maptiler
Grid shift transformations
For Czech Republic, Switzerland, France and New Zealand are available grid files which would be cool to list under transformations.
These do not have records in official EPSG database.
Czech: http://grass.fsv.cvut.cz/gwiki/S-JTSK-Grid Swiss CHENyx06: http://www.swisstopo.admin.ch/internet/swisstopo/en/home/products/software/products/chenyx06.html New Zealand: nzgd2kgrid0005.gsb: http://help.maptiler.org/coordinates/australasia/new-zealand France, ntf_r93: .. Canada, ... UK, ostn02: http://www.ordnancesurvey.co.uk/business-and-government/help-and-support/navigation-technology/os-net/ostn02-ntv2-format.html
more at http://trac.osgeo.org/proj/
In fact it would be amazing!!! if EPSG.io would provide grid shift files to JavaScript Proj4 as an array structure via AJAX: https://github.com/proj4js/proj4js/issues/62
Perhaps two things here:
- Where freely available grids are available then it would be best for knowledge of those to be added to the source, EPSG database, rather than downstream uses
- Where EPSG already lists them then the computed WKT, proj4 string etc should reflect that. For example http://epsg.io/4277-5339 is listing a wrong +towgs84 param, rather than +nadgrids=OSTN02_NTv2.gsb
Some of the GSB binaries linked from: http://www.eye4software.com/hydromagic/documentation/ntv2/