[mkgmap-dev] DEM: performance with bicubic interpolation

Wed Jan 24 15:57:13 GMT 2018

Hi Nick,

is that so?
I'll change it to
--dem-interpolation=auto|bicubic|bilinear

Gerd

________________________________________
Von: mkgmap-dev <mkgmap-dev-bounces at lists.mkgmap.org.uk> im Auftrag von osm at pinns <osm at pinns.co.uk>
Gesendet: Mittwoch, 24. Januar 2018 16:52
An: mkgmap-dev at lists.mkgmap.org.uk
Betreff: Re: [mkgmap-dev] DEM: performance with bicubic interpolation

Hi Gerd

I'm a bit confused when you mentioned value as that seems to imply a number?

Just to clarify :

the options are:

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

Nick

On 24/01/2018 15:10, Gerd Petermann wrote:

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 at lists.mkgmap.org.uk><mailto:mkgmap-dev-bounces at lists.mkgmap.org.uk> im Auftrag von Andrzej Popowski <popej at poczta.onet.pl><mailto:popej at poczta.onet.pl>
Gesendet: Mittwoch, 24. Januar 2018 14:57
An: mkgmap-dev at lists.mkgmap.org.uk<mailto:mkgmap-dev at 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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