Motive coordinate systems

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xezxey
Posts: 4
Joined: Wed Jun 03, 2020 5:36 am

Motive coordinate systems

Post by xezxey » Fri Jul 10, 2020 6:31 am

Hi, I have a question on Motive SDK and Motive API. So basically what is the camera coordinates of the Motive Camera. Hence the provided of the rotation matrix and translation vector can be form into the extrinsic parameters then if i use any points multiply with this transformation I will get the point in camera coordinates. My question is
1. what is the coordinates system of the optitrack. Is it like an opencv? (You can see the coordinates reference in an attachment).
2. Does it use left-handed or right-handed coordinates system? (My guess is right-handed)

Thank you very much
Attachments
coordinates_system.png
coordinates_system.png (56.78 KiB) Viewed 387 times

steven.andrews
NaturalPoint Employee
NaturalPoint Employee
Posts: 579
Joined: Mon Jan 19, 2015 11:52 am

Re: Motive coordinate systems

Post by steven.andrews » Fri Jul 10, 2020 10:44 am

Hi xezxey,

Motive uses a right-hand coordinate system.

We believe the orientation of the cameras to be more like the bottom two examples, with -z coming out the front of the camera.

Best,
Steven
--
Steven Andrews
OptiTrack | Senior Customer Support Engineer
help.naturalpoint.com
support@optitrack.com

xezxey
Posts: 4
Joined: Wed Jun 03, 2020 5:36 am

Re: Motive coordinate systems

Post by xezxey » Fri Jul 10, 2020 10:48 am

Thank you very much
Another one question, an orientation of the camera is the inversed extrinsic? Am I correct?
So we can form an inversed extrinsic parameters by using the orientation and camera position(translation). Am I correct?

Thank you

xezxey
Posts: 4
Joined: Wed Jun 03, 2020 5:36 am

Re: Motive coordinate systems

Post by xezxey » Mon Jul 13, 2020 1:39 am

To be clear, does the orientation and translation that provided from Motive API is the inversed extrinsic? Then given that I can create the inverted extrinsic matrix using these 2 matrix. Am I correct

steven.andrews
NaturalPoint Employee
NaturalPoint Employee
Posts: 579
Joined: Mon Jan 19, 2015 11:52 am

Re: Motive coordinate systems

Post by steven.andrews » Mon Jul 13, 2020 12:29 pm

Hi xezxey,

The matrix returned by TT_CameraPositionOrientation is the world-space rotation matrix of the camera extrinsics. The position values returned represent the world-space position of the camera.

I am not sure if we understand the rest of your question correctly. If you need more information, could you please try reaching out to us, directly, and describe what you are trying to accomplish? We may be able to provide more useful information if we understand that.

Thanks,
Steven
--
Steven Andrews
OptiTrack | Senior Customer Support Engineer
help.naturalpoint.com
support@optitrack.com

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