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Author Topic: Scaling with camera positions  (Read 2363 times)

AnkeRena

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Scaling with camera positions
« on: June 08, 2018, 04:35:35 PM »
Dear all,

I am working on a model of a 400 m high and 2 km wide rockwall. I have an Agisoft project with ~ 430 photos. As the rockwall is not accessible I only have the coordinates of the camera locations and the distances between them. The camera locations are well distributed in the valley and the photos are taken from 15 different camera positions. All the photos are sorted into camera groups. The largest height difference between the camera positions is 140 m.
I got almost all the photos aligned properly but I am still having issues with scaling the model.
By using the camera coordinates and/or scale bars in between the camera positions I get a model which is ~50 % the size of the real rockwall.

Am I missing anything?
Or is the height difference in between the camera locations too small for the height of the rockwall?

I have modeled the same rockwall with different but equally distributed photos from another field campaign and did not have any issues with scaling the model. That model turned out the right size without any further effort.

Any help would be greatly appreciated.

Anke

wizprod

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Re: Scaling with camera positions
« Reply #1 on: June 09, 2018, 08:20:43 PM »
Have you tried aligning with the use of any of the 2 preselection options?

Alexey Pasumansky

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Re: Scaling with camera positions
« Reply #2 on: June 09, 2018, 08:22:23 PM »
Hello Anke,

Can you share the project file with the alignment results and reference information used (camera locations and scale bars) with support@agisoft.com?

I can suggest to use only single set of XYZ coordinates per camera station.
Best regards,
Alexey Pasumansky,
Agisoft LLC

AnkeRena

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Re: Scaling with camera positions
« Reply #3 on: June 11, 2018, 05:06:20 PM »
Hello,

thank you for your quick replies!

Wizprod, I have tried the preselection options for the photo alignment but did not get any improvements.

Alexey, I also tried to use only one coordinate set for each camera station by deselecting the remaining photos in the reference pane but the size of the model remains still the same.

I have sent the project file to the agisoft support.

Thanks
Anke

Alexey Pasumansky

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Re: Scaling with camera positions
« Reply #4 on: June 11, 2018, 06:08:08 PM »
Hello Anke,

I see that you have submitted the PSX file only, but it is actually the link to the corresponding .files fodler, so can you please re-save the project using File Menu -> Save As option to PSX format (PhotoScan Archive type) and send it in addition to your message?
Best regards,
Alexey Pasumansky,
Agisoft LLC

AnkeRena

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Re: Scaling with camera positions
« Reply #5 on: June 12, 2018, 10:34:03 AM »
Hi Alexey,

I guess you meant the PSZ Photo scan archive file? I just sent it to support@agisoft.com.


Alexey Pasumansky

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Re: Scaling with camera positions
« Reply #6 on: June 12, 2018, 12:48:18 PM »
Hello Anke,

Thank you for sending the PSZ file. I've checked the project, but it seems that the scale bars were not used properly.

If you want to create the scale bar between the estimated camera locations, you should select two camera instances in the Workspace pane (one from each camera station), right-click on selection and choose Create Scalebar option.

In your project you have markers without any projections on the cameras (meaning that they are not connected anyhow to the alignment) and the scale bars are connecting those scalebars. It means that both markers and scalebars are not connected to the alignment results.
Best regards,
Alexey Pasumansky,
Agisoft LLC

AnkeRena

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Re: Scaling with camera positions
« Reply #7 on: June 12, 2018, 02:26:56 PM »
Hello Alexey,

thank you for your input. I have now created the scale bars in the right way and firstly tried to improve the result by using the "optimize cameras" tool and then by aligning the photos again. From both workflows I did not get the right scale out of the project. It still is ~half the size.
Do you have any other recommendations?

Alexey Pasumansky

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Re: Scaling with camera positions
« Reply #8 on: June 14, 2018, 09:44:22 PM »
Hello Anke,

Are you confident about the distance measurements between the camera locations? In your project where the markers are placed based on the XYZ coordinates only (with no relation to the cameras/images) the distance estimated between them according to the coordinates (for markers PW22 and PW30) is 20 meters away from the input scalebar distance.

However, I don't see half size problem - the errors on the scale bars are about 5% of their length, though in absolute values it's high.
Best regards,
Alexey Pasumansky,
Agisoft LLC

AnkeRena

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Re: Scaling with camera positions
« Reply #9 on: June 19, 2018, 12:23:50 PM »
Hi Alexey,

I found that the error was in the other project. The scale was wrong because I did not use the scale bars properly as discussed earlier. After fixing those, the rockwall was scaled properly in both projects.

Thanks a lot for your help!