Part I: Ball Tailed
It’s time to make a little ball motion with a tail!
In order to better understand the trajectory of the ball with a tail, I first looked up a reference picture on the Internet. From the reference picture, you can see the change of the ball’s tail in the process of rising and falling.
I found that the tail’s movement is very typical of an S-curve, which is a soft and flexible object with one main driving force at one point. By relying on their own or external momentum, the force transitions from one end to the other. Squirrels, for example, are characterized by movements that are made of spherical and circular shapes. As the squirrel jumps or runs, its tail will curve accordingly.
I chose to divide the animation of creating the sphere’s motion with the tail into two parts. The motion of the sphere is created first, and then the motion of the tail is created. In this way, I can think about the individual objects’ motion and adjust the overall motion curve during the process.
Here’s a draft drawing of my design for the tailed ball movement.
Model diagram of the scene produced:
Making an animation curve of the sphere’s motion. I started creating keyframes of the sphere’s motion by looking at the ball as a single individual. This way, the subsequent production can adjust the direction of the tail’s movement in reference to the ball’s motion.
Video of ball’s basic motion production:
Now let’s make a tail movement pattern. I chose to create the tail motion keyframes first to see the effect of the tail motion more visually.
Tail’s animation curves panel:
Video of the making tail keyframes:
After making the keyframes, I noticed that the tail was still a bit stiff and not soft. So based on the keyframes, I adjusted the controls for the tail separately. Starting with the controller closest to the tail’s root, I adjusted the two keyframes backward in order. For example, the first controller adjusts two keyframes backward, and the second controller adjusts four keyframes backward.
After adjusting the keyframes:
There are two things I’ve found that it is important to keep in mind during the making process.
1. The arc size before and after the parabola will change.
2. Acceleration and deceleration in motion.
Rending video:
Part II: Ball Walker
I collect reference pictures before making keyframes. In these pictures, I can see the changes in the ball’s movements as it walks.
I divided it into two parts to create keyframes. In this case, I started with the ball legs’ walking motion, then adjusted the details of the ball’s movement and stretching. The ball’s legs are very similar to humans, so I also try to create curves based on the human walking posture.
Reference image about human walking motion:
In the process of walking, the left and right feet alternate forward, driving the torso to move forward. In order to maintain the balance of the body, in line with the two legs to bend and stretch, stride, the upper limbs of the arms need to swing back and forth. In order to maintain the center of gravity when walking, one leg always supports the other leg to lift the stride. Therefore, in the process of walking, the height of the head is bound to move in waves.
Let’s make ball walking! There is a formula to calculate the distance the ball will travel. Distance moved from the waist = distance from the front foot + distance from the back foot + distance from the waist.
Using formulas in the process of making the animation will make the ball move more naturally. Since the ball walking is a circular motion, I made “0” “6” “18” “24” first. Then start making intermediate frames.
Keyframe curves for the lower half of the ball action:
Ball’s basic walk keyframe curves:
This is the motion curve of the ball’s head:
I achieved the goal of moving the model by moving the ball controller and the foot controller during the build process, keeping the total controller free of displacement changes throughout the fabrication process.
This is the movement curves of the final overall model:
Playblast video:
However! A problem has arisen!
I noticed that the ball’s walk looks very terrible. After seeing the playblast video repeatedly, I noticed that the ball’s walk looked skating. Also, the ball’s head movement’s magnitude was unnatural. I could see the ball’s head swinging too low or too high as it moved.
In reviewing the process of making the keyframes, I found the problem. When I was making the foot motion, I rotated the circle controller for the ball’s ankles, which causes the entire foot to rotate with the heel as the center point. This causes the foot’s keyframes to be inconsistent, and the foot will slide forward.
Is there any remedy for this? (Of course, I know that redoing it is a good idea. But please let me try to see if I can remedy it.)
I tried moving the foot back to where it should be at each keyframe. It isn’t pleasant processing but looks better than before.
Ball’s modified controller curve:
Plus board that moves up and down at the feet of the ball.
Look again. Well, much better.
Rending video: