Le 23 mai 2020 à 13:52, Bernd Vogelgesang
<bernd.vogelges...@gmx.de> <mailto:bernd.vogelges...@gmx.de> a
écrit :
Unfortunately, the Forest Service Website went offline (maybe
this thread caused so much traffic that it broke down? ;) )
I'm also desperately searching for an affordable way to have at
least some decent accuracy. I do not need submeter, but it
would be fantastic if it was possible to achieve meter accuracy.
I gave up on that Garmin stuff. They might be accurate, but I
have no chance to control this until I return home and put the
recorded data on screen over an aerial image. Those screens are
a joke, and the business logic that prevents me to put
reasonable aerial imagery on the device without paying a
fortune is apita. Maybe this improved cause I last checked 5
years ago.
Mobile phones at least in my case seem to get worse. My
Motorola from 2016 had an accuracy of less than 4 meters, most
of the time less than 2.
Now I bought a Huawei 30 pro cause of the camera (my first
phone with nice pictures!), but the accuracy is a nightmare.
The position is jumping around like a dog on rabies.
I also bought a bluetooth device (Navilock BT-821G) two years
ago. This is much better than the phones GPS, tho it only
receives 20 satellites maximum (The phone claims to receive
some 40). But also this device sometimes, when walking a
transect, is constantly 5 meters off the track for several
several minutes.
As apps averaging the positions were mentioned: Does anyone
have a recommendation on such apps (for Android)? I found some,
but the usability was not that great, and some even didn't
enhance anything.
Furthermore, I stumble upon an article about a module with
u-blox chip. https://www.sparkfun.com/products/16481
Does anyone have any experience with modules like this and what
else is needed? The description of all the stuff leaves me a
bit puzzled.
Cheers,
Bernd
On 23.05.20 18:17, Michael.Dodd wrote:
https://besjournals.onlinelibrary.wiley.com/doi/full/10.1111/j.2041-210X.2011.00118.x
I did this quite a few years ago but in the graph in
supplimentary material it shows how the accuracy of one
consumer grade gps varies over time (at a fixed point). At the
time I also did a lot more measurements using mobile phones
and consumer grade units on a grid of points in the field,
that was not published but basically the phones were often as
good as if not better than the consumer grade gps units
especially when using certain apps to average points.
<https://besjournals.onlinelibrary.wiley.com/doi/full/10.1111/j.2041-210X.2011.00118.x>
Where are my quadrats? Positional accuracy in fieldwork - Dodd
- 2011 - Methods in Ecology and Evolution - Wiley Online
Library
<https://besjournals.onlinelibrary.wiley.com/doi/full/10.1111/j.2041-210X.2011.00118.x>
Introduction. There has been much written about sampling
design, spatial scale and the need for permanent plots in
ecological long‐term monitoring, for example, the paper on
spatial scaling in ecology has been cited over 1500 times, but
one frequently ignored issue, intimately associated with
sampling design, scale and permanence of plots, is how to
locate positions accurately.
besjournals.onlinelibrary.wiley.com
<http://besjournals.onlinelibrary.wiley.com/>
------------------------------------------------------------------------
*From:* Qgis-user <qgis-user-boun...@lists.osgeo.org>
<mailto:qgis-user-boun...@lists.osgeo.org> on behalf of
Nicolas Cadieux <nicolas.cadi...@archeotec.ca>
<mailto:nicolas.cadi...@archeotec.ca>
*Sent:* 23 May 2020 16:34
*To:* Randal Hale <rjh...@northrivergeographic.com>
<mailto:rjh...@northrivergeographic.com>
*Cc:* qgis-user@lists.osgeo.org
<mailto:qgis-user@lists.osgeo.org> <qgis-user@lists.osgeo.org>
<mailto:qgis-user@lists.osgeo.org>
*Subject:* Re: [Qgis-user] wishing for accurate
lattitude/longitude from a cell phone
CAUTION: This mail comes from outside the University. Please
consider this before opening attachments, clicking links, or
acting on the content.
Hi,
This is a very interesting list. It basically confirms what I
thought. Consumer Point and shoot deceives are all around 2-6m
with no canopy. The average multiple positions basically give
you a better idea as a gps may get lucky. It would be nice to
have the full methodology for this and more data (like the
number of satellite and the position of the constellation and
the gps price list) but it’s very interesting none the less.
I was also happy that the data confirms the precision of the
gps Sx-Blue 11. This claims to be sub meter and my tests
indicated that on our office unit but it’s nice to see it done
elsewhere. For about 2000$, this gps is pretty good. As for
the rest, the difference between 150$ and 1000$ is probably
more a function of the options (like maps and screen size...)
and not a question of precision. It would be nice to know what
gps chips they are running...
Interesting thing also is that based on my reviewing the data
on my phone (without graph or cross tabulation tables) is that
the Glonas Constellation does not seem to help much. Quick
stats on this list would confirm this. Maybe this is just a
figment of my imagination because there’s only so much
information you can grad without running proper stats.
Thanks for the post.
Nicolas Cadieux
Ça va bien aller!
> Le 23 mai 2020 à 09:02, Randal Hale
<rjh...@northrivergeographic.com>
<mailto:rjh...@northrivergeographic.com> a écrit :
>
> One other thing that may or may not be of use but the USDA
Forest Service Publishes a GPS Receiver Report that covers
phones - and that's helped if I've had a client go "Well I
have a Apple <something> or a Android <thing>". At least I
feel slightly better going "good enough" or "no not good enough".
>
> It should be good worldwide (but I will admit I think phones
are my 'tech ceiling' these days) but your mileage may vary.
>
> https://www.fs.fed.us/database/gps/mtdcrept/accuracy/index.htm
>
> Randy
>
>> On 5/22/20 8:55 PM, Priv.-Doz. Dr. Maria Shinoto wrote:
>> Somehow I did not follow the discussion, but like to add
some of our experience.
>>
>> We are doing field work in a remote region in the southern
Japanese mountains, archaeological surveys on the ground based
on LiDAR data.
>>
>> A simple Garmin etrex10 is mostly reliable in an area of
40cm by 40cm around a measured point, if used repeatedly at
this point and the point is located in the middle of a valley.
Even cell phones do a good enough job. As soon as we get
closer to the steep slopes, the accuracy of the Garmin is less
than 5 to 10 meters. We can check this with the detailed LiDAR
based map, and geologists told us, that even an expensive
device could not be more precise under these conditions. So we
decided to measure traditionally on the ground if precise
measure is necessary, otherwise note the GPS data and the
location as shown in the map.
>>
>> To sum up, we came to the conclusion not to spend money on
an expensive GPS that may not work in the shadow of steep
slopes -- or in the streets of New York. -- I appreciate any
additional advice, and hope that this experience can save
Steve's organisation some money...
>>
>> Best,
>> Maria
>>
>>
>>
>>>> Am 23.05.2020 um 03:54 schrieb Stephen Sacks
<sack...@earthlink.net> <mailto:sack...@earthlink.net>:
>>>
>>> In order to make widely available some wise advice, I'm
sending to this list a message I received from Neil B. In
addition to Neil's message below, I want to mention that
Nicolas Cadieux also provided similar information, saying I'd
have to pay around $1,000 for equipment that gives
consistently accurate location coordinates. And thanks, also
to Falk Huettmann and Bernd Vogelgesang for their replies.
>>>
>>>
>>> Message from Neil B:
>>>
>>> Hello Stephen.
>>> Glad that you're having su
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