[Tagging] RFC - Feature Proposal - area of steps for pedestrians.

Tobias Knerr osm at tobias-knerr.de
Tue Apr 9 15:42:31 UTC 2019

On 29.03.19 07:05, Warin wrote:
> https://wiki.openstreetmap.org/wiki/Proposed_features/Area-steps

Detailed steps would be great for 3d rendering, so I'm very interested
in the topic as a data consumer. However, reading the proposal leaves me
with open questions. Could you describe the intended logic for
constructing the geometry of the individual steps from an area_steps
relation? I can think of several good heuristics myself, but the notable
"same number of nodes" rule makes me think you have something specific
in mind.

I do have some concerns regarding ease of mapping:

- I'm not convinced that a relation (rather than an area:highway
polygon) is necessary in typical cases. Usually, the most acute angles
of the polygon mark the point where the bottom/top border is separated
from the side border. It would seem sufficient to draw explicit lateral
ways only in cases where that assumption doesn't hold.
- Requiring the same number of nodes for the upper and lower way seems
very fragile. It's unexpected that inserting nodes into a way (or
removing them from a perfectly straight line) would invisibly break data.

Also, you suggest that different step_count values for the left and
right side could be modelled using your relation. But I don't see how I
could tell whether the steps are "missing" from the top or bottom?


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