Mark Burton wrote:
Hi Felix,
Mark Burton wrote:
Hi Steve,
Is there any problem with this option, such that you might not want
to use it?
I am not aware of any problem.
As I understand it, if you do not give it then routing will not work,
as we know (or believe) that all routing arcs have to be more than 5.4m.
I believe that the mimimum distance will depend on lat/lon because the
real constraint is that the source and target nodes must not have the
same coordinates (resolution being 360 deg / 2^24)
If that is so, then we should just set the required behaviour whenever
the route option is given.
Why don't we do that but still provide an option to turn off the
short arc removal (which should never need to be used but may be useful
when tracking down problems).
I realize that there might be other approaches, eg we could stretch arcs
instead of removing them, but if removing them is our current best
approach, lets make it the default.
It seems to be working well enough at the moment.
Shall I change the code to remove the --remove-short-arcs option and,
instead, enable that function if --route is specified and
(the new) --keep-short-arcs option is not specified?
Cheers,
Mark
Yes, but we should be clear about the distance needed. I used =3 because
without specifying it, I had some route calculation working, that
without specifying did not work. If there is really 5.4m then the
default should go for 5.4 -- or just leave the option as it is right now
but use it by default except if say --remove-short-arcs=no is given...
Ahh, I forgot about that aspect. At this time, if you don't specify a
length with the --remove-short-arcs option, it only removes zero-length
arcs. I think that is the most sensible behaviour because we know that
zero-length arcs are bad for routing. The fact that some maps require a
minimum arc length to be specified should be investigated some more to
see what the issue is.
Cheers,
Mark
I think actually the reason for routing to work better with 3 instead of
simply no argument might be, that garmin would not crash on very short
arcs, but simply avoids to change roads often, so by setting 3 or higher
one could actually reduce some unneccessary street changes, hence
sometimes (very rare) better routing over long distances.
Probabely this issue that was a bit controlled by the patch, should be
addressed by other patches however....
Until we have those patches, I am a bit sceptical about dropping the
support to specify the arc length.
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