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<div class="moz-cite-prefix">For srtm I found elevation accuracy of
6m in wikipedia, so my 10m was not that unrealistic.<br>
<br>
Btw. We are talking about interpolating from hgt-data position to
Garmin-data position, aren't we?<br>
<br>
For filling voids, it would be a good idea to use some spline
interpolation as written here:<br>
<a class="moz-txt-link-freetext" href="https://en.wikipedia.org/wiki/Shuttle_Radar_Topography_Mission#Void-filled_SRTM_datasets">https://en.wikipedia.org/wiki/Shuttle_Radar_Topography_Mission#Void-filled_SRTM_datasets</a><br>
<br>
Henning<br>
<b><br>
</b><br>
On 23.01.2018 20:59, Henning Scholland wrote:<br>
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<blockquote type="cite"
cite="mid:a7d2483c-a764-2093-7bf9-a696d52249e6@hscholland.de">
<pre wrap="">Hi Andrzej,
I also suggest to make interpolation optional.
So far I don't understand your argument. I agree, compilation time is
not the only criteria. The question is, what is the benefit for the user.
For example: If accuracy of srtm is +- 10m and the difference between
with/without interpolation is +-1m, then it's definitely not worth
spending any effort on interpolation. Only in cases, where interpolation
accuracy is on same level than srtm accuracy, it starting to be worth
spending time for it.
Do you have any values for differences with/without interpolation with
same input data?
Henning
On 23.01.2018 20:22, Andrzej Popowski wrote:
</pre>
<blockquote type="cite">
<pre wrap="">Hi Gerd,
there are different kind of bicubic interpolations. I'm not good at
this math, I think the previous version was actually bicubic spline
interpolation. See other possibilities here:
<a class="moz-txt-link-freetext" href="http://mrl.nyu.edu/~perlin/cubic/Cubic_java.html">http://mrl.nyu.edu/~perlin/cubic/Cubic_java.html</a>
I don't know, which type of spline or cubic interpolation is best for
DEM. Maybe differences aren't big, but I think it is better to have
good interpolation than fast one. You compile a map once but then many
people can use it.
It shouldn't be difficult to include an option like:
--dem-interp=..
</pre>
</blockquote>
<pre wrap="">
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</pre>
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