--dem-interpolation=auto or bilateral or bicubic ?

Nick

Hi all,

I like Andrzejs suggestion and created a patch that implements and documents the option like this:

--dem-interpolation=value
        Use this option to speciy the method that is used to interpolate
        data from hgt raster to the DEM raster. The value bicubic gives the
        highest precision but is slower, bilinear is faster but less precise,
        it tends to smooth the profile and thus also reduces DEM size compared to
        bicubic. The value auto means that bicubic is used where is seems
        appropriate according to hgt resolution and dem-dist value, else bilinear
        is used. If not given, the default is auto.

Please suggest improvements, else I'll commit that tomorrow.

Gerd

________________________________________
Von: mkgmap-dev <mkgmap-dev-bounces@lists.mkgmap.org.uk> im Auftrag von Andrzej Popowski <popej@poczta.onet.pl>
Gesendet: Mittwoch, 24. Januar 2018 14:57
An: mkgmap-dev@lists.mkgmap.org.uk
Betreff: Re: [mkgmap-dev] DEM: performance with bicubic interpolation

Hi Gerd,

maybe someone will add more input to this discussion, but for me now
following solution make sens: provide option dem-interplation with 3 values:
- bilinear - fast interpolation for all layers,
- bicubic - precise interpolation for all layers,
- auto - default settings - automatically switching between bilinear and
bicubic, depending on DEM and HGT resolution.

--
Best regards
Andrzej
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