by June 30, 2004 0 comments



The principles of classical animation say that in a general walk cycle, a human takes 12 steps to walk, but it has been done in 16 steps. This can be easily reduced to 12 steps in computer animation. Thus, the whole cycle, including the left and right foot, can be done in a total of 24 frames, 12 frames for each foot.

Walk, in any animation plays, an important role because it gives the character a personality. It is a challenge for any animator to develop a convincing human walk as it requires a lot of observation, timing and sense.

Direct
Hit!
Applies
to:
3D modeling and animation professionals
USP:
Creating a convincing walk effect in character animation
Links: www.pcquest.com/multimedia

As Richard Williams says in his book Animator’s Survival Kit, “almost every person walks in a different way”. So, one should first visualize the personality of a character before animating the walk. With experimentation, you can tweak the steps and create various kind of personalities (happy, lazy, sad, tired) for your character. Once you do that, you can achieve the walk in any software. 

Download the MAX file ‘my_character.max’ from www.pcquest.com/multimedia. This is 3D Studio MAX’s biped with little tweaks and a start up pose to make it easy for you. You can also create a similar pose. You need to create major key poses for the right foot in frames 1, 4, 7, 10 and 13 and repeat the same for the left foot. We have marked the functions of the various buttons that you have to use in screenshot 1. 

On frame 1, select the complete biped and press the Set key from Key Info panel/motion. This will ensure that all body parts calculate their key timings from this frame.

Select the right foot (green) and press ‘Set Planted Key’ from Key Info panel. This will help in fixing the foot to the ground. After planting the key, press Select Pivot and adjust the pivot for the right foot at the heel center. This is done to achieve rotation for the heel.

STEP BY STEP
1. Rotating the heel 
2. Various buttons you will use and their functions

Select the left foot (blue) and press ‘Set Planted Key’ again to fix the foot to the ground and set the pivot at ball joint. 

Go to frame 4, rotate the right (green) foot around by 15 degrees to help it to confirm to the ground level. For the left (blue) foot, press the sliding key button. Now press Select Pivot and change the pivot to toe center and press the sliding key button again.

Rotate the right (green) foot around by 10 degrees at the toe, so that it touches the ground at the toe tip. In this step the body weight is going to be transferred on the right foot with little support from the left foot.

Select the left (green) hand and move it back and up a bit. For the right (blue) hand, move it a bit forward and up. Refer to screenshot 3 for positions. This is done to balance the upper body movement to that of the lower.

Select Body Vertical and Horizontal from Track Selection and move the pelvis forward and a little lower, so that the pelvis is at the center of both the feet. Again, check the screenshot 3 for reference. 

Go to frame 7, select the Body Vertical and Horizontal buttons and move the pelvis over the right foot with a little bend in the leg. In this posture, all body weight is transferred to the right (green) foot. See screenshot 4.

STEP BY STEP
The hand also needs to move along with the walk The body has to look balanced at all stages of the walk
The swing of the hands and the swagger of the step (how long a step, etc) have to match the mood of the character being animated The palms move in a wave motion over time

Now, move the left foot to a neutral position a little above the ground and press the set free key, like a passing position. The opposite hands move forward to support the legs and balance the whole body.

On frame 10, press the Body Vertical and Horizontal buttons and move the pelvis a little up and forward. Now rotate the right foot around by 5 degrees on the ball joint in a forwarding position and the left foot around by 15 degrees as the heel is going to touch the ground. In this scenario, the right foot will be in a forward position. This is the position of maximum height. The right hand moves forward to follow the left foot and the left hand will follow the right foot for balancing the upper body. 

In frame13, move the left (blue) foot as it matches the body posture in frame 1. Set 
the planted key while heel touches the ground, move the pivot at the heel center and press the planted key again. 

Repeat the same steps for the other foot in the similar manner till frame 24. This will complete the whole walk cycle. 

For making a convincing walk, it is important that you take care of the pelvis positions. The various pelvis positions are shown in the reference pictures. They form the basis for a normal walk; by changing them you can create different walk styles.

Tajinder Jeet Singh Technical Core Committee, Maya Academy of
Advanced Cinematics

Quick Tip




n To achieve more convincing motion, you can rotate the upper spine around 5 degrees in the Z axis at frame 1 and in opposite directions at frame 24. This way, the left shoulder at frame 1 and the right shoulder at frame 24 will get forward to support the respective leg movements. This happens automatically when we create a walk or run.

n To balance the body for the above act, rotate the pelvis in cross move at frames 1 and 24. Both the rotations can be around 5 degrees in opposite directions.

n Always begin the animation at frame 1, keeping frame 0 as backup of your file.

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