Is there any way to retain vertical datum information after transforming?

Hi @smicheau01,

How are you transforming the coordinate system for the shapefile?

Have you tried using the CsmapReprojector? The CsmapReprojector is able to handle both horizontal and vertical datum transformations.

Hi Andrea, I am using the CsmapReprojector. Through analyzing the data, I have confirmed the reprojection is working correctly. The problem is that there is no record of the new vertical datum. For example, before reprojecting, the ESRI WKT tells me the vertical datum is CGVD1928. After the reprojection is complete, there is no where I can see information about the new vertical datum. It disappears from the ESRI WKT and there appears to be no record of it. Is this expected?

Hi @smicheau01,

Unfortunately, this is a limitation and a known issue that our development team is aware of (PR 41877). I will update you when this is supported natively in FME.

The good news is there are a couple of workarounds available:

First you need the ESRI WKT description of the coordinate system. You can get the WKT string using ArcCatalog by just creating a dummy Shape file with the right X,Y and Z coordinate systems and then editing the .prj text file. (There are probably other ways to obtain this..)

 

Then there are two methods you can do go about it: 1. In a text editor open the file <FME Install Dir>\\Reproject\\Exceptions\\esriwkt.db.

 

Search for the FME coordinate system short name you choose for creating the WKT

 

- if you don't find an existing entry for it add one near the top of the file like this:

 

ESRI|<FMEShortName>|<paste the string from the .prj file here>

 

Note: <FMEShortName> must already exist

 

If you do find an existing entry, modify it to replace the projection string with the one from the shape file. Now in FME Workbench when ever you write a feature class with that FME coordinate system set for the destination the feature class should be defined with the specified vertical datum.

 

Note: You must make sure to define the feature class to have Z coordinates in the properties of the FME destination feature type.

2. In a workspace use a CoordinteSystemDescriptionConverter to convert Esri WKT to an FME coordinate system name, and then use a CoordinateSystemSetter to attach it to features. The writer will output the WKT exactly.