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<p>Hi Gerd</p>
<p><br>
</p>
<p>A binary file sounds very 'Garminesque' and if its a matter of
speed then I would prefer such a format -</p>
<p>btw has the --dem-interpolation option been implemented yet ?<br>
</p>
<p>Nick<br>
</p>
<br>
<div class="moz-cite-prefix">On 25/01/2018 11:59,
<a class="moz-txt-link-abbreviated" href="mailto:thesurveyor@wolke7.net">thesurveyor@wolke7.net</a> wrote:<br>
</div>
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cite="mid:trinity-68e43ef6-5821-43a6-8bde-fc95c9239e63-1516881568494@3c-app-gmx-bs80">
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<div>Hi Gerd,</div>
<div> </div>
<div>first many thanks for your work on mkgmap.</div>
<div> </div>
<div>for the list of available hgt files: I prefer a human
readable format</div>
<div> </div>
<div>Regards,</div>
<div>Gert </div>
<div> </div>
<div> </div>
<div>
<div name="quote">
<div><b>Gesendet:</b> Donnerstag, 25. Januar 2018 um 12:40
Uhr<br>
<b>Von:</b> "Gerd Petermann"
<a class="moz-txt-link-rfc2396E" href="mailto:gpetermann_muenchen@hotmail.com"><gpetermann_muenchen@hotmail.com></a><br>
<b>An:</b> "Development list for mkgmap"
<a class="moz-txt-link-rfc2396E" href="mailto:mkgmap-dev@lists.mkgmap.org.uk"><mkgmap-dev@lists.mkgmap.org.uk></a><br>
<b>Betreff:</b> Re: [mkgmap-dev] How to handle missing
hgt files or files with voids?</div>
<div name="quoted-content">Hi all,<br>
<br>
I've played with the list of available hgt files created
by Henning.<br>
I've coded a reader for the list so that mkgmap can<br>
check if a missing hgt file should exist or if it covers
ocean.<br>
The idea is to print a warning if a file was not found
when it should be.<br>
The check is fast, but the list is long, so I wonder<br>
if I should store it "as is" in the mkgmap binary like
we do with LocatorConfig.xml<br>
or if I should use another format.<br>
The most obvious for me would be a binary file
containing 180*360 bits, a 1 bit for every<br>
file that should exist.<br>
<br>
What do you think?<br>
<br>
Gerd<br>
<br>
<br>
________________________________________<br>
Von: mkgmap-dev
<a class="moz-txt-link-rfc2396E" href="mailto:mkgmap-dev-bounces@lists.mkgmap.org.uk"><mkgmap-dev-bounces@lists.mkgmap.org.uk></a> im
Auftrag von Gerd Petermann
<a class="moz-txt-link-rfc2396E" href="mailto:gpetermann_muenchen@hotmail.com"><gpetermann_muenchen@hotmail.com></a><br>
Gesendet: Montag, 15. Januar 2018 14:25<br>
An: Development list for mkgmap<br>
Betreff: Re: [mkgmap-dev] How to handle missing hgt
files or files with voids?<br>
<br>
Hi Henning,<br>
<br>
I'll see if I can use srtm.zip.<br>
I think voids are interesting. When I started coding DEM
support I searched my PC for *.hgt files and found them
in several places.<br>
Later I found out that some of those files have voids
and that better data exists (assuming that files without
voids have fewer errors)<br>
So, I think it would be good to have a list of those
files that have voids.<br>
<br>
I'll see what is needed for this.<br>
<br>
Gerd<br>
<br>
________________________________________<br>
Von: mkgmap-dev
<a class="moz-txt-link-rfc2396E" href="mailto:mkgmap-dev-bounces@lists.mkgmap.org.uk"><mkgmap-dev-bounces@lists.mkgmap.org.uk></a> im
Auftrag von Henning Scholland <a class="moz-txt-link-rfc2396E" href="mailto:osm@hscholland.de"><osm@hscholland.de></a><br>
Gesendet: Montag, 15. Januar 2018 12:21:09<br>
An: <a class="moz-txt-link-abbreviated" href="mailto:mkgmap-dev@lists.mkgmap.org.uk">mkgmap-dev@lists.mkgmap.org.uk</a><br>
Betreff: Re: [mkgmap-dev] How to handle missing hgt
files or files with voids?<br>
<br>
This would be the list of all hgt-files available on
viewfinder.<br>
<br>
In each zip-file of viewfinder there are 6° in E-W
direction and 3° in<br>
N-S. The scheme of naming is also simple. That list I
also attached.<br>
<br>
In general I think it's better to just output a list,
which<br>
hgt-files/viefinder-tiles are missing than writing a
downloader. I mean<br>
in total it's 13GB of data. If you need to download it
manually, you are<br>
more aware of what you are doing and not just download
them all.<br>
<br>
Regarding voids: I think if there is a possibility the
user can fix the<br>
hgt file, A list can be helpful. Otherwise I don't know
if a list would<br>
be helpful. Only use case I see is to ask the user to
use better data.<br>
But then we need a list, which source is best in which
area. And finally<br>
all the different sources need to match each other.
Otherwise it will<br>
lead to a hard border between 2 sources. I think this
will be much to<br>
complicated...<br>
<br>
Maybe for advanced users there can be a Warning message,
hgt-file<br>
N00E100.hgt contains 3 voids. So user can compare
different sources<br>
manually.<br>
<br>
Henning<br>
<br>
On 15.01.2018 16:55, Gerd Petermann wrote:<br>
> Hi Henning,<br>
><br>
> checking data is not that easy, but I'll think
about that option.<br>
><br>
> I'd like to add a short howto that describes ways
to get good hgt data, but I don't know any method for
Windows users.<br>
> phyghtmap is good, but installation on Win is
complex and doc for that looks out-aged.<br>
> Srtm2Osm seems out-dated, as well as Groundtruth.<br>
><br>
> So, up to now I try to guess what areas I have to
download from viewfinder.<br>
> Any hints ?<br>
><br>
> Gerd<br>
><br>
> ________________________________________<br>
> Von: mkgmap-dev
<a class="moz-txt-link-rfc2396E" href="mailto:mkgmap-dev-bounces@lists.mkgmap.org.uk"><mkgmap-dev-bounces@lists.mkgmap.org.uk></a> im
Auftrag von Henning Scholland <a class="moz-txt-link-rfc2396E" href="mailto:osm@hscholland.de"><osm@hscholland.de></a><br>
> Gesendet: Montag, 15. Januar 2018 09:05:24<br>
> An: Development list for mkgmap<br>
> Betreff: Re: [mkgmap-dev] How to handle missing hgt
files or files with voids?<br>
><br>
> Hi Gerd,<br>
><br>
> regarding 1) I can create a list of existing tiles
of Viewfinder (which covers all land area so far I see).
But it will be a long list. I remember it's about 25000
files in total. So maybe it's easier to create a polygon
or at least take the list and let software create the
polygon. An easier way can be to check if data is
available. No data might be sea. Of course it's not 100%
sure, as there are deserts and ferries.<br>
><br>
> Another idea I had during the weekend was to output
a osm-file with missing areas. So then user can check.
But I came to conclusion, that it's easily visible in
the map later. So I'm not sure it's useful at all.<br>
><br>
> Henning<br>
><br>
> On 2018-01-15 15:45, Gerd Petermann wrote:<br>
><br>
> Hi all,<br>
><br>
> 1) The current code (only) writes a log message
with severity WARNING for a missing hgt file:<br>
> "file xxx.hgt not found. Is expected to cover sea."<br>
> I wonder if we can create a list of files that can
exist or maybe a polygon that can be tested so that<br>
> tiles which are knwon to cover land are reported as
errors.<br>
> When you look at <a
href="http://viewfinderpanoramas.org/Coverage%20map%20viewfinderpanoramas_org3.htm"
target="_blank" moz-do-not-send="true">http://viewfinderpanoramas.org/Coverage%20map%20viewfinderpanoramas_org3.htm</a><br>
> you can see that such a polygon would be quite
complex.<br>
> Did anybody already try to define such a polygon or
list of files that would cover only ocean?<br>
><br>
> 2) Should mkgmap print a warning when voids in the
hgt file(s) have an influence on the DEM data?<br>
> I think yes, but it is a bit more complex to
measure the real effect.<br>
> Reason: We read the 4 hgt values next to the wanted
DEM point and use interpolation to calculate the height<br>
> that is stored in the DEM file.<br>
> If one or two of the 4 points are voids they may
still have no influence if the wanted point is very
close to one that<br>
> is not a void. Another problem is that a single
void might be used several times.<br>
> So, another option would be to add an option like
--dem-check-hgt which could read all existing hgt files
and<br>
> report the number of voids for each. I'd prefer
this because it would have no impact on performance for
normal<br>
> processing. Or maybe there is already a tool for
this that works on all platforms (win,linux,mac) ?<br>
><br>
> Comments?<br>
><br>
> Gerd<br>
><br>
><br>
><br>
><br>
><br>
> _______________________________________________<br>
> mkgmap-dev mailing list<br>
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