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International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B2. Istanbul 2004
5.] Spatial Decision Support Systems
Decision Support Systems (DSS) and Spatial Decision Support
Systems (SDSS) can be defined as interactive, computer-based
tools that use information and models to improve the decision-
making process (Feeney et al, 2002). These systems have
intuitive interactive interfaces, the ability to combine analytical
models with data, the capability to explore alternative solutions,
the support of a variety of decision making styles, and the
ability for interactive and recursive problem solving (Densham,
1991). Decision support systems used to address complex
issues such as sustainable development require a combination
of structured (programmable) and unstructured (based on
human decision) problem solving techniques. In a DSS,
decision alternatives may be evaluated on the basis of multiple
criteria (Malczewski, 1997). Decision-making stakeholders and
technical specialists may range from novice to expert.
Participatory decision support systems that facilitate
collaborative decision-making result in more effective and
equitable decisions (Jankowski and Nyerges, 2001).
The following sections will provide an example of a component
in an evolving Decision Support System. The component is
called the Georgia Basin Digital Library (GBDL) and it is an
integral part of by the PATHWAYS decision support
framework. GBDL was developed to facilitate decision making
for sustainable development of Georgia Basin region of
southwestern British Columbia Canada
[http://www.georgiabasin.info].
5.2 Georgia Basin Digital Library
GBDL is primarily aimed at members of the local community
within the Georgia Basin, as well as experts interested in issues
of sustainable development (Talwar, 2003). It is composed of
the following modules: News & Information, Local Stories,
Ideas & Perspectives, Library Collections, and Future
Scenarios. The two GBDL modules that display interactive
Web maps are the Local Stories and Library Collections
modules. At present, the SDKI-Vis project is working on the
evaluation and improvements to the Library Collections
module.
The Library Collections module uses Open GIS Consortium
technologies [http://www.opengis.org] in a distributed
environment to permit users to search metadata registries of the
Canadian Geospatial Data Infrastructure [http://www.cgdi.ca]
and visualize spatial data hosted by a wide-range of geospatial
data warehouses. Layers of raster and vector geospatial data can
be selected and combined for dynamic Web map creation (see
Figure 5). Rudimentary functionality is available for zooming,
panning, and modifying the order of layer stacking and
displaying a locator/overview map. However, users cannot
modify the selection of symbols and colours as they are based
on a Style Layer Descriptor (SLD) usually developed by the
data provider.
The map-based layer selection module of the GBDL Library
Collections offers the user many map layers that can be turned
on and viewed together. This open invitation to explore geo-
referenced data from many dispersed databases can be a
meaningful and powerful way to foster visualization. However,
the invitation for unrestrained browsing can result in
misrepresentation of information by users not familiar with the
data integration issues such as working with data at various
scales and projections. User interaction should be provided
through a well-structured interface in order for exploration to
Ua
Un
increase curiosity rather than cause frustration. The work
involving the Georgia Basin Digital Library will propose
improvements to encourage browsing of the information, and to
provide greater assurance that a user's explorations will be
satisfying. The aim is to align the GBDL to the strategy of
weightless, intuitive operation.
One example of a map interface from the Library Collections
module of the GBDL, which the SDKI-Vis team is attempting
to improve, is shown in Figure 5. While it is beneficial that the
legend serve as the on/off control for each layer, this legend
provides only the name of the symbol, while it also needs to
reflect the symbol as it appears on the map. It would seem
more useful to move the map navigation controls to the map,
letting the user push and pull at the map image itself. Other
icons could be re-ordered to make better use of screen space
and to create relationships between the devices that control the
display and the map itself.
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Figure 6. The proposed redesigned Georgia Basin Digital
Library interface
The redesign and implementation of the new interfaces to the
GBDL is being conducted in cooperation of the SDKI-Vis
project and PATHWAY S project teams.
6.0 CONCLUSIONS
Innovative web-based interactive visualization techniques will
facilitate access to information, integration of multi-source
data, hypothesis testing and communication of integrated
knowledge. Visualization tools, in particular user-friendly
interfaces, can contribute to the increased use of earth sciences
