I want to gradually move in on a still. I was using the 3d warp effects scale and position parameters. Setting the keyframes to spline produces a pretty good ease in/out effect that I'm looking for, however, not in exactly the way I want.
I want to cut to the image, with scaling in movement already at it's maximum speed and I want that speed to remain consistent until it approaches the end keyframe where it initiates the gradual change in acceleration that selecting 'spline' keyframes produces.
At the moment, if I set either of the two keyframes to spline, it automatically sets them both to it and produces an effect where when I cut to the still we appear to be looking at a static image and then begin to notice the camera gradually start moving in and then gradually stop, it's that gradual start I want to get rid of, whilst maintaining the gradual stop, but it doesn't seem to be possible to change the keyframe interpolation asymmetrically.
I guess nobody else wants to do this, or there just isn't a way to specifically do that. For posterity, though, I figured out what to do as a workaround, and it's simple enough.
Initially I hoped I could set a keyframe to before the clip starts when in the effect editor, therefore skipping the entire 'ramp-up' movement and cutting in to the clip when the effect is mid-stride and already at a constant velocity. However, even though you can see clip segment span to beyond the in and our boundaries represented in the effect editor window, it wouldn't allow me to put keyframes there. Hence me posting my question.
What didn't occur to me until after though, is that you can set a keyframe anywhere you like within the in and out boundary, and then alt+drag it out of that boundary after. It's annoying, because you can't move the position indicator within the effect editor window outside of the in and out span, thus you cannot figure out where you're placing this keyframe by an exact amount of frames, only roughly with mouse gesture movement, but it's good enough. Of course you could also trim the clip back at the head by the number of frames you want the movement to begin, set a keyframe at the beginning of the clip, set the keyframe to fixed, and then trim the head forward again to your original starting position, but that's more of a hassle and wasn't very satisfactory to me.