Hello,

I have been using Tracker occasionally for research (mechanics/impact testing) and I really like it to look at video and do some quick tracking of objects.

I have questions/suggestions on two topics:

1) Calibration
For motion in a plane, a planar calibration can be used to improve the tracking in case the camera is not perfectly perpendicular to the plane of motion.
Typically, a pattern of round targets (e.g. four circles at the corners of a rectangle of known dimensions) or a checker pattern can be used for that.

Is there a way to do that in Tracker (I can only find sticks affecting both directions)?
If not, that could be nice to implement to increase the accuracy.
(Note: Allowing multiple planes within the software could also help).

2) Tracking:
I would like to detect and track automatically a round target (i.e. a round object with high contrast put on a moving or fixed body). These are commonly used in testing (e.g. for impact, along with checker targets).

The circle option seems to require defining manually points for the fitting, and then tracking the zone with the autotracker could be used to compute the displacement of the region (seems like the circle is static).

However this would likely be less reproducible (and perhaps accurate) than finding the most likely center of an object automatically by fitting (e.g. after clicking inside).
This could also help calibrating the image in a reproducible way (between two targets at a know distance, or more cf. 1).

Thanks!
Philippe
PS: I can provide links to illustrations if needed