[mkgmap-dev] Feedback on --generate-sea

Sat Jan 9 18:28:30 GMT 2010

Hi Charlie,

> Firstly, Mark, many thanks for working on the sea polygon issue.

You're welcome.

> I've found two problems with --generate-sea.  One is relatively minor, 
> the other a bit more of a problem.
> 
> 1 (minor). If you use an options file via the mgkmap -c switch, the 
> comma separated list of generate-sea sub-options cannot have any spaces, 
> or you get an error
> generate-sea:polygons,no-sea-sectors works fine, but
> 
> generate-sea:polygons, no-sea-sectors results in the error:
> Unknown sea generation option ' no-sea-sectors'
> Known sea generation options are:
>    multipolygon      use a multipolygon (default)
>    polygons | no-mp  use polygons rather than a multipolygon
>    no-sea-sectors    disable use of "sea sectors"
>    land-tag=TAG=VAL  tag to use for land polygons (default natural=land)

Yup, you can't have spaces in the option list as it is now.

> 2 (major). If an island border has the tags
> natural=coastline
> boundary=administrative
> 
> Then, using Mark Burton's style (or even the default style) these 
> islands get flooded.
> 
> Attached is a screenshot taken from the Geofabrik Italy extract showing 
> the whole of Sicily flooded. Other islands that don't have a coastline 
> containing a boundary=administrative tag are fine.
> 
> The only way to stop the flooding is to remove the 
> boundary=administrative rule completely.  This is strange because as the 
> natural=coastline rule occurs first (in both the default and in Mark's 
> style) then the coastline should be set before any administrative 
> boundary rule matches.

Could the problem be that those ways are referenced in a multipolygon
and they are being deleted by the multipolygon processing? I am using a
small patch that stops that from happening (it was posted to the list a
while ago). 

Cheers,

Mark