From AAAI Technical Report FS-98-04. Compilation copyright © 1998, AAAI. (www.aaai.org). All rights reserved.
VISCO- Querying GIS with Spatial Sketches
Volker Haarslev and Michael Wessel
University of Hamburg, Computer Science Department,
Vogt-Kolln-Str. 30, 22527 Hamburg, Germany
http://kogs-www.informatik.uni-hamburg . de/-haarslev/
http://kogs-www.informatik.uni-hamburg.de/-mwessel/
Please visit the VISCO homepage at
http://kogs-www.informatik.uni-hamburg.de/-mwessel/visco-engl.html
Summary
u
We demonstrate the visual query system VISCO that offers a sketch-based query language for defining approximate spatial constellations of objects. VISCO smoothly
integrates geometrical and topological querying with
deductive spatial reasoning. It is based on a strong
physical metaphor visualizing semantics of query elements. Approximate queries rely on combined topological and geometrical constraints enhanced with relaxations and "don't cares" that could be visualized
through live animations. VISCO is presented in full
detail in (Haarslev & Wessel 1997; Wessel & Haarslev
1998).
The visual query system VISCO (Vivid Spatial Constellations) provides a sketch-based query language for
defining approximate spatial constellation:; of objects.
Our query language can express geometric as well
as topological constraints. The query language elements are visualized with the help of a naive physics
metaphor utilizing rubber bands, (cross) beams, swivel
joints, nails, marbles , etc. The meaning of VISCO's language elements is immediately graspable from the physical properties of their visualizations, e.g. a rubber band
may be stretched, shrunk and wrapped around in contrast to a (rigid) beam, a marble can roll around and
change its position in contrast to a nail.
In contrast to related approaches (see (Haarslev &
Wessel 1997) for details) that usually focus on topological descriptions we adopt a bottom-up approach and
parse the sketches and their geometry as drawn by the
user. VISCO takes the geometry of query sketches seriously but supports the annotation of meta information which can be used to specify almost pure topological queries. The user may add meta information to
a sketched query. This meta information specifies relaxations, additional constraints or "don't cares" that
define the interpretation of the query. The visibility
of user-defined relaxations and "don't cares" is a major advantage of our approach. In our opinion this explicit meta information (which ha::; to be supplied by
the user) is important since drawings are always in a
sense "overspecified" and their (relaxed) interpretation
strongly depends on the application domain.
For instance, the simple query shown in Figure 1
103-
300 m .
. Size Indicafor .
Marble
=point (position may change)
Antenna = line segment
(length may change)
Size Indicatof
300
m.
Origin
= pain} (fixed)
Rubberband .(matches polYline)
Arrow at origin (transparency not rotatable)
Constant Enclosure (enforces inside)
Transparency Film =aggregate with local coordinate system
(translatable, 300 x 300 m. unscalable, not rotatable)
Figure 1: A simple VISCO query (annotations in italic
font)
could by described as "Search for a lake of (nearly) arbitrary form that is not bigger than 300 x 300 m.".
The semantics of the elements used in the query are
explained in Figure 1 by annotations. This query is
also shown in Figure 2. Screen shots of VISCO's other
interfaces are displayed in Figure 3.
References
Haarslev, V., and Wessel, M. 1997. Querying GIS with
animated spatial sketches. In 1997 IEEE Symposium
on Visual Languages, Capri, Italy, Sep. 23-26, 197
204. IEEE Computer Society Press, Los Alamitos.
Wessel, M., and Haarslev, V. 1998. VISCO: Bringing
visual spatial querying to reality. In 1998 IEEE Symposium on Visual Languages, Halifax, Canada, Sep.
1-4. IEEE Computer Society Press, Los Alamitos. In
press.
·,
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Figure 2: The Graphical Query Editor of VISCO: the main window (left) and the "Buttons" window (right)
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Figure 3: Execution and result inspection (left); the map viewer (right)
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