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Dear Xavier, <br>
Many thanks for that. <br>
Best regards,<br>
Stelios<br>
<br>
<br>
<div class="moz-cite-prefix">On 05/03/2014 16:44, Xavier Pennec
wrote:<br>
</div>
<blockquote cite="mid:53173859.80406@inria.fr" type="cite">Hi
Stelios,
<br>
<br>
The standard values should be ok for the tape and azimut
measurement.
<br>
They are defined in the file grades.th (in therion/lib) that I
included (actually we should read 99% of the values within range
instead of 95% in this file but a small variation does not really
matter).
<br>
<br>
Best
<br>
<br>
Xavier
<br>
<br>
<br>
Le 05/03/2014 12:16, Stelios Zacharias a écrit :
<br>
<blockquote type="cite">Dear Xavier,
<br>
<br>
Thank you, this is exactly what I was looking for. I would
imagine therefore a similar setting will allow small or no
changes to be made to the az and the tape measurements when
closing loops.
<br>
<br>
Something like:
<br>
sd tape 1 cm
<br>
sd azimuth 1 degree
<br>
<br>
Cheers,
<br>
Stelios
<br>
<br>
<br>
On 05/03/2014 12:02, Xavier Pennec wrote:
<br>
<blockquote type="cite">Hi Stelios,
<br>
<br>
if you believe that your clino measure is plus or minus 10
degrees (in standard deviation, meaning that 95% of the
measures at p/m 20 degrees), then you state before your data:
<br>
sd clino 10 degrees
<br>
<br>
You can put a higher value, for instance 1000 degrees or even
more, which means that all measurements (which will be between
-90 and 90) are in the flat part of the Gaussian, i.e. they
have the same probability. With such a sd, the (weighted)
least-squares loop closure algorithm will preferably change
the clino measurement than any other (provided that this
allows closing the loops). Now therion will report the closure
error in meter and percentage error and the only difference
should be a decrease of error in X and Y and an increase in Z
(but usually little change on the norm of the 3D error).
<br>
<br>
Hope that helps
<br>
<br>
Xavier
<br>
<br>
Le 04/03/2014 15:52, Stelios Zacharias a écrit :
<br>
<blockquote type="cite">Dear all,
<br>
<br>
I recall a discussion here about using a fairly broad sd
value to allow loop closure when trying to transfer paper
surveys into Therion - I may be misremembering.
<br>
<br>
I recently surveyed a closed loop with a broken clinometer
(spinning wildly with no fluid to damp the motion), so for
each leg of the survey I have distance and azimouth
accurately and slope as an approximation. How would I set up
the sd (if indeed this is how I would do it) to close the
loop and correct my approximate / estimated slopes?
<br>
<br>
I look forward to hearing from you.
<br>
Stelios Zacharias
<br>
<br>
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