# 2 distincts stations in one adjustement

by **Antoine Chabert** , Wednesday, November 18, 2020, 12:30 (10 days ago)

Hi,

Our goals is to compute in group 2 distincts stations, in one JAG3D adjustment.

We have tried to adjust network of 2 distincts stations : TPN16 & TPN17.

Separately, the adjustment network of each station works well – you can find 2 reports in attached files (A & B).

When we merge all the terrestrial osbervations & newpoints & refpoints of both stations without adding links between stations; we are getting a bad result from the adjustment network in jag3D – You will find the report C attached.

When we merge all the terrestrial osbervations & newpoints & refpoints of both stations with adding links between stations; we are getting a bad result from the adjustment network of jag3D – You will find the report D attached.

It looks like JAG3D does not understand the global adjustment with 2 stations.

Is it a problem of our configuration / use of JAG3D? (we have tried to insert the stations like datum point but we get an error message).

Is it a limit of JAG3D adjustment ?

Thanks a lot for your return,

Best regards

## 2 distincts stations in one adjustement

by **Antoine Chabert** , Wednesday, November 18, 2020, 12:35 (10 days ago) @ Antoine Chabert

files are vailable on demand

## 2 distincts stations in one adjustement

by **Micha** , Bad Vilbel, Wednesday, November 18, 2020, 14:14 (10 days ago) @ Antoine Chabert

Hello,

It looks like JAG3D does not understand the global adjustment with 2 stations.

Well, as shown by the screenshot at the github project website, that is not correct.

Is it a problem of our configuration / use of JAG3D? (we have tried to insert the stations like datum point but we get an error message).

Maybe, it is a problem with your configuration. However, without having your data, it is hard to figured out what is going wrong. I believe, it is a problem of your data handling. If possible, provide your data via Dropbox or any other service like that.

Please note: You have to separate each set of directions in it's own group. So, if you put all directions together in a single group - which means all directions share the same information about the unknown orientation - the adjustment will usually fail.

Is it a limit of JAG3D adjustment ?

No, I dont't think so - see the screenshot at github.

kind regards

Micha

--

applied-geodesy.org - *OpenSource* Least-Squares Adjustment Software for Geodetic Sciences

## 2 distincts stations in one adjustement

by **Antoine Chabert** , Thursday, November 19, 2020, 15:25 (9 days ago) @ Micha

Hello,

Thank you for your complete answer. I really appreciate it. I made some progress and indeed, it was a problem of configuration.

To sum up our work and needs:

In our construction site, we have 3 kinds of points :

• AUS : points need to be determined measure by TPN16 OR TPN17,

• REF : points measured by TPN16 OR TPN17 fixed, has references,

• CD : doubles points near to each other measured by TPN16 AND TPN17 –

NB : CD are in our case considered as AUS (need to be determined – but they could be REF).

Then, we have 3 kinds of terrestrial measurements :

• Dataset A. : Hz, V, D of TPN16 (1st station) – with normal precision 0.3mgon & 1mm => for AUS & REF

• Dataset B. : Hz, V, D of TPN17 (2nd station) – with normal precision 0.3mgon & 1mm => for AUS & REF

• Dataset C. : Hz, V, D of links between TPN16 & TPN17 (with high precision – 0.03mgon & 0.1mm) => for CD

Then, we want to insert all this information in JAG3D.

We have differents options :

• Use C only – it is not work because JAG3D understand a new station : CD

• Concatenate A&C – report C.html in attach file

• Concatenate B&C

What is the best option ? What JAG3D configuration is adapt to our site ?

Otherwise, we make a post in October 20 to learn if it is possible to insert constant vector 3D in JAG3D. The answer that was not possible and we have to insert measurement between points with high level of precision.

Do you think that the configuration made up is ok for this need ?

Kind regards,

Antoine

## 2 distincts stations in one adjustement

by **Micha** , Bad Vilbel, Thursday, November 19, 2020, 18:49 (9 days ago) @ Antoine Chabert

Hello,

I've downloaded the file (should I remove the link from your posting?).

However, I have some questions to get a better impression of your network (and the problem).

• AUS : points need to be determined measure by TPN16 OR TPN17,

These points are only measured by one of the stations (no redundancy)?

• REF : points measured by TPN16 OR TPN17 fixed, has references,

Again: The reference points are only measured only once by one of the stations (no redundancy/no connection)?

• CD : doubles points near to each other measured by TPN16 AND TPN17 –

Okay, these points connect both stations, right? However, what is a "double point"? And what means "near to each other" in this context? Is, for instance, PR_Z4-60-3_C-1 and PR_Z4-TPN17-60-3_C-1 such a "point pair"?

• Dataset C. : Hz, V, D of links between TPN16 & TPN17 (with high precision – 0.03mgon & 0.1mm) => for CD

Otherwise, we make a post in October 20 to learn if it is possible to insert constant vector 3D in JAG3D.

Ah, okay, you refer to this posting?

So, you have dX, dY and dZ between the CD point pairs and you convert these Cartesian values to polar measurements, right? Is dZ pointing to the same direction as the vertical axis of the instrument in your network? Contains the Excel files such information on dX, dY and dZ?

kind regards

Micha

--

applied-geodesy.org - *OpenSource* Least-Squares Adjustment Software for Geodetic Sciences

## 2 distincts stations in one adjustement

by **Antoine Chabert** , Friday, November 20, 2020, 16:03 (8 days ago) @ Micha

Hello,

Thanks for your fast return!

You can delete the link, but it is not a priority.

All the points (AUS+REF+CD) have not a strictly redundancy; there is only points measured by one station.

CD / doubles points connect both stations. A double point are 2 prisms near to each other like 10cm max. One prism is oriented for TPN16; the other is oriented for TPN17. In our monitoring site, we consider that the vector 3D between this 2 points are constants.

PR_Z4-60-3_C-1 and PR_Z4-TPN17-60-3_C-1 are such a point pair.

I give you the file contains the construction of this pairs in the link below :

Exactly, that was our post and we are trying to make it in practice.

Yes we have dX, dY and dZ in our data file CD_LINK-TPN16_17.xlsx (available in the link above).

For your information, this work is static today to know how JAG3D works but later our goal is to use it in automatically way.

Thanks,

Regards,

Antoine

## 2 distincts stations in one adjustement

by **Micha** , Bad Vilbel, Friday, November 20, 2020, 18:02 (8 days ago) @ Antoine Chabert

Hello Antoine,

Exactly, that was our post and we are trying to make it in practice.

Okay, I modified your project. Please take a look at antoine.zip.

I believe, the directions between the CD points cannot be used together with a "true" set of directions because the orientations differ. I was not sure, how you ensure, that the directions between the CD points are similar orientated. For that reason, I disabled these observations.

I would also suggest to use some kind of trimmed coordinates to avoid numerical instabilities, i.e., reducing all X/Y/Z coordinates to their average values.

In present configuration, your networks is not controlled. Since no true redundant observations are available, thus, you have no chance to remove possible outliers.

/Micha

--

applied-geodesy.org - *OpenSource* Least-Squares Adjustment Software for Geodetic Sciences

## 2 distincts stations in one adjustement

by **Antoine Chabert** , Monday, November 23, 2020, 14:18 (5 days ago) @ Micha

Hi,

"Okay, I modified your project. Please take a look at antoine.zip --> https://dev.applied-geodesy.org/tmp/antoine.zip."

Thanks, we analyse that you differentiate "stations" and "new points" in 2 distincts groups in "new points" ?

Is it a good practice ? does it change something in the adjustment ? Should we insert it in our project ?

"I believe, the directions between the CD points cannot be used together with a "true" set of directions because the orientations differ. I was not sure, how you ensure, that the directions between the CD points are similar orientated. For that reason, I disabled these observations."

All the direction are calculated between the CD, with always the same formula. We oriented it from the north. An excel file is attached where the calculation is available.

But I am not sure to understand why you disabled these observations. Why did you do this ? Indeed, the project had a particular geometry; with strains between the CD points : in directions sets ; zenith angles & slope distance.

Theorically, we can not disactivate once parameters : directions sets and you can not always adjust the network.

But in practice, we can adjust the network... How does it work ? Where the strains in directions sets are usefull ? They seems to be useless...

"I would also suggest to use some kind of trimmed coordinates to avoid numerical instabilities, i.e., reducing all X/Y/Z coordinates to their average values. "

You mean that we should do a preprocessing : approximation values (CTRL+M) ? before do the command "adjust network" ?

"In present configuration, your networks is not controlled. Since no true redundant observations are available, thus, you have no chance to remove possible outliers."

Yes we know this low quality of our networks but in case of AMTS monitoring, we did not find a solution to make redundancy.

Thanks,

Regards,

Antoine

## 2 distincts stations in one adjustement

by **Micha** , Bad Vilbel, Monday, November 23, 2020, 15:57 (5 days ago) @ Antoine Chabert

Hello Antoine,

Thanks, we analyse that you differentiate "stations" and "new points" in 2 distincts groups in "new points" ?

Is it a good practice ? does it change something in the adjustment ? Should we insert it in our project ?

No, such separation has no effect on the results. However, I'm not part of your project, so I have to re-organise the project to get a better impression. It was just for me. Sorry for confusion.

All the direction are calculated between the CD, with always the same formula. We oriented it from the north. An excel file is attached where the calculation is available.

But I am not sure to understand why you disabled these observations. Why did you do this ? Indeed, the project had a particular geometry; with strains between the CD points : in directions sets ; zenith angles & slope distance.

Whereas a direction is a un-orientated observation, a direction angle is defined between a station and two target points. For that reason, a single direction makes not sens because it only contributes to the unknown orientation. However, if *really all* directions between the CD points are derived within the same datum, you can enable the group. In this case, all directions contribute to the same unknown orientation redundantly. As already mention, I was not sure about this fact and, therefore, disabled such pseudo-observations.

Theorically, we can not disactivate once parameters : directions sets and you can not always adjust the network.

But in practice, we can adjust the network... How does it work ? Where the strains in directions sets are usefull ? They seems to be useless...

Are you referring to the unknown orientation? This parameter describes the discrepancies of the north-direction of your frame and the zero-direction of the total-station (angle-encoder). See above, a direction is not an (direction) angle. A direction of 100 gon (90 °) does not imply that the target point is located in the east.

"I would also suggest to use some kind of trimmed coordinates to avoid numerical instabilities, i.e., reducing all X/Y/Z coordinates to their average values. "

You mean that we should do a preprocessing : approximation values (CTRL+M) ? before do the command "adjust network" ?

No, just averaging the coordinates in Excel, for instance, and reduce each coordinate by the mean. Currently, the network extent is about 500 m x 500 m. If, for example, the origin is set to 0/0, the maximal coordinate becomes 500/500. Small coordinate values will increase the numerical stability because of the 64 bit limit of double values.

Yes we know this low quality of our networks but in case of AMTS monitoring, we did not find a solution to make redundancy.

Okay, it was just a note, but if you keep it in mind - no problem.

regards

Micha

--

applied-geodesy.org - *OpenSource* Least-Squares Adjustment Software for Geodetic Sciences

## 2 distincts stations in one adjustement

by **Antoine Chabert** , Monday, November 23, 2020, 17:48 (5 days ago) @ Micha

Hello Micha,

Whereas a direction is a un-orientated observation, a direction angle is defined between a station and two target points. For that reason, a single direction makes not sens because it only contributes to the unknown orientation. However, if really all directions between the CD points are derived within the same datum, you can enable the group. In this case, all directions contribute to the same unknown orientation redundantly. As already mention, I was not sure about this fact and, therefore, disabled such pseudo-observations.

Indeed, all the directions are derived within the same datum. But in this case, I do not understand how JAG3D can calculate his network without enable the group. I thought that there should have a geometric problem : no complete link between CD points. Why JAG3D can calculate this group ?

I thought that we need vector 3D constant between couple of points, dX, dY, dZ. But we get the option to insert raw data with high level of precision. We insert it in JAG3D, with 3 differents kind of observations ; without directions sets, we lost an essential information in 2D.

Are you referring to the unknown orientation? This parameter describes the discrepancies of the north-direction of your frame and the zero-direction of the total-station (angle-encoder). See above, a direction is not an (direction) angle. A direction of 100 gon (90 °) does not imply that the target point is located in the east.

No I do not referring to the unknown orientation of the total station. We understand well this concept.

We are referring to insert an orientation between points to generate vector 3D or eccentricity to the CD points presents in our network

No, just averaging the coordinates in Excel, for instance, and reduce each coordinate by the mean. Currently, the network extent is about 500 m x 500 m. If, for example, the origin is set to 0/0, the maximal coordinate becomes 500/500. Small coordinate values will increase the numerical stability because of the 64 bit limit of double values --> https://en.wikipedia.org/wiki/Double-precision_floating-point_format.

Ok thanks you but this subject is ok.

But it is introduce a problem of our georefencement points. Today, we are in France and we used local EPSG (for exemple, 2154 in this worksite). But JAG3D adjustement do not consider the projection : we can not integrate this information in the metadata of one project. Is it right ? Or we don’t use correctly JAG3D ?

If not, it could be an usefull update.

Thanks,

Kind regards,

Antoine

## 2 distincts stations in one adjustement

by **Micha** , Bad Vilbel, Tuesday, November 24, 2020, 07:35 (4 days ago) @ Antoine Chabert

Hello,

Indeed, all the directions are derived within the same datum. But in this case, I do not understand how JAG3D can calculate his network without enable the group. I thought that there should have a geometric problem : no complete link between CD points.

To calculate your network, the link between the CD points is not needed here. Each station can be adjusted independently. Thus, you can also disable the distances and vertical angle group of the CD points. Adding more information doesn't change this effect - the network is still estimable. The pseudo-observations between the CD points are further information. If this information is enabled, dependencies between both stations are introduced.

But JAG3D adjustement do not consider the projection

In general, it is a projection problem and not an adjustment one. JAG3D is designed to adjust a network. Moreover, you are using UTM coordinates but UTM is not defined in 3D - there is no slope distance or vertical angle in a map projection.

regards

Micha

--

applied-geodesy.org - *OpenSource* Least-Squares Adjustment Software for Geodetic Sciences