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Boyd

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Boyd
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  • Garmin eTrex - Creating a trail map using track recordings

    It seems a bit strange to me that it cannot be more accurate though!
    It will not seem strange if you become more familiar with the technology. Garmin's handheld devices are accurate to within about +/- 5 meters (16 feet). And Garmin claims +/- 3 meter (10 foot) accuracy for the GLO. Think about what these numbers mean. If you go to a marked location and record your position two times, those points will (theoretically) be within 5 meters of the true location. However, one of the points could be 5 meters north of the actual location, and another could be 5 meters South. So, the distance between two points recorded at the exact same location could be 10 meters (33 feet) and the GPS would be within its specifications. You can see this graphically in the image I posted (and the thread about accuracy I linked to).

    If you are trying to map a trail that is only 1 meter wide, that is a huge error. But, such are the limits of consumer devices. None of them (including the GLO) were designed for making precise maps of small areas. Want more accuracy, no problem. SXblue makes some nice bluetooth receivers with sub-meter - or even centimeter - accuracy. Cost is in the $3000 to $7000 range

    https://sxbluegps.com

    Trimble is considered the "gold standard" for highly accurate GPS receivers. Expect to pay in the same range, although you may find some in the $2000 range.

    https://geospatial.trimble.com/GIS

    These are professional tools where no trade-offs have been made to keep the price low enough to appeal to a mass audience. There are other bluetooth receivers in the consumer space you might consider however, such as Bad Elf

    https://bad-elf.com/collections/bluetooth-gps

    and Dual

    https://gps.dualav.com/explore-by-product?category=GPS

    I considered these two companies when I got my glo a number of years ago, but felt they did not offer any advantages at that time. Things may have changed today, so you might want to do your own research.
  • Garmin eTrex - Creating a trail map using track recordings

    I think will need to learn a lot more before you have the proper frame of reference to really understand this kind of issue. If you just record a track on the eTrex, it will be a big mess, zig-zagging all over the place - would look much worse than the blue line above. You need to walk the trails a number of times, then overlay all the tracks on each other to get an idea of where the trail really is. Then, if you want a "pretty" map you will need to draw your own smooth line over what you recorded. I think you could do all of this in Basecamp, although it's not what I use.

    Also, if making a trail map is the main use for the GPS then I would not get an etrex or any other Garmin handheld. They are just not intended for that usage, they are primarily designed for hiking and design trade-offs have been made to make the batteries last a long time while still providing a screen that is readable in sunlight.

    See the thread I linked to in my first post about the Garmin GLO and accuracy. I also reviewed the GLO here in 2013:

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

    It will be cheaper than an eTrex and should be much more accurate. The big advantage is that it updates your position 10 times per second while Garmin handhelds only update once per second, so you get a lot more data to work with. And it will be compatible with (literally) hundreds of apps for your iPhone or Android phone. There are also apps that allow you to make maps right on the phone.
  • Garmin eTrex - Creating a trail map using track recordings

    Yes, that's certainly possible and I have done something similar using a variety of devices over the years (eTrex Legend C, GPSMap 60csx, Oregon 400 and Montana 600). I actually got the best results with a Garmin GLO, which is a stadalone GPS device that broadcasts your position over Bluetooth, where you can then use it with the Android or iOS app of your choice. See this thread:


    http://forums.gpsreview.net/discussion/30108/what-is-gps-accuracy-testing-the-garmin-glo-in-the-forest

    However, there's no reason why you couldn't do this with one of the new eTrex devices. Where it gets more complicated is turning the data into a map. I have been making maps for a long time and have professional software for this, but that won't be a good option for you. The simplest approach is to simply record a track on the eTrex and then import it into Garmin's free Basecamp software. You can edit it there and export it to a .gpx file. The .gpx file should be usable by others with Garmin handhelds as well as most smartphone apps. But the downside is that you will have very little control over the appearance and it won't be like a real "map" that also has other features.

    You could convert the .gpx file to a Garmin format map, but this gets rather involved and also has a limitation when it comes to mapping relatively small areas. Garmin's map format is limited to about +/- 2.5 meters accuracy (about +/- 8 feet). This might not be an issue for you, but I found it did not properly capture all the winds and turns of the little trails on my own property. So I used Garmin's "custom map" format (.kmz files) which is what we call "raster imagery". This kind of map is really just a "picture" and is much more accurate than Garmin's standard vector-based maps.

    Now this all gets rather technical, so I won't go into further details. But if you have specific questions, I'll try to help.
  • Don’t see 24k map displayed in Oregon 750

    I think City Navigator still has the option to download a map to your computer. Doesn't it? Not really sure, it has been a long time since I tried. But with the topo products, there is no way to install the map on your computer. The only way to do that was to purchase the DVD version, and those are long gone. Third party maps are still available to install on your computer, such as most of the maps at gpsfiledepot and my maps at boydsmaps.com. :)

    If you are using a Mac, you can use Disk Utility to create an empty disk image, then you can copy the contents of a card (or internal GPS memory) to the image. Basecamp will see that just as though it was a physical card.

    There is no built-in software to do the same thing on Windows, however you can use a RAM disk, I have done this with an free program and it worked. On either the Mac or Windows, this is different from Garmin's old system, you are basically just creating a virtual SD card which you need to manually mount and eject.
  • Which GPS will allow tracks to be loaded to it.

    Sorry, but alan is right. Garmin does not make any automotive models that can receive tracks. The Zumo is a very expensive way to get this capability. But if you don't care about the cost, there is also the Overlander and GPSMap276cx.

    https://buy.garmin.com/en-US/US/p/685257
    https://buy.garmin.com/en-US/US/p/539722/pn/010-01607-05

    Now... depending on what you want to do, you might have a look at this little free program. It can convert your tracks to transparent Garmin maps (.img files) that you can overlay on another map by enabling it at the same time. This should work on any Garmin automotive device, such as the Nuvi and Drive series.

    http://www.javawa.nl/imgfromgpx_en.html

    Here's another similar program that is not free. But it's a lot cheaper than a Zumo. ;)

    https://www.gpx2img.com