[Therion] Loop closure / deviation of broken clino

[Stelios Zacharias]

Dear Xavier,
Many thanks for that.
Best regards,
Stelios


On 05/03/2014 16:44, Xavier Pennec wrote:
> Hi Stelios,
>
> The standard values should be ok for the tape and azimut measurement.
> 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).
>
> Best
>
> Xavier
>
>
> Le 05/03/2014 12:16, Stelios Zacharias a écrit :
>> Dear Xavier,
>>
>> 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.
>>
>> Something like:
>>  sd tape 1 cm
>>  sd azimuth 1 degree
>>
>> Cheers,
>> Stelios
>>
>>
>> On 05/03/2014 12:02, Xavier Pennec wrote:
>>> Hi Stelios,
>>>
>>> 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:
>>>   sd clino 10 degrees
>>>
>>> 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).
>>>
>>> Hope that helps
>>>
>>> Xavier
>>>
>>> Le 04/03/2014 15:52, Stelios Zacharias a écrit :
>>>> Dear all,
>>>>
>>>> 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.
>>>>
>>>> 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?
>>>>
>>>> I look forward to hearing from you.
>>>> Stelios Zacharias
>>>>
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>>>
>>
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>
>
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