Dr Nigel Trodd

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Sourcing Geodata

• Dr Nigel Trodd
• Coventry University

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giservices require
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geospatial data consist of

• geographical entities
• attributes
• metadata

geospatial data are useful only if
available accessible fit for purpose referenced
to a common spatial referencing system
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Aim objectives

• To identify understand the process of building
  a geospatial database
• We will
• identify sources of geographically referenced
  data
• exemplify techniques to acquire geospatial data

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importance of data acquisition

• constrains data analysis
• influences output quality
• determines economic viability
• 50 of the total cost
• 70 - 80 of the time of a GIS project
• revolve around data acquisition

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the cost of data
10 seats 10 seats 100 seats 100 seats

Hardware 30 3.4 250 8.6
Software 25 2.8 200 6.9
Data 400 44.7 450 15.5
Staff 440 49.1 2000 69.9

Total 895 100 2900 100
Source Longley et al. 2001
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the data stream in GIS
a system to

• capture
• store
• check
• integrate
• manipulate
• analyse
• display spatial data

• capture
• store
• check
• integrate
• manipulate
• analyse
• display spatial data

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sourcing data

• Determine location
• Georeferencing system
• Determine extent of phenomena
• from reality to spatial data structures
• Characterise properties of phenomena

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data sources

• Primary data sources
• Field survey
• Questionnaires
• Aerial photos satellite images
• Secondary data sources
• Maps other published documents
• Government databases e.g. health, crime, social
  security, land registry
• Private sector databases e.g. credit rating,
  lifestyle (EPOS)

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primary data sources
Field survey
Satellite Navigation System
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GPS GLONASS principles
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Limitations Working environment Selective
availability Range uncertainty
Data quality
SA on SA off DGPS
Horizontal 100m 10-20m lt1-5m
Vertical 160m
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GPS applications
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remote sensing the acquisition of physical data
of an object without touch or contact (Lintz
Simonett 1976)
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Earth observation by remote sensing
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to local
Global
IKONOS 1m-sharpened multispectral image Poppy
fields in Kandahar, Afghanistan Image courtesy of
United Nations Office on Drugs Crime
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Change detection deforestation fragmentation
in the Amazon
1975
1986
1992
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secondary data sources
digitising scanning
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but
Cartographic licence and Data Currency
Imagery-1997
Map-1978
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how to avoid digitising
electronic data transfer
spatial data mining
Nick Chrisman http//faculty.washington.edu/chrism
an/G460/Lectures.html
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Government organisations with GB geodata holdings
Ordnance Survey GB Ordnance Survey Northern Ireland Topographical grid references
HM Land Registry Land ownership house prices
Highways Agency Traffic flow
Post Office Postcode
Environment Agency Flood
British Geological Survey Geological geomagnetic
UK Met Office European Centre fir Medium-Range Weather Forecasting Weather climate
Natural Environment Research Council Environmental
Forestry Commission Vegetation
National Park Authorities Biodiversity visitors
Office for National Statistics Demographic
National Health Service Patient estates
Higher Education Statistics Authority Student
UK Passport Service Travellers
English Scottish Heritage Historical
The National Archives Genealogical
The Countryside Agency Rural
Police Authorities Crime
Central Office of Information Government
Local Government Address demographic
Home Office Identity card
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Geocoded socio-economic survey
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uk census

• Population census
• every 10 years since 1801 except 1941
• target resources plan service provision

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uk census 2001

• 2001 census held on Sunday 29 April 2001
• 255 million operation organised by Office for
  National Statistics, General Register Office for
  Scotland and Northern Ireland Statistics
  Research Agency
• Population, Health, Housing, Employment,
  Transport, Ethnic Group
• Legal obligation to complete a census form but
  identification of individuals protected for 100
  years by Census Confidentiality Act 1991

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uk census 2001 statistics

• Data release completed 17 September 2003
• Census Area Statistics
• Enumeration district

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uk census further info
Census 2001 http//www.statistics.gov.uk/census200
1 ONS (1998) Report on alternative methods of
obtaining the information currently collected in
the Census of Population http//www.statistics.gov
.uk/census2001/pdfs/1998altcensusrep.pdf ONS
(2003) Proposals for an Integrated Population
Statistics System http//www.statistics.gov.uk/dow
nloads/theme_population/ipss.pdf
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but
Ordnance Survey British Geological Survey
ONS Census National LANDMAP satellite
imagery 1 of total UK digital data volume
and the rest? and what about 'soft' data?
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soft data

• Communities assets, land use
• Individuals e.g. farmers, preferences fear
• Private companies e.g. Rail Track, Experian
• Multimedia e.g. photos, video, text, oral
  testimony

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