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<p>Hi,</p>
<p>Just my grain of salt... I believe the latest move from QGIS to
change to a more recent version of the PROJ library (and to rely
more on this library), is seen as a way to move GIS from a
cartographic quality GIS to a Survey level precision GIS. This is
a good move but, as many have seen on this list, not an easy one.
Things seems to have calmed down recently as people start
understanding the error messages and as QGIS adapted to user
demands.<br>
</p>
<p>The only way, as I see it, that GARMIN is "privatizing the
geography", as you nicely put it, is by selling map to their map
capable units. It would be nice to have the capability of
uploading our own maps to those units. Apart from that,
positions, waypoints and tracks can be uploaded and download
with propitiatory and non propitiatory software. I believe QGIS
had a plugin capable of doing that with multiple consumer level
GPS but I have never used it. Maybe they have been more
aggressive lately? I don't know.<br>
</p>
<p>As for the High resolution-precision problem, It's important to
remember that typical consumer level chips are not made to give
you more than 2 to 10m precision. This is not because of any
effort on there part to make the units less precise. It's simply
because of the way a position is obtained by these units. Using
the same point and shoot method (or Code Measurements
instantaneous position determination), A 100,000,000$ GPS might
give you a slightly better position but only because is has a
better internal clock and a better Geoid model. In order to get a
more precise positions, professional GPS units use things like
RTK, Dual frequency, DGPS, but most importantly, they store the
satellite information for later use in a post-processing
software. These function are simply not built or used in phones
or consumer GPS devices. Any unit using instantaneous position
determination will always be plague by orbital errors, satellite
cloak errors, Ionospheric and troposphere errors, multipath and
receiver noise... The only thing they can change is the receiver
clock and the antenna. A technique called PPP, or Precise Point
Positioning is a technique were one uses a single GPS unit to find
precise position after a long observation. Again, the most we can
do with consumer lever gps is to average out positions. This is
not PPP which uses the rinex files stored in the unit, correct for
clock and ephemerides... <br>
</p>
<p>If you are interested in bringing High precision GPS to the
table, I suggest RTKlib (<a class="moz-txt-link-freetext" href="http://www.rtklib.com/">http://www.rtklib.com/</a>) for post
processing. Again, you will need a deceive capable of storing the
satellite information if you want to do this. A plugin from
RTKlib to QGIS could be made it guess. That would be nice.<br>
</p>
<p>Cheers!</p>
<p>Nicolas <br>
</p>
<p><br>
</p>
<div class="moz-cite-prefix">On 2020-05-25 1:47 p.m., Falk Huettmann
wrote:<br>
</div>
<blockquote type="cite"
cite="mid:CA+BKNPD45LYEoUgwOE6BvR9pU_-ohZF3=yg57GcGu8hcNuXSCA@mail.gmail.com">
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<div dir="ltr">Dear List,
<div>I think these GPS high resolution suggestions are great; </div>
<div>thanks.</div>
<div><br>
</div>
<div>But my real interest/question here is, how can we bring it
home to QGIS ?</div>
<div><br>
</div>
<div>I see GARMIN essentially trying to sell and impose on us
their GIS system,</div>
<div>same applies to OpenStreet Maps etc etc. So they try to
privatize geography and public space and information, </div>
<div>which I am mostly opposed to.</div>
<div><br>
</div>
<div>Instead, I wonder how we can use QGIS and release the
commercial</div>
<div>data into Open Source and public use ?</div>
<div>That's for HIGH RESOLUTION data discussed here.</div>
<div><br>
</div>
<div>Thanks for such questions and solutions.</div>
<div><br>
</div>
<div>Very best</div>
<div> Falk Huettmann PhD, Professor</div>
<div> Uni of Alaska Fairbanks</div>
<div><br>
</div>
</div>
<br>
<div class="gmail_quote">
<div dir="ltr" class="gmail_attr">On Mon, May 25, 2020 at 9:41
AM Kirk Schmidt <<a href="mailto:kirk@nortekresources.com"
moz-do-not-send="true">kirk@nortekresources.com</a>>
wrote:<br>
</div>
<blockquote class="gmail_quote" style="margin:0px 0px 0px
0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
<div>
<p>Hi List:<br>
</p>
<p>In my experience, the key is writing output in rinex
format so that the rover data can be corrected either
using PPP if you can collect your GPS data over and
extended period of time or use pre-existing (or self
deployed) base station over a know coordinate to provide
correction data. Most consumer grade units output the
final position solution, not detailed satellite data which
is required for followup processing.<br>
</p>
<p> Kirk Schmidt<br>
</p>
<div>On 5/25/2020 2:31 PM, chris hermansen wrote:<br>
</div>
<blockquote type="cite">
<div dir="ltr">
<div>Martin and list,</div>
<div><br>
</div>
<div>To me, in general, I think I would try to go with a
Raspberry Pi based solution. The hardware isn't all
that expensive and the easy ability to do stuff
directly with the output of the device in Python or
some other programming language seems to be preferable
to messing around with Android or iOS applications.</div>
<div><br>
</div>
<div>One of many articles that may be of interest <a
href="https://learn.adafruit.com/adafruit-ultimate-gps-on-the-raspberry-pi?view=all"
target="_blank" moz-do-not-send="true">https://learn.adafruit.com/adafruit-ultimate-gps-on-the-raspberry-pi?view=all</a></div>
</div>
<br>
<div class="gmail_quote">
<div dir="ltr" class="gmail_attr">On Mon, May 25, 2020
at 9:25 AM Martin Weis <<a
href="mailto:martin.weis.newsadress@gmx.de"
target="_blank" moz-do-not-send="true">martin.weis.newsadress@gmx.de</a>>
wrote:<br>
</div>
<blockquote class="gmail_quote">Dear list,<br>
<br>
I would like to add some things here, since I am
trying to use RTK GPS<br>
in the field with mobile devices.<br>
<br>
> 1) Accuracy of GPS Devices<br>
<br>
RTK GPS or any more precice GPS technology will be
external, you cannot<br>
get around the missing measurements and lack of
algorithms in consumer<br>
grade chips.<br>
<br>
Then it depends on the capabilities of the device to
receive satellites<br>
of all systems (one or multiple frequencies/signals)
and be able to<br>
apply correction data (a question of algorithms). For
better equipment<br>
the prices rise quickly.<br>
<br>
There are some low cost devices evolving, a new chip
was recently<br>
announced: Skytraq PX1122R for about $100. Could be
tested with a break<br>
out board and antenna, e.g. see board at navspark
shop. The module even<br>
supports PPP, which might be especially interesting
where mobile network<br>
is not available.<br>
<a
href="https://navspark.mybigcommerce.com/px1122r-evb-px1122r-multi-band-quad-gnss-rtk-evaluation-board/"
rel="noreferrer" target="_blank"
moz-do-not-send="true">https://navspark.mybigcommerce.com/px1122r-evb-px1122r-multi-band-quad-gnss-rtk-evaluation-board/</a><br>
<br>
Other low cost solution were mentioned (emlid/REACH,
Catalyst, etc).<br>
<br>
<br>
Am 23.05.20 um 21:51 schrieb Michael.Dodd:<br>
> One app that claims to do a lot of what high
precions gps does is> Mobile Topographer Free –
Apps on Google Play<br>
<br>
> 2) Software<br>
<br>
On Android I was able to get the external signal into
the system, you<br>
need the app "Bluetoth GPS" (or similar) or a
USB2serial + app (better<br>
avoid tiny plugs and large cables during field work).
Additionally you<br>
need to override the internal GPS position with the
Blue GPS App in the<br>
developer settings (mock provider).<br>
<br>
My impression was, that most Android applications
target the accuracy of<br>
the device only, so e.g.<br>
<br>
* you cannot zoom to cm-levels, only ~100m<br>
* not many proper GIS Apps are available, most are
expensive<br>
* Tracking usually does not rely on cm-grade
positions, so the apps are<br>
not made for it<br>
<br>
One particular thing is, that with high accuracy of
the signal, an<br>
internal computation in single precision float will
not suffice (all<br>
computations must be in double precision), and you may
end up with a cut<br>
off of the last position digits, e.g. if you have 8
digits, 4 before and<br>
4 after the decimal separator (e.g. in DDMM.MMMM
format), then you end<br>
up with coordinates cut down to 2-3 decimeters in the
real world<br>
(typical GPS mouse output, not so uncommon).<br>
<br>
So, looking into that aspect may be required, and only
few Apps may<br>
implement that (e.g. expensive "surveyor" apps for
professionals? did<br>
not test).<br>
BTW, sponsoring the double accuracy implementation for
QField is<br>
welcome, as mentioned ot the webpage. It is already a
very usable and<br>
FLOSS GIS solution for the field, especially useful if
you have a QGIS<br>
workflow already ;)<br>
<br>
Finding proper solutions and recommendations still
required...<br>
<br>
<br>
<br>
>
------------------------------------------------------------------------<br>
> *From:* Qgis-user <<a
href="mailto:qgis-user-bounces@lists.osgeo.org"
target="_blank" moz-do-not-send="true">qgis-user-bounces@lists.osgeo.org</a>>
on behalf of<br>
> <a href="mailto:j.huber@post-ist-da.de"
target="_blank" moz-do-not-send="true">j.huber@post-ist-da.de</a>
<<a href="mailto:j.huber@post-ist-da.de"
target="_blank" moz-do-not-send="true">j.huber@post-ist-da.de</a>><br>
> *Sent:* 23 May 2020 20:35<br>
> *To:* <a href="mailto:qgis-user@lists.osgeo.org"
target="_blank" moz-do-not-send="true">qgis-user@lists.osgeo.org</a>
<<a href="mailto:qgis-user@lists.osgeo.org"
target="_blank" moz-do-not-send="true">qgis-user@lists.osgeo.org</a>><br>
> *Subject:* Re: [Qgis-user] wishing for accurate
lattitude/longitude from<br>
> a cell phone<br>
> <br>
><br>
> Hi Steve,<br>
><br>
> I think there are two different aspects to your
question:<br>
> 1) Accuracy of GPS Devices<br>
> I agree with others that you can't expect a
better accuracy than the 10<br>
> to 30 feet you observed with a smartphone or a
simple handheld GPS. This<br>
> might improve by averaging, but this takes time.
Survey grade GPS<br>
> devices are very expensive. It is possible to get
good modules and<br>
> antennas as components, but building a complete
GNSS system requires<br>
> time and skill. This would reduce cost, but only
to several hundred<br>
> instead of several thousand dollars, so this is
no option in your case.<br>
> Besides, you will still need a correction data
service (usually costly)<br>
> or use two receivers (rover and base).<br>
> So you probably have to stick with your phone,
which is more flexible<br>
> regarding the software than a handheld GPS.<br>
><br>
> 2) Software<br>
> The accuracy of the recorded position should not
depend on where you tap<br>
> the screen - a good app should allow to record
the current GPS position.<br>
> I am using Locus Map (Asamm Software) for a while
now, it works quite<br>
> well, although it does not allow position
averaging. There is a free<br>
> version, you could try that first.<br>
><br>
> Regards,<br>
> Jochen<br>
><br>
> Am 22.05.20 um 20:54 schrieb Stephen Sacks:<br>
>><br>
>> In order to make widely available some wise
advice, I'm sending to<br>
>> this list a message I received from Neil B.
In addition to Neil's<br>
>> message below, I want to mention that Nicolas
Cadieux also provided<br>
>> similar information, saying I'd have to pay
around $1,000 for<br>
>> equipment that gives consistently accurate
location coordinates. And<br>
>> thanks, also to Falk Huettmann and Bernd
Vogelgesang for their replies. <br>
>><br>
>><br>
>> Message from Neil B:<br>
>><br>
>> Hello Stephen.<br>
>> Glad that you're having success. I would like
to start off by saying<br>
>> that it is best to always reply to the
mailing list and not directly<br>
>> to the person who submitted the email.
Mailing lists work really well<br>
>> in that there is a pool of people out there
who may be able to offer<br>
>> advice or may have an alternate method to
solve the problem that may<br>
>> turn out to be a better way. On the flip side
by maintaining the email<br>
>> chain through the mailing list, the follow up
emails that provide<br>
>> information are stored in the archives which
benefits anyone searching<br>
>> the internet to have the complete trail of
information.<br>
>><br>
>> As far as your results they are acceptable
for the device you're<br>
>> using. GPS in phones are never built to
precision survey standards and<br>
>> there is no reason for them to be. If you're
within 30ft of where the<br>
>> phone thinks you should be then you can
easily navigate the rest of<br>
>> the way by visual sight. High end equipment
to achieve sub-inch<br>
>> accuracy is probably in the range of
thousands of dollars. One thing<br>
>> to keep in mind is there is a difference
between the accuracy of a<br>
>> device and to what level of precision they
display. While the app on<br>
>> the phone may display 8 decimal places of a
lat/long coordinate and<br>
>> tell you if you have moved a foot, it doesn't
help that the coordinate<br>
>> it is displaying is out +/- 30 feet. The
accuracy of a device can also<br>
>> be affected by the environment where the
device is being operated. In<br>
>> regards to cell phones, they use multiple
sources to determine<br>
>> location such as GPS, cell phone towers, and
wifi points to perform<br>
>> the triangulation. Lack of line of sight to
satellites, signals from<br>
>> cell towers bouncing off of surrounding
buildings, or someone's<br>
>> wireless router using inaccurate position
information can all affect<br>
>> the accuracy of what is being displayed on
your phone.<br>
>><br>
>> So the question is how are you determining
that the coordinates are<br>
>> wrong? If you have information that you trust
to be authoritative then<br>
>> adjust your points to those values and carry
on. I have no advice or<br>
>> opinions on inexpensive devices that may help
with a more accurate<br>
>> reading.<br>
>><br>
>> Please do not respond directly to me. This
email account is not<br>
>> actively monitored and I don't always have
the time to follow up with<br>
>> the emails. All the best with your
endeavours.<br>
>><br>
>> ~Neil B.<br>
>><br>
>> On Fri, May 15, 2020 at 7:52 PM Stephen Sacks
<<a href="mailto:sacks44@earthlink.net"
target="_blank" moz-do-not-send="true">sacks44@earthlink.net</a><br>
>> <mailto:<a
href="mailto:sacks44@earthlink.net" target="_blank"
moz-do-not-send="true">sacks44@earthlink.net</a>>>
wrote:<br>
>><br>
>> Hi Neil,<br>
>><br>
>> With your help, I have successfully
brought the corners of our<br>
>> gardens back from Pennsylvania to the
Promenade here in Brooklyn<br>
>> Heights, New York. Thank you.<br>
>> At the risk of wearing out my welcome,
I'm now asking for more<br>
>> advice. My point features are
approximately where they should be<br>
>> but not exactly, some points are just a
few feet off and some are<br>
>> 10 or even 30 feet off. I imported the
data trying both EPSG 4326<br>
>> and 4269.<br>
>> I'm now convinced that the problem is
due to (1) my Google<br>
>> Pixel 3 cellphone, (2) the app I'm using
("Latitude Longitude"<br>
>> published by gps-coordinates), and
especially (3) my<br>
>> less-than-steady hands. I capture
coordinates by standing at<br>
>> spot, waiting for the blue dot to settle,
and then touching the<br>
>> blue dot. Often I don't touch the screen
at exactly the right<br>
>> place. I tried another app ("GPS
Coordinates" published by<br>
>> Financept) which is better in that it
allows me to zoom in, but<br>
>> I'm still not always getting it right.<br>
>> I'm thinking now that I need
specialized equipment. That is<br>
>> what I want to ask you. Can you
recommend some inexpensive device<br>
>> that will allow me to simply press a
button to record accurately<br>
>> the coordinates of the point where I'm
standing? Keep in mind<br>
>> that this is a community project with no
funding. I live on<br>
>> Social Security and a university pension,
but I'm willing to pay<br>
>> something in the range of $50 or a bit
more. Do you know of<br>
>> anything at such a modest price, or would
I have to pay much<br>
>> more? Or perhaps you know of better
software for my Android Pixel<br>
>> 3 phone.<br>
>> Thanks in advance for any advice you
might offer.<br>
>> Steve<br>
>> <br>
>><br>
>><br>
>>
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-- <br>
<div dir="ltr">
<div dir="ltr">Chris Hermansen · clhermansen "at" gmail
"dot" com<br>
<br>
C'est ma façon de parler.</div>
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General Manager
Nortek Resource Solutions Inc.
RR # 1
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B0K 1W0
Tel (902) 922.3607
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