[OSM-talk] Summary about "Convert to data layer" (was: Stupid Josm question)

Immanuel Scholz immanuel.scholz at gmx.de
Sat Jul 1 23:45:16 BST 2006


Hi,

many opinions were already said, but since JOSM's behaviour for your use
case changed recently, I will bring some enlightment into the affair. ;-)

I assume you are using JOSM version 103 (which is the latest beta). If you
are using version 100 (josm latest release), you may want to upgrade now,
since your asked way of editing is not very good supported by the release.


[Phillip asked]
> I'm obviously missing something obvious here, but given that my GPS
> tracks, loaded into josm and with the 'Draw lines between raw GPS points'
> option, produces beautiful looking roads  - why am I then painstakingly
> adding nodes and segments in an attempt to make an approximation of those
> automatically generated by josm?

If your GPS data looks fine, then you can convert it into a "data layer"
in JOSM and so skip to draw your streets on top of the gps track. This is
recommend especally for those lonesome motorways going hundrets of boring
kilometer to the horizon.. ;-)

To do this, load the gps track and choose "Convert to data layer" from the
"Layer" menu on top of the screen or from the context menu in the layers
dialog.


> (btw, is approx 50 nodes for a 2 km stretch of minor country lane a bit
> excessive, or what you need for accurate map making, as I think it is
> ....?)

If the street looks good, it is ok. If it would look good if you remove
some points, remove them ;-). But don't overdo the cleaning up. Other
things are more important, as example to just enter some data. Or to
check, that nobody already entered your street ;-)


[Joerg added]
> What I do is:
>  - Take my gpx-,mps-,...-tracks
>  - convert and filter them with something like
>      osm-filter.pl --out-osm --use_reduce_filter gpx-*.gpx
>  - load the resulting osm File into josm
>  - in josm edit it as of deleting duplicates, glitches, ...
>  - then tell josm to upload that to the Server.

The --use_reduce_filter - script is a nice way to clean up everything some
bit. Thanks for the hint. ;-) How does it work exactly?


[Andy suggested]
> When you load in the gpx file to JOSM, hit the "No" response to "Do you
> want to open as raw data" and you will find all your trackpoints turned
> into nodes and each separate continuous log turned into a way.
>
> Not advisable to use this method in areas where there is already a lot of
> data.

Neither advisable nor possible anymore ;-). The message box has been
removed in Revision 103 and the only way to "open" gps data as non-raw
data is to first normally open them and then convert the gps layer into a
data layer (which will automatically merge it into any existing data layer
- no support for different data layers yet).

However, if you using Revision 100 (josm.jar - latest release), this is
the way to go.


[Gabriel said]
> Right click on the gps data layer, `Convert to data layer'.  The resulting
> nodes however will have 'ele' and 'time' tags, and don't forget to remove
> the waypoints before uploading.

If this is true, it is a bug. Converting gps layers to data layers should
preserve neither the "ele" nor the "time" tag (all properties should be
stripped). What revision do you use?


Ciao, Imi






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