Hi Alistair I would definitely link all the survey centrelines. The implication is that you have some errors in the survey, but you know that the straight mine level needs to be straight so the error isn’t there. One thing you could try is to set the SD for the level to be very low, and the SD for the rest of the cave to be quite high. When Therion distributes the error, most of this should go to the survey sections either the highest SD, and the level should be less distorted. Best regards Ben
Sent from my iPhone > On 14 Nov 2020, at 11:49, alastair gott <[email protected]> wrote: > > HI Therion people, > > I'm helping with a project we've got a cave/mine system with a really > straight mine level for one of the entrances, which we have the centreline > data for (but no sketches to show where the points are). > > When the system was joined up together with all the entrances there was a > kink in the mine level. so to counteract this, I removed some of the unknown > survey points in the centre of the level and hung the survey on some points > at the beginning and end of the level. > > I now want to add in a section of cave in the centre of the level. I have > connected this quite well in a map at a lower level with just the one > entrance coordinates in it, but when I run the full map with all the > entrances in, the model then tries to remove the loop error by doing it's > statisical wizardry. > > Unfortunately in doing so, it shifts the start of the level (the entrance) to > the east. and then leaves the section of cave out unconnected. > > If anyone can help, then the config for the full system is here: > http://www.cave-registry.org.uk/svn/PeakDistrict/Castleton/peak_speedwell_model/ > > This is what I get: > > <image.png> > > > the config for the one entrance coordinate is here: > http://www.cave-registry.org.uk/svn/PeakDistrict/Castleton/peak_speedwell_model/speedwell_mine/Speedwell_mine_thconfig.thc > > and these are the two selects if you want to run it at the lower level: > select bottomless_pit.speedwell_mine > select oakden_level.speedwell_mine > This is what I want: > > <image.png> > > > > If I add in a survey point to hook it to, then I get this: > <image.png> > > > Rather than this: > <image.png> > > > Adding in more survey points further down the passage to the south only > increases the amount of distortion in a small space of passage. as there are > three loop closures at the bottom of the picture [just below the red circle) > which the model is running (i've just not included the maps on the drawing > for clarity). > > > Regards, > Alastair Gott. > > [email protected], > M: 07931779380. > _______________________________________________ > Therion mailing list > [email protected] > https://mailman.speleo.sk/listinfo/therion
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