R: [mkgmap-dev] [PATCH v3] - beware of the bollards!

Wed Jul 8 19:24:31 BST 2009

--- Mer 8/7/09, WessexMario <wessexmario-osm at yahoo.co.uk> ha scritto:

> Da: WessexMario <wessexmario-osm at yahoo.co.uk>
> Oggetto: Re: R: [mkgmap-dev] [PATCH v3] - beware of the bollards!
> A: "Development list for mkgmap" <mkgmap-dev at lists.mkgmap.org.uk>
> Data: Mercoledì 8 luglio 2009, 19:55
> 
> 
> Marco Certelli wrote:
> > No Dermod, it doesn't solve the issue.
> > 
> > In fact the Mark's patch just make in a clean way (in
> the IMG only) what I did before in a dirty way (in the OSM
> data): mark's patch surrounds the barrier with a couple of
> ways that has the access=no/foot=yes/bicycle=yes
> restrictions (exactly as if they were footways in OSM) but
> without touching OSM data.
> > 
> > I also do not see a solution for the routes
> starting/ending in the 2 short ways around the bollard: The
> problem is that garmin GPS checks the access only when it
> "enters" a way. If you are already into the forbidden way
> (becouse you start a route from within the way) the fact
> that the way is unaccessible is not checked by garmin.
> > 
> > I guess the only way to reduce the issue is to make
> the 2 ways as short as possible (maybe 10 meters might be
> enough) just to reduce the probability to start/end within
> them. After all, the precision of the GPS cannot tell you on
> which real side of the bollard you are if you actually are
> very close to the barrier.
> > 
> > Ciao
> I'm not sure of the issue here.
> Are you saying that for (say) car routing, if the user
> starts on a footpath, then it's not calculated correctly?.
> You could say "so what?" If the user asks for a route from
> a location that they shouldn't have access to (eg: car on
> "foot=yes, car=no" footpath), then ignore that local
> restriction  (as Garmin would from not entering the way
> ) and just route out as normal.
> If the request is illogical, does it make sense to apply
> too much logic to the answer?

My experience is that Mapsource tries as much as he can to respect access restrictions. But if there isn't any other way, it will not respect them.

So, if you start a route (or if you end a route) on a footway and you ask for a car routing it will find a route! On the footway. And if the only way to go from a road to another is a footway, it will route your car on that footway. This does not apply to oneways: oneways are always respected. 

This is what I've seen so far. The reason of this I do not know but maybe Garmin consider map errors:
1) if you are on a way, well it is clear you can go in that way. Maybe the map is wrong
2) if there is an unreachable road, this is probably a map error again.

Ciao.