[mkgmap-dev] New locator branch

Fri Mar 18 15:14:22 GMT 2011

in general they are not sorted. only coastline ways are directional.
I don't think there is any algorithmic approach to solve this. the only solution is to keep the whole relation in splitter or close the gaps in splitter before throwing away the rest.

On 18 Mar 2011, at 7:43 , Stefan Schunck wrote:

> Hi,
> 
> stupid question: 
> If the polygon points are sorted (i.e that area is always to the left side of the border; anti clockwise orientation ), then the multi polygon algorithm could know that solution 4 is incorrect.
> 
> Stefan
> 
> 2011/3/17 WanMil <wmgcnfg at web.de>
> I have a big problem to continue the development on the locator branch.
> 
> I observed that a lot of admin_level boundaries (2,3,4,5 and sometimes 6,7,8,9,10,11) are not useable because they are not completely contained in the tile data. The polygons are closed automatically but this is only a good guess in which direction they have to be closed. The probability is quite high that they are closed in the wrong direction.
> 
> I have attached a picture which visualizes the problem a bit more.
> 1. Red and green are two relations with e.g. admin_level=4. The black rectangle shows the tile bounds.
> 2. The splitter does not put the complete relations into the tile. So the read boundary is contained partial only.
> 3. The multipolygon algorithm automatically closes the red boundary with best guess.
> 4. Now we have two different boundaries with admin_level=4 which cover exactly the same area.
> 
> I think this will be a big source of complaints. So before continuing with the locator branch I think it will be more worthy that the splitter is able to put complete relations to a tile.
> Anyone here who wants to start with that?
> 
> WanMil
> 
> 
> 
> I have created a new branch for the automatic locator changes.
> It can be downloaded from http://www.mkgmap.org.uk/snapshots/
> 
> WanMil
> 
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