June 17, 2009
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Publications on Computational Cartography :
- C. Gold et al. :
- D. Keim et al. :
- F. Leymarie et al. :
- M. McAllister et al. :
BibTeX references.
Map
Generalization by Skeleton Retraction
Christopher M. Gold
and David Thibault
Proc. of the 20th International Cartographic Conference (ICC)
pp. 2072-2081, Beijing, China, August 2001.
Terrain
Reconstruction from Contours by Skeleton Generation
Abstract
Generating terrain models from contour input is still an important
process. Most methods have been unsatisfactory, as they either do not
preserve the form of minor ridges and valleys, or else they are poor at
modeling slopes. A method is described here, based on curve extraction
and generalization techniques, that is guaranteed to preserve the
topological relationships between curve segments. The skeleton, or
Medial Axis Transform, can be extracted from the Voronoi diagram of a
well-sampled contour map and used to extract additional points that
eliminate cases of “flat triangles” in a triangulation. Elevation
estimates may be made at these points. Based on this approach it is
possible to make reasonable estimates of slopes for terrain models, and
to extract meaningful intermediate points for triangulated irregular
networks (TINs).
Primal/Dual Spatial
Relationships and Applications
Christopher M. Gold
9th International Symposium on Spatial Data Handling (
SDH)
Vol. 4a, pp. 15-27, August 2000, Beijing, China.
Abstract
It is well known that extraction of the skeleton of
a polygon from its outline
may aid in the perception or classification of its form. It has also
been
suggested that the ‘exoskeleton’ may be used to express the
relationships between objects in space. A new algorithm has been
developed
that extracts both the boundary and the skeleton of the spatial
representation
of an object in one easy step, based on local properties of the
Delaunay/Voronoi
diagram, without requiring additional information, such as point order
or
polygon labelling. This displays and preserves the fundamental
relationships
between the boundary and the skeleton that helps considerably in many
cartographic problems. Illustrations include contour map input and
terrain
visualization; watershed and flow estimation from river network input,
and
drainage network estimation from basin boundaries; topological
reconstruction
from scanned map input, and text recognition and placement in cadastral
maps.
The concept of preservation of the ‘form’ of the skeleton suggests
methods for map generalization without significant loss of meaning.
Spatial
uncertainty may also be addressed in terms of the boundary sampling
requirements
and permissible locational error without loss of the ability to
interpret
the basic form, spatial relationships and meaning of the map.
Keywords: Voronoi diagram; Topology; Boundary detection;
Crust; Skeleton.
Medial-Axis-Based
Cartograms
Abstract
Cartograms are a well-known technique for showing geography-related
statistical information, such as demographic and epidemiological data.
The idea is to distort a map by resizing its regions according to a
statistical parameter, but in a way that keeps the map recognizable.
This article describes a method of continuous cartogram generation,
which strictly retains the input map's topology. It presents an
algorithm that makes cartograms by iterative relocation of the map's
vertices, guided by a modified medial axes transformation. Application
experiments show that the proposed algorithm can make high-quality
cartograms in interactive time, even for large maps. Additional
examples help to demonstrate its potential.
Keywords: cartogram, contiguous cartograms, mesh transformation,
drawing
algorithm, information visualization, geovisualization, medial axes
transformation, cartodraw.
Towards the Automation
of Road Extraction Processes
F. Leymarie (2), N.
Boichis (2), S. Airault (1) and O. Jamet (1)
SPIE European Symposium on Satellite and Remote Sensing III*
vol. SPIE-2960, pp.84-95, Taormina,
Sicily,
Sept. 1996.
A joint ¹IGN-²Syseca project
Abstract
Syseca and IGN are working on various steps in the ongoing march from
digital photogrammetry to the semi-automation and ultimately the full
automation of data manipulation, i.e., capture and analysis. The
immediate goals are to reduce the production costs and the data
availability delays. Within this context, we have tackle the
distinctive problem of 'automated road network extraction.' The
methodology adopted is to first study semi-automatic solutions which
probably increase the global efficiency of human operators in
topographic data capture; in a second step, automatic solutions are
designed based upon the gained experience. We report on different
(semi-)automatic solutions for the road following algorithm. One key
aspect of our method is to have the stages of 'detection' and
'geometric recovery' cooperate together while remaining distinct.
'Detection' is based on a local (texture) analysis of the image, while
'geometric recovery' is concerned with the extraction of 'road objects'
for both monocular and stereo information. 'Detection' is a low-level
visual process, 'reasoning' directly at the level of image intensities,
while the mid-level visual process, 'geometric recovery', uses
contextual knowledge about roads, both generic, e.g. parallelism of
borders, and specific, e.g. using previously extracted road segments
and disparities. We then pursue our 'march' by reporting on steps we
are exploring toward full automation. We have in particular made
attempts at tackling the automation of the initialization step to start
searching in a valid direction.
* Conference on Remote Sensing for Geography, Geology, Land Planning,
and Cultural Heritage, organised (and proceedings edited) by:
Daniel Arroyo-Bishop; Roberto Carla; Joan B. Lurie; Carlo M. Marino; A.
Panunzi; James J. Pearson; Eugenio Zilioli.
DOI: 10.1117/12.262454
From Manual
to Automatic Stereoplotting: Evaluation of Different Road Network
Capture Processes
S. Airault, O. Jamet and F.
Leymarie
International Archives of Photogrammetry and Remote Sensing,
Vol. 31(3),
ISPRS, pp. 14-18, 1996.
Medial Axis
Generalization of River Networks
Michael
McAllister and
Jack
Snoeyink
CaGIS, Vol.
27, No. 2, April 2000.
Journal of the Cartography and Geographical Information Society
Abstract
We examine some benefits of using
the medial axis as
a centerline for rivers and lakes. One benefit, automatic
centerline
generation, has been used for many years. We show that additional
benefits can be derived from the geometric relationships between the
medial
axis and the riverbanks or lakeshores. These include area
estimates,
association of centerline analysis to banks, and definition of opposite
for riverbanks. We also report on our experience at approximating
the medial axis with a Voronoi diagram of point sites.
The Computational
Geometry of Hydrology Data in Geographic Information Systems
Extracting Consistent
Watersheds from Digital River and Elevation Data
ASPRS
Annual Conference, pp. 121--131, Portland, OR, USA, May 1999.
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2005-9.
Comments, suggestions, etc., mail to: ffl at gold dot ac dot uk