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[mkgmap-dev] default style lines enhancements

From Greg Troxel gdt at lexort.com on Tue Jul 28 13:52:35 BST 2020

Ticker Berkin <rwb-mkgmap at jagit.co.uk> writes:

> With the data as it stands, for sensible routes in the above situation
> and others as expressed in my earlier email, mkgmap needs to generate
> footways that join up all ways that lead into the car park with a
> footway. With the current technology this can be done with
> circumference footway and mkgmap:set_{semi_/un}connected_type provide a
> really good way of not doing this where the footway won't solve any
> routing issue and might cause routing island problems.

And it will generate paths that may not actually exist, or might be
signed no trespassing.   Gerd has said that he doesn't want to
synthesize data that isn't in OSM, and I think this is wise.

> I wouldn't object if OSM mappers joined all paths and the entrance
> road/parking aisles within the car park and maybe there should be a
> policy to do this and then there is no problem.

There is broad consensus that this is the right thing to do.  Editors
warn about "way end close to other way".

> However, there is a good argument that the correct OSM mapping is to
> show paths exactly as they are and not have to invent and add 'virtual'
> bits of footpath just to keep routing engines working sensibly because
> "mkgmap expects it like that".

It is not about mkgmap.  It is pretty much all routers.   A path
represents "you can travel along this way with this mode and this
access".  That's exactly what is going on, at a simple level.  At a more
complicated level, you can claim that the parking lot is  pedestrian
way, but that isn't really true.   It's really that the thing that looks
like a path comes to the edge of the path and there is a way to continue
walking onto pavement to get to the space between aisles.

If there is a sidewalk around the lot, then map it.   And add ways to
get from sidewalk to the middle.

> Other things that have been mentioned:
> - What about a path that runs up to or along the side of a car park but
> there is no access between them, eg an enclosed car park with a road
> along-side. I'd say that this is just incorrect mapping if the car park
> shares a node with the road but there is a barrier between.

It is almost always (alwyas?) incorrect to have a parking lot share a
node with a road.   That would imply that the parking lot beings on the
road centerline.

> - If starting within the car park, the route might tell you to walk
> around the edge rather that direct to the highway. Yes and no; it will
> plot a route to the closest edge and then to the best exit for the
> final destination; It should be obvious to the GPS user that they can
> just walk directly to the best exit. Without the change the only option
> you might get is onto the road network which could be entirely wrong.

with correct mapping, you usually get a sensible route along parking

I really do not understand the resistance to making the map data
represent what you can do on the ground.  It seems really obvious that
this is sensible, and that is the majority view within osm tagging.

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