NZ Open GPS Project

Community developed auto-routing maps of New Zealand

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Tracklogs - some thoughts

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Tracklog Setups

I was doing some thinking the other day around tracklogs and posted on the forums for input from users

Time interval - everyone seems to go for 1 second tracklogs
Advantages

Disadvantages

  • Causes rest stops to generate bunches of trackpoints - can be deleted in an editor
  • Variable distance between points depending on speed

I've done a little table of time interval vs tracklog limit (10,000 point)


Distance interval
Advantages

  • Fixed 'resolution' eg 10m or less between trackpoints

Disadvantages

  • Tricky to set up on some GPS units eg Legend (minimum metric distance is 100m 10m, so have to change to yards and set the distance to 3 or 1 yards for example, then change back to metric!)
  • Can really chew up memory


Auto with more / most / normal / less / least frequencies
Advantages?

Disadvantages

  • Chunky tracklogs that may not be of use for map making

 


RC on the forums posted an interesting (and potentially serious) anecdote on tracklogs:

A word of caution is necessary here when using 60 and 76 Extreme series models and invoking 1 sec tracklogs...

As you know, these units only save a limited number of points to the internal memory (10,000 points - I think). Once filled, the display on your GPS screen either stops dead or "wraps around". The latter means that earlier points are simply overwritten by latter points.

If you have enabled saving tracklog to card it doesn't really matter as once at home you can retrieve the gpx file from the unit.

However, if for example you're in the bush (uncharted routes) and rely on tracklog to "back track" to earlier point or intersection etc, if you had a very long tracklog, you may find that earlier points alarmingly disappear off your screen if you had used 1 sec tracklog and have had the unit on for several hours. It may be impossible to find the earlier points or your way back !

I have had one person reporting this situation to me resulting in an uncomfortably cold night out in the bush!

A workaround that I use in these situations is:-

1. Turn off 1 sec tracklogs when arriving at beginning of the track/route and use a "least often" or similar method of recording and/or
2. Mark important intersections with waypoints while on the track

Last Updated on Thursday, 08 October 2009 08:00  

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