Discussion in 'Main Message Board' started by Terry, Feb 10, 2020.
Looking for a GPS distance measurement App.
I just use Google maps right on my phone.
Google Earth works also.
QGIS (open source Graphic Information System). You can import using or create your own polygons, and do manual and calculated distances. The package itself can get very large so only import the plugins that you need. Having said that, if you take the time to learn what the plugins do you can create some pretty interesting things.
Hunt on X works good to on my phone within a yard or two
Geo measure has worked for me. My elevation is an interesting app to have on while driving.
Google Earth seems very accurate, within a foot or so if you have sharp images or points to measure from. I also have a Garmin hand held GPS and it is usually within about a yard and sometimes up to 2 yards.
Sports tracker is real handy for saving a track for hunters.
Sorry, but there is no civilian GPS system that is any more accurate than around plus or minus 25 feet. Google Earth (which has better resolution than Google Maps) has an accuracy of
that's an accuracy of around 130 feet with error range of 1.5 to 563 feet. That means that Google is probably accurate to around 250 feet or so on the average.
I used a app called gps tape measure for awhile till i got a range finder.. the range finder verified the app was pretty close.. within a couple yards..
I worked with GPS and aerial photography for close to 20 years. It should be accurate within the range your equipment is designed for. Surveyors have equipment available that is less than 30 cm (~11 inches) or less depending on how much you want to spend - and that is after post processing data and shooting points more than once. GPS uses several satellites, with atomic clock, and transmits an am radio signal tagged with the time it leaves the satellite for your unit to calculate position. Something like a reflective surface or tree canopy destroy accuracy. An analogy is if you hung different length strings from different spots on your ceiling and brought all the ends together. They should only meet in one spot.
Photographs are only as accurate as the people who process the data, digitally stitch the photos together, and the size of the pixels used.
So, google earth and such are capable of estimations, and that's about it. I often did area calculations with a sub-meter GPS and it is commonly accepted that there is about 20% error.
I'm going to use this to place steel targets.
Plenty close enough.
That isn't correct. With RTK differential correction accuracy is within one inch. It isn't cheap but it is civilian. WAAS (free differential correction) you can expect within 10 feet or less, in my experience 5 feet or less.
I use its map mode for my target placement and ranging. Sure gps is only within 40 feet some times but I can see that it set my target right at the base of this tree and I can see the tree on the satellite imagery so I place the targets map marker at the tree instead of 15 feet away where my little blue dot it actually showing up.
This app is the best.
To answer the original question. For measuring distance with GPS I use Backcountry Navigator Pro. https://www.backcountrynavigator.com/
I use the app almost daily.
I also like sportstracker. Originally got it for sports tracking, but it has a good, easy to use track maker, so I use it for woodsy stuff. Record entire weekends with it.
Google maps does still have a measuring tool, hidden: https://support.google.com/maps/answer/1628031?co=GENIE.Platform=Android&hl=en
Most of these are difficult to use because of the accuracy of picking points only. You finger has a lot to say about it, etc.
Single antenna GPS accuracy is indeed around 25 ft. We don't use GPS. Our phones have WAAS, WiFi (when relevant), Glonass, and often more. Trickery with antennas, sampling, etc means you can get legit accuracy to 8 ft, sometimes less.
Accuracy is usually (IIRC) R85, which means there's an 85% chance that the actual location is within a circle off whatever the accuracy is.
Also get a GPS raw data tool. For Android, I like GPS Test: https://play.google.com/store/apps/details?id=com.chartcross.gpstest&hl=en_US It will give you not just position in ANY system you can imagine, but also speed, elevation, and... accuracy. Good to check that before you use the data.
To measure distance accurately without too much actual learning of surveying or map making, just record points with the GPS as best you can, write them down, and use a distance tool like this: http://boulter.com/gps/distance/
That will eliminate the finger accuracy issues, etc.
When I got my Garmen eTrex GPS I took readings all over (new toy) and Google Earth can put them onto their map. It rarely missed over 2 yards and was usually closer than that. I got closer reading when it faced the west for some reason. Here is an old picture plotting trees in my yard. I held the unit right against the trunks and took readings. This GPD reads US and Russian satellites.
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