Check point markers don’t update coordinates with changed control or projections

[Faulty_geo]

I am using coded target scale bars to control model scale and geometry. I am running several different models with the same photo set to test changes in accuracy with different scales.  I am using the check point markers to understand model differences.

General workflow: align photos, find coded targets, create scale bars, update and optimize cameras, add markers as check points.

The check point coordinates (local coordinates) show up as soon at I place them, but if I adjust the location in any other projections, the coordinates do not change. If I move the original marker I placed, the coordinates don’t change. If I change the scale bars and re-optimize, the coordinates don’t update. If I keep the check point markers and realign the model from scratch, the coordinates don’t update.

Is there any way to verify that the coordinates are accurate? I seems they’re pulling XYZ from a single photo’s estimated location. I’m using Metashape 1.5.1

[JMR]

It seems like you are adding markers on the model and that's why they show coordinates (source values) instantaneously.
I have argued if this is the right behaviour with devs, in my opinion it may leads to confusion but there are reasons to keep it as is.
Rather than doing this way, you should add the new marker in the project tree and then place it on photos. This would keep empty the source coordinates, and the check point will behave as a checkpoint not as an additional constraint.
A workaround it is to clear location for this reference point.
Regards
GEOBIT

[Faulty_geo]

Thank you for your response! I thought if I didn't check the markers in the reference pane, they would remain independent.

A couple of clarification questions:
1. When you say "clear location for reference point," do you mean right click the marker and clear? This removes XYZ and keeps the markers on the photos, but when I export the markers there are no coordinates, which I still need. I was hoping for estimated X, Y, and Z.
2. I tried your suggestion and added a marker to the project tree, then placed on the photos. However, when I export the markers I have the same problem and have no X, Y, or Z information. I'm using the "export" icon and selecting "markers" in the dialogue, leaving all options checked including "save estimated values."

You are right that these two options seem to have the same end result.

I still want to know what the coordinates are in model space (local coordinates), based on the geometry that Agisoft generates. I realize they are not real-world coordinates since I'm not adding coordinate information, but that's sort of the point.

[JMR]

1. Yes that the "clear" I meant. but after using it, unless you have cleared also projections, you should keep having estimated values for the marker and it should change every time you move its projections.
2. When you export the markers they all must have estimated values in coordinates unless they have no projections, so please make sure that your are checking the "save estimated values" in the export dialog

Regards
GEOBIT

pd. out of curiosity. Why do you stay 1.5.1...?

[Faulty_geo]

The key problem here is that none of the markers have estimated locations (X est, Y est, Z est) and at no point in the process that do those field populate. When I place a marker on a photo, it generates X, Y, and Z coordinates but the estimated field are blank. The markers do not have outside control- they are added to the model as a check point and have not been surveyed, etc. I want the location in local coordinates.

This was true before clearing the coordinates as well. They do not appear after optimizing the model, or as far as I can tell, making any changes. The only items that have estimated values are the scale bars (est distance), which are "checked" in the reference pane.  I've attached an example of the screen when estimated values are selected from the reference toolbar.

I'm using 1.5.1 because I do not have administrative privileges on this computer to update the project. Also, I started these projects before I know 1.6 was available and did not want to switch part way through to keep everything consistent. Do you think updating will fix the problem?

[JMR]

It seems this chunk has nor been referenced, that would explain no coordinates can be estimated.
A simple workaround could be to assign coordinates (with accuacy values as low as 10m) to four markers on your model defining a local system. As your main source of metric control are scale bars, dont worry about loosing accuracy because markers will be so low weighted that they will hardly have impact in your model.
Regards

[Faulty_geo]

This appears to be working, I now have estimated XYZ for all markers, even the ones I didn't assign coordinates to.

One more question: Since I don't want the markers to influence geometry, does it make sense to skip optimizing the model after adding the XYZ for 4 markers? For example:
1. place scale bars and optimize
2. place markers, export locations for marker X, Y, Z
3. clear locations/reference for marker check points
4. set marker accuracy to 10 m
5. import local coordinate locations for 4 markers using file from step 2
6. export auto-populated X_est, Y_est, Z_est. Do not optimize.

It seems like if I optimize at step 5 the marker locations will slightly influence model geometry, even if the marker accuracy is set to something as high at 10 m. Or am I thinking about this wrong?

[Alexey Pasumansky]

Hello Faulty_geo,

In the version 1.6 you can disable markers in the Reference pane (not just uncheck, but right-click and choose Disable option) - in this case neither their coordinates nor projections will be considered for the optimization stage.

[Faulty_geo]

Hi Alexey,

Thank you for the tip. I upgraded to Metashape 1.6 and tried disabling the markers. I picked up where I left off in the workflow I described above, where the model was not optimized again once adding in a few local coordinates to generate X_est, Y_est, Z_est.

I also tested if the marker locations would change if I optimized the model again, with the markers disabled. I figured since I already optimized the model once with scale bars and no markers, the estimated marker coordinates should not change if they were disabled.

The result: the marker estimated coordinates only changed a little bit (generally less than 0.05 mm). My guess is this change could be explained away by updating Metashape versions, if the way the models are optimized was updated between 1.5 and 1.6. I am satisfied enough with this small change, since it's low enough for the project I'm working on to be inconsequential.

I think this is issue is resolved, since I have found a way to get estimated coordinates within the model by only using scale bars to constrain the model geometry.