Alright... I got it... I had to Multiply the Invert of the previous
frames' rotation by the current rotation and then convert that Rotation
to Axis and Angle and Multiply the angle by 24 (1/FrameStep) before
resetting it in a Axis and Angle to Rotation node. I can't just multiply
the rotation because I guess at one point it goes over 360 degrees and
resets itself. If I multiply the angle in an Axis and Angle to Rotation
node, then it gives me correct results. Thanks to those who tried to
help me.
-Mathieu
Francois Lord wrote:
It's all in Arnold, I suppose?
I remember fiddling with this. Let me see if I can find something.
On 31/07/2012 16:35, Mathieu Leclaire wrote:
Yeah... of course.
I've tried using subtract and multiply with rotations and
quaternions, and multiply the results... I've tried so many things, I
can't recall all of them...
The best results I had came from rotating an x-axis vector (1,0,0) by
both orientations (previous frame and current frame) and using a
cross product and an angle between multiplied by 24 (or 1/Frame Step)
and use those values in an axis and angle to rotation node... that
gave me perfect results as long as it spins around the Y axis. If it
spins around another axis, it won't work. So I'm still looking...
-Mathieu
Francois Lord wrote:
I'm sure you thought about it, but just in case...
Is the motion blur too weak by a factor of 24?
:)
On 31/07/2012 15:35, Mathieu Leclaire wrote:
I cache an ICE tree with particles created in the modeling stack,
so I have no linear and angular velocity. I need these values for
proper motion blur.
Linear velocity is easy to calculate: subtract previous frame
position by current position and multiply the resulting vector by
the inverse of the Frame Step. That gives me proper linear motion
blur.
Now I need to do the same thing for AngularVelocity, but I can't
seem to find the right way to calculate it. The motion blur on the
particles are always too weak compared to the same animated
objects. How can I calculate the appropriate AngularVelocity value?
-Mathieu
