efficiency of object sources and collisions?

[joconnell]

Hi Folks,

Using fairly good sim settings I can get really nice sim results using simple sources and just the blocking controls on the fume grid but when I start using objects sources and object collisions I get quite steppy results and far slower sims. I'm working on a lot of avalanche stuff that has to integrate into live action footage so it has to integrate and interact with the ground and any objects that it comes into contact with. I was wondering in terms of sim speed and quality, does the level of poly detail of the collision objects or object based emitters make a huge difference to a fume sim? Or is it a case of the object being broken down into voxels regardless of its topology? Would I be better off with really simple poly layouts for my objects or will fume do its own voxel subdivision around the object relative to the size of the ffx grid?

Also with particle sources I get quite dotty results - in terms of particle and fume substeps what level would I need to go to to match the smoothness of using a simple fume emitter? I know it depends on how quickly the particles are moving but I've had nice results with fast moving simple sources with no substeps at all - is it more to do with the particles radius controls being like the volume of the simple source?

Cheers!

John

[Rif]

"does the level of poly detail of the collision objects or object based emitters make a huge difference to a fume sim?" "Would I be better off with really simple poly layouts for my objects or will fume do its own voxel subdivision around the object relative to the size of the ffx grid? "

Nop objects get Voxelized in the grid based on the Spacing amount and isnnt related to topologie as far as i knowand iv seen..

"more to do with the particles radius controls being like the volume of the simple source? "

Yes for the radius at first .. When doing an FFx Sim with Particle Base , this is the Parameter that you want to tweek at the first .. U dont want to have a Radius bigger than a Cube of the grid basicly ..Your goal is to avoid that.. And i know its hard cause of no Viewport ( "AB Stile" ) Particle Radius Visualisation but its still manageable ..

and Then , Blur Source Object checkbox in the OBj\Src Tab is also helping his part ..

Also use Subsamples if needed based on the speed of what u got moving per particles and how much velocity your pushing from them !

Again , i suggest building u r volume with lots of small particles disturbing and pushing ..

Also , you can use the AFC Curve in the Rendering Tab for Controling Opacity of the Smoke ( but so that the life of the smoke dies smoothly and no poping ) .. u can even create crazier effects playing with that shading afc..

hope that help ..

[joconnell]

Rif once again you're a star

The info about the particle radius was the key there - it's gotten rid of the "dotty" look from my thinking particles sources. Still having huge problems over here with cameras coming from xsi into max so haven't set up fume sims - it seems like it'll come together in the end though :?

Thanks again!

John