Sourcing Geodata Dr Nigel Trodd Coventry University

Sourcing Geodata Dr Nigel Trodd Coventry University

giservices require software people data method hardware

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

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

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

…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 Staff 440 49. 1 2000 69. 9 Total 895 100 2900 100 450 15. 5 Source: Longley et al. 2001

the data stream in GIS a system to capture store check integrate manipulate analyse display spatial data

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

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

primary data sources Field survey Satellite Navigation System

GPS & GLONASS principles

Limitations Working environment Selective availability Range uncertainty Data quality Horizontal Vertical SA on 100 m 160 m SA off 10 -20 m DGPS <1 -5 m

GPS applications

remote sensing …the acquisition of physical data of an object without touch or contact (Lintz & Simonett 1976)

Earth observation by remote sensing

Global… IKONOS 1 m-sharpened multispectral image Poppy fields in Kandahar, Afghanistan Image courtesy of United Nations Office on Drugs Crime … to local

Change detection: deforestation & fragmentation in the Amazon 1975 1986 1992

secondary data sources digitising & scanning

but Cartographic licence and Data Currency Map-1978 Imagery-1997

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

Geocoded socioeconomic survey

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

uk census 2001 census held on Sunday 29 April 2001 • £ 255 million operation organised by Office for National Statistics, General Register Office for Scotland 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

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?

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