[Tagging] The actual use of the level tag

[Tobias Knerr]

On 22.01.19 22:18, Tobias Zwick wrote:
> First, I am still in the dark a bit how this affects SIT with S3DB
> compatibility, perhaps Tordanik can explain.

My comment regarding S3DB compatibility was about the related issues
that were brought up in this thread (e.g. indoor features outside of a
building outline). Your suggested tagging for non-numeric levels would
not harm S3DB compatibility, as long as mappers reliably add the levels tag.

To respond to the points from your previous mail:

On 21.01.19 20:16, Tobias Zwick wrote:
> In the current SIT scheme*, in this case, it is required to add 5
> additional outlines, one for each floor (indoor=level)

Using the currently documented tags, that's mostly true (the levels
where the number is actually used as the ref wouldn't require the
indoor=level) element. I admit that this is more work than one would
want for a simple case.

However, in addition to your suggestion, there are multiple other
possible approaches for making this easier. One is the level:ref key.
Independently from SIT, this has been proposed for use on individual
indoor elements alongside level. When you have a building that isn't
actually fully indoor-mapped, but simply has a few POI with level tags
(which is likely to be the much more common case), this might be an option.

If we wanted to do something similar to your suggestion (i.e. place a
tag on the building outline), this would be possible without redefining
level to allow non-numeric levels: We could invent a new key – say,
"level:refs" – that would be added to the building to indicate the
locally used level labels:

level:refs="LG,UG,M,1,2"

Then, if you want to know what to display for an element tagged as
level=0, you can just look it up in that list. This approach is pretty
much the precise mirror image of the one you suggested earlier, and
requires the same amount of elements and tags.

So which approach is the best? To be honest, I'm not sure about that
yet. But I agree that the current SIT definition leaves room for
improvement.