Coordinate Reference System

Data stores will try and infer the Coordinate Reference System (CRS) from the data. Some data stores provide the ability to override this. Overriding will not re-project the data, it will simply provide information about the current spatial reference system. You can check the CRS of the data by clicking on the ‘i’ button next to the geometry column of one of the tables in the data store’s input mapping and output mapping tabs. The CRS may need to be overridden because:

• Sometimes, the source data store does not provide any information about its CRS.
• If the data is to be used with, or written to, another type of data store, it is useful to be able to define the CRS in the encoding used by the other data store.

1Integrate uses the CRS to:

• Ensure that all data processed by a session is using the same reference system.
• Enable the writer to correctly specify their CRS.

Understanding CRS codes

The CRS codes provided have a number of caveats, depending on which Data store or integration platform is being used.

• FME, as-standard data stores and Oracle all understand EPSG codes and are able to translate between the local encoding (i.e the FME CRS name or Oracle Spatial Reference Identifier (SRID) and the corresponding CRS code).
• FME, where possible, will return its own encoding with a tag of "FME" and an EPSG code.
• As-standard data stores understand only EPSG codes.
• The Oracle data store understands the Oracle SRID and EPSG codes.

These values are represented in NAME=VALUE pairs. For example:

• For a Spatial Reference Identifier (SRID) would be in the form SRID=81989
• For an EPSG code, it would be in the form EPSG=27700

Note: When data is read from FME and written to Oracle, if no Oracle-specific SRID is defined, the Oracle data store will attempt to find one corresponding to the EPSG code. EPSG codes are a standard way to describe geospatial coordinate system and are maintained by the European Petroleum Survey Group.