[OSM-newbies] Converting GPX to ways

[Richard Weait]

On Thu, Apr 22, 2010 at 5:38 PM, Gavin Scott <gavincscott at gmail.com> wrote:
> So I have uploaded some tracks using Potlach. I click edit then select edit
> and then tick the box Convert GPX tracks to ways and when it opens I cannot
> select the GPX track to turn it into a way. Is there a size limit - it has
> 1500 nodes or points - is this the problem?
>
> Also does teh same functionality exist in josm - can I turn a gpx track into
> a way without having to retrace it?

Yes, the gpxedit (or is it editgpx?) plugin in josm allows this.  The
josm plugin will also display a very helpful and serious warning about
not converting gpx tracks into ways for openstreetmap.  So please
don't convert gps tracks to ways and upload them to OSM.  They don't
meet the standard of quality that we can accomplish with human
editing.  Here's why.

Most gpx tracks are full of junk.  Junk from bad reception.  Junk from
when we stop for coffee.  Junk from a random reflection from a
building.  Junk from when we left our intended track because we were
distracted by a pretty sunset.  This junk should all be filtered out
by the "wet ware" that is the considerate editor who collected that
rack and is editing and adding data to OpenStreetMap.

The drawbacks of gpx tracks are even greater when using a track
collected by somebody else.  Were they walking on the sidewalk, the
traffic lane, or down the center of the carriageway?  Was the track
post-processed to add or remove anything?  Was the track even
collected by gps?

Let's say the track doesn't suffer from any of these drawbacks, and
that it is technically perfect.  Convert it to a way and you'll end up
with a way with far too many nodes.  It is a rare sub-section of a
trace that should have one node per second of gpx file.  Uploading a
way directly converted from a gpx track is in all likelihood a really
poor bit of mapping.

And a final, and serious problem with direct conversion of a gpx track
to an OSM way.  The conversion won't consider junctions with existing
OSM ways and data.

For all of these reasons, we use gpx track files as guidelines to
assist us in our mapping, but not as a substitute for our judgment and
experience.  So while editors may allow gpx conversion, it is not
recommended.  So, again.  Please don't.

You might ask why such a task is possible when it is not recommended.
(I might ask that as well)  I don't know.  ;-)  But I am glad to have
the gpx functions available in josm because I use that the edit my gpx
files before contributing them to OSM.  I remove the distracting
extras at the beginning and end of the trace before converting back to
gpx and upload to OSM.