Title: OGP Surveying and Positioning Committee The EPSG Geodetic Parameter Dataset
1OGP 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)
2The EPSG Geodetic Parameter Dataset
- OGP SP / EPSG organisational background.
- Overview of the dataset.
- Relevance to regional and local EP operations.
- Future plans for the dataset.
3Organisational Background
4OGPs 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
- EP, GIS, remote sensing, telecomms (location
based services)
5EPSG Geodetic Parameter Data SetCore Geodetic
Parameters
Coordinate Reference System
Coordinate Transformation
Datum
Coordinate System
Source/Target CRS
Ellipsoid
Axis / Axes
Method
Parameters/values
Prime Meridian
Map Projection(Projected CRS only)
Note Transformations are not part of the CRS
definition
6EPSG Geodetic Parameter Data SetUser Interface
7Relevance to regional and local EP 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?
8Example 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
9Relevance to regional and local EP 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
10Relevance to regional and local EP Operations -
Example
- 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
Actual vibrator Mappedtrack
seismic line
11Example - 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, EP
- differing legality
- differing accuracy
- Using an incorrect variant might be significant
- computer applications that include transformation
as part of CRS definition can be dangerous
12Future 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.
13EPSG Geodetic Parameter Dataset
Thank you