[mkgmap-dev] default style lines enhancements

Mon Jul 27 18:31:03 BST 2020

Hi Greg, 

In the case I showed, I would probably have tagged it as you mention in view
A as there is a parking aisle drawn. However, many small car parks do not
have parking aisles, and in that case I would not probably draw a footpath
right across the car park and would go for view B. As one can normally walk
anywhere on a car park, by definition you can also walk around the edge to
any connected point, hence it seems reasonable to me to add the car park
perimeter as foot routable. If you use Foot (OSRM) instead of Foot
(GraphHopper) for OSM routing, it does take you around the edge of the car
park. For vehicles, I would only expect a car park to be a start point or an
end point, so it does not need to be routable. In the case of a fence, the
route around the edge is a routing artefact and you would actually walk
across it, so if two paths join a car park you should be able to walk
between them whether or not there is a fence around the edge. Perhaps a
better solution would be to join each point that stops at the edge of a car
park together with a routable way. A new option to handle this?

Regards,
Mike

-----Original Message-----
From: Greg Troxel [mailto:gdt at lexort.com] 
Sent: 27 July 2020 17:53
To: Mike Baggaley <mike at tvage.co.uk>
Cc: 'Gerd Petermann' <gpetermann_muenchen at hotmail.com>; 'Development list
for mkgmap' <mkgmap-dev at lists.mkgmap.org.uk>
Subject: Re: [mkgmap-dev] default style lines enhancements

"Mike Baggaley" <mike at tvage.co.uk> writes:

> I create foot routable (but not vehicle routable) ways around car parks in
> my style (I don't use the default style). This allows pedestrian routing
> around the car park in cases like
>
https://www.openstreetmap.org/directions?engine=graphhopper_foot&route=42.45
> 938%2C-71.35133%3B42.45856%2C-71.35058 which is a few yards away from the
> previous example. It is common for footpaths to start at the edge of a car
> park and in my opinion it is incorrect to add to OSM a non-existent
footpath
> across a car park purely for the purposes of routing.

That's really something to bring up on tagging.  As I see it there are
two views:

  A) one should continue the footpath in a way that represents how a
  person could walk to connect it to the parking aisles (that they also
  can walk on).  While there isn't something that is visibibly a
  footpath, there is in fact a place you can continue to walk from the
  edge of the lot to the parking aisle/driveway.

  B) Really there is a surface and one can walk anywhere there isn't a
  car parked, and thus the footpath should only represent the footpath
  and be joined to the edge.  Thus the carpark is really a routable
  pedestrian area.  This should either be the default or it should be
  tagged this way.

Two comments:

  I think A is the majority view in OSM by a wide margin.

  In B, you have to somehow deal with a fence around the lot, and be
  careful not to create routable ways that can't be traversed.  In this
  case, there is a fence on the SW side (not shown in OSM probably) but
  I think not on the NW side.