I am exploring the few ways of interpoling rotations in houdini, and it seems that quaternions can only be interpolated linearly. why is there no spline or cubic equivalent for them? is it mathematically impossible?
or maybe I am doing things wrong, but if I simply rotate a box, and set a qlinear() interpolation for all the animation segments, and the change of rotation axis is very abrupt.
I found a little work around by working the resulting rotation channel in chops and apply a few filters in order to smooth the movement, but is there a better way?

hi,

I have absolutely no knowledge in quaternion math yet, but have you set keyframes to your channels yet? If you try to rotate it interactively, you might notice that it may jump at certain degree. But if you set keyframes to the rotation channel, it should fix the problem. Or at least in theory…

Don't take my word for it.

You are correct, frading - Houdini does not have a qcubic() or such interpolation function yet.

yet? does that mean this will exist in the future?

As far as my latest discussion with SESI went over this, they realise that the suite of quaternion interpolation functions is incomplete and they are going to be working to address that. As far as versions are converned, I'd hope that 6.1 would have it.

Cheers,
Jason

great, this is good news. But you are sayin “the suite of quat interp fonctions”? do that mean there are several such fonctions? I have only seen the qlinear(). which have I missed?