Howdy Houdini Gurus!

I am rendering some out of the box volumetric smoke. I am having a problem with popping in the render. The metaballs, copied to a particle system, which generate the i3d do not change dramatically frame to frame. However when I render it, the resulting volumetric shifts dramatically as if one of the metaballs were turning on and off?

Is there any i3d wizdom out there?

Thanks in advance!

is this in H7?

How is your PScale looking?

In all of my experience with I3d, one of the biggest things that causes popping is the Pscale. Your metaballs might look like they are expanding and shrinking like normal, yet your render still shows popping? Pscale is your problem.

If it is indeed a Pscale issue, then add a property pop to ur particles chain and in the scale channel, type in:

if($LIFE<.5, $LIFE,1-$LIFE)

-jon

Is the expression stating: if float $LIFE drops below .5 (halfway through life), then return the same float number $LIFE, otherwise return its compliment value?

This is how the expression works: $LIFE works between 0 and 1, 0 being just born, 1 being dead. For $LIFE<.5, this means that when life is less than .5, or 50% of alive or dead (you be the optimist or pessimist ), it returns $LIFE. Else, if $LIFE>.5, then the equation returns, 1-$LIFE, which shrinks the particles's size. So for example, if $LIFE==.75, then the return value is .25, or 1-.75.

I interpret the expression as growing the particles in size from 0 until the life of the particle is halfway lived, then after that it shrinks it back down to 0.

If you need to increase the size of the particle, without doing it @ the sop level, then the expression is as follows:

if($LIFE<.5, n*$LIFE, n*( 1-$LIFE)) where n is your modifier.

-jon

hey rudeypunk

do u have any expressions in ur copy sop?

do u filter ur iso surface?
have u tried rendering ur iso procedurally at the object level?

all the best

aracid