chart drawing facility. GNUPLOT also creates its results as
PPM raster files on the server.
To combine the output of GRASS and GNUPLOT we need
further tools to combine the results and merge them to-
gether for displaying as a thematic map. The process is
outlined in figure 3. The PBMPLUS-programs (Anonym-
ous, 1995) are used to convert PPM-files to GIF and Tom
Boutell's gd-library (Boutell, 1995) and Martin Gleeson's Fly-
Tool (Gleeson, 1995) are used to patch together and mark up
the various images to get a final map as shown in figure 4.
Interface for DB -
Chart Generation Output
-—--—* |GNUPLOT
p e ee EI
= Interface for
a
P T Map Generation ~~" GRASS
e
+
5
"à
S
3 Interface for ~~~ | PBM-TOOLS
Image Processing Functions ETT AS
Figure 3: Map composition and preparation
5 CONCLUSIONS AND FUTURE WORK
In this paper we have presented some aspects of an Environ-
mental Information System based on WWW. A more detailed
description can be found in (Mayer-Fóll and Jaeschke, 1995)
where the work of other GLOBUS team members has been
published, e.g. on line hypertext documents on toxic waste
deposits, keyword tools, in depth evaluation of some CORBA
products and CCI applications.
At a client's workstation, only a Web Browser is used - no
further software components are needed for browsing hyper-
text documents, accessing relational and other databases, the
display of maps and tabular data as business graphics charts.
The current Web Architecture has some drawbacks, which
severely limit the interactivity of graphically oriented and
forms based applications, creating a big load on the WWW
server.
To address this we are currently evaluating JAVA and JAVA
enabled browsers to move some processing steps back to the
client. For example JAVA will allow us, to perform some local
error checking, drawing of vector data on the client screen and
perform local interactions like zooming and panning without
any server involvement.
On the server side we are looking at the OGIS (Buehler, 1994)
and ISO activities to implement a CORBA encapsulation for
certain GIS operators and data access methods. This will -
in the long run - make the WWW based EIS independent of
proprietary GIS software systems.
405
5.1 Acknowledgements
The project GLOBUS has been financed by the Ministry of En-
vironmental Protection of the State of Baden-Wiirttem berg,
Germany. The project has been overseen by a steering com-
mittee, staffed by people from various state agencies. We
gratefully acknowledge their fruitful discussions and support.
The students S. Behrens, U. Beutler, C. Habeck, P. Kirsch, B.
Mayer, P. Palmer, C. Rolker, O. Scheffczyk, M. Schoel and
M. Walz were instrumental in the implementation effort at
FZI. At IPF, the students M. Bose, C. Hofmann, H. Krassin
and A. Trager were involved in implementing GIS services and
visualization tools. We gratefully acknowledge their support.
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