Apply detail to smoke using Volume Procedural

[JH12]

Hi,
This is probably a simple bit of VOPs, but I can't seem to get it.  I'm wanting to use a Volume Procedural to add some detail and noise to a low res smoke sim.  When I add the noise to the cvexvop, driven by the P and output as density, it is creating noise but filling my whole bounding box, because obviously its adding density driven by noise at every position.  How would I restrict it to apply only to the existing smoke, or use the smoke density as a mask? 

I thought that by first multiplying P by the density would work (such that where smoke density equals 0, no noise would be added) but does not seem to.  

Thanks for the advice

volumeprocedural.hiplc

[Noobini]

I don't know much TBH, but I had a go anyway, here's my tinkering...so basically, if density is below a certain threshold, then leave density unchanged, else.....go nuts...

I guess to the naked eye, you think there's an empty voxel...but infact there's a density of 0.000something there, hence it looks like it's not working right......but it is...

Edited December 5, 2018 by Noobini

[JH12]

Thanks Noobini.  I can see your theory here but it doesnt seem to be working for my set up.  Would you mind sharing your .hip?  Thanks

[Noobini]

sure, just switch between volumevop1/2 and you'll see immediate difference

vu_volumeprocedural.hiplc

[JH12]

1 hour ago, Noobini said:

sure, just switch between volumevop1/2 and you'll see immediate difference

vu_volumeprocedural.hiplc

Thanks.  Yes can see a difference in the viewport but have you tried rendering it?  I just get black from the second version (which was also happening when I tried to build the vop according to your picture)

An issue seems to be that the "density" inside the cvexvop is not referencing the density of my preexisting volume.  Because even the following in the cvexvop will render black.  

Edited December 5, 2018 by Fireandsmoke

[Noobini]

nope, sorry don't know what you're doing with the geo vexvolume and/or billowy smoke material

[JH12]

It does appear from some reading that when using the Volume VOP Global Parameters inside the CVEX vop it will not import the density of the subject volume, it rather is a blank canvas. 

So the question is then, how would you import the density of a volume into a CVEX vop?

[Noobini]

in your pyro_import, render tab, if I blank out the Procedural Shader (/shop/vm_geo_vexvolume1), it works...well I 'think' it works coz as said, I don't know what the usage of these are in the first place.

[JH12]

15 hours ago, Noobini said:

in your pyro_import, render tab, if I blank out the Procedural Shader (/shop/vm_geo_vexvolume1), it works...well I 'think' it works coz as said, I don't know what the usage of these are in the first place.

Not sure what you mean to say... if you blank that out, then its just rendering the volume without the procedural.. so naturally it will render the smoke.  
This issue I'm having is with the volume procedural applied, how do I import that density of the existing smoke into the cvex shader, so I can use the volume procedural to augment my existing smoke.