Mosaic distortion under powerlines

akhillyer · October 6, 2020, 10:33pm

Hello-
I’m using Pix4d Mapper to orthomosaic the ground under powerlines and I’ve been getting a radial distortion pattern in certain parts of the mosaic. See screenshot. Is this caused by the overhead lines in the point cloud? Can I fix it by disabling those points in the dense point cloud? If not, what else could it be?

Beata · October 7, 2020, 12:16pm

Hi @akhillyer,

Could you please share here with us the Quality Report of the project?

I will help us analyse the problem.

Thanks!

akhillyer · October 7, 2020, 2:44pm

Yes, please see attached pdf.
Note that there was only one camera used in the field, even though Pix4D detects 2 cameras. The 2 camera models detected by Pix4D have the exact same parameters.
Bigelow_report.pdf (4.0 MB)

Thank you.

akhillyer · October 7, 2020, 4:32pm

Hello-

I posted the Quality Report on the website about 1 1/2 hours ago.

I’m attaching it again here, although I’ve run the mosaic again since the version that I posted on the website.

Thank you.

Anne

Bigelow_report.pdf (3.99 MB)

Beata · October 9, 2020, 1:33pm

Hi,

Could you also send us the screenshot of the very same area shown in the first screencast but from the point cloud? Is the point cloud flat? Also, are the images sharp? Do they have any blurriness? Can you check the photos from that area it in the rayCloud?

Thanks

akhillyer · October 9, 2020, 3:37pm

Aha, yes. The point cloud looks flat to me, but I am not experienced in working with point clouds. In “Cameras.png” this photo (DJI_0311.jpg) appears to be badly calibrated. It looks like there is a bright spot in that photo in the upper right corner. There is a gap in the automatic tie points over that spot on this photo and neighboring photos.

Thanks.
Anne

Blaz · October 14, 2020, 10:02am

Thank you for sharing the files. The point cloud looks good and I do not believe it is the source of the blurry orthomosaic.

Most probably, one of the images was not properly calibrated and is causing issue when it is blent into the final orthomosaic.

Could you place some additional Manual Tie Points (MTPs) in the area with the blurry effect?

If this does not help, I would suggest removing the image DJI_0311.jpg and process the project again.

Best,

akhillyer · October 16, 2020, 6:51pm

I added 5 MTPs in the blurry area but it didn’t help.
Then I removed DJI_0311.jpg and reprocessed the project. That solved the blurring problem.
Thank you!