Forum

Author Topic: Adding markers for georeferencing of an orthomosaic  (Read 735 times)

UAV_project

  • Newbie
  • *
  • Posts: 25
    • View Profile
Adding markers for georeferencing of an orthomosaic
« on: September 17, 2020, 05:30:04 PM »
I have looked through a number of threads and pieced together what I thought should work for importing markers and assigning them their image and real world coordinates. However, after running the script I fear that something is wrong since when I check the reference tab in the GUI, it doesn't show that my markers have their real world coordinates assigned.

Here is the code I am using:

Code: [Select]
        import Metashape as MS

        # set the coordinate ref system of the markers
        crs_ = MS.CoordinateSystem("EPSG::%d" % crs)
        chunk.marker_crs = crs_
       
        # set the z-accuracy very high because we don't have a good measure for this
        chunk.marker_location_accuracy = [0.05, 0.05, 1000]
       
        file = open('./export.csv', "rt")#input file
       
        # skips header
        lines = file.readlines()[1:]

        for line in lines:
            line = line.strip('\n')
            sp_line = line.rsplit(separation, 6) #splitting line
            # Strip extra quotation marks if they exist
            for i, item in enumerate(sp_line):
                sp_line[i] = item.strip('"')
               
            camera_name = sp_line[0]
            marker_name = sp_line[1]
            x = float(sp_line[2]) #x-coord in pixels
            y = float(sp_line[3]) #y-coord in pixels
            cx = float(sp_line[4]) #world x-coord of marker
            cy = float(sp_line[5]) #world y-coord of marker
            cz = float(sp_line[6]) #world z-coord of marker

            # flag to indicate if marker is found
            flag = 0
           
            # Create a Projection from the pixel coordinates
            pixel_coord = MS.Marker.Projection(MS.Vector([x, y]), True)
           
            # get the camera with same name as the name in current line
            for cam in chunk.cameras:
                if cam.label == camera_name:
                   
                    #searching for a marker with the same ID as in txt file
                    for marker in chunk.markers:
                        if marker.label == marker_name:
                            # assign the marker's x,y coords in the current cam
                            marker.projections[cam] = pixel_coord
                            flag = 1
                            break
                   
                    # if marker ID not yet existing in the chunk then create
                    if flag == 0:
                        marker = chunk.addMarker()
                        marker.label = marker_name

                        # assign the marker's x,y coords in the current cam
                        marker.projections[cam] = pixel_coord
                        # Add the world coordinates to the marker
                        marker.Reference.location = MS.Vector([cx, cy, cz])
                        # Set the accuracy of the marker's coords
                        marker.Reference.accuracy = MS.Vector(accuracy)
                        # enable the marker
                        marker.Reference.enabled = True

                    # move onto the next line of the text file
                    break

        file.close()
        print("Import finished.")

One additional question to this. If I add the markers like this, can I then later use the reference_preselection mode when I am trying to match the images? If so, would the following be correct (after having added the markers as above):

Code: [Select]

chunk.crs = chunk.marker_crs
chunk.updateTransform()
chunk.matchPhotos(generic_preselection=False, reference_preselection=True)


Thanks!

UAV_project

  • Newbie
  • *
  • Posts: 25
    • View Profile
Re: Adding markers for georeferencing of an orthomosaic
« Reply #1 on: September 17, 2020, 05:50:45 PM »
Here is a screenshot of the markers in the GUI after I ran the Python script to add them. As you can see they lack Easting and Northing coordinates, although they should be there if my code is written correctly.

Alexey Pasumansky

  • Agisoft Technical Support
  • Hero Member
  • *****
  • Posts: 13211
    • View Profile
Re: Adding markers for georeferencing of an orthomosaic
« Reply #2 on: September 17, 2020, 07:26:58 PM »
Hello UAV_project,

I think that in the second part of the script you should use:
marker.reference.location = ...
marker.reference.location_accuracy = ...
marker.reference.enabled = ...

instead of marker.Reference...


Reference preselection (source values) can be used only if the camera location coordinates have been loaded to the source tab of the Reference pane.
Best regards,
Alexey Pasumansky,
Agisoft LLC

UAV_project

  • Newbie
  • *
  • Posts: 25
    • View Profile
Re: Adding markers for georeferencing of an orthomosaic
« Reply #3 on: September 18, 2020, 02:53:29 PM »
Great it works now, thanks!