I have a strange issue.

I have particles being emitted from a surface, and then passed through an advectbyvolumes node to create an inky smoke like effect. I have “geometry velocity blur” turned on, and “allow motion blur” turned on in the mantra node, and everything looks fine, except that mantra stops mid-frame while rendering, and all CPU activity drops to 0. Turning “allow motion blur” off fixes this freezing, but destroys the smoke effect.

Any idea how I can fix this? It seems to be related to the number of particles I'm emitting too.

I'm also running on Ubuntu 9.04 32 bit

Thanks
- Stevie

Hi Stevie,


It sounds like you may have a particle passing too close to camera?

What happens if you increase the value of your Near Clipping plane?


cheers,
-j

Hi Jacob,

Thanks I'll have to give that a try. I did notice that if I ignore the advectbyvolume node, the problem seems to go away. Any ideas why this might cause it?

I'll go and try altering the near clipping plane…

Changing the near clipping plane doesn't seem to help unfortunately.

I also tried changing the advectbyvolume node to advect position instead of velocity (maybe it's to do with the particle getting velocity information from the dop network? I don't know too much about this stuff so I'm only guessing ¬_¬), and that seemed to help a little. However I've now lost the handy velocity blend slider so I've got less control. (Probably unrelated but now mantra fails to render at all, getting stuck on “creating attributes”. It's not going too well today!)

If anyone has any more insight on this, I'd be very pleased to hear it!

thanks
- Stevie

Hi Stevie.

I'm a year late to your post, but am also seeing my renders freeze on the advectbyvolumes POP. Did you arrive at any solution or workaround? Whether or not it's the culprit, my GUI freezes on the advectbyvolumes/velocity_source/transform_into_our_parents_space sub node.

I'm running Houdini Apprentice v11.0.547 on Mac OS X v10.6.4

Thanks.

-Greg