dr nigel trodd coventry university sourcing geodata
Post on 23-Dec-2015
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geospatial data consist of
geographical entitiesattributesmetadata
geospatial data are useful only if
available & accessiblefit for purpose
referenced to a common spatial referencing system
Aim & objectives
To identify & understand the process of building a geospatial database
We willidentify sources of geographically referenced data exemplify techniques to acquire geospatial data
importance of data acquisition
constrains data analysisinfluences output quality
determines economic viability50% of the total cost & 70% - 80% of the time of a GIS project
revolve around data acquisition
…the cost of data
10 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 100Source: Longley et al. 2001
a system to
the data stream in GIS
capturestorecheckintegratemanipulate analysedisplay spatial data
capturestorecheckintegratemanipulate analysedisplay spatial data
sourcing data
Determine location Georeferencing system
Determine extent of phenomena from reality to spatial data
structures
Characterise properties of phenomena
data sourcesPrimary 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)
Limitations
Working environment
Selective availability
Range uncertaintyData quality
SA on SA off DGPS
Horizontal
100m 10-20m <1-5m
Vertical 160m
remote sensing …the acquisition of physical data of an object without touch or
contact (Lintz & Simonett 1976)
IKONOS 1m-sharpened multispectral image
Poppy fields in Kandahar, Afghanistan
Image courtesy of United Nations Office on Drugs Crime
… to local
Global…
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
uk census
Population census
• every 10 years since 1801 except 1941
• target resources & plan service provision
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
butOrdnance 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?
soft data
Communities – assets, land useIndividuals e.g. farmers, preferences & fearPrivate companies e.g. Rail Track, ExperianMultimedia e.g. photos, video, text, oral testimony
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