Maya 2012 Tangents — Function Curves

 

In ani­ma­tion every­one tends to work slightly dif­fer­ently.  I am not say­ing that this is the only way to work but I tend to work in the fol­low­ing curve flow in my process.

Pass 1 - Stepped: Great for set­ting up thumb­nail style key poses.
Pass 2 - Lin­ear: Good for set­ting ini­tial time. Action too fast = Keys too close together. Action too slow = Keys to far apart.
Pass 3 - Auto: Best of both worlds Spline / Plateau
Pass 4 -  Fixed, Plateau, Flat, and or Spline. Very spe­cific curve type for spe­cific reasons.

Maya Curve Types

1. Stepped
2. Stepped Next 
3. Lin­ear
4. Spline
5. Flat
6. Plateau
7. Clamped
8. Fixed
9. Auto (New 2012)

Found on toolbar

    Stepped - Con­stant value until there is a new value.  A good use of the Stepped Curve is with a proxy cam­era to estab­lish cam­era cuts.  To avoid motion blur issues you should replace the proxy cam­era posi­tions with sep­a­rate ren­der cameras.

Tip & Trick:

1. Cre­ate or Import Ren­der Cam
2. Par­ent con­strain the ren­der cam­era to the proxy.
3. Delete the con­straint.
4. Advance to the next cam­era place­ment.
5. Repeat 1 — 5 for all cam­era positions.

    Lin­ear - Con­stant rate of change.  This curve type is great to use while try­ing to estab­lish the ini­tial tim­ing on an ani­ma­tion.  If the action hap­pens to quickly then the keys need to be spread fur­ther apart.  If the action hap­pens to slowly then the key need to be brought closer together.

    Auto - An Auto tan­gent type will adjust the tan­gency of a slope as to flat­ten out as it get closer to the value of the key adja­cent to it.  THis is a nice fea­ture and seems to be based off of the AutoTan­gent Script.  THe best of both spline and plateau seem to be at play here. Pit­fall: the slope flat­tens more than needed as the key is adjusted. If you manip­u­late to the desired angle and then move the key it will hold the desired slope.

    Spline - Equal slope going in and out to a keyframe.  This will give nice smooth motion; how­ever, it will cre­ate over­shoots that are unwanted.

    Flat - A flat curve type sim­ply sets the tan­gent angle to be a zero slope.  Most com­mon pit­fall I see stu­dents doing is select­ing the whole curve my mis­take and then con­vert­ing to flat.  The will cause a slow and go type of effect like a car with an accel­er­a­tion problem!

    Plateau - A Plateau curve type will elim­i­nate over shoots as long as the key frame val­ues are within a tol­er­ance range.  This range is greater than the clamped func­tion. Pit­fall: Con­vert­ing the whole curve. Make sure you only use it where nec­es­sary or it can inter­fere with ease in sit­u­a­tions that you have already set up.

    Clamped -  A clamped curve type was most com­monly used to elim­i­nate over­shoots on foot and leg move­ments. Basi­cally we two keys are with a small value dif­fer­ence from one another that dif­fer­ent on slope is clamped off.  The end result is much like flat and plateau but the tol­er­ance range is much smaller.  Pit­fall:  is in not zoom­ing in on your curves to make sure that the val­ues of the keys are equal.

Found in Menu Set

Fixed - A fixed curve type sim­ply fixes the slope of the curve to a spe­cific value.  If you move the value or time of the keyframe the slope will remain the same.  Note: Any­time you break a tan­gent it auto­mat­i­cally con­verts to a fixed tan­gent type.  If you are curi­ous as to what the tan­gent type is for your keys:

1. Select some keyframes
2. In the Graph Edi­tor nav­i­gate to Dis­play -> Spreadsheet.

In Maya 2012 the tan­gent type but­ton at the top of the graph edi­tor acti­vates when a sin­gle keyframe is selected.

Stepped Next -  Stepped Next curve is used with FBIK.  The dif­fer­ence between the Stepped and Stepped Next is that there is no con­stant value out.  It sim­ply is reversed so that the value does not hold on the out tan­gent but rather switches to the new value immediately.