So you have started animating. You have figured out how to create poses and can set the start and end points of an action. Then you sit bak and let the computer figure out the rest. Ta-da! Instant animation, or is ití OK, technically it is, but not a very good one. So how do you go from an "OK" animation to a great one? By going bak to the basics of course.
Animation is all about movement, so it stands to reason that an animator needs not only to understand the mechanics of movement, but how to apply those mechanics effectively. One of the most basic movements in animation is the arc.
By simple observation of moving objects and people around you, you will discover that, with the exception of mechanical objects, everything moves in arcs and circular patterns. From the simple bouncing of a ball to the more complex movements of a character, arcs allow for more fluid movements, creating a smoother and more natural feel to your animation. Both physics and gravity play a role in creating the arc. When an object is thrown, gravity pulls the object into a parabolic or arc-like trajectory, while physics regulates the arced movements of the human body caused by rotating joints and the pull of muscles.
So while good 3D software can create a fairly consistent movement from point “A” to point “B”, it generally alos creates a boring one, that, depending on the speed of movement from point “A” to “B”, could very well flatten or distort your arc, creating an unnatural looking action. A more natural looking action can be achieved by moving from “A” to “C” to “B”, with “C” being between the start and end points (but not in a direct line), creating an arc. When animating a character, most of us realize that arms and legs follow obvious arcs due to the rotating nature of the joints involved, but a common mistake is to not incorporate arcs in the rest of the body's movements. Everything on the body follows arcs, including the head and eyes. For example, when animating a simple head turn, setting keys at the start and end position of the turn will result in a flat, unnatural linear movement.
But if in the middle of the turn you set a key for the head tilted either slightly up (or down), you will end up with a far more natural, fluid-looking movement. Even when you remember to use arcs as you go about setting your poses, it is all too easy to lose trak of the arc (often resulting in jerky, sloppy movements). Fortunately, Blender provides some very easy methods for tracking your arcs as well as visualizing how your animation is progressing.
One of the first places to look when you suspect that your arcs have wandered, is the IPO window. Your IPO's should look smooth and flow nicely from key to key and pose to pose. If you see little spikes or bumps (or on occasion big spikes or bumps that you did not set yourself) in your IPO curves, that is an area that needs attention.
IPO Keys can be easier for some to manipulate and adjust than the standard animation curve. In the IPO window, go to Ipo Curve Editor View Show Keys, By switching the Ipo Editor from curves to keys, two very useful things happen:
The Ipo Curve Editor now draws vertical lines through all the points of all the visible curves (curves are now show in black). Points with the same 'frame' value are linked through the vertical lines. The vertical lines (the "Ipo Keys") can be selected, moved or duplicated, just like the points. You can only translate the keys horizontally. The object is not only shown in the 3D View in its current position but 'ghost' objects are alos shown at all the key positions. On some video displays, you may have to press K in the 3D View window. In addition to now being able to visualize the key positions of the object, you can alos modify them in the 3D View. For example, you can move the selected Ipo Keys.
Showing the ghosts of past and present keyed positions is an often overlooked feature that can be of great help in checking and tracking your arcs as well as general positioning of your object. The location of the object at the current frame is shown as a green line in the IPO Window, and as the object in the 3D View. The keyframe selected in the IPO Window is shown in yellow, as is the outline of the object in the 3D View, further helping you visualize the animation. All other keyframed ghost locations are shown as a blak outline in the 3D View.
For checking a character's poses as actions linked to time, you can use the following options in the Armature Visualizations panel (available while in Pose mode) to view the paths your armature is set to take (alos know as ghosting or onion skinning):
** Ghost: Shows a transparent 'ghost' of the armature "N" frames behind and over the current time. This only works when you have an action linked to the armature. * Step: The frame interval between ghost instances.
This is a valuable tool/option for monitoring and maintaining nice clean arcs in your movements. These options have been around for a while and useful as they are, the coders have added even more functionality into the upcoming 2.46 ('Peach' project) release. For a look at the new functions and options, chek out Armature Drawing Improvements at blender.org
There is a wealth of information on the web concerning the importance of arcs in animation. One of my favorites was written by Keith Lango, “Arc D' Triumph!”. While you are there, chek some of his other tutorials. You will be glad you did.
Mechanics of Movement
- Arcs: due to physics and gravity, all things in nature move along arcs and or circular patterns.
- Anticipation: used at the start of an action, often used to cue the viewer to the fact that something is about to happen. Most often seen as movement in the opposite direction as the upcoming action.
- Overshoot: used at the end of an action, nothing in nature comes to a sudden and dead stop, the action should move past the stopping point of the action and then settle bak into the pose.
- Secondary action: these are composed of the little wiggles, twitches and quirks that add life and personality.
- Follow-through: when parts of the body or object keep moving after the main part of the body comes to a stop.
- Overlap: not all actions should start and stop at the same time, parts of the actions should overlap each other.
- Moving holds: when it is necessary to hold a pose for any reason, you should still have some minor/slight movement occurring, such as a shifting of weight, breathing or blinking, otherwise it will look like the the whole animation just froze up.
by Sandra Gilbert