Animation Curves Animation curves are powerful tools that allow you to have maximum control over your animation. However, if your curves are handled incorrectly they can become overwhelming to wrangle. Here are a few tips to help you get the most out of your animation curves. Some of these concepts should be familiar.
While working in a Layering method Focus on the root- The center of gravity is the most important thing to get right when layering animation. Everything else will depend on it. If you can start from the root of the character and absolutely nail the physicality. You can use the curves of the root to inform the movement of the rest of the body.
Copy curves up the joint chain and offset- If you are dealing with a repetitive action such a run there will be several parts of the character that will loop in the same timing cycle. A quick way to rough this animation in is to solve for the root_y of the character, copy that curve to the root rotate x and the rotate x of all of the joints up the spine and even the neck and head. You and then play around by offsetting the position and scaling the values of the curves until you have some animation that feels organic.
Damper your curves to show energy settling- One of the things that will steal from the believability of your animation is the lack of residual energy. Body parts tend to stay in motion until something stops them. By dampering your curves you can show that gravity is gradually decreasing the movement of body parts. A dampered curve looks like a sin wave that gradually shrinks on one side.
Create sets- Use a script or a selection set to make groups of related controls easily selectable. Use the the curve of the driving force to inform the controls that follow. For example if you see a sharp move upward on the Y translation of your root, the chances are you will want to put positive values on the X rotation for the spine joints so that they drag against the upward root movement.
Scale your curves- Subtle animation can be difficult to refine because the movement is so small that it is hard to gauge if the mechanics are working properly. A great way to tackle this is to set buffer curves and scale up the curves for the section. By working larger it will be easier to troubleshoot timing, spacing and overlap issues. Once the scaled up version looks good you can refer to your buffer curves and scale the motion back down.
While working in the Pose to Pose Method In step mode key every control on full poses- By keying every control for a pose you will be locking all of the elements of the character into position and keeping your curves clean. You will most likely not be utilizing every control, but you want to make sure that you are holding it's value. If you don't key it in and that control is used in a pose further down the timeline, eventually that value will drift over a series of frames causing floaty movement. Sometimes I do not include the facial controls when keying the full character.
Work clean- Keep track of what controls you are using to form a pose and try to stick to the same ones for your next one. By keying the same controls you will avoid animation curves that counter each-other.
Use tight break downs- Well what do tight breakdowns have to do with using curves? If you use breakdowns to fill in the gaps of your animation you will be relying less on the computer in-betweens. That way you will be saving your use of curves for what they are best at...refining.
When my keyframes are all set and I start breaking down my shot. I like to insert full breakdown poses on every controller on at most every 4 frames. When I set the break downs I am focusing on my transitions. Will this breakdown pose favor the previous pose and act as an ease out or will it favor the following pose and act as a fast out? Should I add a breakdown after my key that overshoots the pose? I keep these things in mind so that I use the posing of the character to dictate how the animation curves will be shaped.
Switching over- Once you have full poses on every control of the character on every 3-4 frames than you are safe to switch into a spline curve type. I like to use a spline type that will show a nice preview of my animation without having to clean up any tangent handles. I do this by using plateau tangents or spline with the auto-tangent script.
Hold off on offsetting- Once I switch over I will hold off on offsetting keyframes until I have taken a pass to tighten up the timing and posing. This is the first time I am seeing the animation on ones so there may be some tightening up to do. I will push full poses around on the timeline to adjust the timing and adjust the placement of certain body parts so that I can work some built in overlap into the poses. By working this way I am able to get my animation pretty far along before digging into individual curves.
Tie down your curves. -Usually, the first time i adjust animation curves on a pose to pose shot is the tie down. In this pass I will go through and edit the curves on the main body parts. (Usually the root spine and head, sometimes limbs) When I go through to clean up the curves I am looking for places where the curve is obviously not flowing like it is supposed to. For example maybe there is a curve that makes a hard transition that ends at two equal keys that form a flat. If I am not looking for a hard stop in my animation I will adjust that first keyframe that makes up the flat to ease out of the transition.
Cancel out counter animation- The tie down pass enables you to clean up your curves but it also serves as a pass to help you get familiar with what is going on under the hood and which controls are doing the heavy lifting. You should keep an eye out for counter animation during this pass. Counter animation happens during a transition where the value of one control cancels out the value of another. This tends to happen frequently on the rotate Y axis for Stewie and Bishop. If you see places where one control counters another see if you can remove the animation from one of the controls and add it to the other or redistribute the movement equally between the two controls.
While working straight ahead. Use Gimbal mode on your rotations- If you use gimbal mode for your rotations your curves will be cleaner. Each handle of the manipulator will correspond to a single curve in the curve editor. Using local and world modes will set values on all of your control's curves every time the manipulator is moved. This can make your curves more difficult to wrangle.
Set your default curve types to spline- When you are working straight ahead you want the poses that you set in the view to flow seamlessly from one to the next. Setting your default curve types to spline can help withe this process.
Frame staggers- A frame staggers is a quick way to add texture your movement. Staggers are great for showing wind effecting part of a character or showing trembling limbs while a character is lifting or pushing something. To create a stagger use the insert key tool to put a key on every frame of the control curve you want to stagger. Select every other keyframe and drag the value up to the extreme for the stagger. Grab the bottom row of keys and drag them down to the lower extreme of the stagger. Then take a pass through and adjust value to add some randomness to the movement.
Well there you have it. These are some tips and tricks that I use to get the most out of my time spent in the curve editor. Try some of these ideas out and see how they work for you.