lecture introduction gis

8/12/2019 Lecture Introduction GIS

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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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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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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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What is a GIS? - definitions

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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

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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


Known locations on earth

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GIS 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

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(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 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 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 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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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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Vector model example:

opograp ca map scre e a a

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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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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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Raster model example:

Travel time to

highway access

cont nuous ata

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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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Raster disadvantages

Topological relationships are not explicit

Requires huge computer memory for high resolutions

Poor cartographical presentation on low resolution

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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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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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Source: T.Nijeholt at nl.wikibooks

G hi D d


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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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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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lecture introduction gis

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