Messages

1

Camera Calibration / Re: Point cloud / Ortho are skewed/tilted (no GCPs)

« on: May 15, 2020, 03:54:22 PM »

Hi Paul,  Thank you so much! the adaptive camera model fitting option was the last missing piece i think. I aligned the photos with your options and created the dense point cloud with the full picture set and it looks amzing (see below). Just out of curiosity: Is it recommended to do a filtering of the dense cloud similar to the sparse cloud with the gradual filter option? I couldnt select it, thats why i wanted to ask if usually you wouldnt want to do that? Thanks again for your help! you are my hero oif the week haha.

BR

Jannic

2

Camera Calibration / Re: Point cloud / Ortho are skewed/tilted (no GCPs)

« on: May 14, 2020, 05:37:22 PM »

Okay, I don't know what i do wrong but I have an error of  14m (total error) instead of the 1,9m you have. Even tho I checked the " rolling shutter compensation" before aligning the pictures... Is there anything im missing?

Thank you so much!

BR

3

Camera Calibration / Re: Point cloud / Ortho are skewed/tilted (no GCPs)

« on: May 14, 2020, 05:07:29 PM »

Based on the images in that set, I'd say that Paulo is right about the rolling shutter correction.

It made a huge difference to the alignment and camera calibration, which was fairly nonsensical without it applied.

I found that I had to go into Tools->Camera Calibration and enable it before aligning cameras, as I couldn't get back to a sensible solution by enabling it retrospectively and then optimising if I'd already done the alignment.

Out of habit, after alignment, i also used Model->Gradual Selection to remove points with reprojection error greater than 0.3, reconstruction uncertainty greater than 100, and projection accuracy greater than 10 before doing an optimise, before building the mesh and orthomosaic, but the big difference was in enabling rolling shutter correction.

I haven't worked with that kind of image before, but it could be that 60 images over that sort of area at that altitude with that sort of camera, in just 2.5 minutes, is moving too fast.

You can have a look at my project here in case it helps https://we.tl/t-qFY25pcF8m

Thanks a lot! I had a look at the project you send and the error rates are much lower than the ones i have using the same phjtots and checking "Enabling rolling shutter compensation"... Im trying again to align them right now. Could it have an important impact wether i use "source", estimated or sequential? (left it on source till now)

4

Camera Calibration / Re: Point cloud / Ortho are skewed/tilted (no GCPs)

« on: May 14, 2020, 05:04:11 PM »

Just another thought while i download the images, if you flew 2 sets of images, at different altitudes it could be that although the GPS XY are good, the altitudes are not so good relative to each other (i don't understand how altitude is calculated but believe it can be a source of problems!), which may cause it to tilt up in an effort to reduce the overall error.

It would be easy to test that by unchecking the coordinates for either the upper or lower flight, and hitting the update button to see if it levels out.

Would I do that by uncheking those photos in the Reference window in the camera column?

5

Camera Calibration / Re: Point cloud / Ortho are skewed/tilted (no GCPs)

« on: May 14, 2020, 11:43:03 AM »

Hi Paulo,

Do you mean single line like shown in the image below? (screenshot of one mission plan, I fly the same mission on two altitudes with adjusted overlap). Yes, its really high. I have no idea why tho, as the pictures were taken straight to the ground. Okay i'll try that! Here is a link to the pictures taken at 95m above ground.

https://drive.google.com/open?id=1zN6dMgbDwZssitnZ1NOrj9bdi3hmjRPP

Thanks so much for your help!

Cheers

6

Camera Calibration / Re: Point cloud / Ortho are skewed/tilted (no GCPs)

« on: May 14, 2020, 09:29:31 AM »

Hi James,

Thanks for your answer! Yes, I'm using the pro version. but dont have any GCPs. I attached a screenshot of the reference pane.

Thanks in advance for your effort!

7

Camera Calibration / Point cloud / Ortho are skewed/tilted (no GCPs)

« on: May 12, 2020, 01:11:26 PM »

Hi folks,

I gonna be straight up: Its my first try with Metashape, but i spend a couple hours already trying to fix this bug and searching for solutions. So the answer to this might be obvious... I have photos of a  building site shot with an UAV to generate an orthohoto. But after aligning the photos and every othger step after, the photos are tilted  and not "nadir" as they were shot. As a result the projected point cloud is also tilted but worse, also skewed.... which leads to othophotos where i can see the wall of a house etc... I think the problem is in the calibration of the camera, but i couldnt find the solution...

I the exact same problem already with pix4D with this project, but there is an option where you can prioritise internal camera parameters, which fixes this problem. I shot the photos with the DJI Mavic 2 Pro. If anyone could help me out, this would be great! been struggeling with this for days...

Cheers

Jan