[Tagging] Orientation of an adit?
kevin.b.kenny+osm at gmail.com
Fri Mar 10 14:34:51 UTC 2017
On 03/10/2017 08:48 AM, Tod Fitch wrote:
There are a number of abandoned adits and mine shafts in an area I’ve
done some mapping in. When looking at old USGS topographic maps of the
area, I’ve noticed that they used to align their symbol for an adit to
show its orientation.
My inclination, at present, is to use either:
Where the value would be in degrees clockwise from north, though I
doubt that more accuracy is needed than just compass points.
I rather like this idea (which, I'm afraid, means that the consensus here
It would be useful not only for adits, but also for cave entrances.
Moreover, I'd like to see such a thing on small dams, small waterfalls, and
other directional point features. I know that the hydrographic ones can be
deduced from direction of the flow of the watercourse, but that, too, is
difficult to extract from the OSM data model - difficult enough that I know
of no rendering of OSM that is able to use the conventional symbol of blue
hashmarks across a stream to represent a waterfall or black ones to
represent a dam. It would similarly help for point objects used to
represent barriers such as gates.
I can just now hear, nevertheless, a chorus asserting that the information
is available by other means and therefore does not belong in OSM. An adit
or a cave entrance (that isn't a sinkhole) pretty much has to go into a
hillside, and a waterfall or a dam flows downhill, so with information
about local topography, the direction can be determined. The conventional
symbol for a gate would be drawn across the roadway (and presumably the
roadway direction is available), and so on. The fact that this hasn't been
done yet, I'd argue, indicates that it is difficult enough that a little
bit of auxiliary data might help!
And now I've got something added to my "to do eventually if nobody gets to
it first" list - a piece of programming to take features of this sort, find
corresponding points on interpolated data in an elevation data set, and use
gradient information to come up with a direction for rendering the symbol
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