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Community Manager
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RTF Drone IMU - Camera extrinsics

Hi,

Has anyone worked out the IMU to Camera coordinate transformations for the RTF drone? These are the transforms from the Flight computer IMU coordinate frame to the camera coordinate frames for the two R200 IR cameras.

This is helpful input for accurate visual-inertial odometry.

Thanks.

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Highlighted
Community Manager
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Hello Brian,

 

 

Thank you for your interest in the Intel Aero drone.

 

 

You can find more information on the IMU here: https://github.com/intel-aero/meta-intel-aero/wiki/94-(References)-Sensors-GPIOs-LEDs-CAN-bus# inertial-measurement-unit-imu-pressure-and-magnetometer-sensors

 

 

If you need more assistance with this can you provide more details about what exactly are you trying to do? What is the scope of your project?

 

 

Regards,

 

Octavian
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Community Manager
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Hello bunderhi,

 

 

Could you please let us know if the information provided earlier was useful?

 

 

Regards,

 

 

Casandra
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Community Manager
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Sorry for not getting back to you earlier.

What I am trying to do is determine the coordinate transforms required from the Flight Computer IMU to the two IR cameras on the RTF drone. You need these parameters as part of the calibration process for the camera and IMU go perform Visual-Inertial odometry.

The following is an example from a different kind of setup to illustrate the idea. I can't see the orientation and position of the FC IMU on the Aero drone to help me estimate the translate and rotation required. I can make best guesses but if someone has the actual measurements that would be great.

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Community Manager
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Hello bunderhi,

 

 

 

Thank you for your patience.

 

We did some research and found some useful information in the following link:

 

https://github.com/IntelRealSense/librealsense/blob/legacy/doc/projection.md# r200 https://github.com/IntelRealSense/librealsense/blob/legacy/doc/projection.md# r200

 

 

I think this should have information regarding the camera extrinsic's.

 

Unfortunately, we do not have any information on the specifics for calculations or code.

 

 

I hope this helps, let me know if I can assist any further.

 

 

Regards,

 

Casandra

 

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Novice
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Hi everyone,

I also have the exact same question. I also need this transformation for Visual-Inertial Odometry. What we need is the transformation from the IMU (located in the flight controller) coordinate frame to the camera coordinate frame.

A transformation consists of a translation (3d vector) and a rotation (quaternion).

The translation defines the shift between the IMU center and camera center. The rotation defines the rotation between the IMU coordinate frame (xyz) and the camera coordinate frame (xyz).

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Community Manager
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Hello bunderhi, Hello chillax,

 

 

Thank you for your interest in the Intel Aero Ready to Fly Drone.

 

 

As stated above, we did some research and found some useful information in the following link:

 

https://github.com/IntelRealSense/librealsense/blob/legacy/doc/projection.md%23r200 https://github.com/IntelRealSense/librealsense/blob/legacy/doc/projection.md# r200

 

 

I think this should have information regarding the camera extrinsic's.

 

Unfortunately, we do not have any information on the specifics for calculations or code.

 

 

Can you tell me if this is helpful?

 

 

Regards,

 

Casandra

 

 

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Novice
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Dear Cassandra,

I really appreciate your effort, but this document is not helpful. It describes the projection mathematics and relationships between camera coordinate systems.

What we need is the relationship between the IMU (inside the flight controller) and the camera coordinate systems. Can't put it any simpler.

A few page documentation of the flight controller would also be helpful, but there is no documentation available for the intel aero flight controller (just one page in the compute board document).

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Community Manager
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Hello bunderhi, Hello chillax,

 

 

Thank you for your patience. Unfortunately, it seems that it is up to you to do the code and calculations.

 

What we did find, is a couple of example codes for ROS and from a DroneKit that could be of use:

 

http://python.dronekit.io/examples/create_attribute.html http://python.dronekit.io/examples/create_attribute.html

 

http://wiki.ros.org/mavros# mavros.2BAC8-Plugins.imu_pub http://wiki.ros.org/mavros# mavros.2BAC8-Plugins.imu_pub

 

 

You could also have a look at the PX4 firmware code if you would like to understand better how it reads the IMU.

 

You can find more information here:

 

https://github.com/PX4/Firmware

 

https://dev.px4.io/en/setup/building_px4.html

 

 

I hope this helps.

 

Regards,

 

Casandra

 

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Beginner
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Hi chillax

Do you figure out the parameter calibration for the RTF?

how do you get the intrinsic parameter of the camera?

BTW do you know how to change the operating frequency of the imu.

As the data I recorded by ros it seems like the operating frequency of the imu is near 50hz.

Thanks for your help.

Thanks

Xupei

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