On Fri, Jan 10, 2020 at 11:58 AM Florian Lohoff <f...@zz.de> wrote:

> Footways are not part of the by car routeable network. And
> access=no/access=private or highway=track and neither.

This depends on the router, AFAIK Magic Earth navigates over private
roads. It even combines it with access=destination roads that are
connected to them.

> > IMHO, this also does not matter for POIs with an address on a building. The
> > satnav should take the coordinates of the POI, not the centre of the
> > building in which it is placed. Taking the centre of the (large) building
> > might lead to problems.
> >
> > So yes, one should try to map as many service roads, paths, internal
> > corridors as possible to help routers. And yes, the coordinates taken by
> > the router for the endpoint are important.
> > but is this caused by addresses on buildings vs. on nodes ? no, not always,
> > e.g for (apartment) buildings with multiple entrances with only address
> > info on the building, it can go wrong. Not for small detached family houses.
> Commercial dataset map addresses back to nodes on the road - On specific
> points. We as OSM rely on algorithms to do this automatically - And
> fail in an astonishing large amount of cases.
> If you go to the center of a park by car there is no way the algorithm
> can decide on the best spot to go there by _car_. So it uses the centroid
> of the park, tries to find the nearest highway usable by your mode of
> transportation. If that happens to be by car you might end up multiple
> kilometers away from the optimal place to be. And there is nothing
> we can do about it with this level of data abstraction.

There is no single 1 spot that is the best, even not for cars (or
vehicles). Satnavs should allow you to refine the search for
centroids. After telling the system that you want to drive to a park,
it should (or could) offer you a few choices. Whether this is based on
park entrances being mapped or parking places nearby is up to the
software. I think this is not always solvable by mappers.

As for car navigation not taking paths and driveways into account.
Again, that is a problem of the navigation software.
I know OsmAnd uses driveways, as it always took my neighbour's
driveway since in OSM it comes close to my house than my own driveway.
OsmAnd does ignore any fence you draw. BTW, the private footpath to
the frontdoor is not mapped.
I do not think mappers should try to work around software limitations
of their favourite satnav program. Those programs should be improved.

We are so used to give an address and assume the software will bring
us to the right spot, perhaps that flow has to be changed and not the
data driving that flow.



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