Extrinsic parameters

[yvtheja]

Hi,

I am working on a project where I need to have the extrinsic parameters of the camera. I think they should be changing continuous w.r.t to the pose of the camera. Could you please help me with where exactly you are computing the matrix in the code?

Thank you.

[stephanweiss]

Hi, the cam-imu extrinsics are assumed to not change over time. The "dynmics" are encoded in the Fd matrix in the SSFCore.cpp

Best,

Stephan

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Von: Vishnu Teja [email protected]
Gesendet: Freitag, 10. Juni 2016 14:17
An: ethz-asl/ethzasl_ptam
Betreff: [ethz-asl/ethzasl_ptam] Extrinsic parameters (#84)

Hi,

I am working on a project where I need to have the extrinsic parameters of the camera. I think they should be changing continuous w.r.t to the pose of the camera. Could you please help me with where exactly you are computing the matrix in the code?

Thank you.

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[yvtheja]

Hi @stephanweiss,
Thanks a lot for your reply.
I couldn't understand the co-ordinate system you are following completely. It would be really helpful if you can provide some documentation on that if you already have any.

Does the world system coincide with the camera system at the start of visual odometry? And when the camera starts moving, the extrinsic matrix [R|T] should be changing as the co-ordinates of the camera changes with w.r.t to the world right? How could extrinsics aren't changed?

I couldn't find the file name SSFCore.cpp. Could you please help me with the pointer?

Thanks a lot in advance :)

[stephanweiss]

Hi,

please see details on the frame in this publications:

http://publications.asl.ethz.ch/files/weiss11real.pdf

Best,

Stephan

---

Von: Vishnu Teja [email protected]
Gesendet: Montag, 13. Juni 2016 11:38
An: ethz-asl/ethzasl_ptam
Cc: Stephan Weiss; Mention
Betreff: Re: [ethz-asl/ethzasl_ptam] Extrinsic parameters (#84)

Hi @stephanweisshttps://github.com/stephanweiss,
Thanks a lot for your reply.
I couldn't understand the co-ordinate system you are following completely. It would be really helpful if you can provide some documentation on that if you already have any.

Does the world system coincide with the camera system at the start of visual odometry? And when the camera starts moving, the extrinsic matrix [R|T] should be changing as the co-ordinates of the camera changes with w.r.t to the world right? How could extrinsics aren't changed?

I couldn't find the file name SSFCore.cpp. Could you please help me with the pointer?

Thanks a lot in advance :)

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[yvtheja]

Hi @stephanweiss ,

I have tried to understand the paper but couldn't understand it completely. But the problem I am trying to solve is getting /vslam/pose_world co-ordinates in camera frame. I am new to Visual Geometry and I am sorry if I am troubling you.

Where could I find the file SSFCore.cpp?

Thanks a lot!

[stephanweiss]

please refer to e.g.

http://www.springer.com/us/book/9780387008936

for an introduction to 3D Visual Geometry.

---

Von: Vishnu Teja [email protected]
Gesendet: Dienstag, 14. Juni 2016 11:36
An: ethz-asl/ethzasl_ptam
Cc: Stephan Weiss; Mention
Betreff: Re: [ethz-asl/ethzasl_ptam] Extrinsic parameters (#84)

Hi @stephanweisshttps://github.com/stephanweiss ,

I have tried to understand the paper but couldn't understand it completely. But the problem I am trying to solve is getting /vslam/pose_world co-ordinates in camera frame. I am new to Visual Geometry and I am sorry if I am troubling you.

Thanks a lot!

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[yvtheja]

Hi @stephanweiss ,

I have already done with some basic concepts from Autonomous Mobile Robots, Roland Siegwart.

I am running PTAM with a monocular camera( Microsoft Lifecam HD ) and I couldn't understand if we are using IMU sensor in my case.

It would be really helpful if you can give me a clue how I can convert the co-ordinates publishing under /vslam/pose_world into camare frame. I tried to search for Fd matrix and SSFCore.cpp in https://github.com/ethz-asl/ethzasl_ptam but there is none.

Thank you.

[stephanweiss]

Fd is the state transition matrix and has nothing to do with the coordinate transformation.

Please ask your advisor or google on "coordinate transformation" for details on this topic.

Kind regards,

Stephan

---

Von: Vishnu Teja [email protected]
Gesendet: Dienstag, 14. Juni 2016 15:17
An: ethz-asl/ethzasl_ptam
Cc: Stephan Weiss; Mention
Betreff: Re: [ethz-asl/ethzasl_ptam] Extrinsic parameters (#84)

Hi @stephanweisshttps://github.com/stephanweiss ,

I have already done with some basic concepts from Autonomous Mobile Robots, Roland Siegwart.

I am running PTAM with a monocular camera( Microsoft Lifecam HD ) and I couldn't understand if we are using IMU sensor in my case.

It would be really helpful if you can give me a clue how I can convert the co-ordinates publishing under /vslam/pose_world into camare frame. I tried to search for Fd matrix and SSFCore.cpp in https://github.com/ethz-asl/ethzasl_ptam but there is none.

Thank you.

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