[mkgmap-dev] problems at map intersections?

Fri Jul 17 21:49:40 BST 2009

Hi

> Since no one replies to my mail, I'll do it myself ;)

Thanks for studying the problem so closely - it is very useful.

> What I found is the following. Splitting a file with a border will
> produce a file that has the exact "bounds", without the overlap, in the
> resulting map.

That is intentional; the bounds should not overlap and should meet exactly.
There is extra data in the file that extends beyond the bounds and mkgmap
should cut the lines at exactly the bounds.

Cutting the lines at the exact boundary is bes done in mkgmap
rather than splitter for several reasons, for example you have
to know whether something is a line or a polygon to know what to
do.

> Then, in addToOverviewMap, I added "-1" to the minimum lat/lon values:
> int minLat = roundDown(bounds.getMinLat(), overviewMask) -1;
> int minLon = roundDown(bounds.getMinLong(), overviewMask) -1;

I think that three things must line up exactly, the tiles them selves,
the areas within the overview map and the areas in the TDB file.
Probably one or more of those are out of step.  Its also possible that
it only goes wrong in certain circumstances such as +ve or -ve longitude.
The next step is to find out exactly which one is wrong and compare with
a working map if necessary.

Cheers,

..Steve