OSGB36 update

[David Staveley]

I've been using the OSGB36 projection plus OSTN02/OSGM02/Newlyn datum in the UK, but I've just found they have released OSTN15/OSGM15 as per this link : (https://www.ordnancesurvey.co.uk/blog/2016/09/ostn15-new-geoid-britain/). I couldn't see it in the options on my LS. Is it buried in there somewhere, or not implemented yet?

 

[Vladimir Prasolov]

David,
Thank you. We will add the new realization of OSTN15/OSGM15 in next GeoData release soon.

 

[David Staveley]

Thanks Vladimir

 

[Matt Johnson]

OSTN15/OSGM15 are available in GeoData 2.3.11.30526 which is available in the PreRelease branch of J-Field now.

 

[David Staveley]

Thanks Matt. I can't see the update yet, but I will try it out as it becomes available

 

[Vladimir Prasolov]

Hi David,
It is released. Great Britain and Ireland OSGM15 geoid and OSTN15 grid was tested on GridInQuest II ver. 1.0.1.653.

 

[David Staveley]

I've tested it in the field. I had a mini heart attack when previous localizations failed due to the OSTN02 bin being deleted and replaced by OSTN15, but once I changed the localization to use the new file all was well and my old control points were in the right place. I hope there aren't too many confused brits out there as a result of the change, but I can understand deleting the old bin, as they are stupidly large. Many thanks to all involved.

 

[Vladimir Prasolov]

I've tested it in the field. I had a mini heart attack when previous localizations failed due to the OSTN02 bin being deleted and replaced by OSTN15, but once I changed the localization to use the new file all was well and my old control points were in the right place. I hope there aren't too many confused brits out there as a result of the change, but I can understand deleting the old bin, as they are stupidly large. Many thanks to all involved.

I'm so sorry David. I had to inform you about that replacement.

 

[David Staveley]

Apologies for the thread necromancy, but the problem may relate to this update. I'm usually just interested in X & Y coordinates (which are fine), but was recently asked to record some point heights in OSGB36.
Unfortunately the point heights were shown as about 65m where they should have been around 20m and 105m where they should have been around 55m. I'm wondering if the corresponding OSGM15 tables were implemented correctly along with OSTN15.
The thread above suggests that they were, but there is definitely something wrong.

 

[Matt Johnson]

Please share the project archive so we can look at it.

 

[David Staveley]

Attached. This is the set that is supposed to be 20m.
I recall last time that I set up OSTN02, that I also had to set the Datum to Newlyn, but I can't see an option for that this time.
I hope I'm just missing something.

 

[Vladimir Prasolov]

Hi David,
I verified with latest released GeoData 2.4.5.40323. It works fine.
You can select geoid directly without setting height system. Sometimes it is easy to find.
I change coordinate system of the page. The heights looks like you said about 20 meters. Have a good day.

 

[David Staveley]

Ok, I'm being dense. I can't find the screen where you can set the height system. Any pointers?

 

[Matt Johnson]

You need to create a new coordinate system and you will see the screen shown above that lets you choose the height system.

 

[David Staveley]

Got it. Thanks Matt and Vladimir

 

[Survey-Dub]

Vladimir, would it be possible to include the OSGM15 "Malin Head" Height Datum for use in Ireland into GeoData. I can't find it in my "Javad Mobile Tools" for Android. Thanks

 

[Vladimir Prasolov]

Hi Survey-Dub,
There is OSTN15/OSGM15 horizontal and vertical datum. Please select in United Kingdom/Great Britain onshore folder OSGB 1936 / British National Grid. Also select Ordance Datum Newlyn geoid. If it does not work let me know please.
Best regards,
Vladimir

 

[Survey-Dub]

Thanks Vladimir.
The Irish OSGM15 is different to the UK OSTN15/OSGM15 (see attached map). In Ireland we use Malin Head OSGM15 Datum for height and not Newlyn.
I have attached some extra information that might be helpful in understanding the differences.

 

[Survey-Dub]

Results of some testing on 3 Irish CORS Stations attached. Many thanks for the Help with this.

 

[Vladimir Prasolov]

Thanks Vladimir.
The Irish OSGM15 is different to the UK OSTN15/OSGM15 (see attached map). In Ireland we use Malin Head OSGM15 Datum for height and not Newlyn.
I have attached some extra information that might be helpful in understanding the differences.

Thanks a lot! I will request binary geoid model and add it ASAP.