PHYS 123: 2015

Wednesday, December 16, 2015

Creating Stereoscopic 3D Images

Stereoscopic 3D Images
(for red/cyan glasses)

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Friday, December 4, 2015

Recreating Cameras and Lights in Maya

Original

Recreation (0 degrees)

Recreation (45 degrees)

Wednesday, November 11, 2015

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.

Wednesday, November 4, 2015

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

Tuesday, October 27, 2015

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.

Wednesday, October 14, 2015

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

Wednesday, April 29, 2015

Building a Scene in Maya

A Scene in Maya

Wednesday, March 18, 2015

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.

Wednesday, March 4, 2015

Stop Motion Animation of Falling

=SPACE INVADERS=

-Located images
-Scaled images
-Printed scaled images
-Used the odd rule to set progression
-Shot about 48 frames on the floor with overhead SLR
-Added black stripes in Photoshop to each frame to cover up tripod legs
-Arranged and animated in Dragonframe

=CLIP=

-Invader drops a bomb to launch the critter off the ground
-Teleports in a wall to deflect critter
-Catches critter bouncing off the wall
-Teleports out with critter

Better quality version on VIMEO here: https://vimeo.com/142253449
*because Blogger is a flaming piece of garbage when it comes to embedding video:

Monday, February 23, 2015

The Laws of Physics in an Animation Universe

Ice Age 3: Dawn of the Dinosaurs is set on a distant world undergoing a prolonged, and uncharacteristically warm, ice age. Wooly mammoths and saber-toothed cats roam the snowy, and sometimes not so snowy, planes; while odd shaped and poorly bathed sloths make futile attempts to utilize their cognitive array. All is well; except maybe in the instance of the tiny Scrat, whose acorn woes know no bounds... I often wake in the depths of the night, covered in cold sweat, perused by nightmarish visions of acorns; for in my dreams I have peered in to the cold eyes of despair and touched the cackling hell that is acorn ownership.

Rather than subject oneself to that kind of adversity, one could alternatively invest in the geological sector. Say what you will but you probably won’t find yourself climbing a tree in a thunderstorm to save a plot of land, which inadvertently rolled away while you were on the phone with the in-laws. In this world porous formations dominate the geological landscape which has a number of benefits. When thrown out of your high rise apartment by an angry wife one could fall with relative peace of mind, knowing that upon impact the small cells making up the terrain will collapse and absorb ones kinetic energy.

Timecode [00:03:10] shows our wayward hero meeting the floor of a canyon, face first, after a speedy plunge. He walks away unscathed but leaves a detailed extrusion in the topology. On the other hand a large force distributed over a large area results in stable support. Timecode [00:03:18] shows a wooly mammoth run by without making holes in the ground.

Timecode [01:25:42] shows the female Scrat push an acorn in to the ground. It goes in suddenly with force but quickly stops as the energy is dissipated by the crumpling lattice of the geological formation. When more force is applied the ground breaks up in wide spreading cracks, suggesting the lattice becomes denser with depth; when sufficient force is applied the lattice shears along the plane of weakest connections. This behavior is consistent with a porous structure.

Inertia seems to hold in this world. While falling from your high rise apartment, having aforementioned peace of mind, one does not have to worry about landing in the thorny bushes covering the perimeter of ones fine domicile. Knowing that your wife gave you an initial velocity in the horizontal direction one can be sure ones future does not include an awkward conversation with a doctor regarding extraction of things from other things.

Timecode [00:13:49] shows the sloth, while sliding down the mountain, let go of two eggs above his head prior to entering a hollow log. Upon exiting the log he finds them where he left them; above his head. Since no different forces acted in the negative X direction on the eggs they continued to travel horizontally at the same speed as the sloth. In the Y direction the forces acting on the sloth and the eggs are the same however, the eggs are in free fall while the sloth is sliding down a hill. Part of the force due to being in the gravitational field is converted in to horizontal motion for the sloth. However because the log was very short the fact that the eggs were accelerating downward at a faster rate than the sloth can be ignored as there is not enough time for them to drop a non-trivial amount.

As a corollary; momentum is conserved. Timecode [01:17:40] shows the tiger saving the sloth by knocking him out of harms way. Because the tiger has a large mass relative to the sloth, and because momentum is conserved, when the tiger hits the sloth he experiences a small acceleration and continues virtually unimpeded on his trajectory. The sloth on the other hand, having a smaller mass, is violently accelerated out of harms way.

This world also features exaggerated paths of action. When the wife reaches for a household appliance of significant mass and acceptable geometry to launch in your direction, one could exploit the fact that her hand will travel far back before beginning its inevitable motion forward. This could be critical in giving one a chance to successfully dodge the projectile by providing an early warning system.

Timecodes [01:25:24] and [00:47:09] show characters follow through with the motion of their limbs and facial muscles in a way that would indicate high inertial mass. The inertial mass isn’t necessarily equal to the gravitational mass in this world and could be very high for most elements. As a result it requires more time to slow a moving limb, resulting in it traveling on its original trajectory for a longer period of time. The same could apply to facial muscles. Once your bushy eyebrows and floppy ears are in motion it takes time to stop them.

On a few occasions this world does not conform to our laws of physics. Timecode [00:20:39] shows what I call the impossible soap bubble. The male Scrat tries to catch up to the female Scrat by jumping inside his soap bubble and hitting the top with his head to translate it vertically. This would not be possible in our universe because during the jump the Scrat would apply a force to the bubble in the negative Y direction; causing it to go down. His momentum upward would be equal to the momentum of the bubble downward. When his head would impact the top the momentums would cancel out; him and the bubble will return to accelerating downwards at “1g”. At best if there was no gravity he would break even but with it he won’t even get that.

Timecodes [00:36:40] and [01:25:45] show objects and creatures stretch greatly under relatively low forces. The Scrat fight scene and the Scrat goo scene show relatively weak molecular cohesion. The attractive forces between molecules are weak enough that one can stretch once own body. In addition these forces are not proportion to 1/r^2 like our universe; they stretch yet hold. I would say that while the forces are weak they are more proportional to 1/r^1 as they do not wane at a distance as quickly as in our universe.

Animators seem to hold on to the majority of probable physics to create an environment the average person can relate to. They alter specific scenes to bring comedy or emotion in to the work or to otherwise emphasize something. I think creating physics that are drastically different works well in abstract games but in majority of the films, shows and games a fair amount of our physics has to be present to make a connection with the audience. Much like one designs an audio amplifier to give the most accurate reproduction possible, then colors the sound with a specific harmonic distortion signature, animators create a realistic landscape and alter it in specific ways to communicate better with the viewer.

Wednesday, February 18, 2015

Paper 1 (outline)

ICE AGE 3

=High Porosity Geological Formations=

Falling objects form deep extrusions in the ground; the boundaries are clean and show a large degree of detail; animals walk away unscathed but disoriented.

Small cross-sectional area and high rate of speed of the falling Scrat collapse the porous ground forming a body shaped extrusion on impact. [00:03:10]

When a mammoth runs by moments later his foot does not cause a hole because the weight is distributed across a large area. [00:03:18]

Female Scrat pushes acorn in to the ground causing an initial extrusion, followed by cracks propagating at high velocity. [01:25:42]

This is consistent with a porous structure.

=Inertia=

Inertia seems to hold in this world.

While sledding down the hill the Scrat let go of two eggs above his head prior to entering a hollow log, he found them where he left them after exiting the log; above his head. The eggs have continued to travel horizontally at the same speed as they were before they we let go of. Vertically (elaborate complication)[00:13:49]