Re: [Jointtrack-users] Need help for Calibration format

[Shang Mu <sm...@gm...>]

I assume you mean the OpenCV stuff is complicated, and not JointTrack. If
it's the other way around, please let me know :D

JointTrack calibration parameters, using the symbols (other than a and V)
on the OpenCV documentation page you referenced:

principal distance: a * f_x  or  a * f_y
x-offset:  a * c_x
y-offset:  a * c_y
pixel size: a

position of x-ray source:  solution of point M to the equation    0 =
[R|t]M'
image normal:  negative of the 3rd row of the R matrix; in other words,
solution of vector V to the equation  [0 0 -1]' = R*V
image up:  2nd row of the R matrix; in other words, solution of vector V to
the equation  [0 1 0]' = R*V


On the same page you referenced, there is also a
cv::calibrationMatrixValues() you can use to get the intrinsic values,
where the "aperture" size would be your x-ray detector size (if what you
are working on is using x-ray...)

JointTrack assumes your images are already distortion corrected, and are
isotropic (each pixel has the same dimension in x and y, therefore the
principal distance or focal length f_x = f_y).


Shang



On Fri, Apr 21, 2017 at 1:59 PM, Bardiya Akhbari <bar...@gm...>
 wrote:

> Hello everyone,
>
> I'm trying to convert our calibration data from the OpenCV format
> <http://docs.opencv.org/2.4/modules/calib3d/doc/camera_calibration_and_3d_reconstruction.html> to
> the format that JointTrack is able to read for biplane tracking, but it
> seems complicated to me. Would you help me out with this?
>
> Thank you so much.
>
> Best Regards,
> Bardiya Akhbari, Ph.D. Student
> Biomedical Engineering, Brown University
> Address: Box G, Brown University, Providence, RI 02912-G
> Bioengineering Lab, Department of Orthopaedic Research
> The Warren Alpert Medical School of Brown University and Rhode Island
> Hospital
> Address: 1 Hoppin Street, CORO West, Ste. 404, Providence, RI 02903
> E-mail: bar...@br...
> Linkedin: https://www.linkedin.com/in/bardiyaakhbari
>
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