The problem, is that you cannot do a calibration fo a GPS since it will depend on the satellite constellation which change all day long even if you don’t move. So calibration of a GPS is a no no! If you use accurate GPS measurements, either baseline measurement, of PPP post processing (but you need a GPS slightly more expensive that the regular handheld ;-) ) you can have an accuracy of a few millimetres. So the std-dev should always be given explicitly for GPS. Phil
On 11 Sep 2017, at 21:24 PM, Martin Sluka via Therion <therion@speleo.sk> wrote:
There is an application for Android Mobile Topographer (Pro). In Pro version it is 15 EUR?
It has many very interesting features to measure and use GPS including calibration on known point etc.
There is only one problem with this application. It has no automatic backup of measured data. So only way around is export data to an available format and save it manually. Topographer crashed on my Android tablet and I loose all my GPS points. On other hand the uninstallation and new installation was without any problem. Just to backup a folder with exports before.
m.s.
11. 9. 2017 v 20:53, Xavier Pennec via Therion <therion@speleo.sk>:
One of the problem for a predefined accuracy of gps measures is that it really depends on each measurement. I usually use a stddev of 2 to 3 times the figure of merit (FOM) of the GPS averaging procedure for x and y coordinates and 4 to 5 times for the altitude. This can range from a few meters (this has to be on a plateau with no trees) to 50/100 m for measurements in forests with a few satellites only (there are also often reflections on cliffs that perturb the measure).
Xavier
Le 11-Sep-17 à 19:10, Benedikt Hallinger via Therion a écrit :
No, i meant the following:
currently one has to give std-dev explicitely: fix 1.2a 0.5 0.5 0.5
it would be nice to use instead: fix 1.2a gps where the term "gps" is some predefined accuracy, like in grade definition
Am 2017-09-11 10:08, schrieb Bruce Mutton via Therion:
Benedikt wrote
The option to use "alias names" for fixes instead of directly numbers would be good, this would allow to ship standards with therion and allow the user to to define custom ones, just like in grade definitions.
Not sure I understand correctly what you mean.
We can make alias now, using equate. This is what I usually do for gps fixes.
In a cave survey 'index data file'... centreline cs lat long fix gpsEntrance01 <lat> <long> <altitude> [<stderr> etc ] fix gpsEntrance02 <lat> <long> <altitude> etc
equate gpsEntrance01 53@<survey1> equate gpsEntrance02 1@<survey14> equate gpsEntrance01 AliasNameCreatedByThisStatement endcentreline
ie 53@<survey1>, gpsEntrance01 and AliasNameCreatedByThisStatement are all alias' of each other. They all refer to the same physical point. The last name is created by the equate statement, whereas the others all exist prior to the execution of the equate statements.
Or were you meaning something different?
Bruce
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------------------------- Xavier Pennec Senior Research Scientist / Directeur de recherche Asclepios project-team, INRIA Sophia-Antipolis 2004 Route des Lucioles, BP93 F-06902 Sophia-Antipolis Cedex, France +33 4 92 38 76 64 +33 6 78 35 16 90 http://www-sop.inria.fr/asclepios/ -------------------------------
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