Dubious elevation data from GPS

General talk
1

There are some objects like Node: ‪۰۱۳‬ (‪1236638011‬) | OpenStreetMap which have some GPX debris.

Is it better to remove or keep dubious elevation info such as ele=1544.712402? Or do something else?

Definitely some accuracy is spurious, even accuracy to meter is unlikely.

(in this case I think that removing

cmt=07-DEC-09 10:23:15
description=07-DEC-09 10:23:15
sym=Drinking Water

would be nice, though yes, I am aware that benefits of such edit are very small)

2

Hi, I’m not sure about deleting the ele tag, but I’m in favour of rounding the value to metres and deleting the 3 other tags you’ve listed.
Ale

3

Data such as this is absolutely not appropriate for an automated edit, without asking the basic question “what was the original adder of the data actually trying to record here”.

This example may very well be an amenity=drinking_water (or may well have been 13 years ago when added). Many others will not be, because the Garmin list of features doesn’t map one to one with OSM tags.

Of all the tags, ele is the most verifiable (although thinking that an value expressed to the nearest micron is accurate is clearly silly, and rounding to the nearest meter makes sense). A GPS unit with a calibrated barometric altimeter will in my experience probably record values within a couple of meters or so, but something reliant on satellites won’t be especially useful as a reference. Here (in Shiraz) the recorded value is likely a few 10s of meters too high.

What would be far more interesting than tidying useless cmt etc. would be going through OSM data, find what was originally added as or converted from Garmin waypoints and (from looking at the original data) guessing which OSM tags were wrong. To do that, of course needs the data with the original Garmin tags in place, something that in many cases you’d need to get from object history.

4

to be clear, I am not proposing one

I was thinking about what to do in a manual one

amenity=drinking_water was present from start.

Do you think it is likely that someone mapped things on their Garmin, matching various water features to sym=Drinking Water and then matched all sym=Drinking Water to amenity=drinking_water and uploaded that?

Or how else amenity=drinking_water present from start would be likely to be wrong?

5

We can see what happened by looking at the changeset. They collected a bunch of POIs on their Garmin, and then added them to OSM. In this changeset, in each case the chose a main OSM tag, for example amenity=restaurant for a POI named Restaurant… Some of the other POIs have been updated with more correct data since

They’re still around; they edited OSM a couple of times last year.

We see quite a lot of people adding POIs as personal markers (especially from e.g. MAPS.ME). In that stuation, it’s not guaranteed that a POI added to OSM with a certain tag actually matches that OSM tag in real life, but that doesn’t seem to be the case here. If you look at a later changeset, some of those Garmin POIs got modified into the later better mapping of the area, and some got deleted as you’d expect.

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