We added the conformal + distortion transformation grid to FME 2018.0 Build 18240. If you have anything earlier than that, FME will use the conformal transformation only.

Once you have a new-enough build, you can specify the transformation in the CsMapReprojector:

For additional details, see here: https://knowledge.safe.com/articles/44498/new-australian-national-datum-gda2020-support-with.html

Thanks for the info @paulnalos

I have just installed FME 2018.1 build 18567.

So, if I leave the Transformation as <Auto>, which transformation grid will FME use? How do I know which transformation FME is using as Default.

For example, I am reprojecting from EPSG:28355 (GDA94 / MGA Zone 55) to EPSG: 7855 (GDA2020 / MGA Zone 55).

The default is the conformal-only transformation.

That said, given the importance of getting this choice right, if you keep the "auto" choice, a warning is printed:

CS-MAP Reprojector: Using 'GDA94_to_GDA2020_conformal_only_7P_FME' for GDA94 <-> GDA2020. If you wish to use the other transformation instead, use a CsmapReprojector transformer and select that transformation explicitly. The choice between the two transformations is highly important for data quality. See the technical manual at http://www.icsm.gov.au/gda/tech.html for details

(The URL at the end of that message is no longer available. I'll have it changed to: http://www.icsm.gov.au/sites/default/files/GDA2020TechnicalManualV1.1.1.pdf

Do you know how to change which grid file FME uses by default?

No dramas if you don't know off the top of your head, I can contact FME support.

If you have the default configuration (FME Workbench -> Tools -> FME Options... -> Default Paths -> Shared FME Folders -> <documents>/FME), then you can simply add a file to that folder (FME folder within Documents), with the following text:

GDA94|GDA2020|XFORM|FWD|GDA94_to_GDA2020_conformal_and_distortion_NTv2_Grid_FME

... this will change the default to the conformal + distortion grid.

The other default uses the following text in a different place:

GDA94|GDA2020|XFORM|FWD|GDA94_to_GDA2020_conformal_only_7P_FME

(but if you like the current, conformal-only, default, no need to take any action at all).

Hi @paulnalos I am following up on this almost a year later! Thank you for your help so far.

To reiterate... I want to force FME to use the conformal and distortion grid every time I reproject between GDA94 and GDA2020, and I don't want to have to manually add the CsmapReprojector transformer every time I do a reprojection. So in other words, I want to change the default transformation that FME uses from "conformal only" to "conformal and distortion".

I tried setting my Shared FME Folder to the Documents\\FME folder, and then created a text file (called MyTransformation.txt) in the FME folder containing the text that you suggested:

GDA94|GDA2020|XFORM|FWD|GDA94_to_GDA2020_conformal_and_distortion_NTv2_Grid_FME

But this did not change the way FME did the reprojection.

I found a file called TransformationExceptions.db in the Reproject\\CsmapTransformationExceptions folder under the FME installation folder. Perhaps this is what you were referring to above when you said "The other default uses the following text in a different place"?

Anyhow, I opened the file in a text editor and modified the following line:

GDA94|GDA2020|XFORM|FWD|GDA94_to_GDA2020_conformal_only_7P_FME

...to...

GDA94|GDA2020|XFORM|FWD|GDA94_to_GDA2020_conformal_and_distortion_NTv2_Grid_FME

My testing has shown that this correctly changed the default FME transformation from "conformal only" to "conformal and distortion".

Can you confirm that I have done the right thing here?

I see my mistake now! I wrote:

> If you have the default configuration (FME Workbench -> Tools -> FME Options... -> Default Paths -> Shared FME Folders -> <documents>/FME), then you can simply add a file to that folder (FME folder within Documents), with the following text:

> ...

But it is not correct to place that file just inside <documents>/FME. You need to place it inside <documents>/FME/CsmapTransformationExceptions.

The change you made (to the equivalent directory within the FME install) is also good. However, it will be overwritten when you next install or upgrade FME.

@paulnalos your solution above worked for me.

Thank you again for your assistance.