1 Topic by nicolas.bailly

  • nicolas.bailly
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Hello,
Thanks for this software that is really helping our research group to analyze videos of falls. We are currently working to evaluate the accuracy of measurement that we are able to obtain on a video of fall and the image calibration is the most critical aspect for our analysis, because the fall is never exactly in the camera plane. Kinovea's Calibration grid is for the moment the best tool we have found to take into account the camera's position: thanks again for that!

To go further and especially to make automatic analyses during our error calculations, we would like to have access to the positions of the four corners of the calibration grid both in pixels before calibration and in cm after calibration. Having access to the position of the marker in pixels and in cm after the calibration would also be very useful.
Is this possible in the software? And if not, would it be possible to add this function ?

Best regards,
Nicolas

2 Reply by joan

  • joan
  • joan
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Hi,

Right now there is no way to get this from the user interface.

If the calibration is static (the grid is not moving), then the corners of the grid can be found in the KVA file in the "Calibration" block. This has the coordinates of the grid quadrilateral in image space in pixels. The vertices are named ABCD starting at the corner in the top-left (for the default grid placement) and going clockwise. In other words the direction vectors are always X-axis: DC, Y-axis: DA.

For a moving calibration it's more complicated. I should probably just allow pixels as a "metric" in the units selector. I'll check if that works without side effects.

3 Reply by nicolas.bailly

  • nicolas.bailly
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Thanks, I didn’t think to look in the Kinovea file: this is very useful.
I also think that it would be great if pixels could be allowed as a metric in the unit selector.
Bests,