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

Andy Robinson Andy_J_Robinson at blueyonder.co.uk
Sat Apr 29 22:36:59 BST 2006


The other reason for the timestamp requirement was to help with filtering
GPX data in the future, for instance when evaluating new data layers against
much older data layers.

Creating false timestamps is not difficult but of course not encouraged ;-)


Andy Robinson
Andy_J_Robinson at blueyonder.co.uk 

>-----Original Message-----
>From: dankarran at gmail.com [mailto:dankarran at gmail.com] On Behalf Of Dan
>Sent: 29 April 2006 22:20
>To: Andy Robinson
>Cc: Talk Openstreetmap
>Subject: Re: [OSM-talk] Problem when uploading GPX tracks without time data
>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
>> 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
>> Always download the active log. This means you need to think about how
>> you will be out between downloads and what the logging frequency needs to
>> to achieve a workable time. My Legend with its 10,000 track point limit
>> 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
>> be uploaded to OSM as a single file. No need to separate out the
>> 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
>> 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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