[mkgmap-dev] issues with tile boundaries

Fri Mar 15 12:23:45 GMT 2013

Seems that my message doesnt reach the list with attachments, so I try it again:

Attachments:
https://dl.dropbox.com/u/64716698/OSM/mkgmap/corners.jpg
https://dl.dropbox.com/u/64716698/OSM/mkgmap/gap.jpg

> I noticed a gap in my maps and artefacts at the outer tile boundaries
> when I tried to make a Europe map.
> Maybe it is my mistake, because I have drawn a few big rectangular
> polygons over Europe and let the splitter calculate those areas. I
> then let mkgmap run and combined the img tiles of those sections. When
> I look at the total map there are some issues.
> 
> First, there is a big gap at 49.5 longitude (a few 100 meters wide)
> between the northern and southern part. It is only visible at the
> highest zoomlevels (<200m). When I zoom out, the gap disappears and
> routing is possible. If I make a different selection of a fewer tiles
> around this latitude, the gap is not there.
> 
> See gap.jpg
> 
> North tile
> 10131034: 2306867,4096 to 2344960,22528
> # : 49.499996,0.087891 to 50.317383,0.483398
> 
> South tile
> 10135076: 2301952,4096 to 2306867,40960
> # : 49.394531,0.087891 to 49.499996,0.878906
> 
> If you look at the Garmin units, 2306867 is not divisible by 2048.
> Could this be the reason?
> Is it a bug in the splitter or should I use an option to let the
> splitter draw areas that exactly fits with 2048 garmin units?
> 
> Second, I noticed in the corners of the map that the background
> polygon does not match.
> See pic "corners.jpg".
> 
> 10132142: 3266560,1212416 to 3327481,1444704
> # : 70.092773,26.015625 to 71.399996,30.999985
> 
> Again, the most northern latitude 3327481 is not divisable by 2048
> 
> I also notice that the map disappears when zooming in at the border
> tiles (only at very high zoomlevels, like 100 m or closer).
> 
> I use splitter r297 and mkgmap-r2513, precompiled sea tiles (in
> splitter and mkgmap) and a custom background (generate-sea:
> land-tag=natural=background), maybe this is also relevant to mention?