IK vs FK Rigs

Another Alec class today talking about the common faults in the walk cycles. Luckily none of these were mentioned in my own critic. These were;

  • In the contact pose; the heel roll on the back foot not being used, hips too high
  • In the down pose; the hips actually have to go down
  • The passing pose; the leg in contact is more likely to straighten and the foot roll should correct this
  • Overlapping follow through; swing the hand out a bit more to give the idea of drag, favor the inbetweens to the forward pose more for the shoulder and back for the hand/ elbow. An offset can also be created by moving the elbow/ hand keys forward a few frames each
  • The gimble lock causing arm problems; rectify on the unifeuler or by changing the rotation order.

He also advised us to play about with the IK/FK rig switch. I had mostly kept the FK when doing the walk cycle, however, Alec showed an easier way to do the spine, making it a more curved S shape- something I struggled to get for the jump.

I had a look into the actual meaning behind both of these phrases to understand when to use them.

So, IK stands for Inverse Kinematics. It uses node control rotation of the chain. In other words, if you move the hand, the rest of the arm follows. It is normally used when something has to be planted, for example, a hand against a wall while the rest of the body is animated.

IK.jpg

Diagram courtesy of Digital Tutors. (Digital-Tutors Blog, 2013).

FK stands for forward kinematics, in which the joints rotate down a hierarchy. It provides more control than the IK but it means each joint must be moved independently. When animating this, you must start from the top of the arm down to the hand.

FK.jpg

Diagram courtesy of Digital Tutors. (Digital-Tutors Blog, 2013).

I will definitely have a look at the IK for when fixing the body mechanic animation that I had blocked already.

References

Digital-Tutors Blog. (2013). Understanding Inverse and Forward Kinematics. [online] Available at: http://blog.digitaltutors.com/understanding-inverse-and-forward-kinematics/ [Accessed 18 Oct. 2016].

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Walk Cycle and Body Mechanic- Pose to Pose/ Straight Ahead

When creating both the animation I found this video really helpful in describing how to create the final outcome. It broke the steps down, giving a better idea of what I needed to complete the movement.

  1. Video reference– recording yourself doing the action really helps in understanding how the body reacts to certain motions. In my case, I used a video reference online but also enacted the  movements myself, to get a better feel for what I had to do.
  2. Key Poses- these are the main poses involved in each of the action, in the walk cycle there are 5 and in the jump there are 6. These give an idea of the overall movement and need to be correct before moving on
  3. Breakdowns– once the key poses are met, we add in what are known as in-betweens or breakdown poses. This is done until the action looks as good as possible in stepped mode (no computer interpolation)
  4. Splining– this is were the keys are converted from stepped to spline. The computer is not very good at interoperating this- therefore the better the blocking, the better the splining is.
  5. Smoothing and Offset– this is when the animation is polished. Overlapping actions are created by moving keys ahead a few frames, for e.g.. the arm movements in the walk cycle, the hand keyframes are going to be a few frames ahead of the rest of the body.
  6. Adding life– this is used to include finishing imperfections in the character, to give a bit more of a realistic feel. It could be things like lip puckering or even an eye twitch.

A useful guide to creating the animation- I found this especially useful for the jump action. (YouTube,2016).

The process above is basically describing Pose to Pose animation. This describes the process of creating the key poses and then adding the breakdowns. Another way to animate is through Straight Ahead, starting from the first frame and creating the following poses until the animation is in completion. When doing the walk cycle I initially tried the pose to pose method, finding it hard, and when using Digital Tutors, I realised that Straight Ahead was the better method.

This video gave a bit more an understanding to the vocabulary involved in pose to pose. (Youtube,2016).

References 

YouTube. (2016). The 6 Steps of Animation. [online] Available at: https://www.youtube.com/watch?v=5CZdTdMmp2w [Accessed 15 Oct. 2016].

Jump Research

I wanted to do some research into previously animated jump cycles. This could also help with reference later on. I also wanted to know the best way too create this jump i.e. on the spot or forward.

I really liked Andrew Coyle’s jump on the spot- almost like a gaming move.

Andrew Coyle’s jump animation. (Vimeo, 2016).

Alec showed us the jump below. I really like the personality demonstrated in the heavy head- giving a bit of humour to the every day move.

I found the addition of weight in this rather nice. (YouTube, 2016).

I originally thought I could give a dramatic sequence to the jump but due to the struggle I had with the initial walk cycle, I realised the difficulties in this for me. I also really liked this as it gave the breakdown for how the jump was created. (YouTube,2016).

I really liked the over exaggerated secondary motions above, I also found the removal of the arms great as it let me focus on them, and the body movement along. The second, as mentioned previously, being something I struggle with identifying. (YouTube, 2016).

 

References

Vimeo. (2016). Jump: Multiple Views. [online] Available at: https://vimeo.com/151151637 [Accessed 15 Oct. 2016].

YouTube. (2016). Vertical Jump : Key frame Animation : 牛山雅博. [online] Available at: https://www.youtube.com/watch?v=TL1Luzd2od8 [Accessed 15 Oct. 2016].

YouTube. (2016). Class 2, Week 7 – Animation Mentor (Box Jump – Final). [online] Available at: https://www.youtube.com/watch?v=wafsC0eV6g0 [Accessed 15 Oct. 2016].

YouTube. (2016). Run Jump Animation Breakdown. [online] Available at: https://www.youtube.com/watch?v=RDSZfl2_NSs [Accessed 15 Oct. 2016].

Jump animation

To start my research into how the jump animation would be created, I wanted to get an idea of the key poses that would be incorporated.

I noted that there were 6 poses;

  • The idle
  • anticipation/ build up
  • Initial jump contact
  • Highest/ peak pose
  • Recovery
  • Neutral/ idle pose

02_anticipation_jump_richardwilliams

Richard William’s jump breakdown.(Williams, 2001).

As Williams’ poses are very exaggerated, I wanted to have a look at a realistic reference. I found a great one online. Using this, I refined the feet positions and the arms. In fact, I redid the arm movements entirely, due to some faults I found that twisting of the upper arm was occurring when I moved them passed a certain point. Alec explained that this could be due to two things; the gimble mode and the twist correction not being on. I did both of these things and it prevented the twisting to a certain point- I think it also gives to the limits of the rig itself.

The jump reference that I used. I slowed the video in Quicktime Player to get a better look at the poses. (YouTube, 2016).

After I created this rough blocking, I went back and added additional poses, to give a better idea of timing. Andrew Coyle explained this really well in his blog. He created a really useful diagram (below) of the breakdowns of body positions for the jump.

Screen Shot 2016-10-15 at 12.11.40.png

Andrew’s diagram. (Cloytoons.wordpress.com, 2016).

This was one of the things I found the most confusing when doing the walk cycle- the shape of the back and tilt of the hips. This was a really great reference for me – Andrew would be proud!

My next stages will be to start polishing up the jump itself, giving a bit of ease in and out, and fixing the overlapping action in the arms.

Wish me luck!

References

Williams, R. (2001). The animator’s survival kit. London: Faber.

YouTube. (2016). Jump Reference 59.94fps. [online] Available at: https://www.youtube.com/watch?v=m4kr4dGU4qA [Accessed 15 Oct. 2016].

Cloytoons.wordpress.com. (2016). Animation | CLOY TOONS. [online] Available at: https://cloytoons.wordpress.com/category/creative-strategies/animation/ [Accessed 15 Oct. 2016].