OpenStreetMap Forum

The Free Wiki World Map

You are not logged in.

#1 2010-01-08 15:52:59

Emilien
Member
Registered: 2009-11-23
Posts: 36

Road from GPS track == lots of nodes...

Hi,

I've just created a new track from a GPS track I've taken lately, using the Potlatch online editor. It's a very sinuous dirt road in the mountains, so there are a lot of curves in the track, meaning a lot of GPS points. In total the track now contains 1649 nodes (!!)
You can see the track here: http://www.openstreetmap.org/edit?lat=1 … gpx=600334

My question is: what should I do with that track? It seems that 1649 nodes is really excessive, but how should I reduce that? Do I need to manually delete nodes that don't seem necessary, or should I have used some script before uploading the track? Or should I not use the option to create the track from the GPS data at all?

Thanks for your answers.
e2jk

Offline

#2 2010-01-08 16:08:08

PHerison
Member
From: Rhein-Main
Registered: 2008-04-04
Posts: 1,443

Re: Road from GPS track == lots of nodes...

JOSM has a Plugin which tries to reduce the nodes. Don't know how good this is.
I don't use the GPX-to-OSM-way function. If I have a track I use the manual drawing option and common sense.

Offline

#3 2010-01-08 16:17:12

wambacher
Member
From: Schlangenbad/Wambach, Germany
Registered: 2009-12-16
Posts: 16,130
Website

Re: Road from GPS track == lots of nodes...

Emilien wrote:

Hi,

I've just created a new track from a GPS track I've taken lately, using the Potlatch online editor. It's a very sinuous dirt road in the mountains, so there are a lot of curves in the track, meaning a lot of GPS points. In total the track now contains 1649 nodes (!!)
You can see the track here: http://www.openstreetmap.org/edit?lat=1 … gpx=600334

My question is: what should I do with that track? It seems that 1649 nodes is really excessive, but how should I reduce that? Do I need to manually delete nodes that don't seem necessary, or should I have used some script before uploading the track? Or should I not use the option to create the track from the GPS data at all?

Thanks for your answers.
e2jk

i'm using PRUNE to edit my gps-tracks - remove unwanted or bad points looking like stars on my screen - and reduce the number of points with special buildin functions.
after that i load the track to josm, but only as local file.
then paint the new way/track/street over the original gps-data.

regards

wambacher

that's "my way" to do the job.

Offline

#4 2010-01-08 17:02:24

chris66
Member
From: Germany
Registered: 2009-05-24
Posts: 9,417

Re: Road from GPS track == lots of nodes...

PHerison wrote:

JOSM has a Plugin which tries to reduce the nodes. Don't know how good this is.
I don't use the GPX-to-OSM-way function. If I have a track I use the manual drawing option and common sense.

Hi,
the JOSM Plugin works ok, you can adjust the "compression-rate" somewhere in the advance
options.

I also never convert tracks to osm-highways directly.

Chris


Mapper aus dem Münsterland/NRW. Nicht auf fakebook.

Offline

#5 2010-01-09 11:15:43

greencaps
Member
Registered: 2009-10-05
Posts: 423

Re: Road from GPS track == lots of nodes...

Under windows you can use Gpx2SlippyMap to reduce the number of nodes in a track. http://tinyurl.com/yl9a7hp  You can 'also' display the track on an osm slippy map.

Offline

#6 2010-01-09 15:52:28

japa-fi
Member
Registered: 2008-09-24
Posts: 44

Re: Road from GPS track == lots of nodes...

gpsbabel is useful tool, if you are not afraid of the command line (vs. gui) application.

gpsbabel -i gpx -f walk.gpx -x simplify,count=400 -o gpx -F walk-simple.gpx

Above takes in walk.gpx which is of gpx format, reduces it to 400 points by removing those points which have least effect on the track shape, output to walk-simple.gpx (also in gpx format)

Offline

#7 2010-01-10 10:09:56

stephan75
Member
Registered: 2008-05-28
Posts: 2,741

Re: Road from GPS track == lots of nodes...

Have a look at http://www.routeconverter.de/en ... you can display GPS-Tracks on many maps and modify the Points, even reduce them to a good amount.

Offline

#8 2010-01-13 13:43:46

Richard
Member
From: Charlbury, UK
Registered: 2007-04-24
Posts: 364
Website

Re: Road from GPS track == lots of nodes...

There's something weird going on there. Potlatch is meant to simplify automatically when you import. I'll investigate why it's not doing in this case.

Offline

#9 2010-01-14 02:10:38

Emilien
Member
Registered: 2009-11-23
Posts: 36

Re: Road from GPS track == lots of nodes...

OK, so in the end I just deleted the track made from the GPS data, and simply draw over it in Potlatch. That way the number of points were greatly reduced (428 nodes instead of 1649, and the new track is longer that the first one)...

Richard, when going to http://www.openstreetmap.org/edit?gpx=600334 and selecting the option to create the track from the GPS data, it will create a track containing 1890 nodes. The GPS data contains 2185 points, so it gets somehow simplified, but I imagine you'd like it to simplify more. But then the question would be until what point should the track be simplified, before it starts losing important points?

Well, I think this topic can be closed.

Thanks all for your input!

Offline

Board footer

Powered by FluxBB