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Animated splines are created and manipulated in the camera viewport only while the rotoscope control panel is open. At the top of the rotoscope panel, you can click a button to get a list of what the left and right mouse buttons do, depending on the state of the Shift key.
Each spline has a center handle, an invisible(!)
rotate/scale handle, and three or more vertex control handles. Splines can be animated on and off over the duration of the shot, using the stop-light enable button
.
TIP: Vertex handles can be either corners or smooth. Double-click the vertex handle to toggle the type. This works during spline creation also, and the vertex type is propagated to succeeding handles that you create, so you can easily create all-corner, all-smooth, or arbitrarily-mixed splines. Corners are shown with a square; smooth points with a round dot.
Each handle can be animated over time, by adjusting the handle to the desired location while SynthEyes is at the desired frame, setting a key at that frame. The handle turns red whenever it is keyed on that frame. In between keys, a control handle follows
a linear path. The rotospline keys are shown on the timebar, and the
and 
“advance to key” buttons apply to the spline keys.
To create an animated spline, turn on the magic wand tool
, go to the spline’s first frame and left-click the spline’s desired center point. Then click on a series of points around the edge of the region to be rotoscoped. Too many points will make later animation more time consuming. You can switch back and forth between smooth and corner vertex points by double-clicking as you create. After you create the last desired vertex, right click to exit the mode.
You can also turn on and use create-rectangle 
and create-circle 
spline creation modes, which allow you to drag out the respective shape.
After creating a spline, go to the last frame, drag the spline to its best-matching location, using control-drag and ALT/command-drag to rotate and scale it as needed for the best match. Only after doing that, drag the individual control points to reposition them on the edge. Then go to the middle of the shot, and repeat that matching process. Go one quarter of the way in, readjust. Go to the three quarter mark, readjust. Continue in this fashion, subdividing each unkeyed section until the spline is in the correct location already, which generally won’t be too long. This approach is much more effective than proceeding from beginning to end.
Tip: Repositioning the spline curve animates the center origin control point and (hidden) rotation/scale point. That saves work, compared to animating each individual control point.
You may find it helpful to create keys on all the control points whenever you change any of them. This can make the spline animation more predictable in some circumstances (or to suit your style). To do this, turn on the Key all CPs if any checkbox on the roto panel.
The splines don’t have to be that accurate. They are not being used to matte the objects in and out of the shot, only to control blips which occur relatively far apart. (We concede that people do occasionally use these splines for more exacting purposes.)
©2024 Boris FX, Inc. — UNOFFICIAL — Converted from original PDF.