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Author Topic: Localization of stereo cameras in local coordinates without external reference  (Read 1240 times)

atorgon

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Hello

I am trying to use Photoscan to compute the successive positions of a moving stereoscopic camera rig. I have used the methods suggested in the forum (http://www.agisoft.com/forum/index.php?topic=9016.0) to automatically add scale bars with the known baseline, hoping to fix in this way the scale factor of the reconstructed trajectory.

Photoscan is able to correctly align the cameras and their relative positions seem right (as well as the reconstructed point cloud). However, I don't get any numerical estimate of their positions. It seems that 3 known camera positions or GCPs are needed in order to define a reference frame and be able to estimate these positions. My problem is that I am exploring an unknown environnement and I don't have any external reference either for the camera position or the observed environment.

Is there any way to obtain the estimated positions in a local reference frame (the reference frame of the first camera for example) without importing any reference position? It seems to me that the knowledge of the baseline should be enough to solve the problem with the right scale in relative coordinates.

Thank you in advance for your help

Alex

PK_2509

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Hi Alex,

you can put the following code line in the Console pane:

Code: [Select]
PhotoScan.app.document.chunk.transform.matrix = PhotoScan.app.document.chunk.transform.matrix
Then you can export the estimated camera positions.

See: http://www.agisoft.com/forum/index.php?topic=7742.msg37030#msg37030

Phil

atorgon

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Great, thank you very much for your quick answer  :) I don't know exactly why it works, but it does!

I think that in future releases, it might be a good idea to allow the user to do that in a more intutive way, with a menu option or something. But in any case, you solved my problem, thanks again!

Alex

Alexey Pasumansky

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Hello Alex,

You can try exporting cameras via File Menu -> Export -> Export Cameras option to "omega, phi, kappa" format. It will contain the information about the cameras' exterior orientation in the internal local coordinates, without a need of georeferencing.
Best regards,
Alexey Pasumansky,
Agisoft LLC