[mkgmap-dev] problems at map intersections?

Fri Jul 17 22:59:59 BST 2009

Steve Ratcliffe schreef:
>> 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.

Are you really (as in really-really-really) sure about the fact that the
maps should not overlap? A map with overlapping bounds seemed to work
better here - especially around the edges. (I hope I described the
problem of getting a blank map sufficiently to reproduce it - it did not
happen when I overlapped the maps).

[...]
> 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.

The overview map seems to suffer from some rounding problem, as the
boundary was a bit shifted to right, up; then when I decreased the
numbers, it was shifted left, down. Luckily, I know just enough about
programming to know that you can't decrease an integer by .5 ;)

> 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.

I can reproduce the problem of a blank map at different map
intersections (see my first mail). The problem shows at highest zooming
levels, when the boundary of the map is viewable (or sometimes just out
of view).

If it were only the difference between the overview map and the real
map, you would expect the map to disappear when the overview rectangle
would be out of sight, but that's not what happens.

Did anyone else notice this problem before? Were you able to reproduce
it? If it helps, I can prepare a map that will have a routing problem
just at the edge (there's a biking tunnel that MapSource avoids, no
matter how hard I try, while letting mkgmap render the map without a
boundary, the tunnel works just fine).

Let me know if you need the map/script/other stuff to reproduce it.

Best regards,

Valentijn

-- 
Durgerdamstraat 29, 1507 JL Zaandam; telefoon 075-7074579