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hello, i'm trying to get AOV's from the pyro shader also. I followed the PYRO FX lessons, and not sure what i'm missing here.

if i do a simple flame sim:

go to the flame_pyro shader: generate point clouds:

go to mantra node: add: Csmoke, Cfire, Asmoke, Afire, Mfire and Escatt or Cscatt

Asmoke, Afire, Mfire all are set as Floats, the rest are Vector...

I get all of the passes. But Afire does not come out with anything and Escatt or Cscatt both give me nothing as well. Is there any reason you can think of? I did not mess with any of the settings. Just did a sim. Generate point cloud. Add the AOVS, and render. Thanks again,

Jonathan

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Also, here is a quick test and there are a couple ABRUPT flickers. Not sure what that is due to. thoughts on that one

EDIT:

I just noticed that the BRIGHT flash, was because I only generated 1 frame of the point cloud... ;)

pyrotest4.mov

Edited by itriix

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Also, here is a quick test and there are a couple ABRUPT flickers. Not sure what that is due to. thoughts on that one

EDIT:

I just noticed that the BRIGHT flash, was because I only generated 1 frame of the point cloud... ;)

Abrupt flickers (jumps in the noise) are caused by your rest fields, check this thread:

http://www.sidefx.com/index.php?option=com_forum&Itemid=172&page=viewtopic&t=16117

Concerning using the burn field: The heat field has a decay rate over time, whereas the burn field is newly defined every frame. The burn field is generally copied max() operation into the heat field. Because of this decay you will probably have a wider range of values to play with in the heat field compared to the almost 0 or 1 difference in the burn field. Remapping the values might help. Also make sure your burn field is imported from dops with your simulation or you won't see anything.

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Thanks Peter,

The initial reset frame and the reset every frame were different in the pyro solver and the flame_pyro shader. minor inconvenience. seems like maybe it should default to the same thing as the pyro solver though?

and now my next question is about point clouds. if i do a lo-res sim. and generate point clouds. and then do an up-res sim... do i need to regenerate the point clouds?

EDIT:

so i thought that the initial reset frame and the reset every frame in the pyro solver being matched in the flame_pyro shader, settings, Start Frame and Reset Rate, was what would fix the flicker but in fact it didn't... here is the new video: *i've upresed from the original also now*

pyrotest4ae.mov

Edited by itriix

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another thing too...

as i've been testing the shader out. it seems to REALLY help to turn down max search radius on the scattering tab. when it's at the default of .8, it might take about 2 + minutes to render a simple simple smoke. but, if i just turn it down a tiny bit. even to .5. the render goes to a matter of seconds.

i know this is in the "tutorials"... but i'm finally trying to test out parameters on my own now.

in fact, i'd really like to hear what everyones work flow is when beginning a "pyro sim"...

example:

start lo res sim... tweak params in the pyro solver... generate point clouds. tweak shader. make up-res sim. tweak params. tweak smoke/fire... scatter? what order?

i'd really like to get a feel for what everyone else does. i know i'm going to have to get used to my own workflow but it'd be nice to compare. it's quite obvious to me that i can end up with thousands of files, a lot of lost time, and not MANY different results if this isn't approached in a good way. Thanks again for all the replies

Edited by itriix

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alright here is a new test... and this time it looks like i fixed the problem of the "flickering" HOWEVER, i definately need to do more testing to verify that what i did fixed this.... and i'm not sure WHY this would fix it.

as suggested from many others, and in other posts, the "initial reset frame" and "reset every frame" on the pyrosolver originally was set to 1 and 50 respectively. in the flames_pyro shader, the settings tab had the : start frame and reset frame set to 1 and 20 respectively. so my first test fix was making sure that those values were the same. so i changed the shaders values to 1 and 50 to match the pyrosolver. i rendered out, and still had flickering. so... here are some more details:

i am doing a 60 frame animation... and the problem tended to happen on frame 51/52... which was odd. seemed quite a coincidence that the frame it was happening on was so close to the "value" being specified. well this time i tried setting the values to 1 and 60... well the problem seemed to be fixed, however, my intuition makes me think that if i render out another 60 frames... that the popping might occur again somewhere else later down the road. we'll see... i'll test that out now and report back what i find.

here is a vid of the current NON popping, 60 frames, values at 1 and 60

cheers,

Jonathan

pyrotest4.1.mov

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alright so, i've been rendering non stop many tests. and it seems like, the only way for me to get the flickering to stop is by setting the initial reset frame and reset every frame in the pyrosolver and the start frame and reset frame to 1 and 60 in the flames_pyro shader.... i just want to know WHERE these values are coming from and WHY 1 and 50 as the values are not working for me? I would like to know WHY 1 and 60 are working and 1 and 50 are not and how to decide from the get go. At first I began to think that 1 and 60 worked because my fps was at 30... but then i double checked and my fps is actually 24 fps... so that's not it... i'm rendering a 120 frame animation.

if i do 1 and 50 as the values, then it seems like every 25 frames almost, the flicker occurs... *so that would go with the dual rest option" and would make sense why it's popping on those frames. but i don't get why... i thought that was the point in the dual rest was to cover up the popping. please someone help me to understand HOW to choose these values, or is it simply RANDOM for each simulation? Do I just HAVE to render out a sequence with different values each time I do a simulation, in order to find out what values are going to work? That doesn't seem right though. Seems there has got to be some logic behind WHAT values to choose here. Okay, thank you all so much. I'm learning a lot!

and the pyro tools ROCK! im loving playing with this. just have a lot more to figure out still so that i can efficiently get fast and good results!

Thanks,

Jonathan

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an observation using the "create rops only" generate mode in the vex pyro shader, for flames_pyro.

after i hit generate, it creates three mantra nodes...

pyro_fire, pyro_smoke and pyro_all... then i wanted to see how they were set up and notices the only real thing that was on the mantra nodes were some pre and post render scripts. the thing is, here is what i get:

in pyro_smoke:

pre-render: opparm /shop/flames_pyro mode ( "pcwrite_smoke" )

post-render: opparm /shop/flames_pyro mode ( "shade" )

in pyro_fire:

pre-render: opparm /shop/flames_pyro mode ( "pcwrite_smoke" )

post-render: opparm /shop/flames_pyro mode ( "shade" )

in pyro_all:

pre-render: opparm /shop/flames_pyro mode ( "pcwrite_all" )

post-render: opparm /shop/flames_pyro mode ( "shade" )

now to be honest, i'm not very sure what this is exactly doing, but what i am curious about is, in the pyro_fire, pre-render script... it says "pcwrite_smoke", should that say "pcwrite_fire" or something instead?

is this possibly wrong?

anyways. something that i just noticed. let me know if this is correct or not. thanks again

Edited by itriix

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a new question about scattering, point clouds and volume step size...

so i know in the tutorials it says that a good rule is to make you're smoke and fire step size about 10 times you're volume step size... so if you have a .1 volume step size, then you can have 1 for the smoke and fire step size...

my question is this:

do i need to regenerate point clouds if i CHANGE my volume step size? If i'm doing render tests with a volume step size of .1, and have my smoke and fire step at 1, if i just want to bump up the quality of the render, with the volume step size, do i need to regenerate the point clouds with a better smoke and fire step? so say i change the volume step to .01, do i need to regenerate point clouds with .1 step now before rendering?

Jonathan

Edited by itriix

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