Fluids Smoke


#1

I’ve recently started playing around with fluids and have gone over a lot of the threads on the board regarding them (mainly the Fluids Fire one, awesome information). What I want to achieve though is the fire as described in that thread, which I’ve gotten down really well, but I also want a nice self shadowed billowing smoke coming off from the top of it. I’m not sure what controls I need to adjust to get that effect. Basically to give you an idea of what I’m going for is an effect like that of in the movie Pearl Harbor when one of the planes was shot down it left a nice billowing black cloud of smoke from the damage done by the opposing forces guns. Fire was flowing out of the engines which I’ve got down, but I’m just not sure how to achieve the smoke. I could easily do this seperately with particles, but that would negate the whole exercise. I know it can be done, would I need seperate emmitters for that effect or could it be done with just a few emmitters in say one container, and if so what settings control the burnoff of the fuel of the flame causing it to smoke? I’m just not sure where to start so if anyone has any suggestions or could point me in the right direction I’d greatly appreciate it. Thanks!

Bill


#2

Like This?

Ive found that the key to getting good thick billowing smoke with maya fluids is to have a simulation with a very dense mass of fluid. For that image i used a dynamic grid for all 4 of the contents methods. The fuid emitter is set to 8 for density and 1 for heat and fuel.
Once you get your thick mass of fluid flowing the way you want, then just use a texture to get the billowing look. I like to use ‘spacetime’, but if you can an afford the extra rendertime, use ‘billow.’ For the coloring, I used a Y gradient that starts with black on the bottom and goes up to a light charcoal color. The incandesence is set to ‘temperature’ with a dark/blueish black for the main base and sharp falloff to a light charcoal. This just keeps the center dark, and makes the very edges of the fluid a bit lighter.


#3

Thanks for the response Brett, I’ll check into that tonight and let you know what I came up with.

Bill


#4

looks good powell. my only suggestion would be to texture the opacity and/or transparency a little - it looks a little too solid with so much shelf-shadowing.


#5

Thought the same thing myself at first but I think it looks better like that. If you were to see that in motion, with the appropriate fire/source at the bottom and comped into a background, I think it would be good. All it really needs is a FG/GI render so light wraps around the bottom some as well.
:thumbsup:


#6

that is a good point… would look better… Also, it would depend on what was burning - tires would create this kind of smoke. But if the fire Bill created looks anything like the one from the tutorial, I dunno that it would quite work. This kind of smoke (below) doesn’t really have a lot of flame visible underneath it. quick flashes of flame, but mostly just heat and smoke. Also in these pics you can see how much less solid it looks. WhiteRabbit’s probably right about the GI/FG being the main culprit there though.


#7

FG and GI + Fluids, mmm sounds like fun rendering time. Thankfully I have 102 Xeons at my disposal heh.


#8

I found the Maya scene that i created that smoke in. Ill re-render it tonite with some FG and GI jsut to see what it looks like…the color needs a bit of tweeking as well…


#9

From what I’ve seen through my own little tests, GI and FG doesn’t actually affect the way the Fluid looks, it just lets the Fluid cast FG shadows onto the floor etc.

:hmm:


#10

So far I haven’t come up with anything really close to what Powell posted. My attempts have yielded some pretty decent white whispy smoke, and some good steam, but nothing close to the big black billowing smoke that I’m lookin for. Anyone else have suggestions?


#11

Well the difference between the real images and the render is that the real one has more depth to it. Meaning the real one has more holes in it, the render is more ‘cilinderish’. Try animating the turbulence position and/or the turbulence velocity on your fluid emitter. As well increase your dispersion and leave your diffusion quite low.
Also I tend to crank up the self shadowing of my smokey fluids to at least 1.


#12

I agree, but I’m having a difficult time just getting something close to that. I’ll futz around with it some more tomorrow and post what I came up with.


#13

It’s because you can’t achieve that look with texturing alone, you need to have an actual simulation that’s really dense and does for real what opacity texturing only simulates. Check out the Nuke fluid example for some reference there. Still need to combine simulation and texturing, and texturing is going to give you awesome results, but I have found that texturing is more limited, especially if it’s animated and not just a single frame render!


#14

Spent a lot of time on fluids whilst working on some stuff for bbc. Had a lot of luck simulating wispy smoke using 2d fluids and found 3d fluids produced great volume effects but were unbareably slow.

One of the guys I was working with produced a fantastic plume of smoke from a volcano by using a particle system and then attaching fluid containers to the particle system, with a time offset using a mel script to perform an ‘xform’ rather than instancing. Slow as hell to render but really good volume effect nonetheless.

Now days I generally use a combination of 2d fluids, sprites and stock footage to get these types of effects.


#15

Hi Aneks. recently…I just do the same test as your friends does…but I do it in different way, My method is to assign a “fluid shader” to a particle (which particle must be set as a cloud type). Then using a “particleSamplerInfo” to tell the “fluid shader” about particle’s information…Like “opacityPP”, “rgbPP”…etc…to do someWhat hardware render effects…
That is…my “fluid particle” can fade out throught “opacityPP” with per particle’s lifespan…something like that…
Acutally, what I did is try to reporduce 3ds max “afterburn” volumetric render system in maya. Because Afterburn is just a particle system but render in vloume…(It’s dose not have any container). And Which maya’s fluid’s motion is happened only in container, If doing some what missle smoke…your container must be huge big that you may cannot stand with it. So, I use this approah to let the particle to form the shape and let fluid to render it in volume…It’s sound’s perfect!..but I got few of problems…I can post my test to you guys tomorrow. I can say it works quite well to me. :thumbsup: (still have some issue to fix anyway).
but Aneks, would you like to tell me more about your friends approah? I really interest in other’s way to do. Cause I don’t know about “xform”… If I’m understand right, is that he is still instancing a fluid container to each particle…and give each a time offset?.. it would be nice if you could tell me more detail’s about it…thanks.
I don’t know If you guy’s know this approah or not…I just want to share it.
Please forgive my poor english…especially in my grammar.


#16

Thanks for the input, I think I was going about it ass backwards and just tweaking the texture and not adjusting the simulation much at all. I’ll start playing around with that more and see what I can come up with.


#17

sorry for my late post…Here is my test.
all the thing needs to be improve… it is just the starting point…
http://home.so-net.com.hk/~donwong/cgtalk/Fluid_as_particleShader_06b.0055.JPG
http://home.so-net.com.hk/~donwong/cgtalk/Fluid_as_particleShader_06b.0082.JPG


#18

hey,
wow, that looks sick… how did you do that?

(yes I read your previous post)
I understand about the ParticleSamplerInfo and all the per-particle attributes, but how exactly do you go about linking a “fluid shader” (not even sure what that is :rolleyes:) to the per-particle attributes…

would you mind running through the steps, and/or some images to demonstrate how to do it? I’ve been wondering how to use normal particles with the benefits of fluids… I looked into driving particle motion with fluid voxels… but thats equally as slow, and I never quite got it to work in full 3D (only 2D)

thanks a bunch!


#19

I don’t know how long I can wait…
I’m pulling my hair over this, this is EXACTLY what I wanted to do but I dont know how to do it, and you’ve seem to have nailed it; I got my particle system animated cool, now I just need the “fluid” shader.

where are you 3don!!!?? :argh:


#20

sorry Gremlin, quite busy at the moment…
no scene on my hand now, but I can try to explain it.

  1. change particle to “cloud” type.
  2. create a static fluid shader, dynamic off, use texture for opacity, make it like a smoke ball.
  3. assign this fluid shader to particle…
    That’s it…now render out you would get your particle in volume…
    But, every particle is identical. and looking bad. Then you now should tune your fluid shader. To break the same look of every “smokeBall”, create a “particleSmaplerInfo”…connect it’s world position to fluid shader’s “texture origin”…render it. It looks random now. Then add all the perParticle attr you like now…like OpacityPP, radiusPP, etc etc… use samplerInfo to connect it to fluid shader.
    The most important things is you smokeBall… what it needs is to tune it. make it look better but keep it from slow render time. And you need to key the texture time to make each smokeBall seems moving…not like a texture…
    um…remember. The opacity in fluid shader is the one to define your smokeball shape…
    I hope it would help you out a bit…
    I’m still improving the come out result…If I have something new.I will post it then…