OGP Surveying and Positioning Committee The EPSG Geodetic Parameter Data Set

1. OGP Surveying and Positioning CommitteeThe EPSG Geodetic Parameter Data Set Presentation to POSC SIG July 12th, 2006 Stavanger, Norway by Palle J. Jensen, Maersk Oil and Roger Lott (formerly BP)

2. The EPSG Geodetic Parameter Data Set • EPSG/OGP S&P Organisational background. • Overview of the OGP/EPSG Geodetic ParameterData Set. • Relevance to regional and local E&P operations. • Future plans for the data set.

3. Organisational Background

4. Overview of the OGP/EPSG Geodetic Parameter Dataset • 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://info.ogp.org.uk/geodesy/ • 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)

5. 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

6. EPSG Geodetic Parameter Data SetUser Interface

7. 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?

8. Example – Describing a geographic location Same point but co-ordinates differ by 100m+ to 4000 kilometres (None of them are wrong)

9. Relevance to regional and local E&P Operations - Example International boundary location • Boundary agreement define location by geographical co-ordinates (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

10. 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 information in header of data file Relevance to regional and local E&P Operations - Example Actual vibrator Mappedtrack seismic line

11. Example - Geodetic Transformations • Operate between CRSs - not part of CRS definition • There may be multiple transformations between any pair of CRSs • e.g. EPSG dataset 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

12. Future Plans • 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-defines and user-defined queries. • Project completion anticipated October 2006. • No change to existing change request processing • but new data will be made available as soon as processed. • MS Access database and SQL scripts will continue to be available. • Seek ISO accreditation for the on-line dataset. • No change to existing data access policy: • data available at no charge to user.

13. EPSG Geodetic Parameter Data Set Thank you