I am trying to convert some Lat/Long coordinates to the British National Grid to no avail. I have read MANY posts here and so many people have the same problem and get no satisfactory answers OR incomplete answers.
Please could someone explain how to do this properly because I notice that some just stick to the 'ArcMap will project on the fly' method which has never worked for me and, if it does, then its not clearly explained from the beginning. This is something that is so important and has been raised by so many people so many times that a solution or tool is required.
I have attached the file with the latitiude and longitude coordinates. I did get them to display in ArcMap but again (like EVERYONE points out) they weren't projected properly and all the points lay to the south west of the UK in the sea! At one point I managed to get the X coordinates using the Project tool but not the Y coordinates (which were all minuses). It beggars belief that there is not a simple way of doing this.
I would be grateful for any help on this and if it works then I'll post an explanation of how it worked.
You'd have to find out what coordinate settings the GPS used in the first place to collect the data and create the shapefile based on that rather than WGS 84 I used. I'm not sure if this will shift them for you or not though.
If the lat/lon coordinates really are in WGS84, you need to set a geographic/datum transformation to convert between WGS84 and OSGB36. The best solution is to follow Jim Sibbald's instructions here which has you download a file from OS, and set up some files on your computer to properly use it. If you have 10.1, you only need to download the file, and place it in your ArcGIS installation, pedata\ntv2\uk folder.
A faster solution to see if the problem is datum transformation-related is to try to set OSGB_1936_To_WGS_1984_7PAR. The points may still be off a bit, but should be better than 30m.