Smoke out of a moving train?

So I have this train. The train is moving. How do i get the smoke to come out of the chimney?
If i move the domain, the smoke does not Emmit from the particles :confused:
If I move the Flow object, it emits… But the path the train moves is huge, i can’t just make a huge Domain…

What should I do? :spin:

Is it not possible?

I’m a little confused by your question. The smoke emitter would be placed inside the chimney, and you might (for example) use a Lattice to cause the smoke (particles…) to follow the desired path, implying the influence of wind. (Or you could make a fancier simulation…)

I think FreeMind wants to use the Smoke simulation for this. And it appears that the smoke Domain cannot change it’s transform values (if you move the domain, the simulation continues wherever the domain was in the first place). Therefore, FreeMind would need an enormously large domain covering the train’s journey, with a smoke flow (via a particle emitter) traveling with the train. In order to get a good simulation on such a large domain, the domain resolution would have to be prohibitively high.

I like the problem FreeMind is posing. I think you could make some nice smoke using forces (like wind, turbulence, and vortex) to make the smoke behave as if it were moving (as though the camera were following the train). Of course, the smoke would have to dissipate fairly quickly. The main question I haven’t resolved yet is how you would move the smoke with the train. My best guess so far is that you’d bake the simulation with the static domain, and then find a way to animate the resulting voxel data (it would probably be an “external file” at that point) to follow the smokestack.

But I’m not sure how to do that, either. I’d love to know how to do it, though.

I was thinking about the same thing the other day, only rockets instead of trains. I haven’t got back to it yet, but I was thinking about particle system/volumetrics as a away around the limitations of the smoke sim. See here:


Holy smokes, Randy. That’s terrific! Please walk us through the process…

Ahh. I “cheat” so much smoke that I’ve only barely glanced at smoke-sim. I know that I can do three or four particle-system runs, going through a lattice, and with just a thimbleful of compositing magic, “voila… smoke… good enuf… done… print it… on to the next shot.” Now, I’ll watch this thread to see how it’s supposed to be done. :slight_smile:

if the smoke simulation is baked, can you move it where ever you want to?

Sorry, that’s all NRK’s work… not mine! see here:

I just think it might be a good course to pursue… but I have not explored it yet. Just trying to share ideas and I don’t know what kind of limitations there may be.


edit: @ ArMan: afaik no you cannot move the smoke sim even after baking, but I could be wrong. It seems to me from what I have used it, it works best at small scale stationary fire/smoke sort of stuff…

if the smoke simulation is baked, can you move it where ever you want to?

it’s pretty much stuck where it is if it’s baked.
That is, this smoke does not respond to a keyframed domain position animation, it just stays in place.
However, if you grab the domain and move it, the smoke snaps to the domains position after you comfirm the grab… Could this be a hard thing to fix for a dev?

But anyway, right now this seems to be impossible.
I think my best bet is to add wind force to the smoke and move the ground instead of the train.

Or, i could just fake it with particles as suggested, ill look into it.

Thanks yall.

you might have to move the background mesh to make it look like the train is moving…just a work around

but yeh ive had problems with this in past and why i dont go near smoke these days.

surely you should be able to move the domain,

+1 on asking the devs to let the domain be movable (animate scale/loc/rot vars). I understand that within the domain things need to be static and relative to the domain, but you could incorporate wind forces etc and then parent the domain to the smokestack or rocket, and voila!

Or am I assuming too much?

parent the background and lights to the camera and animate them to move past the smoke stack and smoke domain?

I am trying to do the train smoke too. I’ve been struggling with it for days. I can get good smoke but as soon as I change the simulation to be a child of the smokestack hierarchy, so that it follows along with the smokestack, it doesn’t render properly anymore. There’s some kind of quirk that needs to be fixed. Revolt-randy, you have a great work around. I’m going to do it that way. Great job!!

As others suggested a few years back, a Lattice is a good way to bend smoke. Then, let the smoke dissipate fairly quickly. (Ecologically friendly, you know – and actually typical of what train firemen tried to do when they weren’t makiing Hollywood movies …)