[mkgmap-dev] splitter r586 still doesn't always align properly with --align-for-dem option

Fri Jan 19 22:35:00 GMT 2018

Hi Gerd,

 > What makes you think that 0,0 is used instead of the upper left cornen
 > given in the DEM section header(s)?

In Garmin's DEM coordinates are always a multiple of DEM pixel size 
(dem-dists). The result is, that all DEMs data are aligned with 0;0. It 
makes easy to join different tiles, since all tiles share the same 
alignment.

Garmin uses DEM pixel size, which is not optimal for HGT. Looks like 
they don't care about HGT alignment, while obviously they use SRTM data.

There should be no shifting of DEM, if DEM coordinates are strictly 
respected by Mapsource od BaseCamp. But there could be artifacts on tile 
borders.

Anyway, it is just a guess. We can make some test with Mapsource, but 
would be difficult to test all different devices. That is why I would 
prefer to make DEM exactly like Garmin, which means, that we can't get 
good alignment with HGT.

-- 
Best regards,
Andrzej