IK solvers. Example for what we use them?

HammerFist3D2D

I have no idea what are they. Are they some kind of custom objects like bones, or they give some special effects on bones, like custom moving/scaling/rotating and such. Please give me excample for what are you using them. Oris ik solver useful at all.

54Strat

Simply put, it's a way of equating the rotations of a chain of joints with respect to one position in space, known as the end effector.

Think of an arm with two bones and you position the wrist, the solver works out the rotations of the upper and lower arm to put the wrist where you want it.

Kurt Russell Fan Club

The way basic animation systems in engines work is by using forward kinematics. That is, if I want to animate my arm, first I move my upper arm, and then I move my lower arm. When I move my upper arm, the lower arm goes with it, so this makes it hard to place my hand in a particular place. It also makes it very hard to make the hand follow a specific arc, or to remain attached to a position as the upper arm or shoulder moves about.

Inverse kinematics works the other way around. Instead of moving the joints starting from the base (shoulder, upper arm, lower arm), you say where you want the shoulder to be and where you want the hand to be, and the system solves the problem of "where does the elbow go?" It's hard work for a person to solve the elbow problem for each frame of the animation, but easy work for the computer.

HammerFist3D2D

Thank you guys. One more question, can it be useful for things like chains or dragons tail pherps?

antweiler

No. For hanging and dangeling stuff its more useful to drive your joints with some kind of dynamic simulation

Moosebish

In my studio, the most common uses for IK's are for legs and arms. We do a lot of animals. If we are doing a creature that uses multiple joints when it walks, like a horse, we typically use a spring solver.

But for things like a tail or elephant trunk, we just use driven keys to control the bend and swing of it.