FumeFX Problem

#1

Im creating a space shuttle launch and Im having a problem getting the smoke from FumeFX to generate correctly. I have 2 sets of Sources. 2 for the Shuttle going straight up, and two for the sideways blast thats on the ground.

My problem is the sideways blast looks flat. It doesn’t have any ripples in the smoke. My first test looked pretty good. I tried to improve upon it and it came out flat and worse, but Im not sure what settings I had that actually had the ripples going. If you can view my settings below and the image, could you tell me what settings I should use to improve it? Btw, the spacing is high because it takes VERY long when its lower.

The self-shadows are also flat and not working well. Im using vray and have a vray sun. Any suggestions?

Test Render

FumeFX Settings

Photo Reference

#2

Try higher Max Iterations, lower quality, add some turbulence, up the vorticity, lower advection stride.

#3

Definitely higher max iterations and Turbulence Noise detail. I believe you also need to turn up your X Turbulence value from 0, otherwise your turbulence noise values won’t be used fully (could be wrong, won’t be at a machine with Fume until Monday).

#4

Thanks for replying guys! What’s the differrence from Turbulence and Turbulence Noise? I see Turbulence has its own settings under the Obj/Src tab at the bottom, and Turbulence Noise under Simulation. This seems like a redundant feature, is it not?

Also Kevin brings up a good point, if my X Turbulence is 0, does the Turbulence Noise have no effect? I kind of wanted to stay away from increasing X Turbulence because I remember my simulation time went up by a huge amount the higher this number was.

Grury, Tonight I will play around with some of your setting adjustment suggestions. If anyone else has any ideas please share! Thanks again!

#5

The turbulence on the source tab applies a noise to the volume thats emitting ie if its a sphere it will apply a turbulence pattern to the volume - make it look like swiss cheese. This is so you don’t a such a uniform emission from object and standard sources.

This turbulence isn’t linked to the turbulence found in the simulation tab - which applies a turbulence to the velocity field in the fume grid.

Hope this helps,

Chris

#6

Thanks Chris, I believe it does help. In my case, I probably wont need a high turbulence under the Obj/Src tab because its not really seen by the camera. Is that correct?

Also, does anyone know why my smoke isn’t really casting shadows on itself? Is it because Im using Vray or Vray sun as my light source? It casts a shadow on the ground just fine, but the smoke itself isn’t creating shadows correctly. I tried making the ambient color closer to black, but the whole smoke turns black instead… Can’t achieve a realistic look.

#7

AFAIK vray lights nor vray sun are fully supported by Fume, IMO you should use standard lights and composite your smoke/fire passes over your action plates.

FYI, whenever you see your smoke rendered in the fume>render tab> ambient color, the light you are using isn’t supported by fume (unless of course you haven’t added the light to the fume illumination list).

#8

Thanks for the lighting tip. I originally decided to composite the smoke in, but i was getting jagged edges on the smoke when I brought it into AfterEffects. I assumed it was just a problem with FumeFX outputting Alpha channels. I saved the Smoke as png 48bit with Alpha. Maybe Im missing a setting in FumeFX to fix the jagged edges?

Question, If I don’t use Vray Lights and use standard lights, do I need to render in scanline for the smoke or can I still render with VRay? Either case, I’ll go back to attempting to compose and avoiding vray lights.

#9

Not sure why you would get jagged edges, you’ll have to post a sample frame. Are the jagged edges near objects or matte objects?

You can still render with vray and standard lights.

#10

Jagged edges were only on the border of the objects not being matted. Soon as I get on the computer with the shuttle i’ll get a test render and post to show what I mean.

#11

I did a test render with the settings changed and the smoke is definitely having the ripples Im going for. Thanks guys!

But Im still having an issue with the shadow. I’ve tried switching to direct light (standard) from my vray sun, and it had no difference. The only difference is that I needed to adjust visual falloff in fumefx.

I even turned off the GI in vray and it made no difference. Do I render in scanline to get this to look correctly?

Example Smoke

#12

If rendering in scanline , you need to go to your light settings, I think in to the shadow properties and enable atmosphere shadows, then obviously make sure you have your smoke set to receive and cast shadows in the fume floater, this should do it. I have never used vray with fume so don’t know about the GI settings, Scanline has always given me acceptable results.

Take it easy,
Chris

#13

You need to do the same in vray too! Also shadow maps will give you shadows from the fume and from objects onto the fume, vray shadows wont (or was that just with afterburn???)

#14

No both, It took me a while to notice this :S

shadow map is the best way to go.

#15

Well Im avoiding scanline because I would have to do a LOT of converting to rendering out the smoke pass with a matte.

I also tried using a Standard direct light with “Shadow Map” and I still had the same problem. Im going to try a few other things when I get home. Such as turning off GI in Vray and see if that helps.

#16

GI in Vray will not light the fumeFX smoke, GI will ony let the fire/smoke emit light. Direct/Spot lights with shadow maps and turning “Atmospheric Shadows” on in the “Shadow Parameter” rollout of the light is the only way to go. Will work well.

#17

Hey Jonathan,
What about using “ab shadow map” in the light Parameter, if you have ab loaded?

#18

I think off the top of my head ab shadow map will also work the same as shadow map.

Basically, using vray shadows will allow fume to cast shadows, but wont allow fume to receive shadows from geo. But will self shadow.

#19

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