Boards.ie uses cookies. By continuing to browse this site you are agreeing to our use of cookies. Click here to find out more x
Post Reply  
 
Thread Tools Search this Thread
07-04-2012, 19:09   #1
Waestrel
Registered User
 
Join Date: Oct 2004
Posts: 334
irish Grid and ITM

So, I see the terms Irish Grid and Irish Transverse Mercator bandied about a lot on the web. What is the difference between the two? I know IG uses the Airy ellipsoid and ITM uses WGS 84, but, what the real deal here?
Waestrel is offline  
Advertisement
10-04-2012, 10:14   #2
ManAboutCouch
Registered User
 
Join Date: Jun 2005
Location: Dublin
Posts: 160
Ordnance Survey Ireland are migrating their mapping from ITM from IG. Right now we're in that awkward phase where both systems are in use. I think IG will take quite a few years to disappear, mainly because there is so much data out there which uses it.

As to why OSi is making the change, it's down to accuracy. As you've said ITM uses a different ellipsoid (GRS80, which was the original basis for WGS84 - WGS84 has been refined slightly since and now differs from GRS80 very slightly) which means much greater compatibility with GPS along with a number of other benefits.

You can get more background information in this PDF from OSi:

http://www.osi.ie/OSI/media/OSI/Cont...March-2011.pdf
ManAboutCouch is offline  
01-08-2012, 00:37   #3
Subpopulus
Registered User
 
Join Date: Sep 2009
Posts: 51
Any idea when the OSI plan to start printing maps with ITM grid lines rather than IG?
Subpopulus is offline  
20-06-2013, 18:12   #4
insomnia087
Registered User
 
Join Date: Jun 2012
Posts: 7
GPS that support Irish (ITM)

I'm looking for a gps unit for around 100 euro that specifically supports Irish (ITM) as a grid format.

Anyone got any info??
insomnia087 is offline  
Post Reply

Quick Reply
Message:
Remove Text Formatting
Bold
Italic
Underline

Insert Image
Wrap [QUOTE] tags around selected text
 
Decrease Size
Increase Size
Please sign up or log in to join the discussion

Thread Tools Search this Thread
Search this Thread:

Advanced Search



Share Tweet