[mkgmap-dev] Remove short arcs

Thu Jan 17 14:28:02 GMT 2013

Hi Gerd

> Yes, today I tried to put it into RoadNetWork, but then I found out that
> this
> routine sees the roads after they were split into smaller parts by
> StyledConverter. So, a lot more program logic has to be changed, and I think

Yes, most of that code should be moved too.
And anyway, shouldn't the short arc code be run after cutting the
roads up anyway? It might also be possible to combine the two
functions.

> that I don't
> understand enough for that :-(
> I hope you can solve this, because I am not that happy with the
> removeShortArcs_v3.patch as well.

I don't understand it either.
I suspect that it might be possible to solve the actual problem
that removeShortArcs is attempting to solve, at the level of building
the NOD file. But the only way to find out would be to find or
construct cases that don't route properly as tests and experiment.

In the short term we need to decide on something to do. We
could disable the failing tests for the moment, go back to the
version that didn't iterate multiple times over the roads, or
go back to running it over all lines.

Running over all lines is a step backwards in my opinion.  The second
option seems fine to me, as long as there are no error messages about
short arcs. Even though the results are different they could well be for
the better. The comments about contour lines in that routine make me
think that it could be simplified now that we are not running it
on contours.  Lastly we could disable the failing tests for now,
since they are false failures.

So it depends on what you think about the original patch that didn't
run multiple times over the ways. If you think it is definitely broken
then we should @Ignore the failing test, and I will try out ways of
re-structuring all that code. I've wanted to do it for a long time
since I think that it is a barrier to any routing improvements.

..Steve