Dr Nigel Trodd Coventry University Sourcing Geodata

gi services require people software 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 seats100 seats $%$% Hardware Software Data Staff Total Source: Longley et al. 2001

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

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

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)

primary data sources Field survey Satellite Navigation System

GPS & GLONASS principles

Limitations Working environment Selective availability Range uncertainty Data quality SA onSA offDGPS Horizontal100m10-20m<1-5m Vertical160m

GPS applications

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

Earth observation by remote sensing

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

Change detection: deforestation & fragmentation in the Amazon

secondary data sources digitising & scanning

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

how to avoid digitising… … electronic data transfer Nick Chrisman … [spatial] data mining

Government organisations with GB geodata holdings Ordnance Survey GB & Ordnance Survey Northern IrelandTopographical & grid references HM Land RegistryLand ownership & house prices Highways AgencyTraffic flow Post OfficePostcode Environment AgencyFlood British Geological SurveyGeological & geomagnetic UK Met Office & European Centre fir Medium-Range Weather ForecastingWeather & climate Natural Environment Research CouncilEnvironmental Forestry CommissionVegetation National Park AuthoritiesBiodiversity & visitors Office for National StatisticsDemographic National Health ServicePatient & estates Higher Education Statistics AuthorityStudent UK Passport ServiceTravellers English & Scottish HeritageHistorical The National ArchivesGenealogical The Countryside AgencyRural Police AuthoritiesCrime Central Office of InformationGovernment Local GovernmentAddress & demographic Home OfficeIdentity card

Geocoded socio- economic survey

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

uk census 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

Data release completed 17 September 2003 Census Area Statistics Enumeration district uk census 2001 statistics

uk census: further info Census ONS (1998) Report on alternative methods of obtaining the information currently collected in the Census of Population usrep.pdf usrep.pdf ONS (2003) Proposals for an Integrated Population Statistics System ipss.pdf ipss.pdf

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