how to make a dryice smoke?

[daehuck]

http://vimeo.com/60070729

I want to make a smoke like this.

I used a pyro fx - dryice but it doesn't look good.

my smoke looks weak and noisy,

but reference video's smoke is very strong and solid(maybe)

Can I get a some advice about this?

Any comment is helpful for me

Thanks.!

Here is my Hip file.

(ignore off geo)

20130617_scene5_smoke2.hip

[kleer001]

First you need a light in your scene to give the smoke some shape. And if it's not thick enough for you you can

- scale up the source density (which it looks like you're animating from 5 to 0 over 36 frames)

- or you can beef it up in the render in your uniform volume shader's cloud density channel

- or directly to the volume so you can see it interactively by putting down a Volume Mix SOP and set the post multiply to however more dense you want it.

I tried the dry ice pyro fx shelf too and the settings looked fine to me.

[substep]

check your scene scale. My guess is an FBX import from maya. The bottle in your scene is over 120 meters tall. If I remember right. When Import FBX, you need to be in centimeters in maya, but treat them like meters. So if an object is the right size at a scale of 1 in centimeters. group it, scale the group to 0.1, freeze transforms, then export that as an FBX. that should give you the proper scale in houdini. You'll get much quicker sim times, higher resolutions grids, and more predictable results when working/simming to scale.

also, try not to save your scenes mid sequence, save on the first frame ")

[daehuck]

check your scene scale. My guess is an FBX import from maya. The bottle in your scene is over 120 meters tall. If I remember right. When Import FBX, you need to be in centimeters in maya, but treat them like meters. So if an object is the right size at a scale of 1 in centimeters. group it, scale the group to 0.1, freeze transforms, then export that as an FBX. that should give you the proper scale in houdini. You'll get much quicker sim times, higher resolutions grids, and more predictable results when working/simming to scale.

also, try not to save your scenes mid sequence, save on the first frame ")

thanks, I have to check the size of grid.

But they intercts correctly when i use a ambelic format. strange...

Anyway thanks for your comment

[daehuck]

First you need a light in your scene to give the smoke some shape. And if it's not thick enough for you you can

- scale up the source density (which it looks like you're animating from 5 to 0 over 36 frames)

- or you can beef it up in the render in your uniform volume shader's cloud density channel

- or directly to the volume so you can see it interactively by putting down a Volume Mix SOP and set the post multiply to however more dense you want it.

I tried the dry ice pyro fx shelf too and the settings looked fine to me.

Thanks. I have to study more in pyro options

there are so many options in pyro and it borders me..

Your comment is very helpful for me

[kleer001]

Thanks. I have to study more in pyro options

there are so many options in pyro and it borders me..

Your comment is very helpful for me

Peter Quint is the man. Also SESI has a good one here:

This one is a little behind the times, but covers a lot of good basics.

https://vimeo.com/44619541

Time spent here is worth it!

http://www.sidefx.com/index.php?option=com_forum&Itemid=172&page=viewtopic&p=117096

[bunker]

You can create dry ice with negative temperature.

[daehuck]

Peter Quint is the man. Also SESI has a good one here:

This one is a little behind the times, but covers a lot of good basics.

https://vimeo.com/44619541

Time spent here is worth it!

http://www.sidefx.co...wtopic&p=117096

Thanks, your link is nice,

I'll watch every video!

[daehuck]

You can create dry ice with negative temperature.

yes, it is closely related with temperature.

but i don't know exactly how it works

So, I have to study harder

thanks for your reply!

Edited June 20, 2013 by daehuck

[old school]

Temperature is what is driving Buoyancy.

Buoyancy is used to affect the velocity of the fluid sim using the Gas Buoyancy DOP installed inside the Pyro Solver DOP asset.

Looking at the parameter interface of the Gas Buoyancy DOP, it literally takes the temperature field as a mask and given a direction vector, usually {0, 1, 0}, takes the "vel" velocity field and adds an appropriate force:

vel = vel + temperature*buoyancyDirection

So if you set a -ve buoyancy direction {0, -1, 0} then the temperature will be used to drive the velocity downwards instead of upwards.

If you want absolutely no temperature to affect the simulation, set buoyancy to 0 then let other forces shaping the "vel" velocity field to take over.

----

In general, if you find a specific piece of functionality on the Pyro Solver invariably there will be a specific micro-solver inside the Solver node that is affecting one or more fields. Invariably it will be the "vel" velocity field.

[daehuck]

Temperature is what is driving Buoyancy.

Buoyancy is used to affect the velocity of the fluid sim using the Gas Buoyancy DOP installed inside the Pyro Solver DOP asset.

Looking at the parameter interface of the Gas Buoyancy DOP, it literally takes the temperature field as a mask and given a direction vector, usually {0, 1, 0}, takes the "vel" velocity field and adds an appropriate force:

vel = vel + temperature*buoyancyDirection

So if you set a -ve buoyancy direction {0, -1, 0} then the temperature will be used to drive the velocity downwards instead of upwards.

If you want absolutely no temperature to affect the simulation, set buoyancy to 0 then let other forces shaping the "vel" velocity field to take over.

----

In general, if you find a specific piece of functionality on the Pyro Solver invariably there will be a specific micro-solver inside the Solver node that is affecting one or more fields. Invariably it will be the "vel" velocity field.

first, Thanks for your kind reply.

So, If i have a negative temperature and negative buoyancy direction {0,-1,0}

smokes will go higher. Is it right? I tested with houdini and it seemes too.

Edited June 21, 2013 by daehuck

[old school]

Yes. Pretty simple. Gas Buoyancy DOP makes it so.

[daehuck]

Yes. Pretty simple. Gas Buoyancy DOP makes it so.

All right.

Thanks for your kind reply again:)