A G.I.S. is an information management tool that helps us to store, organize and utilize spatial information in a form that will enable everyday tasks to be completed more efficiently.

1. USING THE G.I.S. INSTRUMENTS TO OPTIMIZE THE DECISIONAL
PROCESS AT THE LOCAL COMUNITIES LEVEL
Mihai Valentin Herbei – Ph. D. Eng., University of Agricol Sciences and Veterinary Medicine of Banat
Timisoara – Faculty of Agronomy
Ular Roxana - Univ. assist. Ph. D. student, Eng. University of Petrosani, Faculty of Mine
ABSTRACT: "Every object present on the Earth can be geo-referenced", is the fundamental key of
associating any database to G.I.S. Here, term 'database' is a collection of information about things and
their relationship to each other, and 'geo-referencing' refers to the location of a layer or coverage in
space defined by the co-ordinate referencing system. G.I.S. is a system of hardware and software used for
storage, retrieval, mapping, and analysis of geographic data. Practitioners also regard the total G.I.S.
as including the operating personnel and the data that go into the system. Spatial features are stored in a
coordinate system (latitude/longitude, state plane, UTM, etc.), which references a particular place on the
earth. Descriptive attributes in tabular form are associated with spatial features. Spatial data and
associated attributes in the same coordinate system can then be layered together for mapping and
analysis .G.I.S. can be used for scientific investigations, resource management, and development
planning.
1. Introduction and data presentation for administrative support or for
decision support. (Fig. 1. and 2).
G.I.S. differs from CAD and other graphical
computer applications in that all spatial data is
geographically referenced to a map projection in an
earth coordinate system. For the most part, spatial data
can be "re-projected" from one coordinate system into
another, thus data from various sources can be brought
together into a common database and integrated using
G.I.S. software. Boundaries of spatial features should
"register" or align properly when re-projected into the
same coordinate system. Another property of a G.I.S.
database is that it has "topology," which defines the
spatial relationships between features. The fundamental
components of spatial data in a G.I.S. are points, lines
(arcs), and polygons. When topological relationships
exist, you can perform analyses, such as modeling the
flow through connecting lines in a network, combining
adjacent polygons that have similar characteristics, and
overlaying geographic feature. The main purpose for
introducing the G.I.S. technology consists in increasing
the efficient possibilities for maintaining and updating
the data. In the narrow sense, a G.I.S. consists of a
system for data input in vector form, in raster form and
in alphanumeric form, a CPU containing the programs
for data processing, data storage and data analysis and
of facilities for visualization and hard copy output of the
data. In a broad sense, a G.I.S. includes the data, which
are managed by an administration or a unit conducting a
project for the purposes of data inventory, data analysis
Fig. 1 The sketch of G.I.S.

2. Fig.2 Concept of a G.I.S.
2. Structure of a G.I.S. application necessary quality, in conditions of maxim efficiency.
Into the fig. 3 it is presented a general scheme of
The G.I.S. technology is used in all fields for which principle of sources that can be taken into consideration
the spatial information is relevant, that means in all for making the digital map.
fields that use the geographical map for stocking, Acquisitioning the data is the process of conversion
analyzing and representing the data which are of the data for the shape in which it is exists in one that
processed. can be used by a G.I.S.
No matter what is the field, any G.I.S. application The first aspect we may take into account here is the
includes a spatial data base (a digital map) and a soft map precision standard of 0,2 mm that depends on the
which exploit these data bases. scale assures the G.I.S. data to have a precession like
The digital map must contain the spatial data into the following table:
specific to any field whose it is designated to this
application. In order to furnish some useful information, Table 1
this data base must be actual, which means it must CARTOGRAPHIC CLASSIC ACCURACY
represent correctly the terrain (geographic space) that is ACCURACY MAP OF G.I.S.
always under changing. SCALE DATA
This exploitation soft is made from many functions 1: 25000 5m
of analyzing the spatial data contained into the digital 1: 10000 2m
map and of visualizing the resulted information, specific 1: 5000 1m
0,2 mm
to the application field. 1: 2000 0,4 m
1: 1000 0,2 m
3. Accomplishing the digital map 1: 500 0,1 m
The digital map must be made by vaporizing all the In order that the spatial data can be obtained from a
existent resources based on a good analyze of these great variety of sources, it must be done the difference
content and the involved costs, following to assure the between acquisitioning new data and of the existent one.

3. Each data source presumes the existence of some
special programs that are used for transforming the data
into a shape of the digital map.
Fig. 4 Point, line and area objects
Fig. 3 Data sources for G.I.S.
4. Models of data from the digital map
There are two important components of geographic
data: its geographic position and its attributes or
properties. In other words, spatial data (where is it?) and
attribute data (what is it?). Geographic position specifies
the location of a feature or phenomena by using a
certain coordinate system. The attributes refer to the
properties of spatial entities such as identity (e.g., Fig. 5 Vector format
maize, granite, lake), ordinal (ranking, e.g., class 1,
class 2, class 3, and so on), or scalar (value, e.g., water
A vector format represents the location and shape of
depth, elevation, erosion rate, and so on). They are often
features and boundaries precisely. Only the accuracy
referred to as non-spatial data since they do not in
and scale of the map compilation process; the resolution
themselves represent location information.
of input devices; and the skill of the operator inputting
Spatial features in a G.I.S. database are stored in
data limit the precision.
either vector or raster form. G.I.S. data structures
In contrast, the "raster" or "grid-based" format
adhering to a "vector" format store the position of map
generalizes map features as cells or pixels in a grid
features as pairs of x, y (and sometimes z) coordinates.
matrix (Fig. 6). The space is defined by a matrix of
A point is described by a single X-Y coordinate pair and
points or cells, organized into rows and columns. If the
by its name or label. A line is described by a set of co-
rows and columns are numbered, the position of each
ordinate pairs and by its name or label. In reality, a line
element can be specified by using column number and
is described by an infinite number of points. In practice,
row number, which can be linked to coordinate
this is not a feasible way of storing a line. Therefore, a
positions through the introduction of a coordinate
line is built up of straight line segments. An area, also
system. Each cell has a attribute value (a number) that
called a polygon, is described by a set of coordinate
represent a geographic phenomenon or nominal data
pairs and by its name or label, with the difference that
such as land-use class, rainfall or elevation. The
the coordinate pairs at the beginning and the end are the
fineness of the grid or, in other words, the size of the
same (Fig. 4,5).
cells in the grid matrix, will determine the level of detail
at which map features are represented. There are
advantages to the raster format for storing and
processing some types of data in G.I.S..

4. Fig. 6 Raster format
The "raster" or "grid-based" format generalizes map Fig. 8 Attribute links
features as cells or pixels in a grid matrix (Fig. 7).
In both models the geographic data of a certain
territory are organized on many layers or thematic
coverage (Fig. 9.).
The digital map is a special territory is represented
by the sum of all layers that have been defines. A
derived map will be constituted from a layer or a certain
combination of layers from the existent ones.
One of the main problems that should be solved
inside the project of informatics system will be to define
the layers that form the digital map and to establish the
entities that belong to each layer.
Fig
Fig. 7 Vector-raster relationship
The vector or the raster data are also linked (Fig. 8)
to non-graphic information specifying place names and
object numbers, which in databases may further be
linked to a great variety of coded or alphanumerical
attributes (e.g. owners of a parcel, inhabitants of a
house, characteristics of a utility feature, statistical data
for a defined area).
Fig. 9 Layers in a Digital Map
5. Spatial analyses

5. requires both geographic and other information (as well
The most important feature of a G.I.S. consists in its as specific models).
capacity to make spatial analyses, which means to The main spatial operations are as follows:
process the spatial data (geographical data) with the • Operations on a single layer;
purpose to obtain information (reports) regarding the • Operations on multiple layers;
studied area. With this feature of spatial analyze is • Statistic analyze;
different the software dedicated to G.I.S. over the • Network analyze;
software like the CAD. The processing of spatial data is • Analyze of the surfaces – making the digital model
made based on some algorithms specific by using own of the terrain.
operations for these such data.
A geographic information system must include some 6. Examples of spatial analyses
facilities for answering to the following 5 general
questions:
6.1. Operations on a single layer
 LOCATION: "What is at….?"
The first of these questions seeks to find what exists at a These operations are called also operations on the
particular location. A location can be described in many horizontal. For the vectorial maps it is necessary that the
ways, using, for example, place name, postcode, or layers should contain only the graphic primitives of
geographic reference such as longitude/ latitude or x and same type, so it will be used the group of operations on
y. many layers.
 CONDITION "Where is it..?" These operations on the horizontal are as follows:
The second question is the converse of the first and the manipulation of the graphic primitives (operations
requires spatial data to answer. Instead of identifying over the contours and analyze of proximity), their
what exists at a given location, one may wish to find selection (their identification) and their classification
locations where certain conditions are satisfied (e.g., a (grouping the graphic primitives in classes in order to
non-forest area of at least 2,000 square meters in size, make a statistic analyze).
within 100 meters of a road, and with soils suitable for The operations that are made over the contours are
supporting buildings). as follows: selecting a part of the layer (CLIP – coping a
 TRENDS: "What has changed since./.?" part of a coverage), removing some graphic primitives
The third question might involve both of the first two (ERASE), creating some subdivisions (SPLIT),
and seeks to find the differences within an area over assembling some adjacent maps (MAPJOIN), removing
time, for example, changes in forest cover or the extent the limits that separate the polygons of same type
of urbanization over the last ten years. (DISOLVE) and eliminating some lines (ELIMINATE).
 PATTERNS: "What spatial pattern exists...?” The analyze of proximity represents the
This question is more sophisticated. One might ask this identification some contours at equal distance to graphic
question to determine whether landslides are mostly primitive (BUFFER)(Fig. 10).
occurring near streams, or to find out which are the
traffic points where the accidents occur more frequently.
It might be just as important to know how many
anomalies there are that do not fit the pattern and where
they are located.
 MODELLING: "What IF...?"
"What if…" questions are posed to determine what
happens, for example, if a new road is added to a
network or if a toxic substance seeps into the local Fig.10 Diagram of simple buffers and a setback
groundwater supply. Answering this type of question

6. Fig. 11 Geometric spatial queries
6.2. Operations on multiple layers
In order to accomplish the operations on multiple
layers is needed that all maps involved in this process
should be at the same scale and should have the same
system of coordinates.
These operations are called operations on vertical
and they are based on the relations between data on
different layers. So, a complex layer may be dissolved
in thematic layers and many layers may be combined.
These operations are of type “overlay”, proximity
analyze and analyze of spatial correlations.
The overlay analyzes (Fig. 10) creates some
combinations between graphic primitives on different
layers and built links between data based on some
logical conditions imposed of type: AND, OR, XOR, Fig.12 Example of Polygon-overlay analyze
NOT (negation).
These operations are as follows: UNION and
INTERSECT (intersection). UNION makes that two or
many layers should overlap and should result a new
coverage. It uses the logic operator OR and it does not
that the layers should contain the same type of graphic
primitives. INTERSECT uses the logic operator AND,
the result being a coverage that contains the common
part from the layer and data from the second layer. In
this situation the layers must be at the same type of
graphic primitive.
This operation is more used on layers that contain
only polygons.
Fig.13 Example of Raster-overlay analyze

7. execute responsibilities, and respond to request from
6.3. Generating and interpreting the digital model of citizens, potential developers and other clients.
the terrain To accomplish the digital maps and to introduce the
G.I.S. systems into local community sectors will
increase the level and quality of their decisional process.
Being very used in different fields, and starting from the
information necessary to any citizen and till
environment protection, from the marketing strategies to
resources administration, the G.I.S. marked a revolution
in solving the problems. The quality information means
quality decisions. And G.I.S. offers this possibility,
transforming some simple information in real
information and offering the interactive access to them.
8. References
1. DUMITRU, G. „Geographic Information
System”, Ed. Albastra, 2001
Fig. 14 The 3D model of the surface
2. HERBEI M. - “Performing a Geographic
Information System into the areas affected by the
mining exploitations by using modern techniques
and technologies” - Doctorate thesis, Petrosani,
2009
3. HERBEI O., HERBEI M. – “Geographic
Information Systems. Theoretical and
applications”, Ed. Universitas, Petroşani,
4. KONECNY, G. – “Geoinformation”, London,
2003
Fig.15 Example of map of Slope
7. Conclusions
A geographic information system is an information
management tool that helps us to store, organize and
utilize spatial information in a form that will enable
everyday tasks to be completed more efficiently. Since
its rapid growth over the last two decades, G.I.S.
technology has become a vital element for us to
maintain and integrate information. G.I.S. software, and
the hardware required to operate it, have become much
more affordable and easy to use. This has resulted in the
ability to develop a G.I.S. without making large
investments in software, hardware and the support staff
that were once needed to implement it. With the
implementations of G.I.S., we will see dramatic
improvements in the way we access information,