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OGP Surveying and Positioning Committee The EPSG Geodetic Parameter Dataset. Presentation to POSC SIG July 21st, 2006 Aberdeen, UK by Palle J. Jensen, Maersk Oil and Roger Lott (formerly BP). The EPSG Geodetic Parameter Dataset. OGP S&P / EPSG organisational background.
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OGP Surveying and Positioning CommitteeThe EPSG Geodetic Parameter Dataset Presentation to POSC SIG July 21st, 2006 Aberdeen, UK by Palle J. Jensen, Maersk Oil and Roger Lott (formerly BP)
The EPSG Geodetic Parameter Dataset • OGP S&P / EPSG organisational background. • Overview of the dataset. • Relevance to regional and local E&P operations. • Future plans for the dataset.
OGP’s EPSG Geodetic Parameter Dataset Overview • Database containing the definitions of coordinate reference systems from around the world • over 3000 coordinate reference systems (CRS) • over 1200 transformations between CRSs • mature data model • relational data base implementation of ISO / OGC models • evolved from POSC Epicentre • periodically updated - typically twice per year • Latest version 6.10 issued April 2006 • Download from http://www.epsg.org • MS Access 97 database (includes reporting) • SQL scripts • Guidance Notes (user manual and algorithm documentation) • De facto world standard • E&P, GIS, remote sensing, telecomms (location based services)
EPSG Geodetic Parameter Data SetCore Geodetic Parameters Coordinate Reference System Coordinate Transformation Coordinate System Datum Source/Target CRS Ellipsoid Axis / Axes Method Prime Meridian Parameters/values Map Projection(Projected CRS only) Note: Transformations are not part of the CRS definition
Relevance to regional and local E&P Operations - Example Ground Control Point Origin of all recent seismic surveys and well locations in the block Is that good enough? Is latitude and longitude all you need to uniquely define a point on the ground?
Control Point Datum Ellipsoid Map Projection Easting (m) Northing (m) WGS 84 WGS 84 UTM Zone 40 470 657.6 5 445 514.3 Pulkovo 1942 Krassovsky 1940 UTM Zone 40 470 584.7 5 443 266.0 Pulkovo 1942 Krassovsky 1940 Gauss-Kruger 470 582.9 5 443 406.6 Example – Describing a geographic location Control Point Datum Ellipsoid Latitude Longitude WGS 84 WGS 84 49º 08’ 28”.64 N 56º 35’ 52”.30 E Pulkovo 1942 Krassovsky 1940 49º 08’ 29”.46 N 56º 35’ 48”.09 E • Same point but coordinates differ (none of them are wrong) • typically 50 to 500 metres, can be 1500m
Relevance to regional and local E&P Operations - Example • Licence block boundary coincides with international boundary • Boundary agreement defines location by geographical coordinates (latitude/longitude) • Datum not described • Allowance for locating wells within 125m of boundary line • Different assumptions of datum reference will cause different locations of the boundary by 300m
Vintage seismic positioning data used to plan up-hole survey Differences of 385m observed between mapped and actual line location Error traced to incorrect datum description in header of data file Relevance to regional and local E&P Operations - Example Actual vibrator Mappedtrack seismic line
Example - Geodetic Transformations • Operate between CRSs - not part of CRS definition • There may be multiple transformations between any pair of CRSs • e.g. EPSG Data Set contains 38 between ED50 and WGS 84 • differing area of applicability • UK east of 6 deg W, Norway south of 62 deg N, etc. • differing usage • military, E&P • differing legality • differing accuracy • Using an incorrect variant might be significant • computer applications that include transformation as part of CRS definition can be dangerous
Future plans for the EPSG dataset • Work in progress to make the dataset contents available over the internet, with interfaces: • for machines (using Graphic Markup Language). • for humans, through any web browser (web pages will have similar content to that of existing MS Access browse forms and reports); • pre-defined and user-defined queries. • Project completion anticipated October 2006. • MS Access database and SQL scripts will continue to be available. Seek ISO accreditation for the on-line data set. • No change to existing change request processing • but new data will be made available as soon as processed. • No change to existing data access policy: • data available at no charge to user.
EPSG Geodetic Parameter Dataset Thank you