Hi. I am back after another gaming break and finished watching this video with notes. It's exciting to be ready to animate my first walk cycle now. I kind of understand these questions but would like more clarification.
1. I have done research before and now on Ik Fk stuff but this is my first time officially using it so I want to understand them more. He uses Ik for the legs as you can just grab the foot and move the whole leg with it is my understanding where FK is a chained movement. I am confused on how I would in the future switch between the both while animating since both have pros and cons for each situation but I am sure I don't need to know that now.
2. For using the IK Pole for the knee control is that just a easier/better way to animate for most rigs or does the animator just decide in the moment rig depending? I think there are options for that on arms as well?
On the first question, it all depends on what action you are animating. For example: If the character is doing an roundhouse kick. Yes you can use IK to do this, but it is easier to use FK. Why, you might ask? keeping the knee bent while raising it to hip level can be tricky with IK. Also getting the knee to point in the proper direction using IK is easier, but the movement as a whole is easier with FK.
For your second question, it depends on if the rig's options and is more of a preference thing. There are case where one is preferred over the other, but mostly it's a mater of preference. I don't know if it's because of the similarity of our name :-) , but I also prefer the Pole Target vs the leg twist.
Yes, the arms have an elbow pole target/twist.
Hey Brandon.
Let's answer some questions about IK and FK.
Yep - IK is much easier when you need to have the end of the chain stick in place - like a Foot on the ground.
FK is easier for arms when they don't interact with anything. Just walking along swinging by the side of the body = FK
But if the hand needs to be placed on a table or something like that. IK
FK gets you arcs for free, but it's impossible to keep the end of the chain in the same world position if the rest is moving.
IK is way easier to place it exactly where it needs to be but it's not without it's cons.
It moves in a straight line, so it requires more attention to make it arc.
It will "pop" when it goes from straight to bent (or vice versa) - which requires more attention to control
(Side note: you might hear or something called "soft IK" that cushions the pop - however the animator still needs to compensate for this, so it is just a different flavour of the same problem for them - so I haven't seen many rigs both with this anymore)
Switching:
Ideally you want to switch as little as possible. So it might be easier to do the whole shot in 1 mode if possible.
If you do need to switch it's an extra thing you need to keep track of as an animator (and there's already a lot of things)
I used to do this switch over 1 frame and then there was just that 1 frame pop you had to manage. This is what I have been teaching for years.
But then someone taught me that if you blend over 3 or 4 frames it's way easier. And it's true.
Match both FK and IK at the start and end of the transition - exactly where the limb needs to be. Then Blend from 1 to the other over 3 or 4 frames.
It is way easier and the results are seamless. (It only tool me 17 years to learn that trick)
Pole Target vs Leg Rotation (IK):
I prefer the pole target as you hardly need to touch it on the IK legs. But with the leg rotation method you have to pose it exactly where it should be on every key pose.
Good Point on the pole target Wayne. I didn't think about that because in the past I always had to adjust the pole target on every key pose until I watched one of your courses and you mentioned parenting to the IK control bone instead of the root bone.