Animation

Basics of animation, - frame rate, refresh rate, keyframe interpolation! Pixar course on animation.

21 flashcards · Computer Science · by lakesare

1. What is persistence of vision?

   Response to a visual stimulus can persist after that stimulus has disappeared. Persistence of vision traditionally refers to the optical illusion that occurs when visual perception of an object does not cease for some time after the rays of light proceeding from it have ceased to enter the eye.

2. Frame rate VS flicker rate?

   Frame rate - the rate at which different images are displayed on the screen. Flicker rate - is a display refresh rate/vertical refresh rate., includes the repeated drawing of identical frames. The flicker rate is at least as high as the frame rate, as there must be one interruption between frames; however, modern projectors are designed to add additional interruptions, to increase the flicker rate.

3. What is flicker fusion threshold?

   Frequency at which an intermittent light stimulus appears to be completely steady to the average human observer.

4. What is Beta phenomenon? (Wertheimer)

   Series of static images on a screen creates the illusion of a smoothly flowing scene. Many textbooks are unclear over the distinction between beta motion and the phi phenomenon; beta motion is the perceived motion of an object, elicited by successive showing of two related stimuli in different spatial locations, while the phi phenomenon is perceived motion of an unseen object with the visual properties of the scene’s background, elicited by implied occlusion of stimuli at a relatively high freq…

5. What is Phi phenomenon? (Wertheimer)

   Something with the background-colored is moving round, obscuring the dots. The names beta and phi are simply the letters "β" and "ϕ" from the Greek alphabet, and have no particular significance beyond separating the two phenomena.

6. What is flat animation?

   Sequence of drawn images. Also called traditional animation This means that each frame had to be drawn separately by hand. This could take an enormous amount of animators’ time, and the large studios developed many methods to deal with this problem.

7. What is stop-motion animation?

   Characters are models made of clay or a similar material.

8. What animation technique is computer animation closer to - flat animation or stop-motion animation?

   Computer animation, whether flat 2D or 3D, is generally much closer to the stop-motion workflow. A model of each character is initially created, but this time it is a virtual model in 2D or 3D. The appearance of the model has to be defined before starting the animation, but so do a number of manipulation handles that are used to move the character. These handles are called the ‘rig’. Once the model and rig are defined the animator’s job is to move the model frame by frame, as in stop motion ani…

9. What does 'p' stand for in 1080p?

   Progressive

10. What are 2 methods for "painting" a video image on an electronic display screen?

    Interlaced scanning - 1st pass displays all odd numbered lines, 2nd pass displays all even numbered lines, filling in the gaps in the first scan. Progressive scanning - line by line, top to bottom

11. Why is interlaced scanning used?

    Same bandwidth, but TWICE the perceived frame rate and refresh rate. Interlacing provides full vertical detail with the same bandwidth that would be required for a full progressive scan, but with twice the perceived frame rate and refresh rate. The higher refresh rate improves the appearance of an object in motion, because it updates its position on the display more often, and when an object is stationary, human vision combines information from multiple similar half-frames to produce the same p…

12. What is layering in animation?

    A technique, where animation is composed of a number of layers, and only animate the layer or layers where movement needs to be seen.

13. What is curve fitting (in mathematics)?

    Constructing a curve, or mathematical function, that has the best fit to a series of data points.

14. What's x and y on this chart?

    x - Time in frames y - Height of the ball above the ground

15. What sort of interpolation has been used between these two keyframes?

    Linear interpolation.

16. What sort of interpolation has been used between these two keyframes?

    Bezier interpolation.

17. Below are 2 timing charts for the avar controlling the y coordinate of the a ball. Which was used to create this animation?

    The ball speeds up as it moves towards the ground and slows down as moves away from the ground. Since the change in y coordinate is not constant, linear interpolation was not used.

18. Let point A have the coordinates (20, 70), and point B have the coordinates (130, 180). An animation shows a car stopped at point A from frame 0 until frame 60. Frame 60 is the last frame at which the car is at point A; from frame 61 to frame 120, the car moves from point A to point B. It then stays at point B. Sketch the keyframes that could be used for this animation. If linear interpolation is used, what will be the x and y coordinate of the car in frame 66? Write an equation that can be use…

    1. Keyframes are the KEY frames, - as opposed to 'tweening' or 'inbetweening'. Keyframe animation specifies key values of parameters at key times. Keyframing involves taking a start frame and an end frame and generating the frames in between these two, in order to create the series of frames that can be perceived as an animation. This process, which we will look at later, is called ‘tweening’ or ‘inbetweening’.Inbetweens fill the gaps between keyframes. While keyframes are drawn by skilled anim…

19. Name 2 reasons to use stop-motion animation. Instead of more advanced computer-generated imagery (CGI)

    Distinct look. Stop-motion legitimately displays actual real-life textures, as CGI texturing is more artificial, therefore not quite as close to realism. This is appreciated by a number of animation directors, such as Tim Burton, Henry Selick, Wes Anderson, and Travis Knight.

20. What's persistence of vision?

    Persistence of vision is the fact that perception of an object does not cease for some time after the rays of light have ceased to enter the eye. "Persistence of vision" can also be understood to mean the same as "flicker fusion", the effect that vision seems to persist continuously when the light that enters the eyes is interrupted with short and regular intervals.

21. Describe one example of persistence of vision.

    The fact that a glowing coal appears as a line of light when it is moved around quickly has often been used to illustrate the idea of persistence of vision.