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

[albionpjl]

I wish I understood any of this. I just plonk surveys onto the OS landline map and cross my fingers. Generally everything is set to 1936 and that's where we're staying for now. Ditto importing shapefiles from heritage offices- they're usually on the 1936 grid.

By the way, does anyone know if our losing access to Galileo with Brexit will affect GPS surveys and the OS maps/coordinate systems? I recall the bad old days when we only had US satellites to work with and the surveyors had to jump through hoops to compensate for the built-in inaccuracy. Will we be going back to that? (Wondering about run watches' accuracy too, but that's not work related.)

[JanineW]

Hi Albionpjl

That's generally what we do too 🙂

The accuracy of heritage shapefiles is sometimes questionnable anyway.  I think i might just try and forget that i looked into the whole thing.

We hadn't even thought about the Galileo knock-on effect.  I might have to bring that up with someone.

Cheers

[Pointdump · Accepted solution]

Hi Janine,

Thanks for the screen shots. Good to know Autodesk finally included OSTN15. I'm almost tempted to get 2019 to test that transformation.

"...can I use this geodetic transformation to create an OSTN15 co-ordinate system..."
OSTN15 is a Geodetic Transformation between OSGB36 and ETRS89. No need to create a new projection. Just keep using OSGB36 as always. The only time OSTN15 will come into play is if you receive GNSS survey data in ETRS89, specifically if those points were collected using OS Net Base Stations. The OSTN02 geodetic transformation is now obselete, and so too the OSGB-GPS-2002 Coordinate System.
Dave

[Pointdump]

Hi PJ,

You'll still have Galileo, as well as GLONASS and the others. And the US satellites turned off Selective Availability in 2000.
OS has a really good PDF explaining Coordinate Systems. I had to read it about 3 times before it sunk in. I've attached it.

Dave

[JanineW]

Hi Dave,

A colleague and myself have just looked through our setup and we think it's finally sorted (fingers crossed).

The new projection is indeed now working through OSGB1936.National Grid.  When you view the settings for OSGB1936, it now says Source - OSTN15 NTv2 Transformation.

Sorted....I think.

Thanks for everyone's input, and much Kudos to you Dave.