Full text: Systems for data processing, anaylsis and representation

  
  
1.0 Introduction 
Geographic Information System (GIS) is a fast 
developing technology with unbounded area of 
application areas. One of the major problems con- 
fronting this technology is in the area of identifying 
the source of data relevant for the development of 
an applications. 
There is therefore the need for a spatial browser, 
that will provide GIS application developers, the 
means of searching and locating data from various 
sources. MetaView/GIS is a software that provides 
users, a friendly interface for this purpose. It 
reduces drastically the time and effort needed to 
seek desired information on spatial data sets. Meta- 
View/GIS does not disclose the contents of a data- 
base to allow retrieval of a data set. It only 
provides access to the metadata of the data set. 
Such data may include the following: 
e the format and scale of available map data, 
e the name of the database and site information of 
the data set, 
* the agency/organization and contact persons of 
the data set, 
* the projects and applications that have utilized 
the data sets, 
* the documents and guides on the data set, 
* the source and coverage of the data set, 
* the access policy, protocol and cost of data set, 
* etc. 
MetaView/GIS is configured as a client-server 
model to run over Internet. The client is a user 
Unix workstation running a client component. The 
Server component runs on MetaView/GIS site. A 
number of other client-server directory services 
exist for locating and retrieving information across 
the Internet. Such directory services include Wide 
Area Information Server (WAIS)[5], World-Wide 
Web (WWW)[4], Archie[7] and Gopher[6]. WAIS, 
Archie and Gopher provide the user with an over- 
view of likely places to find the desired informa- 
tion, and then help the user locate the specified 
information items. In WWW, a GUI software 
known as xmosaic allows a user to navigate 
through databases with a mouse click in a hyper- 
text mode. 
MetaView/GIS differs from these systems in a 
number of ways. First, MetaView/GIS, operation- 
ally, serves as a partial front end of a commercial 
service DeltaX[1,2]. Second, it provides an X11 
graphical interface at the user's client which relies 
on commercial databases management system and 
not a hypertext system. It conforms to an informa- 
tion structured standard specified by the Canadian 
Inter Agency Committee on Geomatic (IACG). 
Third, users can specify spatial queries. Fourth, 
MetaView/GIS provides more information related 
to a data set than those existing in these directory 
services. However in designing MetaView/GIS, the 
services provided by these systems were taken into 
consideration and in fact are utilized by the Meta- 
View/GIS system. For example, if a data set is 
available free at a site, one may choose to retrieve 
it by employing the services of the other directory 
services. 
In this paper, we present some of the functional- 
ities, design concepts and implementation of Meta- 
View/GIS. Section 2 discusses the design concepts, 
the intended users of MetaView/GIS. User's inter- 
action issues are addressed in section 3. Section 4 
deals with administrative aspects of the MetaView/ 
GIS. Section 5 summarizes this paper and presents 
some projected enhancement. 
2.0 Operational concepts MetaView/ 
GIS 
One of the main difference between MetaView/ 
GIS and the other directory services is the ability 
for a user to specify queries using region selection. 
MetaView/GIS maintain two types of databases: 
one contains map data, the other contains the meta- 
data. The map database contains data for display- 
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