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Noise in Flip fluids


jasonmaynard

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Hi,

I'm trying to figure out what is causing this nose in my Flip fluids (using Melt Object preset). The only thing in the scene that is animated is viscosity coming down. I've tried playing with surface tension/surface tension blur and Velocity smoothing after switching velocity transfer to "swirly kernel". This doesn't seem to get the noise out. What am I missing?

Vimeo link here
 

Thanks in advance!

Jason

Edited by jasonmaynard
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I have seen that kind of surfacing glitch before. I think it might be related to reseeding.

Do you have reseeding enabled?

Are you using the FLIP compression node right before surfacing?

Maybe try a test without fluid compression?

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Resending is off, tried it on also. I did try turning off the fluid compression node. Still has the same issue. I've tried most everything that would be logical. Im newer to Houdini but been in the realflow world a while. Any other ideas?

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What about adding more FLIP resolution? Maybe you are just running it too low? Or maybe you are animating the time scale? It is hard to say without seeing a sample scene.

I found the post I was originally thinking of. It could be a beat pattern against your FPS. Say you have your fluid time scaled to 0.3, which is essentially 30fps and your scene is running at 24fps.

http://forums.odforce.net/topic/30020-slow-moving-flip-causes-mesh-flickering/

Edited by Atom
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I had tried originally doing a high res sim. I backed it off since then to have some faster tests. No time scale animation and time scale is set to default of 1.

I tried a few things from the link you posted with (dilate, smooth, erode and final smooth). It helped some, but still has the rolling pattern and mesh noisiness.

Are you able to open apprentice scenes? I'll upgrade to Indie if needed. Scene zipped and attached. Thank you for your help with this.

Here is a video with the new settings. I also tried with the testpig. You don't see the rolling as much with piggy:

 

 

 

HeadMelt.zip

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Try turning off the Display flag on the AutoDopNetwork. With the flag on you are supplying the same exact mesh twice to the render system. It may be something as simple as z-fighting faces.

 

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Maybe time stretch after the fact? Just kick out the animation as a .bgeo.sc sequence using true time then bring it back in, via a File node, and apply the time stretching then.

Edited by Atom
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I would add some jitter to your inital flip points. That should get rid of the banding. I am attaching a file with the changes. You will still need to mess with the smoothing and such in the particle fluid surface to make the surface not as flickery but, it gives you a starting place. You are also going to have a grand time dealing with UVs if you plan on transferring them to the particle fluid surface (which it looks like you want to....Take a look at the uvquickproject node to see why).

3 hours ago, Atom said:

Maybe time stretch after the fact? Just kick out the animation as a .bgeo.sc sequence using true time then bring it back in, via a File node, and apply the time stretching then.

I'm curious on why time stretching would get rid of banding artifacts like this?

 

MyHead_v07_RB.hipnc

Edited by rbowden
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13 hours ago, rbowden said:

I would add some jitter to your inital flip points. That should get rid of the banding. I am attaching a file with the changes. You will still need to mess with the smoothing and such in the particle fluid surface to make the surface not as flickery but, it gives you a starting place. You are also going to have a grand time dealing with UVs if you plan on transferring them to the particle fluid surface (which it looks like you want to....Take a look at the uvquickproject node to see why).

I'm curious on why time stretching would get rid of banding artifacts like this?

 

MyHead_v07_RB.hipnc

Thank you for taking the time to open the scene and help with this! I rebuilt it using what you did as reference. Keeping the UV's was something I was wanting but hadn't figured out yet. Didn't realize it was as simple as that. Thanks again, here it is rendered now. Still needs some work but is coming along :)

 

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