Smoke from particles to "fat" and "blobby"

[Nygma]

Hi @all,

I have this problem here after creating a smoke sim from a particle object. The particle sim looks fine, but after the fluids are applied it gets way too fat, especially at the tips where I would like to have something much more detailed and small, following the particles.

This doesn't change, no matter if I take up the resolution, or properties of the particles (e.g. Uniform Scale). Maybe I am just doing it the complete wrong way, so I should use volumes applied to the every particle alone instead of applying particles to a smoke container? Or maybe someone has a different suggestion.

Thank you very much.

[kleer001]

can you post a hip file?

Also try animating the particle's pscale attribute and density to decrease based on $AGE or $LIFE to start with.

[Ankit Sinha]

I had similar issue turnout to be density problem, but reducing density might not solve problem straight away. I had to change lot of thing to fix it including shaders and render setting.

Edited February 14, 2013 by Ankit Sinha

[Filipp Elizarov]

First check your Pscale attribute in SOP .It can be too big by default.

Second check your Gas Particle to Field microsolver --> Max Extrapolation Cells by default it 2 but it depends on voxel size.

Third check your vel attribute if you use it.

[Nygma]

Hi @all,

thank you all so much for the help and tips&tricks. Well unfortunately nothing has helped so far. I had the uniform scale animated at first but it didn't change whether it was or not. And the other things mentioned I simply cannot find. I am quite sure I look in the right place at least but I won't find them, sorry. :S

I should mention I am newer to Houdini coming from 12 years of Maya but well... times change. So I have attached a file now, maybe someone can point me to the issue by looking at that?

Thank you very much again.

Particle_Test_Dust.hipnc

[gui]

Hi Carl,

There are 2 things that I think you are missing here.

1. The source volume sop is stamping points using an attribute called density. If all the points have the same density, you don´t need to add that attribute, just control the density in the source volume sop. I added density in the particle sim, using the complement of the life.

2. There is an stamping point tab, where you can change the sample distance. If you lower that number, you will get closer to what you are looking for, but you will have to decrease the division of the volume too, to get more detail. See the attached file.

Particle_Test_Dust.hipnc

[Nygma]

Hi Guilherme,

wow I see - took me some time to figure out what you had done (still having a hard time "visualizing" SOPs in my head) but now I see. It looks way more closer to what I would have liked to achieve. Thank you so much. I will try a few things now and play around with the values and stuff. Just learned a bunch of new things... Hopefully I can figure it out by myself now.

Thank you so much again.

EDIT:

I have one question though - sorry if it might be a silly one - but better asking than wondering:

You have added the density attrib to the particle sim with the Value of "fit($LIFE, 0, 1, 1, 0)" - as I can read it, this means you replace the old MIN/MAX (0,1) with the new MIN/MAX (1,0) depending on the particles age? Does it mean the older the particles get, the less dense they'll become?

Edited February 15, 2013 by Nygma

[gui]

yes, that´s correct. I should use fit01($LIFE, 1, 0) for that, which is simpler, but I leave that way just for you to play with it. Don´t know exactly what kind effect you want achieve, but perhaps what you want is the oposite way, make particles less dense when they are born, and more dense when they get old...

But I should say that I wouldn´t use particle sim for that, because, just with the locator pop, you can source the volumes, and let the dop do the rest. You will get the same result and would be faster, since sourcing for a lot of particles takes time.

[Nygma]

Okay I can see what you mean. I have to try that one as well as I am also not happy with the overall shading possibilities. The Smoke Container with its Billowy Shader looks a bit weird. Maybe it would be the best to do a completely different approach with single volumes mapped onto the particles. I am not sure.

But thank you very much.