conversion to OSTN02 does not work

[Former user]

I have been experimenting with the GridInQuestII dll & dat files and though the OSTN15 conversion works as expected, the OSTN02 does not - it just returns the position unset. Using any number except '0'or '2015' for the RevisionTarget returns an unset position.

[Paul Michell]

Please would you post some code that demonstrates the problem. OSTN02 is only supported in very limited contexts without re-building the binaries from source.

[David Wilbourn]

Hi Paul,

I have made a simple demo project in Delphi. You can download the source and complied version from this link:

https://we.tl/t-7zdEqLz21G

[Paul Michell]

David,

Thanks for the test program. You are calling the dll correctly (Win32/Delphi), unfortunately the official dll is deliberately built with GM02/TN02 disabled. The only binary pre-built with this support is OSGMUpdate which supports one way translation of 02 to 15. This was a deliberate choice to discourage use of GM02/TN02 versions of the BNG/ITM/IG coordinate systems. It is possible to build the dll from source to do what you want by un-commenting the define at line 54 of BNG.pas. The version of the DLL used by Safe Software for FME was built by them like this to support all permutations of the coordinate systems, the official builds will not I’m afraid.

Kind regards,

Paul

[David Wilbourn]

Paul,

Thanks for the explanation, though it would have been easier if that was made clear in the documentation! I will just remove all the (implied) support for 2002 in my program.

David.