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Cheap Entry-level GPSr for Site Mapping

eVoLVeR 0 Points
edited November -1 in GPS Recommendations
Hi there,

I need a GPSr for mapping a remote site location here in Ecuador. I haven't used much GPS equipment before, but am pretty tech savvy and willing to invest time in learning how to do what I need to do.

Basically, I want to find a unit that will ultimately enable me to create a detailed map of a remote area. It would obviously be good if the map is accurate, though I have seen varying definitions of the accuracy of recreation, mapping, and survey level equipment so don't wish to state which of these I require - just the best possible accuracy for the price, with minimal superfluous features.

So, can anyone recommend a reliable unit, available for around $100-150 new or second-hand, that will enable me to store the multiple data points I need, transfer it to my computer (actually a linux machine), so that I can recreate a detailed map from that data.

Many thanks in advance...

Adam

PS Linux compatibility is by no means essential by the way...

Comments

  • Boyd 1985 Points
    All modern consumer devices should have pretty comparable accuracy. Expect +/- 5 meters. Spending more money isn't going to get you much better - new consumer handheld devices range from about $100 to $600 USD. As you pay more, you get more "bells and whistles" but not better accuracy.

    For more accuracy, you will jump up into the $2000-$5000 USD range....

    Can you use a laptop or smartphone to capture the data? If so, you might consider the Garmin GLO for ~$100. I wrote a review here. Not sure what linux support would be, you'd need drivers, etc.

    http://gpstracklog.com/2013/04/garmin-glo-review.html

    If you need a standalone device, the eTrex 10 is arguably the best option - also about $100. https://buy.garmin.com/en-US/US/on-the-trail/handhelds/etrex-10/prod87768.html

    It would mount like a USB disk and you could copy data. You would have to find your own linux software to use that data however. The eTrex 10 doesn't really support maps on the screen, but that doesn't sound like something you would need.

    What software will you use to create the map? That is also important. I use GlobalMapper, which is a powerful GIS package. It will cost more than the GPS however. :wink: You can play with the free demo, which should be completely functional but not able to save anything. It only runs on Windows.

    http://www.globalmapperforum.com/download/
  • popej 57 Points
    eTrex 10 seems to be an obvious answer to your requirements, but I would recommend to pay a bit more for eTrex 20, which have support for maps. You would be able to use your own map in GPS ;)

    Usually maps are created from tracks, which are registered automatically. If you expect to mark many waypoints with description, then could be convenient to get a device with touch screen, like for example Garmin Dakota 10.

    Do you need good accuracy for altitude measurement too? If yes, then consider GPS with barometer, like etrex 30 or Dakota 20.
  • eVoLVeR 0 Points
    Thanks for the replies...

    Not too sure yet which software I'll use to generate the maps, though there does seem to be a few open-source options available in linux. If anyone can recommend linux-based software for generating contour maps from GPS data, I'd appreciate it...

    Don't think that laptop or smartphone capture will be possible, unfortunately.

    I would like good accuracy for altitude measurement, but what are we talking here? What would the difference in accuracy for altitude measurements be between the eTrex10 and the eTrex30, for example, given the latter has the barometer?
  • Boyd 1985 Points
    A basic device like the eTrex 10 uses the satellites to determine elevation and that is not very accurate. You might expect errors of 30 meters or more. In a low flat area, like the place I live (near the ocean), this can often result in erroneous readings that say I'm below sea level by 30 or 40 meters.

    The eTrex 30 has a barometric altimeter. This can provide more accurate readings IF you calibrate it properly. My experience is that it can be harder than you think to calibrate the altimeter properly. :wink:
  • eVoLVeR 0 Points
    Is there a way to ensure the relative altitude values are at least accurate?

    I'm not so bothered about the absolute values, but for the mapping project for this particular it would be nice to get fairly accurate relief maps.

    Otherwise what would I have to spend to get more accuracy on the altitude front? Any models to recommend?

    If that's prohibitively expensive, how accurate can the barometer models be if calibrated correctly?

    many thanks...
  • Boyd 1985 Points
    Sorry, I really can't help there. My experiences - with many different consumer devices - is that elevation readings just aren't very accurate. When I try to manually calibrate the altimeter, I still get questionable readings.

    I am currently using a Garmin Montana 600, a top of the line model. I also have a GPSMap 60csx which many people feel was the most accurate consumer device ever made.

    I make my own maps also. Here in the US, we have free LIDAR data that is very accurate. Here's an online map I made using LIDAR in my own area. This will be much more accurate and complete than anything you can create with a GPS, it is actually a 3d model of the terrain: http://boydsmaps.com

    NASA has free lower resolution data like this that covers most of the world. It is nowhere near as accurate, but you could take a look: http://srtm.usgs.gov

    Maybe your country has something similar available? If you are willing to spend some money, I'm sure somebody can sell you very accurate elevation data.
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