How to get denser & more opaque smoke?

[ecarlsen]

Hi all, I've got a general workflow questions as I continue getting my feet wet with Phoenix FD.

When you're attempting to make a smoke sim thicker and more opaque, like a volcanic eruption of ash or smoke from a gasoline fire, is the best way of doing this to increase the discharge amount in the smoke source? Does increasing the "Smoke" parameter in the source also help? Any other settings you typically go to first?

And is it possible to achieve this look if you're resimulating a low res sim using "Amplify Resolution", or is it important to start high res? My resims haven't looked very dense/opaque when rendered, though it's possible I started them at too low a resolution before amplifying them.

Thanks!

[georgi.zhekov]

Hey,

You can take a look at our volcano example scene here - https://docs.chaosgroup.com/display/...Example+Scenes

As for the denser look - if you mean the simulation part - make sure that your scene scale is large enough. If your scale is too low your smoke will look like a torch, instead of a volcano.

For the rendering part - just set you smoke opacity to something like 0.9 and you should be good.

[ecarlsen]

Hey Georgi, thanks for your fast reply!

It's definitely possible my scene's scale isn't large enough. I've already set up camera moves and several imported smoke sims set up within it, so am wondering if it would work to run the simulation in a larger-scale scene, then import the cache and scale it down in the smaller scene? Or would both need to be larger-scale for it to work?

Also how do you determine how large a scene's scale needs to be? Is there a general size that is recommended, whether dimensions or unit type?

For the volcano example scene, unfortunately I'm in Maya - do you have a similar Maya scene I could check out?

[georgi.zhekov]

There is no need to change the scene - just go into your Grid rollout of the simulator and there you can change the scene scale for the Phoenix simulation.

Generally it's best to start with real-world scale for your scene and then adjust from there.

The scene is for Max only I'm afraid, but I hope we can port it to Maya soon.

[ecarlsen]

Okay thanks!

[ecarlsen]

I have one more question on the scene scale, to make sure I'm understanding it.

Say I'm simulating some heavy smoke for a volcanic eruption, where the real-world eruption would be around 1km (1000m) wide at the base where the smoke/ash is being emitted.

In the Grid rollout, should I set Units to "meter" and Scene Scale to 1,000? Or, if units are derived from Maya, and my Maya scene scale is set to cm, then Scene Scale should be 100,000 because 1km = 100,000cm?

[Svetlin.Nikolov]

Hey,

Not exactly - in the Grid rollout you have a Total Cells info box, which shows how big the container is to the sim, accounting for the Scene Scale.

You have to adjust the Scene Scale so the sim is 1000m / 100K cm wide in that info box

[ecarlsen]

Ah okay that makes sense - thank you both for your help!