Monday, 11 October 2010

Unit 33 - Animation Techniques

Perception:


“The process, act, or faculty of perceiving.”

The ability to recognize there is more than one image, to be able to observe multiple images in one single image.

Image: http://www.ralphverano.com/view_item.php?pid=90075



Persistence of vision:

http://encyclopedia.thefreedictionary.com/Persistence+of+vision

"Persistence of vision is the phenomenon of the eye by which even nanoseconds of exposure to an image result in milliseconds of reaction (sight) from the retina to the optic nerves. This is because persistence of vision depends on chemical transmission of nerve responses, and this biochemical hysteresis is much slower than the light transmission." 

Persistence of vision, this basically is what the eye can see for short periods of time, for example; if you look at a negative image and focus on it, when the image is removed to a blank screen you will see a positive of that image in your eyes. Another example would be a motion illusion, This is were a image is in motion but it is hard to notice what motion it is in. The dancing woman is a prime example, she is moving clockwise and anticlockwise. You really have to focus to notice the change in direction as it's hard to see, I've only seen the direction change twice in several minutes of viewing the animation. The image is a classic example of persistence of vision.


Frame rate:

http://encyclopedia.thefreedictionary.com/frame+rate

"Frame rate, or frame frequency, is the measurement of the frequency (rate) at which an imaging device produces unique consecutive images called frames. The term applies equally well to computer graphics, video cameras, film cameras, and motion capture systems. Frame rate is most often expressed in frames per second (FPS) and in monitors as Hertz (Hz)."

Frames is a sequence of images at a rate, these images produce a constant picture. This gives the impression of motion in the picture. To give a good impression of a motion picture the frames per second (FPS) has to be constant and not lagging. 


Flicker Fusion Threshold:

http://encyclopedia.thefreedictionary.com/Flicker+Fusion+Threshold

"The flicker fusion threshold (or flicker fusion rate) is a concept in the psychophysics of vision. It is defined as the frequency at which an intermittent light stimulus appears to be completely steady to the observer (this article centers around human observers). Flicker fusion threshold is related to persistence of vision."

The flicker fusion threshold is about the amount of FPS you see, the threshold naturally for most entertainment services would be 30 FPS, This is above the minimum threshold which is 24 FPS. Below this number the human eye can notice latency in the picture quality and above the picture will look smooth. For computer and video gaming the standard of frames is usually 30-60 FPS. On a high end gaming PC frames can be in the hundreds depending on the title.

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