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

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

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

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

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

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

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

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

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.

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

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.)

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

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)

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.

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

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

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

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)

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