Richard Speir wrote:
> 
> I keep hearing everyone talking about inverse kinematics but I don't
> know what it is. Could someone please explain it to me?

  In it's most simple form it is a way of describing the motion(s)
of movable joints. In reference to modelling it is much like
if you had three sticks of wood. Two of the pieces are tied to
the ends of the third with string. Now if you laid them straight
on the ground and picked up the far end of on of the outside pieces
you would eventually see the middle piece raise up and follow the
first and eventually the last would follow suit.
  So in modelling it is much the same thing. You decide which joints
are linked together, how much they are allowed to bend and in what
direction. This gives you sets of connected joints that have a
predictable motion that is dependent upon the other pieces in the
string.
  It is all very much like the human joint structure and the limits and
freedoms of motion that are allowed for reach joint and each limb. In
modelling programs they take it a step further and allow you to make very
complicated movements without having to figure out all of the complex
relationships for each individual piece in the string but act upon the
group as a whole.

  You have in all likelihood seen examples of this kind of motion studies
as they apply not only to the virtual world but work has also been done
with this kind of system to describe logical constructions for free
walking robots and animatronics devices used in the motion pictures
industry.

-- 
Ken Tyler

mailto://tylereng@pacbell.net

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