[Therion] loop misclosure error distribution

[Andrew Atkinson]

Cannot

sd <quantity list> <value> <units>

be used to do the same thing?

>From teh survex manual

SD

Syntax

    *sd <quantity list> <standard deviation>
Example

    *sd tape 0.15 metres

Description

    *sd sets the standard deviation of a measurement.

    <quantity> is one of
TAPE|COMPASS|CLINO|COUNTER|DEPTH|DECLINATION|DX|DY|DZ

    <standard deviation> must include units and thus is typically "0.05
metres", or "0.02 degrees". See *units below for full list of valid units.

    To utilise this command fully you need to understand what a standard
deviation is. It gives a value to the 'spread' of the errors in a
measurement. Assuming that these are normally distributed we can say
that 95.44% of the actual lengths will fall within two standard
deviations of the measured length. i.e. a tape SD of 0.25 metres means
that the actual length of a tape measurement is within + or - 0.5 metres
of the recorded value 95.44% of the time. So if the measurement is 7.34m
then the actual length is very likely to be between 6.84m and 7.84m.
This example corresponds to BCRA grade 3. Note that this is just one
interpretation of the BCRA standard, taking the permitted error values
as 2SD 95.44% confidence limits. If you want to take the readings as
being some other limit (e.g. 1SD = 68.26%) then you will need to change
the BCRA3 and BCRA5 files accordingly. This issue is explored in more
detail in various surveying articles.
See Also

    *units

Andrew

On 14/11/12 09:25, Cepe wrote:
> 
> Essentially I need this feature to handle a loop with a part in a
> quarry/mine, with data collected with a total station that i would maintain
> fixed, and part formed by a cave intersecting the mine.
> I think that I can do this with a little workaround (I think but I'm not
> sure of this), calculating only the mine's data, getting the GPS fix
> (calculated) of the intersection stations and then recalculating the entire
> survey with this station fixed but is a long work.
> Reading the Survex manual i founded a SOLVE command that seemed usable for
> my purpose so, before taking this way, I asked... ;)
> 
> 
> Stacho Mudrak-5 wrote:
>>
>> Not yet, it should be implemented.
>>
>> What for do you need this feature?
>>
>> We created therion to avoid doing things like this :)
>>
>> Regards, S.
>>
>> On 13 November 2012 20:08, Cepe <ron7170 at iperbole.bologna.it> wrote:
>>
>>>
>>> Hi!
>>> it is possibile to force Therion to compute one part of a loop
>>> and then to compute the remain part keeping the first computed part fixed
>>> or, in other words, to distribute the misclosure error only in the second
>>> part of the loop?
>>>
>>> Sorry for my very poor english.
>>> Regards,
>>> Fede
>>> --
>>> View this message in context:
>>> http://old.nabble.com/loop-misclosure-error-distribution-tp34675277p34675277.html
>>> Sent from the Therion mailing list archive at Nabble.com.
>>>
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>>
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>