Forum

Author Topic: Usage of reference points as ground points  (Read 2251 times)

Agriflight.be

  • Newbie
  • *
  • Posts: 4
    • View Profile
Usage of reference points as ground points
« on: January 09, 2023, 01:52:04 PM »
Hello,

I am pretty new to Metashape so apologies if this has already been discussed.
I want to map paths in a pretty dense forest. I took 100 points with a RTK GNSS receiver on the ground and I also mapped the area with an RTK drone. There were no leaves on the trees so i was hoping that the drone would find some tie points on the ground. It did, but not everywhere. So i was wondering if it is possible to add my own ground points (from the RTK GNSS receiver) to the dataset in order to make a better DTM.

Thanks in advance,
Regards,
A

Paulo

  • Hero Member
  • *****
  • Posts: 1354
    • View Profile
Re: Usage of reference points as ground points
« Reply #1 on: January 09, 2023, 05:19:50 PM »
Hola agriflight,

if your ground RTK ground points are photo identifiable then marking them on the corresponding images would certainly help your alignment....
Best Regards,
Paul Pelletier,
Surveyor

DayGeckoArt

  • Jr. Member
  • **
  • Posts: 82
    • View Profile
Re: Usage of reference points as ground points
« Reply #2 on: January 10, 2023, 07:58:56 AM »
Do you mean you took GPS coordinates of locations on the ground without markers? You can use those as control points, you just have to place them correctly on the images

Agriflight.be

  • Newbie
  • *
  • Posts: 4
    • View Profile
Re: Usage of reference points as ground points
« Reply #3 on: January 10, 2023, 10:49:52 AM »
Thank you for your replies.
I cannot place markers on the photos because they appear on top of the canopy in my 3d point cloud.

I took many points with my GNSS stick on the paths without placing GCP markers (since the idea is not to use them as gcp's but to "see" where the path lies in my point cloud, 3d model, orthophoto or DEM). The precision doesn't have to be high since it's only paths in the forest. Most of the time, i had a FIX signal, because there are no leaves on the trees and the baseline was 5km. I would now like to include these points in my point cloud, not as markers or references, but as points. I figured that if I run a classification on ground points afterwards, these would be included and so all the tree canopy would be classified as "vegetation" or something else. This way, I could have a more precise DTM

I recently thought of using the function "import/points" but I have to find a way to convert a CSV file into a LAS or other point cloud format. Then, I could import these points into my point cloud.

Does this sound right?