Hi Bruce, With the help of the latest snapshot solving the crash issue, I found the source of these large distortions. The loop closure that I am using is The are due to the limited numerical accuracy (float rather than double somewhere?) in the weighted least-squares for error compensation when we put very large standard deviations (in my case "sd length 400 m)". I had indeed shots for far away for triangulation, and since the length is estimated a posteriori from the map, I wanted to put a very high confidence interval on it. Getting down to a stddev of 50 m solves the problem. Thus this problem is different from the one we experienced in 2013. Xavier Le 10/09/2020 à 07:33, Bruce Mutton a écrit :
Xavier I did have a project that distorted part of a loop 400 m vertically too far downwards. Changing from Therion loop closure to Survex loop closure resolved the problem, and so I have retained that setting ever since. That may have been in 2013, or maybe earlier. On a few occasions since I have checked to see if that problem still manifested, but it did not. I never figured out why it did it for only a window in time/Therion versions. Bruce
-----Original Message----- From: Therion <therion-bounces@speleo.sk> On Behalf Of Xavier Pennec Sent: Thursday, 10 September 2020 09:05 To: therion@speleo.sk Subject: Re: [Therion] Bug with uncertainty on fixed station on windows 10?
Well, on my side, my projects with multiple fixed points with uncertainty that were compiling last years are now generally crashing at compilation. However, since I changed computer, therion and survex version, it is difficult to single out the reason.
With no loop and several fixed points with uncertainty, it seems to crash systematically like in the example I posted. When it does not crash with multiple loops and multiple fixed points with uncertainty, it can either gives a .3d output that seems reasonable in aven, or it can displace one of the fixed points kilometres away, either in horizontal or vertical direction! Just fixing a point at 950 altitude can output a 3d file where the altitude is at -4000m.... A new way to explore abysses! I have just looked at the .3d result so far since I have not drawn all the maps yet in the cases where it compiles.
As soon as I manage to set up a mock-up example, I will post it to document this amazing behaviour.
Best
Xavier
Le 09/09/2020 à 22:34, Bruce Mutton a écrit :
I forgot to point out that most of my projects probably have multiple fixed stations with uncertainty parameters set. I don't think I have experienced any problems, at least in recent times and with recent versions of Therion. So your example is interesting. Bruce
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