Combining laser scans, terrestial images and drone images

[NikosMavronichtis]

Hi,

I am looking for the most efficient workflow in order to use laser scans files (structured form e57), images from a FF camera with a good wide lens (20mm) and images from an RTK drone (Mavic 3E)  for medium scale buildings.
No GCP will be used, georeferencing is not important.
Texture quality is very important.

I have read the tutorials:
https://agisoft.freshdesk.com/support/solutions/articles/31000158320-combined-processing-of-aerial-and-terrestrial-images
https://agisoft.freshdesk.com/support/solutions/articles/31000168474-terrestrial-laser-scans-processing-in-metashape-2-0-0

and have experimented on their combination, but I mostly have difficulties in alignment.

What I think best after proper alignment is meshing from the laser scan point cloud (for the interior areas) and drone (for roof ares), texturing from the images of FF camera (for facades) and drone (for roofs only).

I would like your help in the steps I should follow and any tips for this complex integration in terms of alignment, meshing and texturing parameters as no tutorial is available so far for this case.

Thank you in advance!

[Dieter]

Alignment between laser scans and photos is difficult to achieve. The distance and angle to the object must be almost identical, then it works well.
In addition, since version 2.0 there have been problems with the alignment of photos and scans in Metashape, so we are trying to prevent this.

For years we have been generating building measurements according to the following workflow:

1) Glue control points in the windows, which are visible from inside and outside.

2) Fly over the facade with a PPK drone and, if necessary, align it with photos taken by hand in Metashape.

3) Scan the interior and link it to the exterior facade using the coordinates of the control points in the windows.

Point 3 is not carried out in Metashape, but in a special scan program. The point clouds from the two programs can then be merged and processed further.

Hope that helps,

Dieter

[NikosMavronichtis]

Thank you Dieter


Interesting workflow. May I ask in which software do you carry out the alignment of interior and exterior dataset?

Regarding my case:
I tried to align my dataset with laser scans, drone images and images from a FF camera. Metashape markers have been used. It took a long... but the result seems ok.

The strange issue is that in the reference pane that I see coordinates of the drone images dataset (none from terrestrial camera images dataset) , with great error values and also error values in a very very markers only.  Max error of markers is about 2pixels  and in  meters is very high for those markers. None of those markers is placed in a drone image.

What is wrong with the errors and the coordinate system? I want to get rid of the georeference and use only an arbitrary  local coordinate system.

[Dieter]

The laser scans are calculated with Trimble Realworks, the photos in Metashape. I then read the coordinate files into Autocad via Recap. Floor plans and sections are created there.

I can't say anything about your other problems, except that I've had a number of problems with laser scans within Metashape since version 2.0.


Dieter

[NikosMavronichtis]

Thanks Dieter

[jmaeding]

Dieter,
I use TBC, which you may have a seat of if you have realworks.
TBC can export .rcp format, and makes them 10x faster than recap.
You do have to have recap installed, but do not need a license for it, free is fine.

I was jumping for joy when I figured this out, recap is something I avoid these days.