1. An Introduction to GIS
Land Information Systems
Fahlstrom - Map of the Worls
Silvia Franceschi
Friday, September 10, 2010
2. An Introduction to GIS - Land Information Systems
Objectives:
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Friday, September 10, 2010
3. An Introduction to GIS - Land Information Systems
Land Information Systems (LIS)
Geographic Information Systems (GIS)
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4. An Introduction to GIS - Land Information Systems
Definition:
!
There is not a precise definition for the meaning of GIS
!
The definition depends on the “cultural context”
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Silvia Franceschi
Friday, September 10, 2010
5. An Introduction to GIS - Land Information Systems
Definition:
!
There is not a precise definition for the meaning of GIS
!
The definition depends on the “cultural context”
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Silvia Franceschi
Friday, September 10, 2010
6. An Introduction to GIS - Land Information Systems
Definition:
!
There is not a precise definition for the meaning of GIS
!
The definition depends on the “cultural context”
!
The proliferation of specialised slang
!
Difficulties in understanding between professionals
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Silvia Franceschi
Friday, September 10, 2010
7. An Introduction to GIS - Land Information Systems
Information System:
Set of tools, procedures, and people that have the task to organise,
select, archive, and communicate the data regarding the activities of an
organisation (public or private).
Its objective is to make available to the decision makers all the
information necessary to make the best possible choices.
“Set of tools to acquire, extract, process, archive, and REPRESENT
spatial data from the real world” (Burrough 1986)
“Set of procedures, founded on the use of information technology, used
to archive and process georeferenced data” (Aronoff 1989)
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8. An Introduction to GIS - Land Information Systems
History
Originally developed in Canada, GIS soon spread all over the world. They
are mainly used by public bodies to manage land data.
The use of GIS has grown greatly in the last ten years as an essential tool
for urban planning, and the management and planning of environmental
resources.
Their diffusion is due, mainly, to the great capacity to save, recover,
analyse, model, and map large areas by means of very large amounts of
spatial data.
GIS are now widely used in the environmental field and in research
because of the possibility to access different data correlated by their
position in space.
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Silvia Franceschi
Friday, September 10, 2010
9. An Introduction to GIS - Land Information Systems
Information System:
GIS are information systems dedicated to the study and management of
geographic data. By means of these tools it is possible to:
- collect;
- model;
- manipulate;
- analyse; and
- present
geographically referenced data or, to put it better, GEOREFERENCED data.
GIS allows the superposition of various levels of information regarding an
area. It is therefore possible to obtain a better understanding of the
processes that affect the area and the factors that characterise it.
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Friday, September 10, 2010
10. An Introduction to GIS - Land Information Systems
Information System:
Immagine non modificabile.
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11. An Introduction to GIS - Land Information Systems
GIS – What is it?
!
Geographic Information
! Information relating to the position of an object on the surface of the Earth
! Knowledge of “what is in a certain place at a certain time (we must not forget
the time factor)”
!
Geographic Information Technologies
! Technologies for working with these data
! Global Positioning Systems (GPS)
! Remote Sensing (RM)
! Geographic Information Systems (GIS)
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12. An Introduction to GIS - Land Information Systems
GIS – Geographic Information System
1. Complete tool suitable for land
representation and the processing of CAD DATABASE
data associated with georeferenced
objects.
GIS
2. To each object (points, lines, areas)
spatial coordinates are assigned that
Image
are congruent with the cartographic Processing
base reference.
3. GIS integrates the characteristics of various types of software.
To use a GIS is not limited to just using a software tool, but rather it
means adopting a working method. 10
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13. An Introduction to GIS - Land Information Systems
What a Geographic Information System (GIS) is not.
The most common error when referring to GIS is to confuse the
Geographic Information System with one or more of its component
technologies.
!
- cartographic base
!
- GIS is not a digital cartography
!
- the cartographic base is simply one of the starting
points upon which a GIS is developed
!
- GIS is not a more or less developed software package
!
- it is a system that requires the existence of a well-
defined project by the end user
!
- it is a MODEL REPRESENTATION OF THE REAL
WORLD and, therefore, a working method 11
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14. An Introduction to GIS - Land Information Systems
Application Fields
- Agriculture (land use) - Real Estate Management
- Economics (market analyses) - Earth Observation
- Defence (logistics, planning) - Telecommunications
- Ecology and landscape conservation - Administrative Data
- Utility networks (water, gas, power) Management
- Civil Protection - Infrastructure Management
- Natural Resource Management - Preparation of Maps and
- Land Registry Databases
- Forestry - Mining and Extraction
- Public Health (epidemiology) - Surveying and Topography
- Education - Transportation and Logistics
- Geography - Urban Planning
- Oceanography - Research 12
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15. An Introduction to GIS - Land Information Systems
How does a GIS work?
Immagine non modificabile.
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16. An Introduction to GIS - Land Information Systems
Using Data
GIS allows for the organised archiving of data used in analytical and
management activities.
The geographic data can be correlated with each other, organised into
structures and according to needs.
Generally, the data that can be imported are:
- graphic elements (points, lines, areas)
- images
- attribute data associated with the preceding elements
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17. An Introduction to GIS - Land Information Systems
What questions can be answered?
!
Position: What is there in ...?
!
Conditions: Where is ...?
!
Trends: What has changed ...?
!
Spatial distribution: What spatial distribution is there?
!
Modelling: What happens if ...?
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18. An Introduction to GIS - Land Information Systems
Examples
!
Position: What type of soil can be found at these coordinates? Or near
this type of structure?
!
Conditions: Identify the areas which fall within the temporal buffer
zone (60 days) for water wells
!
Trends: What type of vegetation has undergone changes in comparison
with the 1950 map?
!
Spatial distribution: Is there a correlation between vulnerable areas
and nitrate pollution?
!
Modelling: What happens if the public wells of Milan are polluted?
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19. An Introduction to GIS - Land Information Systems
Main Functions
• Entering and verifying data
• Data transformations: set of operations used to correct and homogenise
the data set (coordinate transformation, editing,...)
• Data storage: in an appropriate DBMS
• Analysis: application of conceptual models that reproduce the physical
phenomenon being studied, with new data being created as a
consequence
• Output of results: in various forms (digital, cartographic...)
• Models of geographic data: the data of a geographic data base are made
up of three components:
• Spatial aspect: geometry/topology
• Quality aspect
• Semantic aspect: alphanumerical, numerical, and statistical attributes 17
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20. An Introduction to GIS - Land Information Systems
Cartography
A MAP can be simply defined as a graphic representation of the real
world. Maps are only a representation, it is not possible to include in a
map all the complexity of reality.
Maps can be used to visualise cultural and physical aspects of an
environment.
Topographic maps are those that represent general information, such
as the disposition of roads, land use, altitude, rivers, water bodies...
However, there are also maps that represent non-geographical
elements, such as the maps of meteorological evolution, temperature,
pressure... The use of these maps is decidedly more specialistic than
that of topographical maps.
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21. An Introduction to GIS - Land Information Systems
Cartography
!
Set of:
!
coordinates associated to elements (points, lines, polygons)
!
relationships between elements
!
attributes of the elements
It can be seen as the reverse of traditional paper mapping:
!
traditional mapping: drawing coordinates
!
digital mapping: coordinates drawing
The content and uses of digital mapping are greater than those of
traditional mapping (in fact, the latter can be derived from the
former).
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22. An Introduction to GIS - Land Information Systems
Scale
The concept of SCALE may seem redundant in digital mapping because
it is possible to view and print the data at an magnification, given that
the coordinates are absolute.
However, the scale depends on the precision of the coordinates.
Nominal scale: scale at which the map print has the same metric
requirements of the traditional map (precision, graphical error).
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23. An Introduction to GIS - Land Information Systems
Spatial Relations between Elements
There are three types of relations between elements: :
!
spatial
!
topological
!
proximity
Directional relations: they depend on the orientation of the map
!
opposite north
!
on the other side south
!
above east
!
below west
and combinations of orientations.
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24. An Introduction to GIS - Land Information Systems
Topological Relations
EQUIVALENCE
PARTIAL EQUIVALENCE
CONTAINMENT
ADJACENCY
SEPARATENESS 22
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25. An Introduction to GIS - Land Information Systems
Proximity Relations
These indicate, QUALITATIVELY and QUANTITATIVELY the distance
between objects:
!
qualitative:
!
near
!
far
!
in the vicinity of ..
!
quantitative: d=1532 m
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26. An Introduction to GIS - Land Information Systems
Information Layers
In digital cartography the information layers can be separated (very
often they need to be).
HYDROGRAPHIC NETWORK
SETTLEMENTS
PRIMARY ROAD NETWORK
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27. An Introduction to GIS - Land Information Systems
Data: Elements and Fields
Spatial data is traditionally divided into two classes: RASTER and
VECTOR
FIELDS or RASTERS: objects defined almost everywhere within the domain of
interest, very often continuous. For example, temperature, pressure, altitude.
They are represented in discrete form with regular matrices of attributes
(matrix models or georeferenced rasters), triangular irregular networks (the TIN
model), or with contour lines.
ELEMENTS or VECTORS: discrete and discontinuous objects that are precisely
defined. For example, buildings, administrative areas, road networks.
They are represented with vectorial models, that may also be topological, with
associated tables of attributes.
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28. An Introduction to GIS - Land Information Systems
Fields
Altitude (DTM: Digital Terrain Model)
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29. An Introduction to GIS - Land Information Systems
Raster
DTM
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30. An Introduction to GIS - Land Information Systems
DTM/DEM
"Digital Elevation Model" (DEM): it represents the elevations of a
particular surface. When using a DEM, the reference surface must
always be stated.
"Digital Terrain Model" (DTM): it represents the elevations of the
surface of the Earth, that is to say the terrain. A DTM is a specific case
of a DEM where the surface represented is that of the Earth.
“Digital Surface Model” (DSM): it represents the elevation of the surface
of the Earth, including those elements that are above the surface.
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31. An Introduction to GIS - Land Information Systems
DTM/DEM
The DTM and DEM describe a continuous surface by means of a
finite number of three-dimensional points (x,y,z values) in space
(x,y,z). The xyz triplets are usually distributed irregularly because
they have been obtained by different measuring methods. These
irregular points are generally put into a regular grid (usually square
with the same amplitude in the x-direction as in the y-direction) by
means of various interpolating methods (e.g. kriging, spline, least
squares,...). Each triplet (x,y,z) of the DTM/DEM represents,
therefore, an area, that is to say, a square of the grid. The squares
are called CELLS or PIXELS (= picture elements).
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32. An Introduction to GIS - Land Information Systems
DTM
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TIN - (Triangular Irregular Network)
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Contour Lines
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Contour Lines
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36. An Introduction to GIS - Land Information Systems
Elements: Points, Line, and Areas
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37. An Introduction to GIS - Land Information Systems
Elements
!
The elements are made up
of:
!
geometric primitives:
! point
! curve
! surface
!
topological primitives:
! node
! edge
! face
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38. An Introduction to GIS - Land Information Systems
Rasterisation of the Elements
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39. An Introduction to GIS - Land Information Systems
Rasterisation of the Elements
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40. An Introduction to GIS - Land Information Systems
Comparison: Raster - Vector
!
Vector !
Raster
!
advantages advantages
!
! memory use ! algebra on maps
! explicit topology ! operations are simple
! “resolution”, precision and intuitive for the
of the coordinates user
!
disadvantages
! some operations are disadvantages
!
taxing ! memory operations
! overlay is complicated ! implicit topology
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41. An Introduction to GIS - Land Information Systems
Raster - Vector
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42. An Introduction to GIS - Land Information Systems
Raster - Vector
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43. An Introduction to GIS - Land Information Systems
Raster - Vector
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44. An Introduction to GIS - Land Information Systems
Topology
Topological relations are relations between objects that are independent
of the orientation of the map, and invariant to elastic or continuous
deformations (e.g. change of reference system and/or coordinate
system). These relations are used to express congruity constraints
Immagine non modificabile.
between objects.
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45. An Introduction to GIS - Land Information Systems
Raster Geometric Primitives
These are based on frames with which space is divided into regular shapes
and sizes.
Each element is defined by its row and column numbers (2D) and layer
number (3D).
The position of the origin of the reference system must be defined.
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46. An Introduction to GIS - Land Information Systems
Raster Geometric Primitives - 2D
GRID: regular distribution of
points defined by the nodes of the
grid, derivable from a 2D structure.
They are completely defined by
row and column numbers.
PIXEL: two-dimensional geometric
primitive, corresponding to the
basic element of a 2D structure.
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47. An Introduction to GIS - Land Information Systems
Raster Geometric Primitives - 2D
GRID: regular distribution of
points defined by the nodes of the
grid, derivable from a 2D structure.
They are completely defined by
row and column numbers.
PIXEL: two-dimensional geometric
primitive, corresponding to the
basic element of a 2D structure.
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48. An Introduction to GIS - Land Information Systems
Topological Geometric Primitives
NODE: 0-dimensional primitive. It can be connected (by an edge) or
isolated.
EDGE: 1-dimensional topological primitive. It represents an orientated
connection between two nodes (that may coincide).
FACE: 2-dimensional geometric primitive, described by an external ring
(a closed set of edges that do not cross) and either none or many
internal rings.
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49. An Introduction to GIS - Land Information Systems
Vector File Formats
The most common vector file format is undoubtedly the shapefile
format: .shp.
A shapefile is made up of a family of files which, specifically, includes:
! .shp contains the information related to the form of the features
! .shx contains an index of the position of the features to speed up the
queries made
! .dbf contains the attributes related to the features
! .prj contains the information related to the coordinate system and the
projection of the data
! .shp.xml contains the metadata linked to the features
Other formats supported by the vast majority of GIS are: tab, dxf, dwg,
E00, ..., ascii.
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50. An Introduction to GIS - Land Information Systems
Raster File Formats
The most common are:
• TIFF
• GIF
• JPEG
• ASCII
The raster files of images that can be viewed with a GIS need to contain
information relating to the coordinate system and the projection. Files
such as TIFF files, therefore, need to be georeferenced. That is to say,
they must be GEO-TIFF files. The information relating to the projection
can be included within the TIFF file itself or it can be written to a
separate file, usually with extension TFW (or JGW).
ASCII files contain all information relating to the region and the
localisation of the data. 47
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51. An Introduction to GIS - Land Information Systems
Overview of Open Source Desktop GIS
•The most widespread GIS in the field of open source GIS are:
-GGRASS: the oldest of the open source GIS. Originally developed by the United
States Department of Defence, it is very powerful in raster analysis
(www.grass.itc.it)
-JUMP: viewer which offers the possibility of vectorial data analysis
(http://openjump.org)
-GVSIG: viewer which offers the possibility of vectorial data analysis. There is
also an integration of raster components but not sufficient for raster analysis
(www.gvsig.gva.es)
-QGIS: considered the simple graphic interface for GRASS (www.qgis.org)
-JGRASS: GIS dedicated to environmental analysis, it allows the viewing and
analysis of raster and vector data (www.jgrass.org)
-uDig: vectorial data and image viewer (http://udig.refractions.net) 48
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52. An Introduction to GIS - Land Information Systems
Overview of Commercial Desktop GIS
I most widespread GIS in the field of commercial GIS are:
• ESRI: ArcGIS, Arcview, Arcreader... probably the the biggest family of GIS
software in the commercial field (www.esri.com)
• ERDAS-IMAGINE: satellite image management (www.geosystems.de)
• ERMAPPER: high-resolution image management ( orthorectification,
mosaic, reprojection, colour balance and compression)
• MAPINFO: very easy to use; best described as a viewer that manages
vectorial data well (www.mapinfo.com)
• AutoCAD Map 2004: advanced management of geographic data along with
image management (www.autodesk.com)
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53. An Introduction to GIS - Land Information Systems
GIS Support Databases
The database is an essential component of the GIS in that it contains all the
information that will be viewed and analysed, both with desktop GIS and
WebGIS. In the field of proprietary databases, the most widespread are:
• ORACLE: with a spatial extension to support geometries (Oracle-
Spatial)
• ArcSDE: spatial database by ESRI
• Access: this is not a spatial database but a mechanism can be
constructed to link information to geometric features.
The most widespread open source databases are:
• Postgres: the most popular, with spatial extension PostGIS
• HSQLDB: this is not a spatial database, it is only a relational database
...
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54. An Introduction to GIS - Land Information Systems
Open Source WebGIS
The two open source development environments for geospatial data
currently used are:
!
GEOSERVER
!
MAPSERVER
Graphic interfaces for these products are available for the production of
WebGIS such as those that are often found on the websites of public
bodies and research centres. Some tools of this type are:
!
Ka-Map
!
Py-WPS
!
...
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55. An Introduction to GIS - Land Information Systems
Open Source WebGIS
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56. An Introduction to GIS - Land Information Systems
Italian Digital Cartography
Immagine non modificabile
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GIS Characteristics
With respect to the purely geometric representation of objects, a GIS
also needs to store and manage the information about the mutual
spatial relationships between the various elements. That is, it must
structure the data and define the topology.
As well as geometric and topological data, the GIS must also allow for
the insertion of descriptive data relative to individual real objects, that
is to say the ATTRIBUTES.
The structure that is capable of saving the spatial and geometric
relations and attributes is referred to as a relational structure.
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58. An Introduction to GIS - Land Information Systems
GIS Characteristics
In a GIS, the coordinates of an object are neither stored with respect to
an arbitrary reference system nor with respect to the coordinate system
of the device being used. They are stored according to the reference
system in which the object is really found and with their real
dimensions, not to scale.
The scale of representation becomes solely a parameter used to define
the level of accuracy and the resolution of the graphical information.
Depending on the scale, smaller elements may not be visualised and one
sees only areas of terrain characterised by the same quantity.
GIS allows us to manage the data like 3-dimensional objects in a real 3-
dimensional system. No longer do we need to simply attribute a height
to an object. 55
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GIS Characteristics
Starting from a TIN, a DTM or a DEM it is possible to:
!
interpolate contour lines
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60. An Introduction to GIS - Land Information Systems
GIS Characteristics
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61. An Introduction to GIS - Land Information Systems
GIS Characteristics
Starting from a TIN, a DTM or a DEM it is possible to:
!
interpolate contour lines
!
carry out a visibility analysis
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GIS Characteristics
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63. An Introduction to GIS - Land Information Systems
GIS Characteristics
Starting from a TIN, a DTM or a DEM it is possible to:
!
interpolate contour lines
!
carry out a visibility analysis
!
generate longitudinal profiles
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64. An Introduction to GIS - Land Information Systems
A partire da un TIN, un DTM o un DEM è possibile:
GIS Characteristics
!
interpolare curve di livello
!
effettuare un'analisi di visibilità
!
generare profili longitudinali
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65. An Introduction to GIS - Land Information Systems
GIS Characteristics
Starting from a TIN, a DTM or a DEM it is possible to:
!
interpolate contour lines
!
carry out a visibility analysis
!
generate longitudinal profiles
!
carry out slope analysis, exposition analysis...
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GIS Characteristics
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67. An Introduction to GIS - Land Information Systems
GIS Characteristics
Starting from a TIN, a DTM or a DEM it is possible to:
!
interpolate contour lines
!
carry out a visibility analysis
!
generate longitudinal profiles
!
carry out slope analysis, exposition analysis...
!
calculate real distance, taking account of the vertical coordinate
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68. An Introduction to GIS - Land Information Systems
GIS Characteristics
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69. An Introduction to GIS - Land Information Systems
GIS Characteristics
Starting from a TIN, a DTM or a DEM it is possible to:
!
interpolate contour lines
!
carry out a visibility analysis
!
generate longitudinal profiles
!
carry out slope analysis, exposition analysis...
!
calculate real distance, taking account of the vertical coordinate
!
query a list of attributes and extract the required values
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70. An Introduction to GIS - Land Information Systems
GIS Characteristics
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71. An Introduction to GIS - Land Information Systems
GIS Characteristics
Starting from a TIN, a DTM or a DEM it is possible to:
!
interpolate contour lines
!
carry out a visibility analysis
!
generate longitudinal profiles
!
carry out slope analysis, exposition analysis...
!
calculate real distance, taking account of the vertical coordinate
!
query a list of attributes and extract the required values
!
extract the morphological characteristics of the terrain
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72. An Introduction to GIS - Land Information Systems
GIS Characteristics
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73. An Introduction to GIS - Land Information Systems
GIS Characteristics
Starting from a TIN, a DTM or a DEM it is possible to:
!
interpolate contour lines
!
carry out a visibility analysis
!
generate longitudinal profiles
!
carry out slope analysis, exposition analysis...
!
calculate real distance, taking account of the vertical coordinate
!
query a list of attributes and extract the required values
!
extract the morphological characteristics of the terrain
!
process quantities relative to the hydrographic network
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74. An Introduction to GIS - Land Information Systems
GIS Characteristics
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75. An Introduction to GIS - Land Information Systems
GIS Characteristics
Starting from a TIN, a DTM or a DEM it is possible to:
!
interpolate contour lines
!
carry out a visibility analysis
!
generate longitudinal profiles
!
carry out slope analysis, exposition analysis...
!
calculate real distance, taking account of the vertical coordinate
!
query a list of attributes and extract the required values
!
extract the morphological characteristics of the terrain
!
process quantities relative to the hydrographic network
!
carry out stability analysis of the catchment
!
carry out hydrological analysis at event scale
!
...
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76. An Introduction to GIS - Land Information Systems
JGRASS
The Research Centre for the development of algorithms implemented in
JGrass is the Department of Civil and Environmental Engineering of the
University of Trento (Italy) and CUDAM (University Centre for the
Defence of Mountain Environments), also at the University of Trento.
The Development Centre is HydroloGIS of Bolzano (Italy), although
there are other developers at CUDAM in Trento.
The JGrass starting point is GRASS GIS, which currently represents the
most important Open Source project in the GIS field. GRASS is slowly
evolving towards an attractive solution for the commercial and
productive sectors. The biggest obstacle to the commercial blooming of
GRASS is without doubt its versatility problem. Many professionals use
Windows and Mac-OS as the preferred operating systems, and many
businesses do not provide the possibility of using Linux (which is the
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JGRASS
JGrass, developed to simplify the use of GRASS on different operating
systems, has set itself the following objectives:
•versatility - the possibility to run GRASS on Windows, Unix/Linux
and Mac-OS indifferently (write once, run everywhere)
•the possibility for anyone, by means of the framework that has
been created, to develop with ease additional modules, particular
functions, and application oriented interfaces by means of XML
scripting
•scripting - the possibility to use a Java-based scripting language in
order to automatise certain processes (programmer and scientific -
work oriented)
•simplicity of use - menu bars, tool bars and icons aimed at
simplifying the interface (end-user friendly)
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Silvia Franceschi
Friday, September 10, 2010
78. An Introduction to GIS - Land Information Systems
JGRASS
Over the last number of years various attempts have been made to
combine the strengths of Java and GRASS. The first of these was the
wrapping of the GRASS libraries in Java by Alexandre Sorokine. Shortly
thereafter, at the Centre for Environmental and Nuclear Sciences of the
University of the West Indies (Jamaica), John Preston began to develop
a Java/Swing application for the visualisation of geochemical maps.
At the beginning of 2003 Dr Rigon, of the Department of Civil and
Environmental Engineering and CUDAM of the University of Trento,
decided to support the Jamaican project in a concrete way by
supplying funds and a developer, and coordinating with the research
group at ITC, which includes Markus Neteler. In this way the
development of JGrass began.
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Silvia Franceschi
Friday, September 10, 2010
79. An Introduction to GIS - Land Information Systems
JGRASS
At the moment JGrass is an application that can be run locally, although
the future implementation of remote running is planned. It is a Java/
RCP application based on an MDI (multiple document interface) and
provides standardised ways of interaction between the interface and the
GRASS kernel.
Although we are trying to keep JGrass, as much as possible, in "pure
Java", some parts are still written in the native language of GRASS by
means of Sun's API JNI technology.
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Silvia Franceschi
Friday, September 10, 2010
80. An Introduction to GIS - Land Information Systems
JGRASS
JGrass is a free and open source GIS that can be freely downloaded
from the website:
www.jgrass.org
All the instructions for use are found on the same webpage, along with
documents of the available commands.
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Silvia Franceschi
Friday, September 10, 2010
81. An Introduction to GIS - Land Information Systems
Thank you for your attention.
G. Ulrici -
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Silvia Franceschi
Friday, September 10, 2010