[gdal-dev] gdaldem aspect is grid-oriented

[Michael Sumner]

True, we don't care where the needle points - we need polar north, it's
entirely dependent on longitude, and in our usual case, stere centred on
south pole, a simple special case.

Cheers, Mike

On Tue, 29 Jun 2021, 01:06 Andrew C Aitchison, <andrew at aitchison.me.uk>
wrote:

> On Fri, 25 Jun 2021, Michael Sumner wrote:
>
> > Hello, we're using `gdaldem aspect` on polar grid products and we need to
> > convert the grid-oriented directions to compass oriented ones,
> > location-specific directions, where "compass north" is dependent on
> > longitude.
>
> I am curious; in the terminology of the British Ordnance Survey maps,
> you are converting from "Grid North" but are you trying
> to convert to "True North" or to "Magnetic North" ?
>
> --
> Andrew C. Aitchison                                     Kendal, UK
>                         andrew at aitchison.me.uk
>
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