Upcoming Deadlines Pick up a clicker, find the right channel, and enter Student ID Second Homework (Mini-portfolio): Due Monday, February 8 th ; 10 points (5 points if late) Third Homework (Shooting Reference) Due Wednesday, February 10 th ; 10 points (5 points if late) For full schedule, visit course website: ArtPhysics123.pbworks.com
Activating your Clicker * Turn on your clicker. * Enter the channel number or letter for joining this class. Hit Enter/Send key. * Clicker should read AP123S258 * Type in your student ID; hit Enter/Send. Clicker is now ready to use. Hit any key to wake the clicker from sleep mode.
Survey Question You have already finished the second homework assignment (mini-portfolio). True (T) or False (F)
Review Question Which h of these spacings has the proportions of the Odd Rule? A) B) C) D)
Odd Rule Rhythm With practice 3 you ll easily recognize the Odd Rule rhythm. 1 5 A) B) C) D)
Homework Assignment #3 Video reference is a useful aid in creating animation and often animators have to shoot their own reference to suit their needs. Your homework assignment is to shoot video reference of an object, such as a ball or a water bottle, falling straight down from a height of about 4 feet. Plan your scene so that the object is clearly visible on each frame; make sure that the background is uncluttered. Stage the scene so that the object is in frame from the moment of release until it hits the ground.
Homework #3 (cont.) You have to be the person in the video dropping the object so you'll probably need a friend to operate the camera. Be sure to keep the camera level and steady; the simplest way to do this is to set the camera on a chair or table. Shoot at least 5 takes, even if they are all more or less the same. You can record one long clip or several short clips. Note that many digital cameras have a movie mode and you can check out digital camcorders from the Instructional Resource Center on campus.
Homework #3 (cont.) Find out the frame rate at which your video camera records; many of them record at either 15 or 30 frames per second instead of the usual 24 frames per second used in animation. A simple way to determine the frame rate is to count the number of frames that it takes the object to fall from a height of 4 feet and consult the table below: 7-8 Frames - 15 frames per second 12 Frames - 24 frames per second 15 Frames - 30 frames per second
Homework #3 (cont.)
Homework #3 (cont.) Create a post on your course blog entitled "Video Reference" and upload your clip(s) into that post. Keep your clips because you will need them for the next homework assignment. This assignment is due by 8am on Wednesday, February 10 th (week from today). 10 points (if late, 5 points)
Physics of Falling Part II
Straight-Ahead Animation In Straight-Ahead animation, you create the first drawing, then the second one, then the third, etc. This style of animation is expressive but it can be hard to plan the scene or go back and adjust the timing.
Principles of Animation A principle of animation is that there are two basic styles, Straight Ahead and Pose-to-pose. 1. Squash & Stretch 7. Slow In and Slow Out 2. Timing 8. Arcs 3. Anticipation i i 9. Exaggeration 4. Staging 10. Secondary Action 5. Follow Through 11. Appeal & Overlapping Action 6. Straight Ahead & Pose-to-Pose Action
Pose-to-Pose Animation In Pose-to-Pose animation, the first step is to create the first and last drawings. First drawing Last drawing Also decide how many drawings to put in between the first and the last.
Pose-to-Pose Animation (cont.) Next, you create the drawing that goes half-way between the first drawing and the last drawing First key Breakdown drawing Last key Finish by creating any remaining drawings in between these drawings.
Pose-to-Pose Animation (cont.) Finish by creating any remaining in-between drawings. In-between In-between Pose-to-pose is less spontaneous than straight-ahead but it s easier to plan a scene from its start and end.
A Fourth Down at Half Time 3 frames per drawing (close-up) First Break -down Last First Break -down Last 6 frames per drawing (medium shot) In time, Key #3 is half way between #1 and #5. In space, Key #3 is a fourth of the way down between #1 and #5. This rule always applies for any key half-way in time from the point of release.
Ball Drop Example A ball drops from 4 feet high. Key #4 is the half-time key (half way between #1 & #7). The distance from the apex to the half-time key (#4) is a quarter of the way down (1 foot below apex)
Question: Timing a Fall Cat falls out of an 8 th floor window and falls one floor (about 12 feet) in 20 frames. How far does he fall in the next 20 frames? A)One floor B) Two floors C) Three floors D)Four floors E) Seven floors (Hits ground)
Question: Timing a Fall Apex C) Three floors First 20 frames The first 20 frames is half time of 40 frames total so the cat is a fourth down at that point. Next 20 frames In the next 20 frames he falls the other 3 / ths 4 of the distance from the apex.
Falling Cat http://www.youtube.com/watch?v=qhgovkqbgk0 C f ll f h i h f 80 f i Cat falls from a height of 80 feet in about 65 video frames (30 fps).
Falling a la Chai a e d c Prof. Dave Chai Animator nmat An approximation to real falling that s easy to use for pose-to-pose animation Physical Falling Falling a la Chai Recipe for Falling a la Chai : b a) Draw interval from first & last keys. b) Divide id interval in half. c) Divide top part in half. Mark this key as the middle key. d) Divide top part in half. e) Divide top part in half. Mark a key. f) Mark another key at spot b) a Key #4 is a bit too high but who ll notice?
Falling a la Chai (cont.) Falling a la Chai uses Fourth Down at Half Time. In fact, it uses it twice. Key #3 if a fourth of the distance down and is half-way in time between keys #1 and #5 Key #2 if a fourth of the distance down and is half-way in time between keys #1 and #3 Physical Falling Falling a la Chai
Drawing In-betweens Drawing in-betweens refers to adding extra drawings in frames in between the key pose drawings. To draw in-betweens of accelerating motion, divide the first spacing by FOUR, then keep the same ratios of 1:3:5:7.
Drawing In-betweens (cont.) Notice that the first in-between drawing is positioned rather close to the apex drawing. The other in-between drawings, although not exactly in the middle, are close to being half- way between the keys.
Up and Down For a ball moving upward the timing i and spacing as it slows into the apex is the same as when it falls downward and slows out of the apex. Going up Coming Down This picture is physically correct but This picture is physically correct but animators tend to shift the up and down positions slightly to avoid an optical illusion called strobing.
Hitting the Ceiling If the spacings near the apex aren t quite right then the ball reverses direction at the top in an unnatural way. It s as if the ball hits and bounces off of an invisible ceiling. G oing up, then down Very Wrong Wrong Right
Hitting the Ceiling Example Wrong Right http://www.youtube.com/watch?v=7hpdsqijxfe This ball seems to hit an invisible ceiling near apex. http://www.youtube.com/watch?v com/watch?v=al6i_ghsc2e This animation slow in and out of the apex nicely.
Perception of Motion* Fundamental requirement for realism in animation is the Perception of Motion. This illusion occurs when a sequence of images is interpreted by the brain as apparent motion. Called Beta Movement. http://www.youtube.com/watch?v=al6i_ghsc2e * Often (inaccurately) called Persistence of Vision
Strobing When the action is slow, the overlapping of an object from one frame to the next helps maintain the perception of motion. When the action is too fast, the perception of motion can be lost because the object seem to In animation this is disappear and reappear. known as strobing
Strobing Example Strobing No Strobing http://www.youtube.com/watch?v=qrgtxgqfg9g The ball seems to appear and disappear around the top and bottom of the bounce. http://www.youtube.com/watch?v com/watch?v=al6i_ghsc2e This animation preserves the perception of motion. Strobing more noticeable in your peripheral vision.
Wagon Wheel Illusion The wheel seems to spin backwards because our perception of motion is confused due to strobing. Often seen in westerns
Example of Wagon Wheel Illusion http://www.youtube.com/watch?v=ukotzy3lqqo Propeller is spinning faster and faster but the p p g video camera has a fixed frame rate that sometimes syncs with the propeller s rotation.
Class Demo: Strobe Light Strobe lights are high- powered lamps with a periodic timer that allows it to flash at a fixed rate. Can demonstrate strobing and the wagon wheel effect.
Nyquist Effect Wagon wheel illusion is an example of the Nyquist effect. Wheel on frames #1 and #2 Illusion Actual Rotation #2 #1 The brain tracks the movement of the spokes by looking for the nearest location on each frame. The Nyquist effect limits how fast a wheel can spin in an animation and still be seen as turning.
Acceleration Stretch Objects visually stretch as they gain speed due to motion blur. Objects do not physically stretch as they fall (not even raindrops). Actual Shape Human eye Motion blur does not depend on the object s material, however, it will look more natural for rigid objects to stretch less than elastic objects.
Stretch for Strobing In traditional (hand-drawn) animation stretch t is a way of reducing any possible strobing by minimizing the blank spacing between an objects t s positions. In CG animation stretch is not easy with current character rigs but optical effects, such as motion blur, can achieve similar reduction of strobing.
Stretching & Dimensions Stretch proportions depend on whether we want to preserve equal areas or equal volumes. 67% Equal Areas Stretch in animation preserves volume 81% Equal Volumes 150% 150% Circle (2D) Sphere (3D) 0.67 x 1.50 = 1 0.81 x 0.81 x 1.50 = 1
Stretching & Dimensions Table below lists the proportions for stretching with equal areas or equal volumes. Values are the same for all object shapes. L L W X Y L 50% 67% 75% 80% 90% 100% 110% 125% 133% 150% 200% W 200% 150% 133% 125% 111% 100% 91% 80% 75% 67% 50% X,Y 140% 122% 115% 112% 105% 100% 95% 89% 87% 82% 71% Area and volume proportions similar in this range
Stretch in Falling The force of gravity does not stretch objects as they fall. Slowing out occurs during falling but all parts of a body slow out together. Common gag in animation but it s not realistic.
Freefall & Weightlessness Freefall is the state of weightlessness that occurs during falling, even though gravity is present.
Class Demo: Falling Slinky Hold a Slinky and its weight stretches it out. Now drop it. What happens? In freefall it s in a state of weightlessness so Slinky immediately contracts.
NASA s Vomit Comet NASA has a special airplane for training astronauts in free- fall weightless conditions. The Vomit Comet nickname tells you it s quite a wild roller-coaster ride. Zero G Corp. offers commercial flights (for $4000) The plane flies between 20,000 and 30,000 000 feet, same as commercial flights.
Riding the Vomit Comet http://www.youtube.com/watch?v=2v9h42yspbo
Ready, Set, Zoom (1955) This clip has several examples of stretch. http://www.youtube.com/watch?v=rv7pwdjjjqk
Ready, Set, Zoom (1955) Stretch in falling is not realistic. Stretch due to the law of inertia (drag) does occur.
Stretch Animation Can accentuate rapid motion blur by using extreme stretch on single frames. These are consecutive frames from Ready, Set, Zoom.
The Dover Boys (1942) The Dover Boys is a classic cartoon directed by Chuck Jones that has great examples of stretch (also called smear ) animation.
The Dover Boys (1942) http://www.youtube.com/watch?v=ztkpmn1ke4g
The Dover Boys (1942)
Falling Speed With this table you can find the speed of an object from the distance it s fallen Distance Speed Speed fallen (inches (miles per from apex per frame) hour) 1 foot 4 5 4 feet 8 10 9 feet 12 15 fallen. 16 feet 16 20 However, this table is accurate only as long as the object s weight is much larger than the force of air resistance. 25 feet 20 25 36 feet 24 30 49 feet 28 35 100 feet 40 50 400 feet 80 100
Falling Speed Example About how fast is Alice falling? She is 4 feet tall. We are shooting on twos (2 frames per drawing). Distance Speed Speed fallen (inches per (miles per from apex frame) hour) 1 foot 4 5 A)5 m.p.h. B) 4 feet 8 10 15m.p.h. 9 feet 12 C) 25m.p.h. 15 16 feet 16 20 25 feet 20 25 D)35 m.p.h. 36 feet 24 30 E) 50 m.p.h. 49 feet 28 35 100 feet 40 50 400 feet 80 100
Falling Speed Example B) 15 m.p.h. Distance between keys is about two feet; shot on twos that s 12 inches per frame. Distance fallen from apex Speed (inches per frame) 1 foot 4 5 4 feet 8 10 9 feet 12 15 Speed (miles per hour) 16 feet 16 20 Either she s only fallen from just 25 feet 20 25 off-screen (above) 36 feet 24 30 or her dress is 49 feet 28 35 slowing her fall. 100 feet 40 50 400 feet 80 100
Falling with Air Resistance 1 3 5 Accelerating Motion Light objects, such as a beach ball, initially fall with accelerating motion. 5 Due to air resistance, Uniform the motion transitions Motion to uniform motion 5 after falling a certain distance. 5 We ll cover air resistance in detail in a future lecture.
Uniform Motion in Profile In uniform motion, the velocity is constant so the spacing from frame to frame is constant when we view the motion in profile (i.e., object moves from left to right or vice versa).
Perspective Uniform spacings are visually not uniform when viewed in perspective.
Uniform Motion in Perspective Uniform motion may not appear uniform due to distortion ti of scale when shown in perspective. Horizon Line Vanishing Point Ball rolling from foreground to background
Falling in Perspective When falling is viewed from directly above the perspective affects the timing and spacing. http://www.youtube.com/watch?v=mgcntulvtou
Falling in Perspective (cont.) The Odd Rule or Fourth Down at Half Time can be used to find the spacings, which determine the object s size as it moves away from the viewer. 1/24 second intervals
Falling in Die Hard An action movie in a 40 story building is going to have lots of good falling scenes. A building story is about 10-12 feet. Nakatomi Building in the movie is 400-500 feet
Falling in Die Hard (Backwards) http://www.youtube.com/watch?v=hpxwesyf_qc
Falling in Die Hard In one of the final scenes the villain falls to his death from the top floor. At 2:02:35 This shot lasts over 12 seconds yet he only falls about one story, which would take about 1 second. For dramatic purposes, it s filmed in slow motion.
Falling in Die Hard In this shot the villain falls for 5 ½ seconds, which is the time it takes to fall 40 stories. At 2:02:45 However, in this shot the stuntman only falls about 20 stories, which takes about 3 ½ seconds. The director slows the film yet we don t notice.
The Most Important Law of Motion The art director is always right.
This Friday is the last day to drop. Next Lecture Paths of Action By Wednesday (week from today): Complete the 3 rd homework (Shooting Video Reference) Please turn off and return the clickers!