HEC-RAS Guides and Tutorials Guides Current: GDAL Projection File Warning PDF Download PDF Download page GDAL Projection File Warning. Current page All pages GDAL Projection File Warning To learn more about projection files and how RAS Mapper uses spatial reference systems, go here.Sometimes a spatial projection file (*.prj) will produce the following warning in RAS Mapper.The warning message is also displayed in the Coordinate Reference System of the RAS Mapper Options window as shown below. One common cause of this error is a field AUTHORITY["X",Y]. The field is usually at the end of the projection file as in the example belowTo avoid the warning message, edit the projection file in a text editor and remove the AUTHORITY field as shown belowThen set the projection file again in RAS Mapper as the warning message should disappear (see figure below). ×