Abstract:
Most public geospatial data is served via standard compliant Web Mapping Servers and Web Feature Servers
available globally. However, it is quite complicated to search and locate the relevant data if the exact data
source name and other parameters are unknown. Catalog servers, which store metadata and provide search
protocols provide a standard way to handle this problem, but only afew Catalog servers exist which limits the
usefulness of such servers for adhoc geospatial data discovery. This paper looks at the advantages of making
available metadata of geospatial data through Catalog Servers for adhoc geospatial data discovery. It looks at
the limitations of searching geospatial data using Web Mapping Servers and Web Feature servers and search
engines such as Google, and presents a case for having increased Catalog Servers. It then looks at a novel way
of building metadata from existing Web Mapping Servers using common data base techniques, which could
then lead to more metadata in Catalog Servers, which would in turn lead the way to better and more efficient
Geospatial Data Discovery. It then looks at a specialized client that is used to search catalog servers over the
web, providing domain experts with a powerful tool to accurately search for data.
1. Introduction I
The rapid increase of public spatial data on the Internet,
coupled with the need for using spatial data in
meaningful ways, is shifting the focus towards the
discovery and integration of data. During the past decade
there has been tremendous growth in the number of
spatial data sources available as public web services, and
these sources are being used in domains as diverse as
finance, education, citizen services, digital media and
emergency response, to name a few. The majority of this
data is made available to the general public as raster maps
in Web Mapping Service (WMS) Servers [I] and vector
data on Web Feature Service (WFS) Servers [2]. The
Geospatial Information Database (GlOB) [3] project lists
1400 WMS servers serving over 330,000 layers,
indicating the scale of data that needs to be searched to
identify data.
With such large amounts of data available for public
use, the task is left to the end user to search, identify and
fetch the relevant spatial data he/she is looking for. The
ability to discover and access geographical data for
planning, visualization and decision making is a
requirement to support communities and activities at
local, regional, national and international level. This is
summarized well in this statement from the Spatial Data
Infrastructure [4] cookbook in its chapter on geospatial
M. Careem and D. Karunarathne are
with the
