It looks like a bug in therion loop closure algorithm. I can have a look at it, if you can send me the dataset.
Best regards, S. On 15 November 2010 09:35, Bruce <dangle at tomo.co.nz> wrote: > I have a mystery, whereby an overland survey between two fixed points > gives a correct pdf plan output with; > > > > loop-closure survex > > > > (I know it is âcorrectâ because the aerial photograph image matches the > features surveyed) but if I specify; > > > > loop-closure therion > > > > then one of the fixed points is about 150m misplaced in plan and the > surveyed features are clearly in the wrong place. > > > > In both scenarios therion.log reports identical average loop errors and > specific loop error statistics. The error over a 500m loop is about 2.3%, > mainly due to a 12m error in elevation (can not trust those gps readings). > The plan error if one of the points has its âfixityâ removed is about 4m, > and the plots produced are correct regardless of the loop closure method. > > > > It is a rather large dataset with many underground loops, and four fixed > surface points. Two of which have overland surveys between them. Only one > of the overland surveys has this problem. > > Using Therion 5.3.5. Can replicate this result on three computers. > > > > Any theories as to what might be going on and how to locate the issue? > > > > Bruce > > _______________________________________________ > Therion mailing list > Therion at speleo.sk > http://mailman.speleo.sk/mailman/listinfo/therion > > -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://mailman.speleo.sk/pipermail/therion/attachments/20101115/3638e34a/attachment.html>
