I guess this could just as easily be a Survex question as a Therion question.
Actually, it's not. In Survex terminology, it would be done like this: *sd length 0.001 metres *sd plumb 0.125 degrees gps surveystart 2.000 - DOWN That is how you are supposed to do a vertical leg with variable clinometer accuracy and length accuracy, but no compass reading (this is taken from Survex's "How do I?" article, when talking about a radio location fix). In Therion, this generates an error "invalid quantity -- plumb". sd length 0.001 metres sd plumb 0.125 degrees gps surveystart 2.000 - DOWN So how do you do the equivalent in Therion without being allowed to use "sd plumb"? Is this a bug in Therion? Does it use clino instead? Can it pass this to the underlying Survex correctly? Cheers, Tarquin
I have GPS readings taken on a pole, with the position being given for the top of the pole. Subsequent Disto readings are taken from the bottom of the pole. The pole is brought to vertical using a spirit level. I have checked the accuracy of the spirit as being 0.125°.
I have the (measured) standard deviations of the GPS positions, so I can specify the standard deviations for the location fix. What I need to work out is how to specify the standard deviation for the pole. It's not a plumb measurement, because it is not purely gravitational. So although I could use "DOWN" that is not actually accurate, since it is really a nearly-vertical measurement depending on the accuracy of the spirit level. It's really a length and clinometer reading.
#length of the pole accuracy measurements sd length 0.001 metres #accuracy of the spirit level sd clino 0.125 degrees
But when working with a supposedly vertical position, even the slightest error in the clinometer angle of the pole could cause the compass bearing to flip to any angle at all. But this seems extreme: sd compass 360 degrees
So what would be the right way to specify it?
Cheers,
Tarquin _______________________________________________ Therion mailing list Therion@speleo.sk https://mailman.speleo.sk/listinfo/therion