[PROJ] NTv1/NTv2/CTable2 and west-oriented longitude shifts

[Lesparre, Jochem]

Hi Even,

I agree. Please, abandon the strange conventions of NTv2 and use east positive, normal column ordering and preferably also decimal degrees instead of arcseconds.

I would prefer very accurate (0.1 mm) grid shift files and an encoding that makes it simple to write and read it. To me this is more important than the best possible data compression. So if possible, use signed integers with no offset (0 is no correction) and 1*10^-9 degree as (default) unit.

By the way, GeoTIFFs also have a map projection. I assume you are planning to use latlon thus platte-carree projection. It would be interesting to also allow other projections (with 1*10^-4 metre as (default) unit). Although this is against ISO, it would make it possible for countries that use horizontal grid shifts on projected coordinates to implement their transformation in PROJ., so they don't have to redefine their national coordinate system like the Netherlands did to accomplish this.

Regards, Jochem



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