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natnat

how to create snowhaze

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hey guys ´n girls,

It's me again. Does anybody know, how to achieve this snowy haze like in my real footage? i thought, i will go for some smokesim for that and popadvectbyvolume some snowflakes, based on their velocity...
Other suggestions?

greetz natnat

snowHaze.mov

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Ground - > Noise - > Particle scatter - > FluidSource -> PyroSim 

On top of that a directional velocity source helps a LOT!

Just be vary of too much curl , you want nice smooth directional velocity with a bit of turbulence. And the Pulse can depend on how fast the snow is flowing.

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u mean, like at first a popforce with with a X vel direction and on top of that a subtle volume velocity with curl noise feeded through a pop adcevt by volumes right?
 

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On 6/23/2017 at 5:37 AM, natnat said:

u mean, like at first a popforce with with a X vel direction and on top of that a subtle volume velocity with curl noise feeded through a pop adcevt by volumes right?
 

Apologies for the late reply, but pretty much yeah.

How i approached this a while back was by advecting particles through the noise on the ground and then having it move in the desired direction using POPFORCE with very low noise and large slow swirl. 

This was used as the fluid source with the velocity field toned down.

On top of that i added an extra directional velocity to push the pyro sim , which was basically just a long thin box emitting straight particle without any noise. Which was converted to a velocity field (with a bit of curl) and brought into the pyro dopnet.

I unfortunately cannot upload any file for this right now, but ill try making a simple setup for you at home tonight.

Edited by bloodhawk

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Hey mate, 

no chase :)
I allready made some progress in term of setting up the initial vel direction through a look up near points...wich works pretty nice on the emitting procedural HF object, so this part is getting the right way :)  
I also added some popforce with a force dir and the curlnoise helps a lot, i think twice the size of the length works good :) (swirlsize)

So far so good... 


 

Bildschirmfoto 2017-06-28 um 14.08.48.png

canyon_parthaze.mov

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my only problem is to get the velfield. If i try to feed my particles results into a fluidsource...i can't see any vel :/ 
or the scene is way too big 1,5km x 3,5km - which is of course insane to translate that in a dense volume^^
at this point...is it possible to cut out the used vel space to decrease the needed voxels - maybe some vdb workflow?
or
is it possible to trail/trace a one-shot particle emission and use that in a loop ?


 

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I upload the file maybe someone could show me, what I'm missing...

greetz natnat

 

 

natnat_snowhaze_v1.hipnc

Edited by natnat
more input

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5 hours ago, natnat said:

my only problem is to get the velfield. If i try to feed my particles results into a fluidsource...i can't see any vel :/ 
or the scene is way too big 1,5km x 3,5km - which is of course insane to translate that in a dense volume^^
at this point...is it possible to cut out the used vel space to decrease the needed voxels - maybe some vdb workflow?
or
is it possible to trail/trace a one-shot particle emission and use that in a loop ?


 



I upload the file maybe someone could show me, what I'm missing...

greetz natnat

 

 

natnat_snowhaze_v1.hipnc

Ill check out the file after work today, but for the velfield did you try dropping a trail sop before the fluidsource node and set it to Compute Velocity? Then in the fluidsource node you under velocity , you might need to play around with the Point Sampling under Stamp point settings. OR you can use a really dense particle layer  that way you avoid having to bump up the point sampling threshold. 

 

Here is an example of how im generating my source density. The same can be plugged into a fluid source node (points only) and then used a separate velocity source. Using 2 different source volume node , one for vel field and one for the density, will be a bit more control over the flow.

The setup for this doesnt need to be crazy complicated, you can always cull the density based on the height.

PyroSource_Test.hip

Edited by bloodhawk
  • Like 1

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I just took a little look on that file, but it seems to be definitly usefull :)
I'll check it and will give an update.

 

 

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