Arnold for rendering particles?

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Old 09 September 2013   #1
Arnold for rendering particles?

Hello!

I want a solution for rendering lots of particles (>1million) in 16bit. Maya's hardware renderer can't do it in 16bit and Mental Ray can't cope with that many particles.

Has anyone used Arnold for rendering particles or nParticles?

It is supposed to be very fast at rendering LOTS of particles, but I just can't find any meaningful documentation on this topic. The page on the Solidangle website is lacking, somewhat.

Specifically I need to know how to connect up the paticle sampler info node to a colour ramp so that I can render the particle's rgbPP.

If anyone out there has rendered Maya particles with Arnold, please can you tell me what that connection should be, or if there is any documentation online.

Thanks!
 
Old 09 September 2013   #2
I don't know about rendering particles with Arnold but u could try Exocortex Fury, Krakatoa or Renderman as an alternative.
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Old 09 September 2013   #3
Originally Posted by mihai112: u could try Exocortex Fury.



I hadn't considered Exocortex Fury - I thought it was Softimage only.

Thanks for the tip!

The studio I work in does already have a few Arnold licences, so if there is someone out there who has experience rendering Maya particles with Arnold, I would be interested to learn how it works.
 
Old 09 September 2013   #4
Just did a quick test, not using particleSampler got random rgbPP on an nParticle without needing to add that as an exported attribute in the Arnold section of the particle shape.
Then I got age by adding that as an exported attribute.
The easiest way that I have found to get point data into shaders is to use the aiUserData nodes. In this case the aiUserDataColor worked for both rgbPP and age. Just connect the aiUserDataColor node into your final shader wherever you want...aiStandard, aiUtility, whatever. Add the name of the attribute to sample in the Color Attr Name section of the aiUserDataColor node. rgbPP or age or whatever attribute you want. Both of those worked for me using the aiUserDataColor even though one is a float and one is a vector.

Set your 'render points as' attribute to the type you would like and rock out.

Arnolds ability to handle point data in shaders is bananas!
 
Old 09 September 2013   #5
just keep in mind, fury and krakatoa render particles in pixel-space, which might be an issue when dealing with z-depth and accumulation of particles.

A always would prefer render particles with Renderman , Mantra or Arnold (rendering RiPoints/Disks with a world scale). It just looks more realisitc.

Just my 2 cents..
 
Old 09 September 2013   #6
Originally Posted by borisb2: just keep in mind, fury and krakatoa render particles in pixel-space, which might be an issue when dealing with z-depth and accumulation of particles.

A always would prefer render particles with Renderman , Mantra or Arnold (rendering RiPoints/Disks with a world scale). It just looks more realisitc.

Just my 2 cents..


By pixel space do u mean that the particle size is limited to the pixel size, if so u are correct about Krakatoa, Fury however does not limit the size to pixels u can have larger particles and smaller ones also for z-depth i never had a problem though i mostly use the depth pass in comp.
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Old 09 September 2013   #7
Originally Posted by animatedfox: Just connect the aiUserDataColor node into your final shader wherever you want...aiStandard, aiUtility, whatever. Add the name of the attribute to sample in the Color Attr Name section of the aiUserDataColor node. rgbPP or age or whatever attribute you want.


That's the ticket!

Thanks very much, Fox.

Now, why can't Solidangle put that in their documentation? I dunno...
 
Old 09 September 2013   #8
Originally Posted by mihai112: By pixel space do u mean that the particle size is limited to the pixel size, if so u are correct about Krakatoa, Fury however does not limit the size to pixels u can have larger particles and smaller ones also for z-depth i never had a problem though i mostly use the depth pass in comp.


I meant they dont change particle-size based on their distance to camera, like having a realworld sphere-size (at least as a far as I know and from what I've always seen and tested myself). So you set a point-size, either sub-pixel or a lot bigger but every particle will be rendered that big. In Renderman, Arnold and Houdini you are dealing with realworld-scale, either as RiPoints, disk-size in houdini or in Arnold as well. I find that pretty important when dealing with depth.
 
Old 09 September 2013   #9
Originally Posted by borisb2: I meant they dont change particle-size based on their distance to camera, like having a realworld sphere-size (at least as a far as I know and from what I've always seen and tested myself). So you set a point-size, either sub-pixel or a lot bigger but every particle will be rendered that big. In Renderman, Arnold and Houdini you are dealing with realworld-scale, either as RiPoints, disk-size in houdini or in Arnold as well. I find that pretty important when dealing with depth.


First off sorry for diverting from the Arnold rendering part but here is a test using point particles with same default particle size and the emitter is a volumetric cube emitting particles away from the camera, the particles closer to the camera are bigger and the ones futher away are smaller so i guess this means that Fury isn't rendering particles in pixel-space, also added a spot light with shadow just for fun.

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Old 09 September 2013   #10
hmm .. interesting. Thats is indeed world scale. Is that just rendered as points or "cloud-like" shape like old-school sw-particles in maya?

Thougt Fury would be pixel size as krakatoa is. Haven't tested Fury yet. Would be able to render say 20M particles in this style?
 
Old 09 September 2013   #11
After a morning of Fury, I can tell you that it is very fast.

Here is what 20m particles with motion blur switched ON and 4 x multisampling looks like:



(note the time taken to render this image is 13.26 seconds)
 
Old 09 September 2013   #12
I was in the beta for Fury for Maya and it's come a long way since the first versions that i tested, but i say that i can handle millions of particles, i think the largest amount i tested was 40 mil and had a decent rendertime, the particles in the image i rendered are default points but it also supports cloud and nparticles so u can go crazy with it.
Nice render dansidi did u use a fluid for the motion, one thing i found using fury is that since it uses the GPU for rendering the particles once u go over the memory limit fury will give and error and for that i try not to use motion bur or depth of field from Maya instead i use those as passes in comp so i will use the most out of the GPU memory.
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Old 09 September 2013   #13
Krakatoa test



Here is a Krakatoa test, which is comparable to Fury in quality and speed. Very impressive results, I think.
 
Old 09 September 2013   #14
So,since you are doing these tests, I am wondering how Arnold does with that particle count?
Have you given it a try yet?
I am pretty sure it will be slower, but just wondering as Krakatoa and Fury aren't part of our pipeline, would be great if you can give it a render.
Just for info.
Thanks!
 
Old 10 October 2013   #15
Originally Posted by animatedfox: So,since you are doing these tests, I am wondering how Arnold does with that particle count?
Have you given it a try yet?
I am pretty sure it will be slower, but just wondering as Krakatoa and Fury aren't part of our pipeline, would be great if you can give it a render.
Just for info.
Thanks!


I'd also be interested to know. Any chance for some feedback?
 
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