Treatment of Coordinate Systems

Some of the data sources that OpenSpirit has data connectors to require both specification of the project's coordinate system as well as the preferred method of doing a datum shift from the project's geodetic datum to the WGS 84 datum. This information must be supplied when the project is created using the vendor’s data management tools. This so called early- binding approach is used by:

  • OpenWorks

  • Kingdom (Kingdom chooses the datum shift for you starting with version 2015)

  • Studio

When OpenSpirit connects to these types of projects the OpenSpirit data connector reads the project's map projection system type and parameters, the associated geographic system and parameters, and the preferred datum shift type and parameters and translates these into standard EPSG nomenclature (see http://www.epsg.org). Then if any application requests spatial data via OpenSpirit (for example, a well or seismic line location) OpenSpirit use its Coordinate Service (based on ESRI's Projection Engine) and the parameters read from the source project to transform the data to the requested coordinate system. If the requested coordinate system has a different datum, then the source spatial data shifted to. WGS84 based on the datum shift method and parameters defined in the source coordinate system.

Other data sources take the late-binding approach and only define the map and/or geographic coordinate system for data stored in their project and do not supply any information on how to do a datum shift to WGS84. This is the approach used by:

  • EPOS

  • Petra

  • PPDM

In order to conveniently use data from these data sources in OpenSpirit workflows we have added the ability when these data sources are configured (for example, made known to OpenSpirit) to specify the preferred datum shift for every datum found in that datastore. So when a PPDM datastore is registered with OpenSpirit a scan is done to find the unique set of datums used in that datastore instance and the administrator is required to choose the preferred datum shift method for each datum to shift it to WGS84. If you wish to use a different datum shift based on where the data is spatially located (for example, use NADCON in the USA but use NTV2 in Canada to shift from NAD27 to WGS84). Then one can configure two OpenSpirit datastore instances that point to the same datastore instance but use different datum shifts between NAD27 to WGS84. In future releases of OpenSpirit we plan to make the specification of datum shift policies more flexible by allowing spatial dependent policies to be set and stored in the OpenSpirit metadata repository along with the EPSG coordinate system definitions.

To start configuring the Data Source, select the desired data source type and version in the data source tree and click the create data source icon CreateDataSourceIcon.gif in the tool bar.