New OSGB co-ordinate system

[JanineW]

The OSGB has developed a new co-ordinate system and I would like to have it working in AutoCAD Map 3D 2012, 2014 and 2016 (several users).  The new code is OSTN15 (to replace OSTN02).  Is there a way I can import a new co-ordinate system into these versions of Map 3D?  I tried the MAPCSLIBRARYIMPORT command, but it just said 'unknown command'.  I've downloaded the files from the OS and I was hoping somewhere I could just run a command that would do it for me, so I don't have to define a co-ordinate system manually.

The downloaded OS files include 4 pdfs, a .GEM, a .csc and a .DAT

Apparently the change will only make about 11-15mm difference, but I'd like to keep everyone up to date if I can.

Any ideas anyone?

Thanks

Janine

[neilyj666]

I suspect Autodesk are more focussed on the shiny Cloud/IW360 platforms as this looks great in the publicity marketing stuff.....I guess you couldn't really "sell" all the geodetic transformations technicalities without the audience losing the will to live...;)

[Pointdump]

Neil,

"...losing the will to live..."

Oh, you're funny! 

Dave

[Pointdump]

And talking about "losing the will to live", check out what we here in the Colonies have to contend with now. I took in a Webinar yesterday on the various flavors of NAD83:

Based on my own observations of one of the surveyor's forums, I'd have to say that 99% of US surveyors have thrown up their hands and just use "whatever".

Dave

[Pointdump]

Janine, Neil, and Steve,

As the leaves fall from the trees, the trail grows cold. I wonder if we'll hear further from Autodesk on this. I e-mailed OS, but the fellow that answered didn't seem to understand my questions. Maybe it was my American dialect.

Dave

[Anonymous]

I had a tweet reply from OS on 19th.

technical team say this [ostn15 NTv2 gridfile from osgb36 to etrs89] is in development, with a user guide to help users incorporate it into their systems.

but they gave no timescale.

[Pointdump]

Hi Steve,

Thank you. And I hope the user guide will shed some light on the practical side of the transformation.

Dave

[Anonymous]

Realised I said I would post a link to the @dragons8mycat blog. It's specific to QGIS but may be some use. Still no word from Ordnance Survey on OSTN15 gridshift file in the traditional direction.

http://dragons8mycat.com/2016/09/add-ostn15-to-qgis-2-16/

[Pointdump]

Hi Steve,

Thank you. That's a good link. I love QGIS.

Dave

[Anonymous]

 Ordnance Survey posted their new set of gsb horizontal gridshift files yesterday, at the link below (sorry the link thing is not working on my ipad).

look in the grey box for the NTv2 format files. You will probably want the one called something like OSTN15_OSGBtoETRS.gsb.

https://www.ordnancesurvey.co.uk/business-and-government/help-and-support/navigation-technology/os-n...

Accuracy reported as 1mm RMS, and no worse than 10mm.

 Regards,

Steve

[Pointdump]

Steve,

Thank you. I'm going there now.

Dave

[Pointdump]

First time I downloaded, it didn't "take". Second time was a charm. So I see they included a 12-page users guide in PDF.

Reading now....

Dave

[JanineW]

Has anyone heard anything from Autodesk about being able to use the Ordnance Survey (GB) new transformation OSTN15?

I posted last year about Autodesk issuing it as a new co-ordinate system, or as a file so we can create a new co-ordinate system.

Can anyone use OSTN15 in their AutoCAD Map 3D yet?

I've heard nothing for months and was wondering if anyone had got the files to work.  If you did, please feel free to advise 🙂

Cheers

[Pointdump]

Hi Janine,

Eventually Autodesk will add that transformation to the library. Maybe 2018? We'll see.

Dave

[chriscowgill7373]

Just checked 2018, I'm not seeing it.

[Thomas_Stuehle]

Hello @JanineW and others,

thank you for coming back and asking about this topic.

To inform you - this case is still on the page of the development team and it has an appropriate priority due to a great number of possible affected users.

The expected time frame for the implementation is unknown but the development team is still working on it.

Thank you,
Thomas

[albionpjl]

I'm late to this party, but having updated to C3d 2019, I keep seeing 'obsolete coordinate system' and 'deprecated coordinate system' while outputting shp files for QGIS.

I've been using OSGB 1936 British National Grid forever (well, since Autodesk introduced named systems, anyway). Latitude and longitude are not useful for anything we do. I have no idea what any of the other GB coordinate systems are or do, and no idea whether I need it be using this new one. Changing coordinate systems doesn't seem to make a difference to the coordinates so I just leave them on 1936.

The coordinates I generate seem to match the GPS when we have surveys done, so I've no idea if this even applies to us, but I'd like to stop seeing deprecate and obsolete. Under what circumstance would it make a difference?

(ps, off on holiday in a few hours so won't see answers for over a week.)

[Anonymous]

Key thing to check that last part of the projection prj file includes EPSG code 27700. Also for the ntv2 mapping requires the ETENSION stuff. Also note the ntv2 file is to ETRS89 at epoch whatever (I can’t remember) not GPS coordinates. Though they will not be out by more than a metre.

…NORTH],AUTHORITY["EPSG","27700"],EXTENSION["PROJ4","+proj=tmerc +lat_0=49 +lon_0=-2 +k=0.999601 +x_0=400000 +y_0=-100000 +ellps=airy +nadgrids=OSTN15_NTv2_OSGBtoETRS.gsb +units=m +no_defs"]]

[Pointdump]

Janine,
OK, I had some time and re-read everything I could find on OSTN15. From OS:
"OSTN15...provides a fit between the GNSS coordinate system European Terrestrial Reference System 1989 (ETRS89) and the OSGB36 National Grid."
OSTN15 is a Geodetic Transformation between the Datums used by ETRS89(GRS80 Ellipsoid) and OSGB36(Airy30 Ellipsoid). The only time you might need this is if you want to use high-accuracy GNSS Survey Data in conjuction with the OS Net Base Stations, which use ETRS89.

To add the OSGBtoETRS and ETRStoOSGB Geodetic Transformations(GSB files) to MAPCSLIBRARY, watch >>>This<<<. However, that's not the end of the story. OS provides 4 point lists, input and output, to test. I was off almost a Meter. I found that some of Map3D's Coordinate System definitions were wrong, like their ETRS89 Datum was actually ETRF89, a realization and not a Datum. So I re-defined the Coordinate Systems and Datums of both ETRS89 and OSGB36. Then after adding the GSB files everything worked fine. Whew!
So I think this is the reason why Autodesk hasn't yet included OSTN15 to MAPCSLIBRARY in 2018. (I don't have 2019 to check.)
Dave

[JanineW]

Hi Dave,

We've just been given AutoCAD Map 3D 2019.  I've checked the MAPCSLIBRARY and we now magically have a Geodetic Transformation 'via OSTN15'.  I have no experience with this, so my big question is, can I use this geodetic transformation to create an OSTN15 co-ordinate system, or am I best off keeping the can of worms closed and continuing with our OSTN02?

Cheers

Janine

[JanineW]

Hi Dave,

We've just been given AutoCAD Map 3D 2019.  I've checked the MAPCSLIBRARY and we now magically have a Geodetic Transformation 'via OSTN15'.  I have no experience with this, so my big question is, can I use this geodetic transformation to create an OSTN15 co-ordinate system, or am I best off keeping the can of worms closed and continuing with our OSTN02?

Cheers

Janine