Water Balloon Head
Recently we've seen an epidemic in CGI pictures that we'd like to bring to your attention. "Water Balloon Head" is an animation disease that we as Spline Doctors would like to warn you about before it's too late. This is a disease that affects us all. We'd like to discuss why it's a problem and how to solve the most debilitating of animation diseases...
Water Balloon Head
headum squashis overanimatis
Symptoms: Animated characters' heads seem to squash and stretch so much that it appears that the head is made of a water.
Cause: Character is rigged to squash/stretch the whole head and not rigged to just squash/stretch the jowl area.
Cure: If the character is rigged improperly and re-rigging is not an option, lessen the use of the squash/stretch control.
Squashing and stretching the head is something that works fine in hand drawn animation, but gets a bit creepy in computer animation. In CGI truth to materials is very important. The images appear real enough that the audience expects the characters to behave in a world of believable physics. A heavy metal beam should not be animated like a wet noodle. A human or animal cranium should not perceiveably squash and stretch. I'm not saying that there shouldn't be squash and stretch in the head, I'm just saying it should be localized in the jowl area (cheeks and lower jaw).
The skull structure can be preserved by maintaining a solid relationship between the eye socket position and the upper teeth. If you can see the upper teeth "floating" up and down you are giving the audience the indication that the character is made of rubber. The skull structure should be preserved. The muscles around the eyes can be squashed/stretched as well as the nose if desired.
Of course there are exceptions to every "rule" in animation, but this is a good limitation to start with. If you really are itching to put squash and stretch into you shot, try putting it into the relationship of the head and shoulders. If you really must squash and stretch the cranium, back off a bit on how much you are using it. Thanks for reading.