Search Envelopes and Coordinate Systems

Using the parameter Search Envelope Coordinate System, you can enter reader search envelope parameters in a different coordinate system than the actual data itself; for example you can have data in an Albers coordinate system, but enter a search envelope in Lat/Long.

This function is available in FME 2008+ for any format that has a set of search envelope parameters, which is usually any database plus a number of other formats.

This screenshot shows where to locate the parameter in the Navigator pane in the Workbench reader parameters. The source data is in Lat/Long, but the search envelope has been specified in meters using a UTM coordinate system.

When you run a workspace with this parameter, FME converts the search envelope into the same coordinate system as the source data, then creates a bounding box from that, as what started out as an envelope may no longer be rectangular after a reprojection. For this reason the output area may be slightly larger than specified.