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Digitale Ruimtelijke Data 2011
Geographical Information Systems en Remote Sensing
Geo ra hical Information S stems
, , ,
Spatial Information Laboratory,
Institute for Environmental Studies
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Outline lecture
What is GIS?
Definitions
Spatial versus geographic data
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What is a GIS? A bit of history
Planimeter (Coradi, 1886)divider caliper (steekpasser) Map engraving on lithographic stone (1915)
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Field mapping Theodolite Kern PG-2 stereoplotter
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What is a GIS? A bit of history
The impact of GIS
'the biggest step forward in the handling ofgeographic information since the invention of the
map (DoE1, 1987, p 8)
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1DoE - Department of Environment (1987) Handling Geographic Information (H.M.S.O., London)
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What is a GIS? A bit of history
Succes of GIS thanks to
Data integration capabilities
GPS
Internet
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Outline lecture
What is GIS?
Definitions
GIS or GIScience?
Applications
What is GIS data?
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What is a GIS? - definitions
Geographical Information System
,
software, people andprocedures designed to
support the capture,
management,,
and display of
spatially-referenced data
for solving complexspatial planning and
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.
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What is a GIS? - definitions
-
GIS is defined according to capability and purpose for
which it is a lied
Often used definition is from Burrou h (1986 :
retrieving at will, transforming and displaying
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What is a GIS? Tool or Science?
Geographical Information Science
Recognition of GIS as a formalisation of geographictheory and practise.
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What is a GIS? Tool or Science?
Concerns about possible misuse of GIS:
Move from GIS as a concert pianist model as a toolconfined to experts, to a child of ten model in which
t e power o GIS is avai a e to a Mic ae
Goodchild, 2006)
GIS should be used in combination with knowledge
instead of bein a substitute for it and eo le usin
GIS should therefore be trained in the nature of
geographical phenomena.
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What is a GIS? Disciplines & applications
Scientific disciplines using GIS
Earth and environmental sciences-Environmental impact / risk assessment
-
Spatial economics-Economic value mapping
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-Erosion/hydrologic modeling
-Geological mapping / mineral exploration
Carto ra h
-Transportation economics
-Land use modeling
Landca e ecolo
Remote sensing/photogrammetry
Geodesy/cadastral surveying
Health geography
Criminology
Civil engineering
Historical geography
Public participation GIS
Forestry
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Climate change sciences
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What is a GIS? Disciplines & applications
Daily life GIS applications
- y managemen energy
infrastructure, water supply,telecommunication, sewage, etc.)
- oca on ase serv ces
-(Militairy) terrain evaluation-Geobrowsers
-Water management (water
boards)
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-Internet mapservices (news
sites, online house finding
management and traffic control
-Land administration (cadastre)
, ,
weather reports, etc.)
-Etc.
- ar nav ga on-Fleet management
-City planning
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-Precision agricultureSee for more examples e.g.
http://www.gisdevelopment.net/application/index.htm
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GIS data
What is GIS?
What is GIS data? Introduction
Raster and vector models
Coordinate systems & projections Georeferencing
Data Quality
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GIS Data
(where)
Attribute data: description of spatial data features
(what)
Topology: definition of spatial data relationships
(how)
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GIS Data
Examples of geographic data
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GIS Data
Examples of spatial data
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GIS Data
Examples of geographic data 122155
Coordinate s stem:
RijksdriehoekstelselNetherlands
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GIS Data
Examples of geographic data
Known locations on earth
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GIS Data
Examples of geographic data
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GIS Data
Examples of attribute data
- The population of town X is 34568 people
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GIS Data
Examples of attribute data
- The number of cars per household per neighborhood is 0,6
Aantal autos per
huishouden
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GIS Data
SpatialNon-spatial
(geometry, object,
entity or feature)
componen(attributes)
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GIS Data
Topology: spatial relations in GIS
Source: http://www.edc.uri.edu/nrs/classes/NRS409/Lectures/3GISdefined/topology.gif
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GIS Data
Examples of topological questions
-
(Amsterdamse bos)?
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Source: Kadaster-TDN, Soil statistics map 2000 Netherlands 1:10.000
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Geographic Data: introduction
Examples of topological
- Can I cross the
Amstel river via the
Utrechtse brugcom ng rom t e
Amsteldijk?
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Source: Google Maps, October 2009
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GIS Data
Examples of topological questions
-
versa?
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Source: Broekhuizen, J., M. Jansen, J. Slot (2008) Segregatie in het basisonderwijs in
Amsterdam, Gemeente Amsterdam Dienst Onderzoek en Statistiek
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Geographic Data structures
Geographic phenomena can have clear boundaries, no real
(diffuse) boundaries or virtual boundaries
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Geographic Data structures
Geographic phenomena with clear boundaries
discrete phenomena, e.g. trees, streams, buildings
(Mostly) presented as point, line or
ol on features in vector data
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Geographic Data structures
Geographic phenomena with no real (diffuse) boundaries
continuous phenomena, e.g. slope, precipitation, temperature
(Mostly) represented with raster data
(or with contour lines in vector data)
Can be visualized/
analyzed in 3Dsurface models
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Geographic Data structures
Geographic phenomena with virtual or agreed boundaries
(Mostly) presented as statistical
ol on areas in vector data.
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Outline Lecture
What is GIS?
What is GIS data? Introduction
Raster and vector models
Coordinate systems & projections Georeferencing
Data Quality
Where to find digital spatial data?
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Geographic Data structures: raster and vector
Two ways of storing geographic features: raster and vector
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Source: http://cookbook.hlurb.gov.ph/files/images/RasterVector.preview.jpg
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Geographic Data structures: raster and vector
Vector data:
Points are stored as single xy coordinates
nes are ser es o po nts
Polygons are composed of closed lines Attributes are attached to each feature
through an unique numeric code
Many attributes may be stored in each file
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Geographic Data structures: raster and vector
Vector model example:
opograp ca map scre e a a
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Geographic Data structures: raster and vector
Raster data:
One gridcell can only contain one value at a time
ost y as ntegers o ten as co e num ers
Floating point (decimals/real) values, or sometimes textcharacters also possible
Stored as an array of values in table or text file
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Geographic Data structures: raster and vector
Spatial detail controlled by cell size (resolution)
5 km500 m 25 km
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g reso u on,
small cell sizeow reso ut on,
large cell size
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Geographic Data structures: raster and vector
Raster model example:
Travel time to
highway access
cont nuous ata
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Geographic Data structures: raster and vector
Suitable for data with high spatial variability
Spatial analysis often simpler and faster,
especially raster overlays (map algebra)
Some types of analysis only possible with
raster
Easy to integrate with satellite data
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Geographic Data structures: raster and vector
Raster disadvantages
Topological relationships are not explicit
Requires huge computer memory for high resolutions
Poor cartographical presentation on low resolution
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Geographic Data structures: raster and vector
Vector advantages
Efficient data storage (about 10% compared toraster data)
Topological analyses are more efficient or only
possible with vector (e.g. network analysis)
Greater spatial accuracy possible (cartography)
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Geographic Data structures: raster and vector
Vector disadvantages
Complex data-structure
Precision of boundaries can be misleading
Production of vector maps is expensive (time-
consuming)
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h d
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Geographic Data structures: raster and vector
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Source: T.Nijeholt at nl.wikibooks
G hi D d
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Geographic Data structures: raster and vector
Choosing your data model (raster and/or vector):
(discrete/continuous)
Choosing not always
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G hi D t t t t d t
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Geographic Data structures: raster and vector
Choosing your data model
(raster and/or vector):
Expected type and scale of
analyses (storage and
processing speed)
Cartographic detail needed
Vector raster conversion
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G hi D t i ti
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Geographic Data: organisation
La er based a roach:
Each topic is stored in a
For ot raster an vector
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Geographic Data: input
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Geographic Data: input
npu a a ypes
canne or g ze maps
Satellite images
Field observations / GPS
Tables
46 Existing GIS data
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Geographic Data: coordinate systems and projections
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Geographic Data: coordinate systems and projections
A map is a projection of the earths rounded surface on a
flat surface
See lectures and practical
on e nes ay e ruary
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Geographic Data: Georeferencing
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Geographic Data: Georeferencing
Georeferencing: Linking information of geographical
More about georeferencing coming Friday, 4 February
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Outline Lecture
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Outline Lecture
What is GIS?
What is GIS data? Introduction Raster and vector models
Coordinate systems & projections
Georeferencing
Data Quality
Where to find digital spatial data?
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Geographic Data: Data Quality
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Geographic Data: Data Quality
To judge data quality metadata is needed
Metadata are the who, what, when, where, why and how of
the data
Identification
Source administration
Data organisation
Distribution conditions
Spatial reference
Spatial extent Quality (accuracy, lineage, completeness, logical consistency)
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More about spatial data quality on Wednesday 16 February
Outline Lecture
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Outline Lecture
What is GIS?
What is GIS data?
Exercise:
Introduction in D107 at 14:00
Practical this afternoon at 14:30 in S203 and S205
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