Is there any way to use a gps track (either already uploaded to openstreetmap, or from the local computer) to define a road or path? So far the best I've been able to do is to upload the gpx file and then show it on the map and trace it by clicking, but that feels very clunky.

asked 30 Aug '11, 21:36

jtappin's gravatar image

accept rate: 0%

This is actually the way you are supposed to map. It might feel clunky at first but you have the chance to use you local knowledge as well as your good judgment to remove small wiggles from straight sections of the road that result from GPS errors and make other improvments. Computers have a very hard time doing that (basically because the don't know the road you travel on). Some editors offer support for converting GPX to a Openstreetmap way, but the result is pretty poor and should not be uploaded as is. In my experience the manually tracing is faster than the automatic conversion follow by all the fixups the way needs.

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answered 30 Aug '11, 21:54

petschge's gravatar image

accept rate: 21%

There are times when it is both valid and most accurate to make a way from an uploaded gpx trace. For example, when a government introduces some new zone boundaries and publishes them as geographic coordinates or tracefiles which (with a little effort) can be saved in gpx format. Or when a person has done all the work in another (probably more efficient) software to clean up a track from their GPSr before upload to OSM.

Then in Potlatch2 it makes sense to use the Alt-click function to make a way from the gpx trace.

However, it seems that Potlatch creates an open way with duplicated first and last nodes when this method is used on a closed gpx track. This is not easily noticed in Potlatch, but it can be seen to be the outcome by inspection in JOSM (for example using the filter for closed ways, or the validator to report ways with duplicated nodes). It is a bit painful to find and manually correct each of those mistakes, so it would be great if there was some way to avoid them in the original conversion.

Is there any way to avoid this problem while 'automatically' converting a closed gpx track (trace) to a closed way, either in Potlatch 2 or JOSM?

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answered 15 Sep '11, 01:17

moreton's gravatar image

accept rate: 0%

That's probably best asked as separate new questions ...

(15 Sep '11, 10:28) SomeoneElse ♦

There isn't really such a thing as a "closed GPX track". Unlike the OSM file format, GPXs are not topological. Two identical lat/long pairs do not indicate a connection, merely that you were at the same point twice.

The GPX conversion function in Potlatch is provided as a convenience for mapping long, previously unsurveyed roads and paths in rural areas, saving you the effort of tracing the route. It is not meant for areas with high connectivity and you should always review everything about your converted way before uploading. I'm loth to make any changes that would detract from this message.

(15 Sep '11, 11:14) Richard ♦

Thanks for the opinion. I can't imagine why a gpx trace used to provide data into osm would have the same first and last nodes unless it was intended as a closed way. Maybe as osm evolves someone will decide that is a sensible feature to automate.

(15 Sep '11, 13:28) moreton
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question asked: 30 Aug '11, 21:36

question was seen: 10,827 times

last updated: 15 Sep '11, 13:28

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