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<div class="m_-994256674077877821moz-cite-prefix">On 03/10/2017 08:48 AM, Tod Fitch
<pre>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 will not.<br>
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. <br>
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!<br>
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<br>