Forum

Author Topic: Combining Laser scan and point cloud data  (Read 635 times)

MichaelH

  • Newbie
  • *
  • Posts: 7
    • View Profile
Combining Laser scan and point cloud data
« on: January 18, 2022, 12:55:37 PM »
I've read that it is possible to combine laser scanned point cloud and UAV photo data.

I have a large point cloud of a building in e57 format uncolored and a set of geotagged photos of the roof and yard area in colour. These photos also have targets if necessary. The Geotags are in WGS84 but the cloud is in a local coordinate system. The cloud is registered but not unified.

Can someone point me to a straightforward workflow to combine this data. Do I need to process the photo data to a dense cloud first? Do I need to add the target points to the scan data? Any help would be greatly appreciated.

Dieter

  • Full Member
  • ***
  • Posts: 147
    • View Profile
Re: Combining Laser scan and point cloud data
« Reply #1 on: January 18, 2022, 07:07:34 PM »
A few questions about it:

How accurate are the GPS coordinates of the images?
In which coordinate system should the result be delivered?
Are there identical (tapable) points between the point cloud and the images?
Does the point cloud only consist of the E57 file or are the original data (scans or photos) available?

Dieter

MichaelH

  • Newbie
  • *
  • Posts: 7
    • View Profile
Re: Combining Laser scan and point cloud data
« Reply #2 on: January 19, 2022, 09:18:45 AM »
Hi thanks for the reply:

-The images are done with Aibotix X6 with a pretty good camera on the gimble so they're very accurate. We were getting discrepancies of <100mm. They're old images as we're now running a DJI copter which we'd use on future projects.

-The result will be in the current scan coordinate system. Its a local Finnish system ETRS-GK27 (ESPG 3881). The images are in WGS 84.

-Some points are similar but the scan was done in black and white while the photos are colour. The GCPs (targets) were put in place after the scan was done.

-All original data is available in any format as it was processed in Leica Cyclone. When I import the e57 I get the basic photos from the scan but no cloud. The photos are in black and white. The scan wasn't captured with the camera fully operational to save time.

Thanks again for the help.

Dieter

  • Full Member
  • ***
  • Posts: 147
    • View Profile
Re: Combining Laser scan and point cloud data
« Reply #3 on: January 19, 2022, 01:17:53 PM »
<100mm  accuray for the GPS coordinates?

What Kind of GPS do you use? Normal, RTK or PPK?

What for an accuray you want to reach for the whole project?

Dieter

Alexey Pasumansky

  • Agisoft Technical Support
  • Hero Member
  • *****
  • Posts: 13729
    • View Profile
Re: Combining Laser scan and point cloud data
« Reply #4 on: February 01, 2022, 03:20:29 PM »
Hello MichaelH,


I would suggest to try following the tutorial:
https://agisoft.freshdesk.com/support/solutions/articles/31000159101-terrestrial-laser-scanning-data-processing

Add laser scan data, add photos to the project, then run Align Photos operation (using only Generic preselection) and see, if the digital photos are aligned to the laser scans (represented with the big blue spheres).


If it doesn't work, than you can try to use the approach mentioned in the very end of the article - re-use the laser scan registration information to orient the scans using Python based on the coordinate information. This approach assumes that you can align digital photos and reference the result in the same coordinate space, as laser scans.
Best regards,
Alexey Pasumansky,
Agisoft LLC