Transformation to local coordinates (dataset from RTK drone)

[NikosMavronichtis]

Hi,

I have a dataset of images from an RTK drone. Errors after the alignment are very reasonable in all 3 axis, as expected.

What I would like to do is to add some images from a terrestrial camera, ignoring any georeference of the model (in WGS84) that the drone images can offer.
As soon as I go to the reference setting and choose a local coordinate system  with the drone images ticked, the coordinates from long, lat go to X Y without any value change and the error goes up 10 times.

What I am doing wrong?  Which is the appropriate workflow for getting rid of the georeference for a dataset, without an loss of accuracy?

Thank you in advance

[olihar]

You need to project the drone images into the GEOid you are using.

[NikosMavronichtis]

Thanks Olihar!

[jmaeding]

I've never heard of that working. The problem is the software is not able to match up enough points to line up the added images.
I'm guessing the terrestrial pics are from hilltops or sides of buildings?
Even shadows that are different than time of drone flight will mess that up.
The terrestrial camera has no coordinates/direction info, right?
So projecting stuff won't help.
I like the idea though, and if you took pics on ground at flight time, that would be useful to add.
Seems like you would have to take multiple overlapping ones though.
This falls into the category of feeding metashape drone and ground photos to get one model.
Anyone done that without garbaging the results?

[Paulo]

Hi al,

i would do the following. Align drone images in 1 chunk and terrestrial shots in another. Then find at lest 3 common points / markers in both chunks, measure them and then use align chunks by markers to align the terrestrial chunk to drone....then merge and you can then go on from there/

Should give good results. Example shows drone orbit shot with terrestrial at front of church....

[NikosMavronichtis]

Thanks Paul for your suggestion.
According to some tutorials for the 2.0 version the workflow should be all the data in 1 chunk. I have not understood why.

Regarding the issue I described in my first message, I found that it was a matter of transformation. As soon as I delete the transformation, the georeference (due to the RTK drone images) is gone and I can move/rotate my model as I want.

[Paulo]

Nikos,

you are right. Since 1.7.0, aligning in one chunk 2 sets of aerial drone images and terrestrial will result in 2 individual aligned sub sets or components without any or very few tie points between them (because of great disparity of resolution between the 2). Then you use markers (at least 3) to align the 2 sub sets. It is equivalent to the 2 chunk approach...

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A new feature has been implemented in Metashape version 1.7.0. - Components. Some additional details about components can be found in the following article - Connected components in the camera alignment procedure. If some image subsets of the dataset are not aligned with each other, they will be grouped into individually aligned parts (so-called "Components"), which will be displayed in the chunk's contents of the Workspace pane:


To align components with each other manually use markers. To switch the display in the Model view to the desired component double-click on its label in the Workspace pane.

After all the components are aligned, select them in the Workspace pane and then use Merge Components command from the context menu.