Nuke Explosions..for Ka-boom freaks only!

#201

Ive got distracted from my nuke tests and am experimenting with a blast coming through a window

http://vimeo.com/10365049

One thing Im really struggling with is the obvious square voxels at the leading edge of the fluid.
(see attached image as the vimeo compression actually hides the problem)

My computer wont cache at the moment so my experimenting is a bit tedious. Has anyone any tips for avoiding the voxel look. I thought i may have too much density being emitted but lowering it didnt seem to help.

Or is it because my camera is so close to the fluid?

Wayne - your getting a really nice look on the smoke tests - is the soft wispy edge achieved by using dissipation or is it more to do with the opacity graph on the shading?

Fluid is 152,320,136.flipped onto its side so Y is horizontal.
I’m emitting a lot of density(100) for 10 frames, then letting a high billow and temperature buoyancy do the rest. Swirl is 15, density scale is 0.85, dissipation is 0.1, temp turbulence is 11.

Any tips would be much appreciated.

Theres some great sims on this thread now - it keeps on getting better!

#202

Hey NWilco,

Cool stuff. The voxel issue you are having may be from a low quality setting. What is your Shading Quality set to? Try raising it past 4.

#203

I don’t think the voxel issue is shading quality (one sees dithering problems when the quality is too low). First make sure render interpolation is set to smooth( although I’m pretty sure it is already ). The sharpness of the opacity transition combined with the render interpolator being quadratic (degree 2) can create noticable grid artifacts. A higher order interpolation would be smoother but quite a bit slower to render( and is not supported currently at any rate ).

Make sure that the density values in the grid are generally lower than 1 (after multiplying by the densityScale value). This insures that they map within the opacity graph range. You might need to make the fluid more transparent or the transition to opacity more gradual to avoid that artifact.

There are artifacts with high detail solve when propagated quickly… these take the form of grid aligned rows of voxels and the lack of smoothness in the distribution can make the interpolation look worse. A solution in that case can be to cache with more subframes. (or increase substeps in Maya2011) If you are using swirl I would make swirl zero when using high detail solve( with high detail on swirl adds more artifacts than detail, I’ve found ).

Duncan

#204

Hey NWilco,

Everything Duncan mentioned is very helpful. Should fix your problems. The only thing I would add to that is maybe, you should crank your density/voxel/sec down a bit. 100 might be over kill. I am also texturing without opacity. For those smoke tests I was simply relying on the lighting and resolution. Texturing without opacity with a high resolution tends to give you soft wispy edges to your smoke. Plus it is super fast when it comes to render times. This is only useful for certain types of smoke. Other types you may have to texture with opacity.

#205

Looking great, going by your vid I would drag the incand input bias to the right a little more to add more heat in the beginning, otherwise looking awesome. Again it depends on what you are trying to achieve.

#206

thanks for the input. I’ll have to make some changes and see how it looks. I did a quick test and took swirl down to 0. the render looked very similar - still with strong cube/voxel shapes. So one of my other setting must be the main cause.
I checked and my ‘shading quality’ render interpolator was still set at linear. As is my opacity interpolation. i will try it with these set to smooth.(attached pic shows settings now ive tweaked them)

#207

Man I love how this threat is going awesome sims and all \m/.

I’m trying to make more puffy sim like 2 weeks now,but no luck T_T it always look like Ink or smth.

Also one thing if you decrease sim rate you can actualy increase swirl to get more details.
This sim is with swirl keyed from 45 to 35 :> and sim rate is .6 .I used fuel/temp this time xD.Solver is velocity only and keyed velocity scale x/-x and z/-z.

O well still trying xD.

#208

The critical one is the render interpolator… always set this to smooth, unless you need a slightly faster render(really smooth should be the default, as people frequently miss this and the different in render speed is not that great).

Using smooth interpolation on the opacity graph might affect the look of your render, but it should not remove any grid artifacts and does not mean “smooth render” but is rather a built in part of all ramp attributes in Maya. It could make the render smoother, but only indirectly.

Duncan

#209

Hey guys,

The stuff you have here is amazing! I have been attempting it for a little while but am failing horribly.

I am assuming you are pulling the emitter upwards and key framing the mushroom cloud itself?
I’m new to using fluids and would really appreciate any help people can give.

Here is what is currently happening gets ready to be beaten up
http://s208.photobucket.com/albums/bb177/blesshiscottonsocks/?action=view&current=failtest.flv

And here are my settings :slight_smile:
http://i208.photobucket.com/albums/bb177/blesshiscottonsocks/Settings.jpg
http://i208.photobucket.com/albums/bb177/blesshiscottonsocks/Picture44.png
Sorry in advance.

#210

@ : BHCS
i m replying for ur both youtbe messg & this one :

first check ur Y res its not properly set, the ratio is way too off.
second I never animate density scale. its not a good idea as the changes in density would be very abrupt instead u can animate the density dissipation or density emission.

there are more than 2-3 workflows discussed here. please go through them properly especially with duncan`s post.

your density & temp buoyancy & also swirl value is way too crazy here. can u have look at the scene file i have posted earlier here in this thread? It might give you a good head start.

hope it helps.
Vik

#211

Thanks for the advice :smiley:

I totally misunderstood what you guys were doing, i was animating the emitter itself… i have corrected some things and got an actual mushroom cloud shape. But it still looks wrong and the trail goes too quickly.
I have been through all my settings but nothing seems to change it for the better.

http://s208.photobucket.com/albums/bb177/blesshiscottonsocks/?action=view&current=lookingbetter.flv

#212

Now this looks better man ;>.maybe if you increase the density that is emmited it will be better and slow it down a little bit :>.You know when I started to learn fluids I check the help file first :>.Theres lots of good and useful info there xD.

Anyway just a thing that I wana share :>.I was always thinking that solver quality is like sub-steps in nParticles (I was wrong ofcourse,but anyway xD)I saw that with higher value the fluid hold its shape more and its not braking that much so I decide to animate it and this is what I get- Scene xD .
I think this could be used to "sclupt"fluid shape better(could be wrong ofcourse),but sim time increase like alot xD.

BTW when will maya 2011 be released I need that autoresize thing like right now hahahaha xD.

#213

Sry for the offtopic,but dude you are amaizing man is that you drawing?This is not skill man this is pure talant RESPECT O_O.

#214

Huh?

finished my second one, it lasts a bit longer and im getting used to the settings

http://s208.photobucket.com/albums/bb177/blesshiscottonsocks/?action=view&current=yes.flv

#215

is this your acc in youtube blesshiscottonsocks?

#216

Yup, :stuck_out_tongue:

third attempt… http://s208.photobucket.com/albums/bb177/blesshiscottonsocks/?action=view&current=ff.flv
i cant seem to get the extreme rolling that everybody else is getting, it seems too smooth. does anybody know what i am doing wrong? :open_mouth:

#217

Decrease the sim rate.
So its you man :stuck_out_tongue: hahahaha xD.

#218

sim rate lowered, its going a lot slower now and i can see whats happening xD but still no idea about getting more detail in my smoke.

#219

ok, started from scratch again and am getting more smoke like renderings :slight_smile:
http://s208.photobucket.com/albums/bb177/blesshiscottonsocks/?action=view&current=boom.flv
you guys are amazing!

#220

Hi BHCS,

Looking good so far. I would emit more temperature and key off density, currently it looks as though you have that on all the time. Also to see more texture detail make your color a gray hue instead of black that way you can see more self shadows. By the way make sure self shadows is on too with hardware shadows and take it off real lights just for starters i think that will hep you visualise things a lot better.