The Laws of Physics in an Animated Universe: Princess Mononoke

The Physics of the Forest: Princess Mononoke

Princess Mononoke is a japanese animated film created by Studio Ghibli in 1997. It tells the story of a young exile, Ashitaka, who wanders into a conflict between animal gods protecting a forest and a human town trying to mine the iron under the forest. He falls in love with a girl raised by the animal gods, San, who the villagers call Princess Mononoke. It is a highly acclaimed animated film, well known for its beautiful scenery shots and excellent animation. Many aspects of Princess Mononoke mirror the physics we know of our universe, with the exception of the magic of the premise, talking animals, gigantic animals, forest gods, and supernatural curses. In fact the animation of Princess Mononoke focuses on being similar to real life when it comes to character posing and local movements, but deviates sometimes when characters move through their environment. In particular, the character animation respects center of gravity very well throughout the film, even with characters that stand on highly raised wooden sandals. Also, inertia is represented accurately in gunshot impacts, hair that waves behind motion, and objects remaining stationary until acted upon. However, a clear difference appears that is common for japanese animated films, in which characters fall faster or slower in different jumps, and gravity is somewhat inconsistent in general. These gravitational differences often appear during action sequences to accentuate the motion being represented, but there is no clear slowdown to convey unrealistic action. Despite the technical differences, the action flows together smoothly and does not readily bring the viewer out of immersion.

It is clear that Princess Mononoke's characters operate under the same center of gravity properties that the physical universe follows. Even in our first introduction to Ashitaka, as he rides his elk along a raised stone wall, when he wants to move over onto the wall. He brings his feet up underneath him on top of his elk, and only then moves his center over to the wall. The motion clearly shows how his feet act as a base of support for his motion. Just a minute later, when a monster tears down a watchpost that Ashitaka and another villager are on top of, as the watchpost tips, both men lose their balance as their centers of gravity move outside of their bases of support. Later on in the movie, we meet a monk named Jigo, a short man who walks on sandals that have a thick wooden beam coming out of the center of the sandal. He stands on these wooden beams, and the animators often use this to play with Jigo's center of gravity. When standing still, Jigo crouches and puts his feet together, both bringing his center of gravity down and directly underneath his small base of support. He often totters back and forth, because when one leg is on the ground, Jigo's base of support is so small, so he goes off-balance. In one scene towards the end of the movie in particular, Jigo is attempting to catch a large iron container rolling down the hill. He stands with his legs wide to maximize a base of support, but when the container hits him, it moves his center of gravity backwards out of his base of support causing him to roll backwards down the hill. In an attack on the village, Princess Mononoke rides a wolf up a hill towards the town standing on the wolf's back. As the incline becomes more steep, the princess moves her body forward, keeping her center under her base of support to stay balanced. This same quality is prevalent through all of the human characters, throughout the film. It is clear that correct center of gravity was a priority for the animators.

On the other hand, gravity is certainly not the same in the world of Princess Mononoke. In one scene in the movie, San, also called Princess Mononoke, attacks the village of Irontown at night. After scaling the wall, she perches on the log wall in front of one of the village guards. The guard attempts to smash a large wooden staff into San, and in response, San hops sideways to another spot on the wall. This hop occurs over the course of 8 frames, and goes about four feet in the air. A jump lasting eight frames would be about 5.3 inches in the physical universe, so it is clear San is acting under a much heavier gravity. A few seconds later we see another example when San jumps about nine feet in the air over to a rooftop and gravity acts completely different from the short hop on the wall. She falls nine feet in nine frames, which is the same time it takes something to fall two feet on earth. Ashitaka, the hero, is also affected by this heavier gravity. Chasing San across the rooftop, he jumps and falls from an apex for about three body lengths over the course of 18 frames. Estimating his height at a conservative five feet, that is 15 feet over 18 frames. The 18 frames would correspond to about 9 feet of falling in earth gravity. However, this is not completely consistent. Just a few seconds after the short hop, San jumps off the outer wall to avoid a gunshot. After reaching her apex she falls for about 20 frames, but it seems to only be ten to twelve feet. This is quite a bit closer to the earth distance, about 11 feet. Later on in the movie, Ashitaka jumps off a cliff, followed by a giant wolf. He falls for 18 frames the same as before, and at first the angle makes it hard to make a good estimate of the distance. However, the wolf following him is about eight to ten feet long. It takes four long strides to make it down the cliff, running along the side. If we estimate the running stride of a wolf to be about one and a half times its body length, that is between 48 and 60 feet. So over the same time of 18 frames Ashitaka fell about fifteen feet at one point and about fifty feet at another. So San is acted on by a heavier gravity than earth at times, and almost normal at others. Ashitaka on the other hand, encounters an even heavier gravity later in the film. It is clear that gravity is quite fickle within Princess Mononoke's universe.

The other physical property of Princess Mononoke's universe that is noticeable is the inertia that is mostly the same as earth inertia. Ashitaka, San, and another character, Lady Eboshi, all show inertia in the waving of their hair as they move. One scene involving a fight between Lady Eboshi and San has several shots of the two women's faces, and the waving of the hair due to inertia is very obvious. Gunshots are also a clear example of inertia in Princess Mononoke. Ashitaka is shot through the chest with a rifle, and because the shot penetrated straight through Ashitaka, the force did not knock him down. Later on, when Lady Eboshi shoots enemy commanders on a battlefield, the shots do not penetrate the men, so the force knocks one off his horse, and the other gets knocked to the ground. In another projectile example, Ashitaka's arrows follow some of the same properties. Ashitaka has superhuman abilities from a demonic curse placed upon him, and so his arrows regularly decapitate or dismember his opponents. Because they are somehow cutting his opponents, the arrow does not exhibit very much force on the entire body of his targets. In an early action scene, Ahitaka's arrow cuts off his opponent's arms, leaving the man standing bewildered. While certainly done for comic effect, because the action separated the arms from the rest of the body, it is realistic that the man would not be knocked over by the attack. In a similar manner, Ashitaka beheads several horsemen throughout the movie, only to have their bodies stay riding for a few seconds before sliding off the mount.

Princess Mononoke is a stunning movie, filled with amazing artistry and intricate animation. The center of gravity that the characters display gives the movement a realistic feel and a natural flow. Also, the inertia shown both helps convey realism and accentuate the action and drama of the involved scenes, and even creates comic moments at times. While the gravity affecting the characters does change throughout the movie, and the action scenes are filled with superhuman jumping and falling off of cliffs, it is handled in such a way that it is not immediately noticeable. It does not pull the viewer out of the reality of the story, and helps create a grand sense of scale within the film. Princess Mononoke is a captivating animated film, a testament to the unique impact that illustration and motion have as a medium, and proper physics are an important part of that impact. Without using good center of gravity poses and representing inertia the way it did, the movie would not have been as immersive or as beautiful as it is.

Note on deviation from outline: After I began writing the paper, I decided that I didn't really like my plan at all. Moro is a wolf god within the story, and it seems you could sort of explain away deviations in her falling with the "she's a god" argument, so I really wanted to focus on the human characters for that analysis. Also, the last section on friction really wasn't turning out to be as convincing as I originally thought. The motion of the arrows was interesting and I wanted to say something about it, but I was trying to say that it the arrows should have been tearing instead of cutting, and the whole "demonic curse" thing was making that argument a little sketchy. Then re-watching some scenes I noticed how dynamic the representation of inertia was, especially in the hair waving, so I went with that instead.

For the sake of completeness, I'll go ahead and write a new and improved outline.

Physics of Princess Mononoke

I. Introduction

a. Short movie summary

b. Thesis: Princess Mononoke preserves realistic character posing, but fluctuates gravity.

c. Essay Map

II. Body paragraph I: Center of Gravity

a. Ashitaka

i. jumping from elk to wall

ii. falling off watchtower

b. Jigo

i. walking on stilts

ii. falling from container

c. Princess Mononoke

i. surfing on wolf.

III. Body paragraph II: Falling

a. Princess Mononoke

i. hopping along wall

ii. jumping across rooftops

b. Ashitaka

i. jumping across rooftops

c. Contradictory examples

i. San jumps with earth gravity

ii. Ashitaka falls with extra heavy gravity

IV. Body Paragraph III: Inertia

a. hair waving

b. gunshots

c. Ashitaka's arrows

V. Conclusion

a. Essay Summary

b. Concluding Remarks