3 replies to this topic

[anthony]

Hello Everyone,

I'm tasked with creating a shot where I have slightly drifting (internal motion) nebula gasses, then an object comes through to effect those gasses and cause them to dissipate (like an arm going through smoke from a fog machine). After going through cmiFX's fractal video, I love how volumes can be sculpted and look natural - but as far as I have found, volumes can not be effected by rigid bodies or forces. So, it seems that I need to create this using a smoke solver. This solver, however, does not seem to have the ability to use fractals to build, as they need to be simmed into place or created from a modeled shape.

Is my best bet to model a very detailed shape and source from volume? I had also thought of, perhaps, having the smoke derive from a particle system - but there doesn't seem to be as much control unless I, again, model a detailed shape and fill it with particles, then derive smoke from them. But this seems to add an unnecessary step (unless anyone thinks I would have more control over the particles, and therefore, would make this shot more controllable).

I've searched for nebula's, but to be honest, none of them look the way I need them to.

I also haven't had much luck in being able to mix both the wispy and billowy textures into the same smoke system.
 cosmos_reference.jpg   231.34K   159 downloads
After this is figured out, I was also wondering if a fractal can be used as a color channel within a smoke material. Alejandro Echeverry mentioned coloring his dragon pyro sim by using a shadow color param - I mention this because it is the closest thing I have seen yet to a multi-colored smoke effect - but I haven't been able to find this param...

To be honest, I started going through the cmiFX tuts and message boards 2 weeks ago to learn houdini just for this shot. It definitely feels over my head, but I don't have much of a choice - I really need to figure this out...

Any advice you may have would be greatly appreciated. Thanks so very much.

[Klockworks]

You can very easily sculpt a volume and then send that to DOPs. Look into the initial data tab on the smoke object. Depending on how you sculpt the volume is which method you bring it into dops. If you end with a volume in SOPs that you really like, bring it in as initial data; if you make a model you really use points to create the volume in DOPs. Since you liked the cmi tutorial I would imagine you will go with sculpting the volume.

For the color, you can create a custom field(called Cd) and advect that around with your velocity.

[Div]

I would sculpt it in sops and then to make it move, react I would use a few microsolvers in dops. Have a look at this sidefx video that should put you on the right path.


"Building Fluid Solvers from Scratch" :: http://www.sidefx.co...2185&Itemid=226

Edited by Div, 26 June 2012 - 01:34 AM.

[jim c]

Yowza! That's a really, really cool video!