[mkgmap-dev] mkgmap-dev Digest, Vol 153, Issue 40 Resolution 23 raster problems

Fri Apr 23 16:47:53 BST 2021

the problem is at some points - that the lines interchange at resolution
23. I know the main problem is phyghtmap. Groundtruth and gnuplot with
b-spline interpolation can do this much better. But at resolution 24 still
never lines intersect, at resolution 23 they do.
(the commenting of the wrong angle fixer didn't seem to help or change
anything - I have to compare tomorrow again however. Just locked myself out
of my compile server somehow entering the password wrong too often).
Yes very steep and 10m equidistance which is not suited for such steep
slopes - but it's possible to create much better contourlines (as seen from
the contourlines on kleineisel.de - they never intersect also at resolution
23).

On Fri, 23 Apr 2021 at 21:38, John Thorn <johnrthorn at gmail.com> wrote:

> I don't think this can be improved.
>
> As I understand it, internally Garmin devices hold coordinates in the
> number of bits specified in the level.
>
> So 24 bits has a resolution of 2.4 metres, 23 bits has a resolution of 4.8
> meters and so on. If you look carefully, all the vertices of the lines lie
> on a square grid.
>
> Having said that, that must be a very steep slope - unless something else
> is creating the granularity.
>
> On Fri, 23 Apr 2021 at 12:06, <mkgmap-dev-request at lists.mkgmap.org.uk>
> wrote:
>
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>> Today's Topics:
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>>    1. Resolution 23 raster problems (Felix Hartmann)
>>
>>
>>
>> ---------- Forwarded message ----------
>> From: Felix Hartmann <extremecarver at gmail.com>
>> To: Development list for mkgmap <mkgmap-dev at lists.mkgmap.org.uk>
>> Cc:
>> Bcc:
>> Date: Fri, 23 Apr 2021 18:01:15 +0800
>> Subject: [mkgmap-dev] Resolution 23 raster problems
>> Any ideas why this is happening?
>> Some of the contourlines intersect each other at resolution 23 - I
>> especially used reduce-point-density=1.0 to try to stop it.
>>
>> java -jar -Xmx47000M /home/contourlines/mkgmap.jar --keep-going
>> --dem-poly=/home/contourlines/bounds/bayern.poly
>> --series-name=openmtbmap-cntrs-DBY-23-Apr-2021
>> --dem=/home/contourlines/hgt/VIEW1/,/home/contourlines/hgt/SRTM1v3.0,/home/contourlines/hgt/VIEW3/,/home/contourlines/hgt/SRTM3v3.0/
>> --dem-dists=5520 --max-jobs=7 --reduce-point-density=1 --transparent
>> --style-file=srtm24 --latin1 95260000.osm.pbf
>>
>> Is there any way to improve this?
>>
>> Look at the screenshots - the small one is resolution 23, the big one 24.
>> If using 10m interval contourlines this is pretty obviously not ideal.
>> Resolution 24 could be nicer - but I guess this is more a problem of
>> phyghtmap (while groundtruth can produce higher quality), but resolution 23
>> really becomes confusing vs 24...:
>> [image: Simplification_23.PNG]
>> [image: Oiginal_24.PNG]
>>
>> If pictures don't show
>> https://openmtbmap.org/23.PNG
>> https://openmtbmap.org/24.PNG
>> --
>> Felix Hartman - Openmtbmap.org & VeloMap.org
>>
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-- 
Felix Hartman - Openmtbmap.org & VeloMap.org
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