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avillabon
03-20-2010, 07:35 PM
I am working on a series of helicopter shots which I have already tracked using PF Farm. What i need to do now is add rising smoke as if there had been many fires the last few days. This of course should look as photo real as possible. One of my main concerns if that it is around 30 seconds of footage which will make the simulations extremely heavy and the other thing is the fact that the camera is so far away from the ground that the size of the sims would be quite massive as well. The good thing is that I could add some extra camera shake if I needed help the effects blend a bit.

Here is a screenshot from 3 different moments of the edit.

http://img338.imageshack.us/img338/9119/helishots.jpg

How would you approach these shots? Regular particles with sprites, fluids? I really like to get some ideas and see what i can do with this.

Thanks for your help!

Alex

sethfair
03-20-2010, 09:56 PM
This seems more appropriate to ask the folks in the Maya Dynamics forum. I don't think there really is any way around the massive computations you will need to do. Lots of emitters and several fluid containers would be required. I had to do a large scene like this and it was quite heavy and intensive. Maya 2011 looks like it might help this a little bit with cache size when it comes out with dynamic fluid containers. I'd be interested to see what others think the best approach is and how yours shot turns out. Good luck.

avillabon
03-20-2010, 10:08 PM
This seems more appropriate to ask the folks in the Maya Dynamics forum. I don't think there really is any way around the massive computations you will need to do. Lots of emitters and several fluid containers would be required. I had to do a large scene like this and it was quite heavy and intensive. Maya 2011 looks like it might help this a little bit with cache size when it comes out with dynamic fluid containers. I'd be interested to see what others think the best approach is and how yours shot turns out. Good luck.

You are right.. can any of the moderators move this thread to the maya dynamics forum?

thanks

Alex

InfernalDarkness
03-20-2010, 10:27 PM
I think you just start small. Make one good smoke plume that works, then replicate it around and see how that works. Learn how much RAM/rendertime it takes to make one acceptable one, to start. Take those sections around your smoke emitters and box in some occluding geometry, which could either be comped out or black holed at rendertime. Keep it simple at first.

Once you have one good sim down, another alternative would be to just render this sim separately, from different angles, and then comp it back in as footage "cards". This could be used in conjunction with active sims, to help build up a sense of volume, or fill in areas that don't need heavy smoke.

Just some ideas!

avillabon
03-20-2010, 10:54 PM
Do you see this as a job for fluids or particles? I personally havent done fluids in maya but I have a few training dvds that i purchased and never saw perhaps now is the time.. What do you think?

Alex

InfernalDarkness
03-20-2010, 11:00 PM
Fluids are pretty easy to work with once you get the hang of 'em. They don't light too well with MR, but they're workable. If you plan on using the sun/sky for example, having any fluids visible breaks the FG environment emission for some reason, at least in my scenes in Maya 2009... But that's workable.

Particles, meh. I don't believe you'll get realistic smoke from particles alone. You could have particles driving your fluid obviously, but I think voxels create the most realistic smoke.

avillabon
04-13-2010, 02:45 AM
Its been about two weeks and i havent had the time to play around with fluids as much as would have liked, but im getting there..

I had to do a couple quick simulations with simple particle systems + cloud shader which were used as a placeholder for the effect. A few days ago I came across another thread where i read that you could actually use a fluid shader to shade your regular particles. This of course would be perfect for me since I already did these particle simulations. I connected the fluid shader to the particles and it renders as expected. The problem I'm having is the fact that they are not fading or rotating like they should. If you look into the particleShapes themselves you can see i have connected a ramp to the opacity as they get older but apparently this is no longer driving the opacity now that there is a new shader connected.. What am i missing?

Im uploading the scene file so you can better see what I have done. You will find emitters from 1-5 and particles from 1-5, the one with the new shader is particle 2.

Hopefully someone can take a look at the scene and help me out with this as this would be a perfect solution! Once i get this working (opacity issue and rotation) I can just tweak the fluid shader to my liking and render it out!

Thanks!

Alex

SheepFactory
04-13-2010, 03:20 AM
Can you please post a link to that thread where they explain how to hook up a fluid shader to a particle shader?

Aikiman
04-13-2010, 03:55 AM
Sorry I haven't had a look at your scene, but are you using 2011? If so you could be in luck as the fluid shader has a texture rotate attribute now that I believe you can connect to particle lifespan for instance. The fluid shader > to cloudies method requires connecting it through the particle sampler node much like cloudy particle works anyway so all your attributes need to pass through this to normalise your settings.

Check the "whats new" in the 2011 help docs for the rotate texture.

Aikiman
04-13-2010, 04:18 AM
To help you out a little, essentially you replace the cloudy shader with the fluid shader on the particle SG node. Now say you want to control opacity, you create your ramp on the particle shape over lifespan as per normal. Then drop a particle sampler node into your DG and middle mouse drag it onto your fluid shape. From there connect opacityPP to transparency, as you know these attributes contradict one another so switch the color chips from B>W to W>B.

Do this also with texture time on your fluid shape, I usually create a userScalar1 attribute and chuck a ramp over lifespan in there then hook that up to any of your fluid shape attributes that go from 0-1 or vice versa. Also as mentioned there is a new attribute which will rotate your texture. I dont know much about this as I havent had a chance to play with it but it is designed for this purpose so have a play. Anything where your values on the fluid shape are NOT normalised then you can try changing the arraymapper on your ramp or use a setRange node to change old min and max to new min and max.

avillabon
04-13-2010, 11:52 PM
Can you please post a link to that thread where they explain how to hook up a fluid shader to a particle shader?

Sure thing!

Its between these two:
http://forums.cgsociety.org/showthread.php?t=375436&highlight=rocket
http://forums.cgsociety.org/showthread.php?f=86&t=155001&page=28&pp=15&highlight=oil+smoke

But in reality its as simple as creating a "Fluid Shape" in the hypershade > materials (this will create a fluidShape shader inside your hypershade). Then I selected the cloud particles and assigned shader to selected.

Alex

avillabon
04-13-2010, 11:55 PM
@Aikiman - Im reading at your comments. will try out a few things and post results/questions

thanks

Alex

Aikiman
04-14-2010, 12:09 AM
BTW in 2009 and above the "thick clouds" preset uses a fluid shader to shade nParticles.

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