[OSM-talk] Problem when uploading GPX tracks without time data

Dan Karran dan at karran.net
Sat Apr 29 22:20:27 BST 2006

On 4/29/06, Andy Robinson <Andy_J_Robinson at blueyonder.co.uk> wrote:

> Saving the track log rather than downloading the raw "Active" log from your
> eTrex is no good. As you say, the timestamps are lost. You will also find
> that the saved log is somewhat filtered and of limited use for OSM editing.
> Always download the active log. This means you need to think about how long
> you will be out between downloads and what the logging frequency needs to be
> to achieve a workable time. My Legend with its 10,000 track point limit set
> at a 1 second logging interval gives me two and three quarter hours, if I
> find that I need longer I change the log frequency to 2 or 3 seconds,
> sometimes part way through the logging.

It's a good point, Andy. Normally I wouldn't separate them, and I
don't actually remember why I did on this occasion (probably flustered
from spending more time travelling between London airports as I did
flying from there to Germany). Most of the data is on the M25 so it'd
be covered already, hence I don't really mind about the accuracy of
those, or even losing them, but there are also tracks on the
approaches to three of the London airports that could be useful, even
if filtered.

> Can start and stop the logging until the unit is full if you like. These
> separate logs are spewed out by the eTrex on download and can quite happily
> be uploaded to OSM as a single file. No need to separate out the individual
> track segments.

I like to upload things from different areas as different files so
they look like more than just a long line between Germany and the Isle
of Man. Still I could - and have been doing lately - separate the
different geographic regions into different GPX files for each of the
active logs. It helps keep the files manageable.

> GPX uploads to OSM require the timestamp on each trackpoint or they will
> fail. This ensures that logs uploaded are not simply made randomly. They do
> not however need any other data other than the Lat and Lon to be valid.

I don't mean to sound rude or anything, but that's crazy if that is
the reasoning behind it... If somebody's gone to the trouble of
creating random GPX points, they presumably have the knowledge of how
to throw in an incremental timestamp for each item - which is what
I'll do with this (legitimate) data if there is a filter on entries
without timestamps...


Dan Karran
dan at karran.net

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