Agisoft Metashape

Agisoft Metashape => General => Topic started by: ArchArch on October 11, 2018, 05:53:51 PM

Title: Model from GPS referenced drone pics: why are my predefined views tilted?
Post by: ArchArch on October 11, 2018, 05:53:51 PM
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!
Title: Re: Model from GPS referenced drone pics: why are my predefined views tilted?
Post by: Alexey Pasumansky on October 12, 2018, 01:08:18 PM
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.
Title: Re: Model from GPS referenced drone pics: why are my predefined views tilted?
Post by: PetriK on March 01, 2021, 03:55:27 PM
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 ?

(https://sova3d.fi/images/Screenshot%20(532).png) (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 (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):
***
Title: Re: Model from GPS referenced drone pics: why are my predefined views tilted?
Post by: Paulo on March 02, 2021, 02:00:14 AM
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)



Title: Re: Model from GPS referenced drone pics: why are my predefined views tilted?
Post by: Alexey Pasumansky on March 03, 2021, 07:02:06 PM
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.