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 #!Rall615 Animation and Frame Rates #!N #!EC #!N #!N In making 
animation for TV, you must be aware of "frame rate." Just 
like all the other references to sampling in the discussion above, 
TV "samples" time at 30 frames per second (25 in PAL). 
That means that at most you can have 30 time-step changes 
per second of video (unless you choose to skip some time 
steps in your data). Generally, you may want to show many 
fewer changes than that or the phenomenon may go by too 
quickly for the viewer to comprehend. On the other hand, when 
you rotate an object you want to make as many small 
changes as you can afford. The result will be smooth animation 
rather than jerky cartoon-like movement. One rule of thumb is to 
rotate no faster than 3 degrees per frame. That means that 
your object would rotate 90 degrees in one second, or 360 
degrees in 4 seconds. Like any rule of thumb, this can 
be adjusted depending on the case at hand. For example, it 
is often useful to record the rotation at more than one 
speed. The human visual system will detect different levels of detail 
in an object depending on its motion rate. This can be 
used to your advantage, to get double-duty out of your visualization. 
Record and play it at one rate, and viewers will see 
one aspect of your data; play it faster or slower, and 
different details will be noticed. And often, it is good practice 
to let an animation "loop" a few times, allowing the viewer 
to observe the entire process from beginning to end. #!N #!N 
The Sequencer also can generate "palindromic" motion in which the object 
swings back and forth rather than jumping from the end of 
a series back to the beginning. Be sure that you use 
this feature in a meaningful way: time steps shown in reverse 
order imply time running backward. Annotation is definitely required in this 
case! #!N #!N #!N  #!F-adobe-times-medium-i-normal--18*   Next Topic #!EF #!N #!N  #!Lall616,dxall617 h Presentation: Issues and Techniques  #!EL  
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