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OGP Surveying and Positioning Committee The EPSG Geodetic Parameter Dataset

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OGP S&P continues to maintain the dataset. ... Actual vibrator Mapped. track seismic line. Operate between CRSs - not part of CRS definition ... – PowerPoint PPT presentation

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Title: OGP Surveying and Positioning Committee The EPSG Geodetic Parameter Dataset


1
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)

2
The 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.

3
Organisational Background
4
OGPs 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)

5
EPSG 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
6
EPSG Geodetic Parameter Data SetUser Interface
7
Relevance 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?
8
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

9
Relevance 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

10
Relevance 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
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 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

12
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.

13
EPSG Geodetic Parameter Dataset
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