[Tagging] Mapping nonexistent paths

[Niels Elgaard Larsen]

Sinus Pi:
> czw., 25.03.2021, 01:27 użytkownik Niels Elgaard Larsen <elgaard at agol.dk>
> napisał:

>> We need to provide a topology that can be used by OSM users using
>> available routers.
>>
> 
> Line of sight is (or should be?) simply an optimization of
> all-corners-to-all routing, surely rather obvious in graph routing.
> 
> Wiki on area:highway -
>> However, as of 2019, OpenTripPlanner
> <https://wiki.openstreetmap.org/wiki/OpenTripPlanner> is the only OSM-based
> router that supports routing over areas. It does so by computing a
> "visibility graph" over the area.


Have you actutally tried OpenTripPlanner?

I did download the jar file, but that was not very helpful.
I also tried using several of the deployments mentioned 
http://docs.opentripplanner.org/en/latest/Deployments/ to see if I could make it 
route trough a local (because the deployments only work on a very limited part of the 
world) park or square, not using the paths. But I was not successful.

So I conclude the users of OSM have practically no access to line-of-sight routing.

> Frankly, it seems either lazy of routers not to perform this, or they
> weren't really worked on since the advent of routable areas. Creating a
> sub-graph of all connections within an area and caching some of them as
> usable links between points shared with other highways is quite simple and
> potentially faster than routing along edges. But in the end it'll still be
> just bouncing off corner nodes, and might not represent what a real person
> would do.

Or could do, because there might be unmapped obstacles.
Or untagged restrictions.

> Hence the possible need for virtual guidelines, which I
> wholeheartedly support.

Good.

-- 
Niels Elgaard Larsen