Sports biomechanics: More than 2 calibration points?
Mikkel Roald
5 Posts
First of all, I'm a big fan of Tracker and use it for kinematic analysis in track and field events, and really appreciate all the time and effort put into it!
For horizontal jumping events (long jump, triple jump), I record stationary videos straight from the side with multiple landmarks on the ground (every couple of meters). However, as it is often preferred to cover up to 20m and it is not feasible to stand 50m from the track I wondered if it possible to correct for this? I have attached a representative photo - in this photo the velocity of the jumper will be underestimated in the right side of the photo.
I am thinking of trying the Radial Distortion filter, but since I don't really want to correct for lens distortions I have my doubts with this.
Another suggestion, which I haven't been able to locate in Tracker, could be the use of 3 or more Calibration Points to extrapolate changing reference frame towards the extremities. Would this be something to consider for the future? For the example above there are multiple small 1m marks which could easily be used. I have attached a doodle of the idea, hope it makes sense.
Please let me know what you think, Best regards Mikkel
Re: Sports biomechanics: More than 2 calibration points? -
Jim Simpson
1 Posts
Hi, This is a little off-topic, but I am trying to get started using Tracker to do some simple modeling of ankle motion during activities. All I am planning to look at is the shank-foot angle, and I saw your post that suggests that you might be able to point me to the resources I would need to get a handle on how to use Tracker for such a project. Any help you could provide would be most appreciated.
Re: Sports biomechanics: More than 2 calibration points? -
Fernando Ferro
14 Posts
"I am thinking of trying the Radial Distortion filter, but since I don't really want to correct for lens distortions I have my doubts with this."
This is not the way the distortion filter works. It is not a linear correction, from side to side of the image. It is a radial one from the center of the image to the border. As soon as you undistort the horizontal axis, you will create a lot of vertical distortion.
