, of course, if
the results are plausible.
following hypothesis shall be proved: The proposed model yields
plausible selections sufficiently close to human perception of reality.
All individual measures are readily computable and plausible by
thesis shall investigate the usefulness of the approach described
above. The test area is the first district of Vienna, an area that is
highly frequented by tourists, contains many points of interest, and is
in most parts pedestrian zone. Demand for pedestrian navigation support
Input data for the test area has to be collected from
different sources, and partly to be supplemented or surveyed. In
particular the digital Multipurpose Map produced by the city of
Vienna shall be used to derive the route network and the visibility
Rectified photos of façades are used to compute measures like façade area, aspect ratio, and color.
It shall be explored if it is feasible that the calculation is embedded in an automated workflow.
evaluate the model human subject testing is used. The subjects are
shown 360° panoramic views of intersections and are told to identify
the landmark they would use for guiding pedestrians. If there is a
significant agreement between the automatically selected landmarks and
the human subjects the hypothesis shall be considered proved.
Denis, M.; Pazzaglia, F.; Cornoldi, C.; Bertolo, L., 1999: Spatial
Discourse and Navigation: An Analysis of Route Directions in the City
of Venice. Applied Cognitive Psychology, 13: 145-174.
P.-E.; Denis, M., 2001: When and Why are Visual Landmarks Used in
Giving Directions? In: Montello, D.R. (Ed.), Spatial Information
Theory. Lecture Notes in Computer Science, 2205. Springer, Berlin, pp.
Raubal, M.; Winter, S., 2002: Enriching Wayfinding
Instructions with Local Landmarks. Technical Report, Institute for
Geoinformation, TU Vienna.
Sorrows, M.E.; Hirtle, S.C., 1999:
The Nature of Landmarks for Real and Electronic Spaces. In: Freksa, C.;
Mark, D.M. (Eds.), Spatial Information Theory. Lecture Notes in
Computer Science, 1661. Springer, Berlin, pp. 37-50.