Forum

Author Topic: Model from GPS referenced drone pics: why are my predefined views tilted?  (Read 1563 times)

ArchArch

  • Newbie
  • *
  • Posts: 7
    • View Profile
Hello! Thanks in advance for your help.

I have successfully produced a model from GPS referenced drone pics. Overall the model looks good. My bounding box is correctly around the model, with the red side below it. It is also in the correct UTM zone.

My question is: why are my predefined views tilted? If I select top (or bottom for that matter), it is shown at an angle instead, tilted, and when I export an orthophoto it too, of course, is tilted at the same angle. I need to export this as both a DEM and Orthophoto to import into a GIS. See image for tilt, shown using the "top" predefined view.

I seem to remember this happening before, but I use Photoscan irregularly and can't remember what I did to fix this before.

Thank you!
« Last Edit: October 11, 2018, 05:59:13 PM by ArchArch »

Alexey Pasumansky

  • Agisoft Technical Support
  • Hero Member
  • *****
  • Posts: 13642
    • View Profile
Hello ArchArch,

I think that the problem is due to the fact that the coordinates of the camera locations are in WGS84 (Lat/Long) while the system of the chunk is set to some UTM projection. So the values that are actually in degrees are treated as meters.
Best regards,
Alexey Pasumansky,
Agisoft LLC

PetriK

  • Newbie
  • *
  • Posts: 1
    • View Profile
Hello!
I'm using Metashape standard version 1.7.1 - windows 64-bit. I made an UAV flight and did use Pix4D-for mission; It will propose automatically to make oblique photos, height 50 meters and overlapping 60%.
UAV is DJI Mavic Pro 2. It has a GPS-recorder & IMU, but i suppose Pix4d is not saving that data into photo's EXIF-data, only the basic camera data.
***

When I import the photos, Metashape is able to create nice mesh, BUT the model is always 70 degrees tilted ( I assume that tilting is somehow interpreted from the oblique photos.
Is there an initial setting that it would make the models/ point clouds directly & exactly into horizontal position ?

(If the screenshot image is not showing, In that picture 3d pointcloud is tilted.

You can also see the pointcloud https://s3dmaps.appspot.com/?p=8.321&i=-9.165&h=-13.220&camE=7.0&camH=13.2&camN=-38.3&camRotX=-0.530&camRotY=0.096&project=745:
***

Paulo

  • Hero Member
  • *****
  • Posts: 932
    • View Profile
Hi Petrik,

I have seen this issue with Mavic Pro 2 imagery. See https://www.agisoft.com/forum/index.php?topic=12443.msg55301#msg55301. I would look at your adjusted PP coordinates (cx, cy) and if they are very large compared to image size, then I would do a new alignment with adaptive camera fitting on as well as rolling shutter....or rather than doing a complete new alignment just do alignCameras, as photos seem correctly matched, using:
Code: [Select]
chunk = Metashape.app.document.chunk
chunk.alignCameras(min_image=2, adaptive_fitting=True, reset_alignment=True, subdivide_task=True)



« Last Edit: March 02, 2021, 03:06:03 AM by Paulo »
Best Regards,

Paul Pelletier,
Surveyor

Alexey Pasumansky

  • Agisoft Technical Support
  • Hero Member
  • *****
  • Posts: 13642
    • View Profile
Hello PetriK,

In Standard edition of Metashape the geotags are not considered, therefore the orientation of the model is arbitrary in the general case. You can, however, adjust the orientation of the model in the coordinate system of the Model view using Rotate Object instrument. But for precise referencing based on the geotags you should use Professional edition.
Best regards,
Alexey Pasumansky,
Agisoft LLC