1. Computer Graphics Imaging Ying Zhu Georgia State University
Lecture 17
Basic Animation Techniques

2. Key frame animation
An animator creates, modifies and inserts key frames for important moments of an animation sequence
Not necessarily at equal time interval
Computer will generate (interpolate) frames between key frames
Animator can not directly modify the in-between frames

3. The animation window configuration
Blender has a pre-defined animation window configuration
Outliner
3D view
IPO curve editor
Timeline
Buttons window

4. How to insert a key frame?
Specify the current frame number
Right arrow key: advance 1 frame
Left arrow key: go back 1 frame
Up arrow key: advance 10 frames
Down arrow key: go back 10 frame
Or type in a specific frame number

5. How to insert a key frame?
In 3D view, press I key to see the “Insert Key” menu
Choose a parameter (or parameters) to record for the current key frame
Loc(atation), Rot(ation), Scale, and their combinations …
Can choose “layer” to do layer animation
More about this later

6. How to insert a key frame?
Move mouse cursor to the Shading (F5) panel, press I to see another “Insert Key” menu
Choose “RGB” to animation color
Choose “Alpha” to do alpha animation

7. How to insert a key frame?
Remember the sequence
Set frame number first
Move the object (or change color/alpha)
Press I to insert a key frame

8. How to play an animation?
Press Alt + A in any window
Drag the green line in the IPO curve editor
Drag the green line in the Timeline window
Press the play button in the Timeline window

9. How to render an animation?
Go to Scene (F10) panel
Set “Output” path
This is where your animation files will be stored
Set Sta(rt) and End frame numbers
Set Format
Choose PNG/TIFF/Jpeg if you want to create your video with a compositing software (e.g. MovieMake, After Effects, Shake, etc.)
Otherwise, you may choose QuickTime, AVI codec, etc.
Can also change image size, aspect ratio, frame rate, etc.

10. How to render an animation?
Set image size percentage (optional)
By default it’s 100% (full size)
If you just want a quick preview, you may choose 75%, 50%, or 25%.
Press the Preview button will set the size to 50%
Press ANIM button
Minimize the render window to avoid slowing down the rendering process
Check video file under the “Output” path you just set
Or press the “PLAY” button to play the video

11. Timeline See animation sequence on a time scale
You can switch between frames and seconds
Has VCR like buttons to play animation, fast forward, or rewind
Can add markers to indicate important events on time scale
Drag the green line to a certain frame (or second)
Press M to add a marker
Press Ctrl + M to name a marker (e.g. “jump”, etc.)

12. IPO Curve Editor
In the IPO Curve Editor, you can see all the key parameters for key frames and the curves that interpolate the key parameters
E.g. the LocX, or RotZ values for the key frames and the curves that interpolate them
By default, IPO curves are Bezier curves. You can change them to linear or constant
An IPO curve records the values of a parameter over the time frame of an animation sequence

13. IPO Curve Editor To modify an IPO curve Press Tab to enter edit mode
Right click key frame point to select and then move it
Right click key frame point handle to manipulate the curve (just like manipulating a Bezier curve)

14. IPO Curve Editor What can you do in IPO curve editor?
Change key parameters by moving key frame points
Insert (Ctrl + LMB) or delete (press x) key frame
You can modify how the key parameters are interpolated by manipulating the curve
Smooth IPO curves
Clean IPO curves, etc.

15. IPO curve editor Different IPO types Object Material World Texture
Shape, etc.

16. IPO curve editor How to make a cyclic motion repeats forever?
Extend an IPO curve with “extend mode”
Select “Curve”  Extend Mode
Constant
Extrapolation
Cyclic
Cyclic Extrapolation
See the helicopter demo

17. IPO curve editor
Most animations are recorded in the LocX, LocY, LocZ, RotX, RotY, RotZ curves
You can use the Time curve to change the speed of the animation recorded in the other IPO curves
A 45 degree slop: no change in speed
A <45 degree slop: slow down the original motion
A >45 degree slop: speed up the original motion
An “up” slop: move forward
An “down” slop: move backward

18. Layer animation
You can use layer animation to make an object disappear and then (perhaps) reappear
Suppose you want an object A to disappear from frame 50 to 60, and then reappear
Set frame number to 49
Select A, press I and insert a “Layer” key (for frame 49)
Set frame number to 50
Select A, press M to move A to another layer
Switch to the new layer where A is now, Press I and insert a “Layer” key (for frame 50)
Set frame number to 61, select A, move it to the old layer,
Press I to insert a “Layer” key (for frame 61)

19. Alpha animation
Use Alpha animation if you want an object to fade in and out
For example, you want an object A to fade out from frame 50 and then fade in at frame 80
Select object A
Move mouse cursor to the Shading (F5) panel, press I to open the “Insert Key” menu
Choose “Alpha” to do alpha animation
In the IPO curve editor, insert keys for frame 50, 60, 70, and 80.
Change the value of key for frame 60 and 70 to 0.0 (which means A will be invisible between these two key frames)
Go back to Shading panel, press “Ztransp” button or “Ray Transp” button
You’ll see the effect in rendered video