On Modeling and Analysis of Multidimensional Geographic Databases - Data Warehousing Design and Advanced Engineering Applications - page 99

Figure 1. Spatial SQL a) Spatial table creation b) Spatial query c) Geographic object creation d) Tabular
and cartographic representations

etc. Finally, the OLAP client allows visualizing
and formulating OLAP queries in a unique, interac-
tive and user-friendly visual interface composed
of graphic displays and pivot tables.

extend classical DBMS with spatial types (i.e.
point, line, etc.) and spatial functions (i.e. overlap,
etc.).As an example, the spatial table representing
French departments, and a spatial query selecting
departments with an area greater than 5000 Km2,
using Oracle's Spatial SQL, are shown on figure
1a and figure 1b, respectively. A tuple creation
and its cartographic representation are shown in
figure 1c and figure 1d, respectively.
GIS's geographic data can be analyzed by
means of spatial analysis methods. They allow
estimating, predicting and understanding spa-
tial data and phenomena by means of (spatial)
statistic (i.e. centroid, etc.), transformation (i.e.
buffer, etc.) and querying techniques. These
methods are supported by visual representation
of maps' features. Indeed, visualization plays a
central role for the spatial analysis process. Map
feature's geometries are represented using a two
dimensional space. Alphanumeric attributes are
visualized with graphic displays (i.e. bars, pies
charts, etc.), coded using visual variables (size,
value, colour, shape, orientation and grain) (Bertin
& Bonin, 1992). GISs make possible to change

Geographic Information Systems

A Geographic Information System encompasses a
set of tools for organizing, memorizing, analyzing
and visualizing geographic information (Longley
et al., 2001).
Geographic information is the representation
of geo-referenced real phenomena. It is described
by a spatial component (the shape and the posi-
tion on earth surface) and a set of alphanumerical
attributes and (spatial) relationships.
Main GIS functionality is the integration
and memorization of geographic data. Data are
organized in layers. A layer represents a set of
geographic data of the same type (i.e. roads,
buildings, departments, etc.). Each element of the
layer (geographic object or feature) is described by
geometry and some alphanumeric attributes. Lay-
ers are stored in GIS using Spatial DBMSs, which