The importance of IK and FK switching

IK and FK explained

Ik stands for Inverse Kinematics while FK is Forward Kinematics.To create more believable arm movement you have to be careful what setting you use to animate. Ik may seem easier to control, however I have learnt from experience this leads to much less natural body movement and allot of other problems further down the animation pipe line.. In nature peoples arms work like an FK rig where the rest of the body follow throughs with the movement of the arms. FK also allows easier portrayel of arcs than IK. while also looking more solid and less floaty than IK.
This overall is an important discovery to creating more believable and appealing animation. Ik still has a use but more for the effect of contact with a surface when a hand is pressing against a table or a door as an example. Even better is to use a split between the two when having difficulty with more challenging arm movements. As an example when I animated my characters arm rising behind the counter press his hand against the table I used the Ik Fk switch on half so it would be a bit of both this is only used once in my animation but it worked out very well.


Here are some tutorials that describe the differences between IK and FK in more detail

IK vs FK

When I made my changes from IK to Fk the difference became so obvious. Here are two videos of mine, one made with IK and one made with FK.

IK

The IK looked less realistic since the arms actually looked like they were broken there was no realistic anatomical movement. Because of this the Ik appeared more floaty and un-natural.

FK

The FK on the other hand appears sturdier more dynamic and more solid. Since the FK is much better for arcs the movement looks more believable and less woolly. The other reason for this is FK is effected by the other joints for example I moved the spine or shoulders the arms will move with them. Ik is only used for small amounts of time. One when he punches the table with his left hand and two with his other hand pressing against the table. 

So the lesson I learned is don't just use Ik. It is only right for certain actions in small amounts. This is such an important animation tip that I never understood until now. Any 3D should take this on board because no matter how surreal the animation believability is crucial or else the audience are going to lose interest or even find the work unappealing to look at.

reference to videos

https://www.youtube.com/watch?v=euFe1S0OltQ

https://www.youtube.com/watch?v=SrhsDkQWTOc