Java·Applied·Geodesy·3D - JAG 3D - 1D network adjustment

JAG 3D - 1D network adjustment (reply)

Micha — Sat, 20 Sep 2025 10:38:11 +0000

Hello,

As for the **alpha value**, if it is also expressed as a percentage, the default is 0.10.
Does that mean 10%?

No, it means 0,1 %. This is the common value proposed by Baarda.

Kind regards
Micha

JAG 3D - 1D network adjustment (reply)

aleksandar95 — Sat, 20 Sep 2025 08:52:33 +0000

Hello Micha,
I have question about Test statistic.
In the **Settings** menu, it says that the values for statistical parameters (most likely the alpha – Type I error) and test power (1-beta – Type II error) are expressed as percentages %. The default value for test power is 80%, which is fine. As for the **alpha value**, if it is also expressed as a percentage, the default is 0.10.
Does that mean 10%? And if I want to set the value to 5%,should I enter 0.05 or just 5?

Thansk.

JAG 3D - 1D network adjustment (reply)

Micha — Tue, 16 Sep 2025 07:32:32 +0000

Hello aleksandar95,

as mentioned earlier, using the manufacturer's specifications is a good starting point for defining the stochastic model. Values that are not specified by the manufacturer must be derived empirically by the analyst, for example based on experience, or must be set to (almost) zero. It is common practice to evaluate the stochastic model within the adjustment procedure using e.g. variance-component-estimation. A proper analysis of your data w.r.t. the selected stochastic model yields the answer to your question.

/Micha

JAG 3D - 1D network adjustment (reply)

aleksandar95 — Mon, 15 Sep 2025 09:19:07 +0000

Dear Micha,
I again have question about 1D adjustment network.

I have a network with 5 datum points (the base network) and 12 working benchmarks on the structure.
I used an instrument with an accuracy of 1 mm/km.
The distance between the points of the base network is 250 m, and the distance between the base network points and the working benchmarks is up to 300 m.
The distance between the working benchmarks ranges from 20 to 50 m.

Considering the number of points and the network configuration, where I have enough redundant measurements,
what values should be set for sigma a (σa), sigma b (σb), and sigma c (σc)?

Thank you

JAG 3D - 1D network adjustment (reply)

Micha — Fri, 21 Feb 2025 13:06:33 +0000

Hello,

When I set sigma a to 0.1mm and sigma b to 1mm, the sigma h values for each measurement are between 0.2 and 0.4, while when I set sigma a to 1mm and sigma b also to 1mm, I get sigma h values between 0.8 and 0.9.
Whats is correct?

Your question cannot be answered in this way. It depends on your assumption and experience.
How do you evaluate the value for σb? The value may be specified by the manufacturer of the instrument, but this does not mean that you have reached this value.

Have a nice weekend
Micha