What exactly is inverse kinematics? A short search tells me it is something like "if the hand goes in a certain position and a certain angle, elbow and shoulder must go into these angles", is that it?

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rootlocus 7 hours ago | parent | next [-]

Imagine placing the feet on the ground at some location and then pinning them there. Now you can move the hips and the upper and lower legs as well as the knee orientations change to keep the feet planted in the same position.

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embedding-shape 4 hours ago | parent | prev | next [-]

This image explains it pretty well, you typically chose between Forward Kinematics, or Inverse Kinematics, depending on what you're trying to accomplish and how you want it to look like: https://www.researchgate.net/profile/Ebrahim-Poustinchi/publ... (imagine the robot parts are human limbs, same thing applies :) )

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numpad0 6 hours ago | parent | prev | next [-]

regular kinematics derive coordinates from joint angles

INVERSE kinematics derive joint angles from coordinates

it's useful when you have a chain of joints and a mug to grab with it

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progbits 7 hours ago | parent | prev | next [-]

Yes. Instead of having to figure out the bone angles one by one you can drag eg a finger and the rest will follow as much as constraints allow.

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steezeburger 7 hours ago | parent [-]

Does it just make it easier to get in a position you want or does it give you more natural looking positions as well or any other benefits? It's pretty fun to play with!

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dagmx 6 hours ago | parent [-]

It means that you can lock the end point to a position and figure out the rest of the pose.

Imagine a character walking with forward kinematics. Every time you move the characters hips , you’d have to rotate the leg joints and make sure the foot doesn’t slide. Remember virtual characters don’t have friction.

IK lets you lock the foot in a spot so you can animate the body above it without having to spend time matching the foot position.

In a real world, this is like if you tried to put your hand on a door handle while jumping up and down. It’s easier to keep position when you hold the handle than if you were to just touch it.

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wang_li 6 hours ago | parent [-]

It also means you can move the point and the rest of the joints adjust. Want to make your model walk? Just figure out the foot motion and the rest of the details are calculated based on joint range of motion and limb length.

	▲	dagmx 5 hours ago \| parent [-]
		Without some extra solving most full body IK systems won’t give you walking motion. It’ll just be like pulling a doll by its limb or QWOP You need a proper motion controller on top to actually have realistic walking motion driven by steps.

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LoganDark an hour ago | parent | prev [-]

Inverse kinematics lets you position the end of a limb and automatically moves the joints for it, rather than you having to move each joint manually.