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Topic: Pivot point for two bodies
Replies: 2   Last Post: Jan 9, 2009 7:42 PM

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Dave Rudolf

Posts: 37
Registered: 10/3/05
Pivot point for two bodies
Posted: Jan 8, 2009 8:46 PM
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Hey folks,

I am trying to find pivot point locations for two connected objects by
filming them and analyzing their relative positions to each other.
So, for a simple example, suppose we have two rigid bodies connected
by a ball-and-socket joint. Now suppose I am tracking features/markers
on the two objects with cameras, and triangulating multiple camera
views to get the 3d locations of those features.

So, if I have three features on one object, I can determine the
position and orientation of that body over time. If I then have at
least one feature on the other object, I can transform that feature's
position into the coordinate system of the other object. So, that
feature will sweep across the surface of a sphere, relative to the
other object, and the center of that sphere is the location of the
pivot point. Problem solved.

Now, suppose I only have two features on each object. I can't find an
exact position and orientation for either object by themselves. So,
has anyone heard of a way to determine the pivot location in this
case?

Thanks.

Dave



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