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nord3d

H12 Pyro Shader & Scattered Emission

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I try to test the new Pyro* with PC-based** scattered emission, but haven't success. Sometimes I can't create the point clouds (files is empty), sometimes they creases but just for 2 frames of 50. And even with .pc file (looks proper), it have no effect in render. In H11 it was easy and "intuitive" for me, but now I guess is it a bug or it's my mistake.

So, can anyone be so kind to explain to me the steps to achieve the lighting from fire in the smock in H12?

Example scene:

Fireball01.hipnc

*Pyro or "Fireball" material, that creates with Explosion and Fireball shelf tools

**Point Cloud based

Edited by nord3d

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There was a change introduced in VEX right after the release candidate was frozen. This had the unfortunate side effect (no pun intended) of breaking the PC-based scattering portion of the Pyro2 shader. Now that we again have access to daily builds, I'll try to address this problem.

Unfortunately, PC-based scattering will remain pretty much unusable (for daily builds) until then.

Sorry about that. Just unfortunate timing.

I'll try to remember to update this thread once a fix is submitted.

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Thank you very much for the comprehensive answer, Mario!

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It fixed in build 12.0.558, as I can see. Is it fixed completely or partially, but, at least, it works now*. I'm still experimenting.

Thanks again, Mario!

*In Traced Approximation mode looks very good but renders very slowly; in Fast mode is fast.

Edit: First screenshots (left - Fast, 0:23; right - Traced, 19:02)

post-5855-133117141517_thumb.pngpost-5855-133117142792_thumb.png

Edit2: Aha! It's so slow because too low (0.3) Shadow Density in Pyro Shader, that creates by the Fireball shelf tool.

Edit3: It is interesting that the Shadow Color in Pyro shader -> Shading -> Normal Shading has subtractive effect...

Edit4: There are more strange things in the Pyro shader. Color correction in Fire requires 1/gamma (such as 0.45 for gamma 2.2), while CC in Smoke has no effect. The emission brightness depends of the Volume Step Size with which PC generated and of the Volume Step Size in mantra ROP.

Edit5: Decreasing Volume Shadow Quality in Mantra significantly speeds up the Traced Emission.

Edit6: Maybe I was totally wrong, because I reuse the old scene. Experimentation continues...

Edited by nord3d
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Hi Alexey,

I'm hoping to get to it this weekend...

A couple of VEX functions had issues, and those have been fixed, which is good. The problem is that my original treatment of PC-based emission unwittingly relied on one of these flaws (and what was solving "fast" was actually fast, yes, but also wrong :) ).

Long story short: even though PC-based emission is now "fixed" (i.e: it doesn't crash or generate garbage point clouds), it is no longer "fast"... which is what remains to be fixed.

Thanks for all your testing.

I'll let you know when a fix is submitted.

Cheers.

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I also noticed about the scattering being rather wrong yesterday. As it is right now, Fast does very little apart from adding some shinyness to bright areas. Something I could do in compositing very easily. The other one is so slow it´s almost unuseable...but I digress. You explained why, so we´ll wait for the fix.

If it means anything Mario, I think your shader is wonderful, scattering or not (but please fix scattering :D hahah).

I have a fireball render going on right now (I will try to post it tomorrow) that is simply gorgeous...at least to my eyes. It´s exactly the quality I was aiming for and couldn´t reach.

You can do wonders with this shader just playing a bit around with the different fractals and ramps. Yup, me likes. :)

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Hello, Mario.

Thank you for the explanation, looking forward for this gorgeous effect completely working. But now, even if it's slow, it's much better than all that I can achieve in H10/11. So, I'll try to render a short animation - can't wait. :)

With best regards, Alexey.

Edited by nord3d

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It fixed in build 12.0.558, as I can see. Is it fixed completely or partially, but, at least, it works now*. I'm still experimenting.

Thanks again, Mario!

*In Traced Approximation mode looks very good but renders very slowly; in Fast mode is fast.

Edit5: Decreasing Volume Shadow Quality in Mantra significantly speeds up the Traced Emission.

Hey thanks for the notes - this has really speeded up my renders - decreasing shadow quality -

It is a great shader - im getting stunning results - although Mario for some reason when i load a scene the shader cannot understand the 'gradient(density)' function as a vector - it interprets as a float and gives me a monochrome image. Im using this function for a normals pass. i've submitted the bug already to sesi. Currently you have to manually change the field color to float then back to vector using this gradient() function.

Also - any news on making smoke_color AOV work correctly with MP renders?

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I can't for the life of me get the point cloud scattering method to work with either pyro1 or the pyro2 shader.

I must be doing something stupid. I can't even seem to get the point cloud files to write out.

What I am trying to do is use a point cloud light scattering method to get some internal lighting in a cloud.

If anyone is able to post a scene of any example of getting point cloud scattering working I would be very grateful!

Or if anyone can give a nice detailed run down of methodology that would be great too.

Thanks guys!

Tom

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hi,

i will be posting a file on this, but what i did was create a seperate fire and a seperate smoke from same object, in the fire setup you use the pyro shader in shading i believer there is point scattering generation option, check the generate option and dump out the point scattering information,

the second part to it is create the smoke again use the pyro shader and this time uncheck the generate option now it acts as a reader and it reads the point cloud data that u dumped, this should give you some starting point to the point scattering

thanks,

Sachin

P.s - the attached file doesnt have the fire file... i am just reading the dumped scatter... you may not be able to see it... since u need to dump it again let me know if u need the entire file

I can't for the life of me get the point cloud scattering method to work with either pyro1 or the pyro2 shader.

I must be doing something stupid. I can't even seem to get the point cloud files to write out.

What I am trying to do is use a point cloud light scattering method to get some internal lighting in a cloud.

If anyone is able to post a scene of any example of getting point cloud scattering working I would be very grateful!

Or if anyone can give a nice detailed run down of methodology that would be great too.

Thanks guys!

Tom

Edited by sachinbangera

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hi folks!

This is somewhat obsolete, because in 12.5 the scattering part was removed from the shader, and now You use the new volume light for that, altogether You will get scattering and lighting from volume.

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hi folks!

This is somewhat obsolete, because in 12.5 the scattering part was removed from the shader, and now You use the new volume light for that, altogether You will get scattering and lighting from volume.

Hi!

Have you got used to the volume light method? I couldn't get my volume light to work right, it lights up the smoke all over the place. Can you tell me the proper steps to set up my volume light and the main parameter to modify like how to control the depth of light scattering?

Thank you very very much!!!

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Bump Sam's question! How do you set up a volume light? I just get nothin......

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Hey!

 

Just select the usual "pyro_import" at object level, and click the shelf tool for vol light. It will use the pyro shader and suck in the volume. It is a good idea to hide the light from the viewport, because it is slow.

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You don't have any material loaded into volume light, also no pyro material on the pyro_import. I think volume light uses the the field which outputs "Ce", thus it will emit light to the surroundings.

This is from the default fireball shelf tool, and added volume light. Advance to frame 20 and render.

volumeLightSetup01.hip

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Thanks mate - I think i figured it out. I needed to turn up Volume Limits on the Mantra node, because it defaults to zero, and needs to be at least 1 to show anything.

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