Geoscience Reference
In-Depth Information
Fig. 12.1 First page of the online query system
The logic and the background structure of the system, and the applications of the
database provide the users with an easy and fine-tuned query, and a quick presenta-
tion of the results (alphanumerical and graphical or map data). Further, the access to
the system can be easily regulated.
The system consists of two major parts: the EDIT is for data loading and
maintenance, while the EDITKE is for online query (Fig. 12.1 ). The online query
system is accessible at http://mapw.elte.hu/edit for those on the elte domain. The
clients of the Virtual Private Network (VPN) can reach this URL through the
certificate of the VPN. The data maintenance application runs on the map server
of the system. The language of the system is Hungarian.
The system was made in Microsoft VisualStudio 2008. The loading application
is a win32 application. The online query was made in ASP.NET. Istv ยด n Elek
developed both application programs.
12.3 Structure of the Database
The great differences between the formats of the raster and vector maps caused
difficulties for the planning of the database. Although there are various raster
formats, they all contain an m x n matrix, which stores the intensity values of a
picture according to a colour model in rows and columns. These data may come
from scanned paper maps or from the signals of digital images. They all follow the
simple structure of raster data models. Descriptive data such as scale, time of
making, sheet number can be added to the maps (namely, to each raster file).
This logic cannot be used for vector maps, because these maps are organized into
layers and feature classes. Several types of information, layers, and feature classes
together can only express the complexity of classical paper-based maps. In addition,
some of the usual descriptive data (e.g., scale, title, and sheet number) cannot be
interpreted for these data. It is obvious that different data structures must be used for
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