Problem with an ETRS89 to OSGB transformation in the project tool

Question

I'm projecting a shapefile currently supplied in ETRS89 format to OSGB 1936 in ArcGIS 10.4.1. I have followed the advice given by ESRI UK  (Adding the new OSTN15 NTv2 transformation — Esri UK ) to ensure that the latest transformation is available.  I have downloaded the transformation files, added them in my Arc directory as per the instructions, and can clearly see the files. However, when I use the project tool in ArcCatalog the transformation (OSTN15_NTv2_ETRStoOSGB) is not visible in the dropdown.  Also if I manually type the name of the transformation into the dialogue box it will not be recognised by the tool.  if I project without the transformation, my points are out by about 105m.  Is there some sort of path issue such that Arc cannot find the transformation?

GavinRudge · Answer

Many thanks for the replies to this post, Melita and Duncan. I achieved a workaround by transforming to WGS84 and thence to OSGB. The accuracy looked good to couple of metres or so, which is sufficient for the analysis I'm working on. I followed Melita's suggestion, repeating all of the steps in the advice from ESRI but ensuring the addition of the carriage return. I still get the same issues, the transformations are not visible in the transformation drop-down, but there is a transformation in the co-ordinates part of the environment variables that looks promising. After selecting it, the warning triangle stays on on the transformation drop-down on the project dialogue box, so I'm assuming the tool is not picking up the transformation. When I run it anyway my points are all off as usual.  I can live with the workaround for now, but would like to find a solution longer term as I could use the extra accuracy for one of my upcoming projects. I'd like to upgrade but I'm too busy. I have to test existing custom tools for forward compatibility and find alternatives or re-install the old version if I can't, so this is usually a day's lost work; although if 10.5 has also fixed the way the quick import tool mangles GML files, it may be worth my time!

MelitaKennedy · Answer

Make sure the entries in the geogtran.txt file (in the PEOBJ folder) are each a single line ad make sure the 2nd one has a carriage return at the end. That is, the last line in the file should be a blank line.Use Notepad, not WordPad or Word. You must restart ArcGIS Pro or Desktop after setting the PEOBJEDITHOME environment variable.

Are you using C:\PEOBJ as the location for the geogtran.txt file? Is that the value of the environment variable?

Hornbydd · Answer

I see you have posted on their website requesting help. Problem is as most users have marched on with upgrades there are probably not many people around with 10.4.1 attempting such UK based transformations. I would start a case on myesri or probably less painful just upgrade if you can. If your IT are giving you the run around saying its not available that's rubbish as you'll be on a maintenance cycle with access to the very latest version and all these problems simply go away...