SVG-BASED VISUALIZATION OF GEODATA QUALITY. TAKING THE
KAKAMEGA-NANDI FOREST AREA AS EXAMPLE
K. Huth1, O. Schnabel2, G. Schaab1
1 - Karlsruhe University of Applied Sciences, Faculty of
Geomatics, Karlsruhe, Germany
2 - ETH Zurich, Institute of Cartography, Zurich, Switzerland
gertrud.schaab@hs-karlsruhe.de
Subproject
E02 funded by the German Federal Ministry of Education and Research (BMBF)
within the BIOTA East Africa project frame considers the analysis of
longer-term forest cover changes in East African rainforests as one of its
major tasks. Here, data sources range from satellite imagery and historical
aerial photography via old topographic maps, official governmental records and
forestry maps to oral testimonies by the local population and place names giving
evidence for much earlier forest extents.
An analysis
of such information will lead to a detailed picture of the forest use history
over the last 100 years. This can be more accurate, i.e. more insights are
expected, if the numerous data layers can be directly compared via their
spatial reference as it is possible by means of a geographic information system
(GIS). However, in a GIS the visualization in connection with a text which is
already summarizing first results by pointing out locations is not feasible.
The visualizing of the varied information together with a text inhabiting
hyperlinks while at the same time illustrating differences in geodata quality
will not only offer the opportunity to the scientist to gain new conclusions,
but can be of use to a wider audience: for plain documentation, for presenting
the results as well as for the individual working with the gathered data and
information by anyone interested.
Therefore,
the aim has been to develop a visualization tool for an integrated examination
of a scientific paper on forest use in the considered area, the complete
geodata gathered and its quality parameters. Hereby, for a start the
implementation of a prototype is sufficient. Nevertheless, for conceptualizing
the tool almost 100 geodatasets covering the Kakamega-Nandi forest complex in
Western Kenya need to be taken into account. The programming applies scalable
vector graphics (SVG) for displaying graphics and JavaScript for the
interactive features.
The
presentation will give background information on other studies aiming at
illustrating geodata quality. Subsequently evolved designs for diagrams
exposing the quality of the different geodatasets are introduced and judged
against each other. The overall concept of the prototype implementation is
discussed as well as finally its features demonstrated. The presentation will
end with lessons learned by setting-up such a tool.