Fluid effects Smoke/Fog looks bad, aliasing problem?

# 1 04-02-2011 , 11:15 AM

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Fluid effects Smoke/Fog looks bad, aliasing problem?

Hi everybody.

I have a problem with some smoke/fog created with Maya fluid effects. It comes out looking well bad, jagged perhaps. Can anyone point me in the direction of getting it to look smoother?
This is the render settings that I've been using:

Min Sample Level: 0
Max Sample Level: 2

(I 've tried Min Sample Level 2 Max Sample Level 4 but the few frames I got rendered out before my computer crashed had the same problem.)

Anti-aliasing Contrast: 0.1

Filter: Triangle

Filter Size: 2.000 2.000

Sample Options:

Jitter (turned on)
Sample Lock (turned on)

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# 2 04-02-2011 , 01:17 PM

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Hi there,

You might be best off trying to adjut the settings in the fluid node, the texture and the edge dropoff as well as the opacity ramps.

you can get this type of effect when your fluid has filled the voxels up, it's more to do with the fluid shape rarther than the render settings.

Cheers

Steve

"No pressure, no diamonds" Thomas Carlyle

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# 3 04-02-2011 , 02:27 PM

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Ok, I see. I can't say that I understand what it is that is filling the voxels up.
This is the settings I've been running with:

Texture Type: Perlin Noise
Coordinate Method: Fixed

Dropoff Shape: -Y Gradient
Edge Dropoff: 0.400

Any idea what I might benefit from changing? I would glady play around with It more but the render is painfully slow on my computer so anymore hints would be grately appreciated.

Also I've tried to turn the Shading Quality > Quality up from 1.000 to 3.000 but that didn't seem to do any difference.

I attached a picture with my settings of opacity and shading quality.

Attached Images

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# 4 04-02-2011 , 02:55 PM

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I've been playing around with the different settings. And yeah I can get squares to become less prominent, but only at the cost of the smoke becoming smoother and at the cost of almost all the detail.

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# 5 04-02-2011 , 08:48 PM

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I don't really know what happend. I changed the Dropoff Shape from -Y Gradient to Sphere and exported just this one frame and it looked as bad as ever. Then I gave up and started a batch render and now it looks incredible! Thank you very much Steve!

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# 6 07-02-2011 , 08:19 AM

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Hi Bugsby,

No problem, glad you got it sorted. You should really change the opacity ramp to a curve to adjust the detialing of the fluid shape.

Generally I pull the first part of thegraph (on the left) slightly to the right then make a curve with it so it look exponential with a fast increase then a slow decay to a vlaue of 1.

"No pressure, no diamonds" Thomas Carlyle

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# 7 07-02-2011 , 08:51 AM

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isn't this to do with your resolution and keeping your voxels square?

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# 8 07-02-2011 , 09:18 AM

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gster123: I will try that, thanks!

honestdom: how do I change the shape of my voxels?

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# 9 07-02-2011 , 02:08 PM

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Join Date: Oct 2007

Location: London

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at the top of the fluid shape under container properties there is resolution.
if its 100 100 100 they are square, but if they are something like 40 100 100 they are rectangular.
so you should make sure there is enough resolution and that you keep them square.

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# 10 08-02-2011 , 08:57 AM

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Hi Dom,

It can be but this makes the voxels stretch and look strange, the hard edges are generally due to opacity settings and such. The heigher the resolution the more voxels that you have, this coupled with an opacity/transparancy goves good looking fluids as the cost of simulation and render time.

Essentially with keeping the voxels square you need to ensure that they are multiples of the size of the container for example if the size of the container is 10x10x5 the resolution needs to be a multiple of this so for a low resolution sim the resolution should be 10x10x5, for a higer res then multiply the size so a high res could be something like 50x50x25.

"No pressure, no diamonds" Thomas Carlyle

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# 11 08-02-2011 , 10:15 AM

The Nurb Herd
Join Date: Oct 2007

Location: London

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ah cool, I don't know fluids that well but knew that was important in some way.
thanks man.

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# 12 08-02-2011 , 04:11 PM

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on the top its looks like a viewing issue. If you took that screen grab from maya render viewer it doesnt display very well lower than 1:1 and can make antialias look crap, so just use a different image viewer if thats the case.

The lower artifact looks like its a deep shadow map resolution issue causing crappy artifacts, increase the resolution to solve that issue.

FX supervisor - double negative

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Fluid effects Smoke/Fog looks bad, aliasing problem?

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