[Tagging] Mapping nonexistent paths

Tobias Knerr osm at tobias-knerr.de
Tue Mar 23 22:31:43 UTC 2021

On 23.03.21 16:13, Sinus Pi wrote:
> The purpose is to display to users a map that will reflect reality. If 
> the square is just an open square, the renderer shouldn't show a 
> "spider" with routes connected in the middle, because that's not how it 
> looks in real life.

Agreed. If virtual paths are added, they should be added in a manner 
that allows us to cleanly distinguish them from paths which are visible 
on the ground. Otherwise this causes problems for renderers that want to 
depict the physical world rather than a routing network.

> And even if routers are 
> finally taught to use line-of-sight routing on areas, not just 
> traversing outer edges and properly finding shortest paths through the 
> area, they might still benefit from some guidance: for example some 
> pedestrian squares might have inclines or kerbs impossible to cross for 
> wheelchairs, and virtual paths could fill that void by having access 
> tags defining proper traversal of an otherwise open terrain.

Those are arguably two distinct use cases, though: Working around a lack 
of line-of-sight routing in popular software vs. providing information 
that even a perfect router can't figure out due to unmapped obstacles.

That's an issue because a router that *can* do line-of-sight routing 
should ignore a basic spider graph – it can do better. If it shouldn't 
also ignore your wheelchair routing hints, it has to be able to 
distinguish them somehow.

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