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
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F-06902 Sophia-Antipolis Cedex, France
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