Can't set TM75 / Irish Grid as drawing coordinate system

[Anonymous]

TM75/ Irish Grid was replaced by IRENET95/  Irish Transverse Mercator but in practice TM75 is still often used by local authorities, Irish Water, etc.

Civil 3D is saying "Can't save projection for current session"

Other projection systems are working, including TM65, but that is out by up to 13m I believe.

This is fairly recent because I recall using it. I've received some drawings to Irish Grid and wish to use Civil3D to transform them

[Pointdump]

Hi Oisin,
I get the same. I'm guessing that a Geodetic Transformation Path will need to be created to get from Ireland-TM75 Datum to ETRS89 to WGS84. I would open a support ticket with Autodesk.
Dave

[Nik.DewhirstH9NMQ]

This issue seems to have been around for a while, if you search by EPSG code 29903 and apply in Map3d it seems to work but when you go back in it has not applied the coordinate system.

If you try to assign in C3D it closes the screen and does not assign the system.

There was a hotfix sometime ago regarding transformations in the British Isles and Ireland but after a lot of tinkering it still did not work.

This is really annoying as all infrastructure supplied by the water company Irish Water is supplied in Irish Grid coordinates however most new mapping is done in Irish Transverse Mercator. Its impossible to convert using C3D

[Anonymous]

Agreed!
I did follow this up with Autodesk Support and I was informed it is with the developer team. Hopefully that goes somewhere.
The deprecated Ireland1965.ING may actually be the Irish Grid 75 amendment, but it's very hard to tell as the difference is at most 13 meters.

[Pointdump · Accepted solution]

Hi Nik,
I just checked C3D 2022. Saved, Closed, Re-Open. It's working fine.
Dave

[Nik.DewhirstH9NMQ]

I had the issue in 2019 and then 2021. Time to upgrade again me thinks

Thanks for that, as soon as I get the upgraded version I will test and report back to confirm