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Deformation analysis (Software)

Micha ⌂, Bad Vilbel, Freitag, 06.04.2018, 15:52 (vor 15 Tagen) @ Pavlo

Hi,

1) All individual epoch were recalculated and all failed observation removed from deformation data set.

Okay.

Point 90P is outside a wall and located on nearby building. So I updated setup.
2) Point 90P is no longer a wall point but with point 101 a reference point. (datum group)

The wall points are the points to analyse and the stations are non-homologous points. Thus, your reference point field is defined by two points i.e., 101 and 90P. This is - more or less - like a minimal configuration. As pointed out in my last posting: What is happens, if 101 or 90P is unstable and shifted? The current configuration is somewhat weak (I don't know a better English term).

An example: In a leveling network, the number of datum points should be three or more. If one of the datum points is unstable (while the other points are stable), it is possible to identify this unstable point. If the network has only two datum points, it is possible to detect the discrepancy between both points but you cannot identify the unstable point itself.

3) Stations are new points. (new group)

Okay.

4) Wall points are datum points, together with point 101 and 90P.

The wall points are the points to analyse, thus, normally, I would define these points as new points.

If this a reasonable thing to do ? Failing component is sigma_a but sigma_a is defined by the theodolite manufacturer, that why I increase sigma_c is this reasonable?

Yes, it is. The uncertainty sigma_a and sigma_c are not independent in variance-component estimation. If you change sigma_c, the value for sigma_a will be changed in variance-component estimation, too.

2) Can this configuration be considered as "correct" configuration for deformation test ?

I would define the wall points as new points. (And I would try to increase the number of points, which defines the datum for the upcoming epochs)

[image]

With this new setup is this still true ? Should point 90P be excluded from datum ?

In my configuration (datum: 101 and 90P), I cannot exclude one of the points but JAG3D detects a (small) discrepancy between both points. The test statistic for Tpost is exceeded (the critical value from F-distribution is 4.2) and the estimated point shift is > 2 mm.

[image]

reagrds
Micha

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