[mkgmap-dev] White stripes in the sea

Thu Jan 3 19:37:35 GMT 2013

>  > I have no idea how to use a TYP file to avoid such problems.
>  > The algorithm to decide if a mixed are should be displayed as sea or
>  > land is the resolution dependant mp cut algorithm as described above.
>  >
>
> Well, I don't yet have an idea how to handle the case when many small
> islands cover - lets say - 70% of the area, but all of them are too small
> to be displayed. I fear we will only display see in that case.
> Anyhow, this problem  has to be solved later.

So in ASCII art it's the following situation:
(s = sea polygon, each l = single small land polygon)

ssssssssssssssssss
slllllllllllllllls
slllllllllllllllls
slllllllllllllllls
ssssssssssssssssss

In the end it is also a problem of the resolution dependant mp cut 
algorithm. At first it would remove all small single land polygons. But 
in an improved algorithm it could try to merge the land polygons.

I guess merging will be quite complex:
- What should be done if two small mergable polygons have some tags in 
common but also some different tags? How is the merged polygon tagged?
- How should the algorithm detect that two polygons can be merged when 
they are not connected to each other? It could calculate fractions for 
each resolution dependant "pixel". So on one pixel the sea might be 30% 
and land 70% and therefore land wins and the pixel is assigned as land. 
This requires a good merging algorithm for pixels...
- ???

WanMil