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Author Topic: Orientation issues  (Read 17957 times)

Alexey Pasumansky

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Re: Orientation issues
« Reply #30 on: October 30, 2015, 03:35:36 PM »
Hello Fkybarless,

We are currently investigating, why the principle point is not estimated correctly. For the next flights we can suggest, if it is possible, to rotate the drone by 180 degrees when flying on the neighboring flight lines. We hope that is will help the autocalibration procedure.

For the current dataset we can suggest to fix the camera calibration prior to the alignment process.
Best regards,
Alexey Pasumansky,
Agisoft LLC

Alexey Pasumansky

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Re: Orientation issues
« Reply #31 on: October 30, 2015, 03:40:13 PM »
Hello Napoleon,

It's not quite clear what exact problem you are facing. As in this thread at least three different problem were mentioned.

So probably you can post a screenshot with the source values of the Reference pane and the model overview with the displayed markers?

Also please note that using coordinates of the markers and Rotate Object at the same time will lead to the contradiction, as the next time you press Update button in the Reference pane the manual object orientation will be discarded.

You can display several chunks simultaneously in the model view if they are aligned with each other (using Align Chunks tool or by the coordinates in the same coordinate system) - just press Show Aligned button on the toolbar.
Best regards,
Alexey Pasumansky,
Agisoft LLC

Fkybarless

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Re: Orientation issues
« Reply #32 on: October 30, 2015, 05:01:11 PM »
Thanks Alexey,

1. I will try the rotation of the drone for the next flight.

2. How do I calibrate the camera?


Paulo

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Re: Orientation issues
« Reply #33 on: October 30, 2015, 07:20:14 PM »
Fkybarless,

from the DJI website, i can see that you have a Olympus M. ED 12mm f/2.0. If this is correct then actual focal length is 12 mm and not 25 mm (which is the equivalent focal length corresponding to 36 mm format sensor). Your sensor is a 4/3-inch CMOS with 4608 by 3456 pixels. This sensor size is 17.3 mm by 13 mm. Thus pixel size is about 0.00375 mm (17.3/4608).

So I would try entering following values for pixel size and focal length in Camera Calibration Initial tab:

- Pixel size (mm): 0.00375
- Focal length (mm): 12

And see if process gives better results after alignment. Adjusted values of Fx, Fy, Cx and Cy parameters should not vary too much from initial values...If they do vary too much, you can always try to use fix calibration button in Initial tab...
Best Regards,
Paul Pelletier,
Surveyor

Napo

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Re: Orientation issues
« Reply #34 on: October 30, 2015, 11:06:52 PM »
Hello Alexey,

Thanks so much for your response. I am attaching the screen shot that you requested (1.jpeg) where everything looks good in the model. But when I export the resulting DEM, the model looks like "upside down" to me (see 2.jpeg). Actually, when I turn on the hillshade on it, depressions look like elevations (see 3.jpeg). I hope that I am being clear on my explanation, I am not an native english speaker... but I honestly really appreciate your help and patience.

Napoleon

Fkybarless

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Re: Orientation issues
« Reply #35 on: October 31, 2015, 10:53:18 PM »

Paulo

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Re: Orientation issues
« Reply #36 on: November 01, 2015, 01:45:00 AM »
Hi Fkybarless,

in this case the lens focal length  is 25 mm and hence you should enter 25 mm in focal length field but keep pixel size at 0.00375 mm as sensor size is still a micro 4/3....
Best Regards,
Paul Pelletier,
Surveyor

Fkybarless

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Re: Orientation issues
« Reply #37 on: November 03, 2015, 05:32:44 PM »
Hello Alexey,

Any news towards solution?

Thanks

Fkybarless

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Re: Orientation issues
« Reply #38 on: November 08, 2015, 07:30:27 PM »
Hello Alexey,

Any news towards solution?

Thanks

Alexey Pasumansky

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Re: Orientation issues
« Reply #39 on: November 09, 2015, 12:50:56 PM »
Hello Fkybarless,

As we have suggested before, to avoid such problems in future we recommend to make a drone to rotate the camera by 180 degrees, when doing a returning flight line. This should make autocalibration process more stable and hopefully issues with the incorrect cx, cy estimation for this camera/lens combination will be solved.
Best regards,
Alexey Pasumansky,
Agisoft LLC

Napo

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Re: Orientation issues
« Reply #40 on: November 12, 2015, 12:42:35 PM »
Hello Alexey.

Any news about my issue??

Thnks

Alexey Pasumansky

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Re: Orientation issues
« Reply #41 on: November 12, 2015, 01:15:47 PM »
Hello Napoleon,

The orientation of the coordinate system axis in the Model view seems fine.

Maybe you can send the project file (without depth maps, dense cloud and with the decimated mesh model) and the DEM that you have exported from it to support@agisoft.com?
Best regards,
Alexey Pasumansky,
Agisoft LLC