[mkgmap-dev] HGT - getElevation()

Tue Jan 16 16:40:54 GMT 2018

Hi Andrzej,

reg. screen shots:
I created my two screenshots this way:
1) locate a position -> create 1st screenshot -> leave MapSource
2) replace map content (I just rename dirs, both maps are created with the same options, just different binaries)
3) open MapSource, press Strg+G two times, create 2nd screenshot
I think the same works with Basecamp, both remember the position in the map in this case.
You can also use Strg+T to jump to a position.

I've also tested quality again now and found that DEM data is clearly better when DEM bbox is aligned to hgt raster.
So, yes, we should align, and I was wrong, there is no need to change splitter for that, we just have to align the DEM bbox :-)

This allows to get the best result out of a hgt file without using a dem-dist value that is lower than the resolution of the hgt file.
Question is if anything is improved with e.g. dem-dists=3312,... when dem-dists=9942 gives the best possible result?

Gerd
P.S. please review new patch, last one did not use moved value for right boundary

________________________________________
Von: mkgmap-dev <mkgmap-dev-bounces at lists.mkgmap.org.uk> im Auftrag von Andrzej Popowski <popej at poczta.onet.pl>
Gesendet: Dienstag, 16. Januar 2018 16:36:22
An: mkgmap-dev at lists.mkgmap.org.uk
Betreff: Re: [mkgmap-dev] HGT - getElevation()

Hi Gerd,

I have tried to align pbf bbox with HGT. I have ceated 2 maps, one with
god alignment and second with left and top edge moved by 1/2 HGT pixel
size. I have used HGT with resolution 3600, so the movement was about
15m. I think shading is the same on both maps. There is no obvious
change, but I can't make BaseCamp to display maps at exactly the same
position, so there is a small movement of all objects. See pictures:
http://files.mkgmap.org.uk/download/396/hgt-aligned.png
http://files.mkgmap.org.uk/download/397/hgt-nonaligned.png

DEM layer is the same for both maps, position and size exactly the same.

I have found, why shading on your map looks more detailed. You have
created only single layer of DEM, while I use 4 layers. Shading with
multiple layers looks softer. Another weird effect is that with single
layer, shading gets softer, when you set "Map Detail" to higher in
Mapsource. With multilayer is opposite, probably Mapsource switches
between layers.

--
Best regards,
Andrzej
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