photos shown lower than reality

[evasilak]

Hi all,
I am starting a new project with photos acquired with a Phantom 4 RTK (at 90m AGL), in conjuction with a DJI-RTK station.

After aligning the photos I realised that the "flying plane" cuts the earth surface!!! which is not possible.

What did I do wrong in Metashape?

I attach an image.

Thankls in advance,
MV

[Alexey Pasumansky]

Hello MV,

Can you post the screenshots from Initial and Adjusted values tab for this project?

[evasilak]

Sure... there you are....

[Alexey Pasumansky]

Hello MV,

I don't see any problems with the focal length value that may cause incorrect height above point cloud estimation for the cameras.

However, you may need to set Fisheye camera type, if there are fisheye distortions observed on the images.

Also do you have any points on the ground with measured coordinates that can be used to validate the results?


The estimated camera locations are on the free side of the black segment (opposite to the blue rectangle). You can modify the scale of the blue rectangles in the Model view by holding the Shift key and using the mouse wheel.

[evasilak]

How do I set the Fisheye camera type? I can see a lot of such distortions in my photos, even if I don't realy like it (would there be a setting in the DJI application?).

I do have GCPs for validating the results, but even when I solve the model, the photo elevation remains low. That makes me wonder about the credibility of the solution....

Which exactly is the "free side"??

Thanks

[James]

hold shift button and rotate the mouse wheel in the 3d view.

the camera representations will grow or shrink (depending which way you rotate the mouse wheel) but the 'free side' end of the black line will remain static indicating the camera position.

edit: oops i see Alexey already mentioned this.

[Alexey Pasumansky]

Hello MV,

Use the option in the upper-right corner of the Camera Calibration dialog to specify the Fisheye camera type (Frame by default). After that I recommend to reset the camera alignment for all the cameras and use Align Selected Cameras option applied to all the cameras in the chunk.

Can you share the project with the alignment results re-saved in PSZ format with check points, if possible, to support@agisoft.com?

[evasilak]

I'm doing it right now... Hope it works... Even though I think it is only an Agisoft display "bug" and the solution should be ok...
I'll run it with Fisheye option on and send it to support@agisoft.com.

Thanks again for immediate response!!

[Alexey Pasumansky]

Hello VM,

I have measured the elevation of the ground in the provided project - it is about 630 meters in one part (northern) and about 670 meters (southern). Whereas the estimates altitude of the camera positions is about 725 meters.
Does it correspond to the performed flight mission?

[evasilak]

well, i thnk so...
the take off point was at 638.8m and i am pretty sure i set the altitude at 90AGL

[Alexey Pasumansky]

Hello MV,

Then it doesn't seem that there's an issue with the latest project you have provided.

The estimated altitude of the camera locations can be checked in the Reference pane -> Estimated values tab.