Question about up/down in a walk/run...

AGoodFella

So this is something that I've been wondering.

We've all been taught when doing the bouncing ball, that the time it takes for the ball to rise is equal to the time it takes to fall down to the same level. And that this applies to the hips for a person.

So, in a walk/run, let's say from the lowest point of the hips to the highest point takes 5 frames, does this mean that it should take 5 frames to fall back down from the highest to lowest? 

But since the person is heavy, we might want to drop the hips quicker, say 3 frames and then make them go to the highest point slower, say 5 or 6 frames. But this goes against the bouncing ball logic...

I'm sure I'm missing something here....

Archanex

I don't think this rule applies to walks for the reasons you listed. I think what they meant was that same principal applies to the hips if a person is airborne where they're being affected by gravity

slipsius

It's not exactly the hips that mimic this in a person. Especially not while walking. When walking, there are so many more variables in play. The weight of a person. the strength of the person. What type of walk they have. If it's a bouncy walk, or more subtle. In a walk, the hips tend to rise slower than they fall. 

When it comes to the ball bounce and how you can use it for humans is this. The center of mass of the person, once off the ground, acts the same as a ball. This means that when they jump into the air, their center of mass will rise and fall at the same speed. It also means that however fast they were going in the left to right direction will also stay constant until they touch the ground again. This doesn't mean their limbs cant move around, or speed up and slow down. It's purely their center of mass. 

AGoodFella

Thanks for the replies, makes sense.

Hito

cartoony walks will follow bouncing ball closer than stylized walk, a realistic one will follow bouncing ball even less. I don't think strict adherence to the bouncing ball exercise is a good idea, forget it entirely if necessary. In a walk the person never leaves the ground so I think the bouncing ball analogy is not all that applicable. Observe and replicate is the best way, sit at a park or transit station and watch how people walk, stand, run, and pay attention to the "bony landmarks", you will gain an instinctual feel for what looks right and wrong. 

There're big differences between walk/jog/sprint as well. Walk up/down is smooth, closer to a wave than bouncing ball, goal is to have as smooth a flow as possible to minimize overall effort. More up/down means more effort must be spent to counter gravity. Jog is closest to bouncing ball, and can be exaggerated even more to a high skip, but even then without the sharp impact points like bouncing ball except in the most cartoony styles. Sprint reverses the trend and has the least amount of up/down.

Heaviness is best conveyed with time spent at the low point, and lightness with time spent at apex. The time to transit between high/low is less important except that the time spent at high/low should reflect the speed of transit. Fast transit conveys more force, so more force is required to counter and bring the mass to rest at high/low points. At the high point the countering force is gravity, at the low point the countering force is effort of the walker. So a strong or light walker would tend to spend more time closer to the apex, where a weak or heavy walker would tend to spend more time closer to the low point.

equal time for up and down transit is easiest place to start, after you have a good base, it's easy to push it one way or the other to get the walk you want.

AGoodFella

Thanks for the explanation, it helped a lot!