ArcGIS Custom Transformation (.gtf) shift inverted in v10.7

[JustinOdell]

Hello all,

In my organisation we have historically created custom transformations (.gtf) that carry 7 parameter shift values between GDA94 (EPSG:4283) and WGS84 (EPSG:4326). We constructed these in ArcMap 10.3 and have recently upgraded to 10.7.

We have noticed a few differences between 10.3 and 10.7, such that:

1. Copying the .gtf files created in 10.3 and inserting them into the Custom Transformation folder in 10.7 results in Error 000365 when attempting to run the 'Project' tool.
2. The way the .gtf file is created appears to be different between ArcGIS versions. Interestingly, the input and output coordinate systems are listed in opposite order when the 2 .gtf files (10.3 v 10.7) are compared.
3. When copying and pasting the parameter values from the 10.3 .gtf file to a new custom transformation in 10.7, you would expect to see the shift occur in the same direction as occurs in 10.3. Instead, it seems the data shift is in fact in the inverse direction, which is obviously of concern.

Can anyone explain if the way custom transformations are constructed has changed between 10.3 and 10.7, and why we are experiencing inverted shifts between GDA94 and WGS84?

[curtvprice]

There have been some major changes to the projection engine since then, including vertical datum support. I'd get on the horn with Esri support for the straight story.

[MelitaKennedy]

Hi Justin, 

Can you contact me via email so I can get some sample files, if possible. mkennedy at esri dot com

The gtf file aren't supposed to be directly editable. The bit of binary at the beginning of the file contains version and string length so it's possible that it's getting messed up and we're failing to read it. 

Thanks,

Melita

[JustinOdell]

Hi Melita,

Thanks for your response. Just to be clear, I understand the .gtf files are binary. We are not attempting to edit the binary files but we were able to open them in notepad for version comparison purposes. We are attempting to reconstruct the .gtf files in 10.7 using the same parameters as those used in our 10.3 custom transformations but are noticing inverted movement.

Sent some files to your email.

[MelitaKennedy]

Thanks, Justin. I just wanted to be sure! I have the files, but am swamped right now. I'll get to them soon.

Melita