1D parameters and datum points
Hello,
the equations defining the stochastic model are given in the Wiki. Even if the content is in German, the equations are interpretable.
Now I want to ask same questions but for 2D.
If I want to put 2 + 2ppm for distance then I need to put in distance: in oa = 2 (mm)
, oc = 2 (ppm) and ob(sqr(d))=0? is it correct?
Yes, this is correct.
What I need to put for angle(direction), if I have instrument standard of 1'' - 0.31mgon, what to put in oa = (mgon), oc = (mm) and ob(sqr(d))= (mm)?
You have to set σa = 0,3 mgon
. If you don't have any further uncertainty, the σb
and σc
are zeros. Usually, a centring uncertainty has to taken into account. Let say, you are able to point the centre of the target with 1 mm
, in this case, you can specify this further uncertainty by σc = 1 mm
.
Also for example if I have 4(x, y) points can I put datum on point 1 (both X and Y) and on point 2 but to put datum only on Y? Is this possible?
Yes, but this is a academic construction not used in any practical application. The stochastic points can be diverted from its intended use to reach such a configuration. For instance, you have the points A
, B
, C
and D
and xA
, yA
and yB
should be used for defining the datum, xB
, C
and D
are parameters to be estimated. C
and D
are new points but A
and B
are stochastic points. Create a file like
A <yA> <xA> 0.00001 0.00001 B <yB> <xB> 0.00001 100.0
The three components that define the datum are fixed (due to the large weight) and xB
is a (more or less) free parameter.
kind regards
Micha
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