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I have been hired to map about 100km of XC ski trails. I am super proficient in GIS but have not done any detailed GPS work since college when I worked with some sort of Trimble explorers. This is a complex network of trails and each segment needs to be a unique feature.

I own a Garmin etrex 30. My guess is that this will not be a great unit for this sort of work. I am thinking of buying a used Trimble GeoExplorer and an antenna that I can attach to my hat so that the GPS can be in a hip pack. I do want my polylines to be accurate and if I remember correctly the Trimble points can be nicely corrected after collection. Any other suggestions for hardware? Do I even need a device this sophisticated?

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    What are you going to do with data? If you're making paper maps for skiers to follow, then my guess is that almost any consumer grade GPS will provide an accurate enough track to build a map from. That probably holds even if you're going to make a downloadable map for skiers. Unless you have parallel trails <10 meters apart, I doubt you'll have any trouble with ambiguity. – Llaves Dec 6 '13 at 0:08
  • Maybe they want 1m accuracy, for serious training or competition purposes. – Martin F Dec 6 '13 at 0:54
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    I should have mentioned that I may build an app at some point. Also the trail segments will be analyzed regarding some conservation easements. Those two points alone should warrant use of a high-res commercial unit. – jotamon Dec 6 '13 at 16:42
  • Have you considered manually digitizing the trails based on high resolution orthorectified imagery (e.g. NAIP)? – Aaron May 10 '14 at 14:56
  • Have you considered getting a map-less data logger you can throw in your backpack or on your key chain to accompany your handheld device? These things can run you between $50-$200 – dassouki Jul 19 '14 at 11:18
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IMHO, you're probably overdoing it. Any GPS will collect an ok trace, and if you collect one on your phone at the same time, you have a second for reference. If you can borrow another from someone else, even better.

Now load the traces over some satellite imagery (Google Earth, Mapbox or other), and you'll have plenty of confidence that your traces are right. They'll probably have details that you need to filter out anyway, like deviations around the track, pauses etc.

Don't forget to load the traces into OpenStreetMap too, and make the world a better place. :)

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Tom and Steve are correct. You could you a consumer GPS or your phone to do this. I have done this testing, and wrote a paper about this. You can see the paper here: http://bit.ly/11nKC5Y to see my results. You will want to check the results of anything you GPS. To tackle your comment about making each segment its own record, you can do this with GIS processing. Where lines overlap, you can make an intersection point, and use this point to split the lines. Or you can collected each line differently in the field, which would allow you to add attributes while GPS'ing.

  • Urban mapping can take advantage of gps, wifi and cell towers (..bluetooth, and more). In more remote areas and depending on tree cover and terrain -that you'd likely find in 100km of xc ski trails- you'd likely want to stick with a commercial unit. – mwil Dec 5 '14 at 16:12
  • @mwil you are correct, but if you read the paper, you will see that we used a USB GPS addition to the Apple iDevices. There are BlueTooth versions available, which I have used in backcountry ski trips, which have no access to any cell network, or wifi – Ryan Garnett Dec 5 '14 at 22:09
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I use a garmin 60csx which seems to have a slightly better reception than garmin 62st (the 'x' in the 60 means hi-gain-antenna - I think 62 is marketed as having a 'better antenna' which might mean better than the 60 baseline... not sure.. .would be good to hear it from a garmin engineer.) Anyway just having the gps in a chest harness or clipped on a shoulder strap on a backpack has given plenty good resolution for the map-making I do, as measured by: 1) correcting the tracks with a satellite view editor, i.e. google earth or arcgis explorer or such 2) doing a few non-scientific experiments of walking a trail out and back again to see if the tracks deviate.

These are not very scientific and there are no doubt better systems out there. Regardless of what you use, try bringing the tracks in to google earth or such and moving them to line up with the satellite view. I know some image servers took their pictures in the winter so you might stand a chance even if the trails are not visible in a summer image.

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