On 07/09/17 14:23, Wookey via Therion wrote: > I've wanted to do this too, but wasn't sure how. > > From *FIX on https://survex.com/docs/manual/datafile.htm > > The standard errors default to zero (fix station exactly). cavern > will give an error if you attempt to fix the same survey station > twice at different coordinates, or a warning if you fix it twice with > matching coordinates.
Hmm therion has an error message from survex 3> /tmp/th5506/data.svx:27: error: Station already fixed or equated to a fixed point 4> *fix 14 57300.000000 52840.000000 240.000000 5> /tmp/th5506/data.svx:28: error: Station already fixed or equated to a fixed point 6> *fix 14 57302.000000 52844.000000 240.000000 but processes it any way > > You can also specify just one standard error (in which case it is > assumed equal in X, Y, and Z) or two (in which case the first is > taken as the standard error in X and Y, and the second as the > standard error in Z). > > So I just checked and if you add some variances you can then give more than > one set of locations for it without getting errors, and the final location is > the average. > > Alternatively you can give them different names (with variances), then equate > them. > > So survex can do the right thing. Hopefully therion will pass this > through so that it works right, but I've not tested that. > > So this works: > *fix pt1 5 5 5 1 1 1 > *fix pt1 5 5.5 5 1 1 1 > > dump3d fixtest.3d: > ERROR_INFO #legs 2, len 0.00m, E 0.20 H 0.25 V 0.00 > NODE 5.00 5.25 5.00 [pt1] FIXED > > And so does this: > *fix pt1_1 5 5 5 1 1 1 > *fix pt1_2 5 5.5 5 1 1 1 > *equate pt1_1 pt1_2 > > dump3d fixtest.3d: > ERROR_INFO #legs 2, len 0.00m, E 0.20 H 0.25 V 0.00 > NODE 5.00 5.25 5.00 [pt1_1] FIXED > NODE 5.00 5.25 5.00 [pt1_2] FIXED Okay that probably will get round it, but is that the right solution? As this entrance has 3 locations it gets a variance, but most of the other 9 entrances only have one fix. This would mean they are deemed perfectly correct, while the ones with more than one location will be moved by the averaging and the surveys that connects all the entrances together. So in this case I could just go through and give a the variances for all the fixes in the data files (it is only a small set.) However it is part of a very large data set, with something like 200 entrances, that will take me sometime (or a script.) Now one of the answers which I might start to do is always be explicit in the variance, however, is it really reasonable for survex and therefore therion to assume a fix is perfect, we know that they are not. 2 gps locations fixed by survey legs all the error is distributed to the survey legs, does not seem right. So what I'm suggesting is that the default for fix to be perfect should be looked at and maybe amended to almost perfect variance. thanks Andrew _______________________________________________ Therion mailing list Therion@speleo.sk https://mailman.speleo.sk/listinfo/therion
