Geoscience Reference
In-Depth Information
British Columbia, and Cagnacci and Urbano (2008), showcasing a system for handling GPS collar
data. QGIS both benefits and suffers from a plug-in system, because the plug-ins add functional-
ity but may cease working as new versions are released, especially if the plug-ins rely on external
software. Software plug-ins, also termed added modules or extensions, allow software to be used for
tasks beyond the original intentions of its authors. They are often written using dynamically loaded
libraries and may be sensitive to changes in application binary interfaces.
It is worth noting that GRASS and QGIS are OSGeo projects, and both rely on the mainte-
nance and development of the underlying geospatial libraries, such as GDAL and PROJ.4. These
dependencies are shared with an important non-OSGeo desktop GIS, SAGA GIS.* SAGA has been
freshly written in a modular form in C++ and has a command-line interface from the shell as well
as a GUI. The GUI differs in its use from proprietary GIS but, once differences are noted, is very
flexible; it is good at displaying large data sets and has many analysis modules. Goetz et al. (2011)
show how SAGA can be integrated with other tools for modelling landslide susceptibility; SAGA
is also used by Branger et al. (2012) with other open-source GIS to pre-process data for distributed
hydrological models.
The Integrated Land and Water Information System (ILWIS)
†
is another desktop GIS application
and was released as open source after its commercial existence was terminated in 2005. Other desk-
top applications include GeoVISTA Studio, described by Gahegan et al. (2008), a problem-solving
environment; like some others, this application seems mainly intended to support research into GIS
and GIS use, especially for visualisation and knowledge discovery.
14.3.3 w
eB
M
aPPing
and
S
erViceS
Lime (2008) describes the evolution of MapServer
‡
in some detail. It is of considerable importance, not
least because its developers and participators established a foundation as its governance model before
other geospatial projects. Indeed, the MapServer foundation was widened to become the OSGeo
foundation in 2006, with MapServer becoming an OSGeo project. It is based on simple principles
but has also been extended with the MapScript scripting language, which may be compiled with the
GEOS library to provide considerable server-side analytical power. The MapChat
§
web application
(Hall and Leahy 2008b, Hall et al. 2010) builds on MapServer; it is an open-source tool for integrating
maps with real-time and asynchronous discussions between multiple users, who can annotate maps to
communicate information. It uses PostGIS as a spatial database back end, and OpenLayers
¶
for client-
side map display - OpenLayers is a JavaScript library that is also an OSGeo project.
MapGuide Open Source** is another OSGeo project, and like ILWIS, it has its background in a
proprietary application. Bray (2008) describes its development as a modern web-based geospatial
platform. It uses an OSGeo library not discussed earlier, Feature Data Objects (FDO), which is an
API for manipulating, defining and analysing geospatial information that is completely data store
agnostic. This permits web service providers to be used as a data source, for example, web map
services (WMSs) and web feature services (WFSs). GeoServer
††
is a Java-based server that permits
geospatial data to be viewed and edited. It is also an OSGeo project and uses OpenLayers and
GeoTools. It offers WMS and WFS interfaces, allowing clients to access data.
Web mapping services include several other application areas. In addition to WMS to serve ras-
terised data and WFS to serve features (vector data), OGC has defined web processing services
(WPSs), in which a server accepts geospatial input data, processes it and transmits the results to the
*
http://www.saga-gis.org.
†
http://52north.org/communities/ilwis.
‡
http://www.mapserver.org/.
§
http://mapchat.ca/.
¶
http://openlayers.org/.
**
http://mapguide.osgeo.org/.
††
http://geoserver.org/.