We are going to render some stuff in Arnold and some in Mental Ray, but
both should react to the same formula. In the end, we are passing an
AngularVelocity rotation value.
Merci pour ton temps Francois. C'est bien gentil.
-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
