[Tagging] Additional detail of Levee mapping via embankments
joseph.eisenberg at gmail.com
Tue Nov 19 09:59:19 UTC 2019
> peaks are contained in DEMs, why map them in OSM
Mainly so we can add their name=* and elevation based on survey.
But also, DEMs have trouble localizing point and line features, so if
you climb the peak or walk along a ridgeline to check the location
with GPS, it is usually more accurate than most DEMs.
For the same reasons, mapping a dyke or embankment or cutting as a
line is a great idea.
Mapping the area is less important, since usually adding 'width=' is
enough, or mapping 2 embankment lines on each side, though I am not
opposed to other mappers doing this if they really want to.
On 11/19/19, Martin Koppenhoefer <dieterdreist at gmail.com> wrote:
> Am Di., 19. Nov. 2019 um 04:49 Uhr schrieb Joseph Eisenberg <
> joseph.eisenberg at gmail.com>:
>> Are you sure that the information that you want is not already
>> available from a Digital Elevation Model?
> I do not agree with this. DEMs (at least what is commonly and freely
> available currently) do not provide the same kind of information, and are
> generally lacking the resolution and in particular, do not contain specific
> detail (e.g. shape), they treat every spot the same, are not focused on
> features (you can recognize the features that are visible and discernible
> on them, but they do not specifically represent them). We could also say:
> the buildings and roads are already on aerial imagery, no need to map them
> ;-). Or peaks are contained in DEMs, why map them in OSM?
> Large embankments should be clearly visible in the topography, so we
>> do not need to reproduce them as 3D model in the database, any more
>> than we need to map the exact contours of a quarry or mountain.
> if there are interesting features on a mountain (particularly those
> features with names or other attributes, wikipedia references etc.), we do
> map them, (e.g. peaks, ridges, passes, ...)
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