[mkgmap-dev] splitter r273 with --precomp-sea parameter

Thu Dec 27 19:01:29 GMT 2012

>  > Why is the sea density map and the usual density map merged before
>  > trimming occurs? My uneducated guess is that it is better to merge after
>  > trimming because the areas that could be trimmed should not be left in
>  > the tiles only by having some coastline parts.
> Trimming occurs after the calculation of the tiles, so it would be
> difficult to
> use the data at this stage. I did not fully understand why coastline data is
> added to an otherwise empty area, so I thought it is better to start
> with something
> and ask for comments.

Please have a look at the attached image.

The green area is the land data contained in the OSM data to be split. 
The blue area is sea but the left coastline (grey) is not contained in 
the OSM data.

If you trim before merging the sea density the left border of the tile 
will be the green line. If you trim after merging the sea density data 
the left border will be the red line because all parts of the grey left 
coastline is not yet loaded.

WanMil
-------------- next part --------------
A non-text attachment was scrubbed...
Name: sea_trim.svg
Type: image/svg+xml
Size: 50999 bytes
Desc: not available
Url : http://lists.mkgmap.org.uk/pipermail/mkgmap-dev/attachments/20121227/d0454a63/attachment-0001.bin 