Special Effects in Animation and Live-Action

My first two term paper scores were both above 80; I will not be writing a third term paper.

Outline of the Third Term Paper

INTRO: Scale models and CGI can be easily spotted when water effects not done well. Careful attention must be paid to not violating the laws of physics. Otherwise it can lead to very unnatural looking dynamics of the natural phenomena.

Clash Of The Titans (1981) 

Water effects done poorly: In large amounts water does not separate in to blobs like that. It stays together in large conglomerations with fine spray off the top when high winds are present; this is clearly a scale model.

Perfect Storm (2000)

Water effects done well: Water holding together, large waves with small period, fine spray of the crests due to high wind; good CGI. No Awkward looking chunks flying around.

CONCLUSION: For realistic looking water effects one must take in to account the correct spectral range for the given amount of water and its velocity. The key is getting the correct balance between the inertial and viscous forces that govern fluid dynamics.

Stop-Motion Character Animation

=A BRIGHT IDEA=

- Drew maze
- Built character
- Shot 179 frames with SLR
- Made 4 scenes in Dragonframe
- Combined scenes in Lightworks

=CLIP=

- Character runs tough the maze
- Character gets on to electrical outlet
- Character lights up

Better quality version on VIMEO here: https://vimeo.com/144629286

Science Fact or Cinematic Fiction

Cinematography is a natural extension of photography and as such shares many of its core traits. Both are built on the idea of taking reality, that has no intrinsic bias, and collapsing it in to a unique perspective; making the audience see the same world but through the eyes of the artist. Sometimes it means reality is distorted naturally, by the virtue of the artist’s bias; other times it is done intentionally, in a specific way for a specific goal. In this paper we will focus on the latter; specifically the distortion of Conservation of Momentum.

In the animated film Ice Age 3 there is a scene I call “the impossible soap bubble” in which the main character Scrat and his frenemy Scratte are drifting in what appears to be soap bubbles.

Scratte is slightly ahead and above Scrat and is making a run for his favorite object, the Acorn, that is drifting in a bubble as well. To catch her Scrat starts jumping off the floor of the bubble in order to impact the top with his head and push it higher, getting him closer to his prize.

Conservation of momentum is distorted here for comedy and general air of silly shenanigans which makes these lighthearted films so entertaining to watch regardless of age group. In the film the Scrat is successful in his attempts and the bubble indeed moves upward. In reality this would not be possible due to conservation of momentum. 

Once Scrat would push off from the floor of the bubble, the bubble would push off him. Having a much higher mass then the bubble his position would remain relatively unchanged while the bubble would move downwards. Whatever small velocity he would gain in the upward direction would be lost moments later as his head would impact the roof of the bubble and the relative momentum would return to its original magnitude of zero.

This analysis neglects air resistance, buoyancy and gravity but the end result is the same. This is not a realistic means of traversing space.

In the film Lock Stock and Two Smoking Barrels there is a scene I call “the impossible shotgun” where Hatchet Harry shoots Dog with a shotgun, causing him to fly back and out the door.

The momentum of the firearm projectiles is greatly over exaggerated in this case for dramatic effect. Realistically the velocity would be far lower, but only if he was on a frictionless floor. If not, the friction between the floor and his feet would convert the impact of the projectiles in to a torque, causing him to tip backwards. Let’s take a look at the physics behind a real life version of these events in terms of conservation of momentum.

Assuming:

-          weight of the victim at roughly 175lb (80kg)

-          friction-less floor so force doesn’t get converted to torque

-          elastic collision so no energy is wasted in crushing bone and tearing tissue

-          all pellets go in to the body

-          Remington's Magnum 00-Buck Load (on the heavy side of what exists)

The resulting velocity of the victim filled with projectiles is about 36 cm/s as you can see from the calculations above. Take a finger and run it along the ruler from 0 to 36 cm while counting out one-Mississippi. You will see that it’s a very slow speed, about 0.8mph; average walking speed is about 2-3mph.

Below those calculations you can see an extrapolation of how much of that same shot it would take to achieve the observed velocity of ~2.5 m/s given the same assumptions; roughly 14 of the same shells fired simultaneously.

Needless to say this is all assuming a friction-less floor and and no energy loss due to deformation/destruction of bone/tissue/cartilage/shot.

In the film Gravity I don't have a fancy name for a scene because conservation of momentum is constantly violated for unknown reasons; probably incompetence. On multiple occasions items like the jet-pack and the fire-extinguisher are used to catch vehicles and stations in the same orbit. It suffices to say that the distances in question are much too great relative to the amount of available propellant (among other issues like vast speed disparities, inability to control tumble with fire-extinguisher, etc).

Generally the way this is done is by switching to a lower orbit to increase velocity (conservation of angular momentum), catch up, and then go up in to target orbit. Or go in to a higher orbit to slow down, wait for the target to come around, and then drop down on it. There is simply not enough momentum to be had from the given propellants to chase objects in the same orbit over the given distances. And even if there was, as soon as you change your speed you will automatically change your orbit whether you want to or not (conservation of angular momentum). In a nutshell they should fire their physics consultant.

If you are going to violate physics you better have good reason. In animation it’s easy to get away with it the spirit of fantasy. The vast majority of animated films either take place in a non-realistic universe or in one where technology has advanced to the point of being perceived by us as magic; at which point we are back to option one.  In non-animated films things are a little different. 

In Lock Stock and Two Smoking Barrels the shotgun scene could have been done better by shooting Dog with something possessing higher mass or blowing a hole though him as opposed to making him fly; which would be more realistic. 

In Gravity they should have used the momentum from propellants to shift orbits instead of unrealistically chasing targets. Although to be fair using them would shift orbits automatically; would have helped if they showed it. And not to nitpick but there is no way one could control the tumble induced by the fire-extinguisher expelling propellant.

I guess in closing I would say movie producers need to spend more money on physics consultants and less on catering. Although on the flip side the general public is not very bright so maybe it would just be a waste of money. Something to think about.

Reverse Video Reference

=REVERSE VIDEO REFERENCE=

CLIP A: https://vimeo.com/142369547

CLIP B: https://vimeo.com/142366711

CLIP C: https://vimeo.com/142366710

CLIP D: https://vimeo.com/142366712



*links to VIMEO because Blogger is a flaming piece of garbage when it comes to embedding video

Building a Scene in Maya

A Scene in Maya

    

Outline of the Second Term Paper

INTRO: Conservation of Momentum is often violated in films.

Ice Age 

Impossible Soap Bubble: Scrat tries to catch up to Scratte by jumping inside his soap bubble and hitting the top with his head from the inside to translate it vertically. This would not be possible due to conservation of momentum.

Lock Stock and Two Smoking Barrels 

Impossible Shotgun: Hatchet Harry shoots Dog with a shotgun, causing him to fly back and out the door. The momentum of the firearm projectiles is greatly over exaggerated.

Gravity

Imposible JetPack:  George Clooney uses his air powered jet pack to match orbital velocities with the shuttle. Later Sandra Bullock uses a fire extinguisher to match orbital velocities with the Chinese Space Station. The momentum of propellant is not enough to bring the characters to sufficient velocities.

CONCLUSION: necessity, comedy, action.