caching out particles

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  07 July 2012
caching out particles


How is everybody caching out big particle-amounts? Has anybody cached out more than 1M particles with nparticles cache-nodes?

Reason for asking: I would like to build my own particle-pipeline for multicaching out particles.

So far I see the possible routes to go:
- build something around cortex or partio (ptc)
- build something around GTO
- rely on RIB-export with 3delight and bring the particles back in maya with RIB-boxes
(not tweakable at rendertime?)
- use houdini

Any thoughts on whats the most straightforward way to go? Are there any other tools already developed?

How much slower would it be to write out ptcs/GTO with python rather than with a plugin?

Thanks a lot

Last edited by borisb2 : 07 July 2012 at 10:22 AM.
  07 July 2012
Hey Boris
Partio all the way I recon. Think someone wrote a plugin in load it in via OpenGL, maybe work with that? Will try and find that link for the delayed load DSO thingy when I get a mo ...

  07 July 2012
maybe you mean this ?

looks promising but it's still in alpha-stage - and also wouldn't solve my goal of writing multi-caches as far as I understand.

> delayed load DSO thingy

If you find that I would be very interested in!

  07 July 2012
Yeah think that was the Partio plugin. Will look for that other link ...
  07 July 2012
Btw, not was I was looking for, but zFluid's particle cache looks promising ...
  08 August 2012
so nobody is using more than 500k particles ??
  08 August 2012
Hi, I'm the author of partio4Maya, redpawfx

Very soon I'll have a new beta version of the plugin up for download
and hopefully it might be of use to you. Check out the upcoming features here:

New version is coming soon, the current download however, is "alpha" but is very usable. fairly stable and being used successfully in production every day at the company I'm working at.

We'll also soon be releasing an arnold procedural and I'm going to be contacting the author of the partio rib generator to see if they're interested in making it compatible with the partio4Maya toolset.

Check it out and let me know if there's anything else specific you might need for your workflow.

  08 August 2012
Hey redpawfx,

sounds great. I had a look at partio4maya already but couldn't get it compiled for Windows. What's the workflow for multi caching out particles? Can that be submitted on a farm?

Also Michals dev looks great for 3delight (different ptc-format). But as far as I understand this is only for rendering particles, not for exporting them?

At the moment I started to build a particle-pipeline around exporting RIBs with the particles stored. Works pretty well, can be submitted to the farm and then tweaked with a DSO Rifilter before rendering. But of course, there's no preview in Maya.

So I am still interested in finding a good pipeline. Also, I'm not quite sure how much slower is it filtering 20M particles coming from RIBs rather than rendering PTCs?
  08 August 2012
Hello guys
In partio43delight code I included small example mel for caching out simulation in several passes.

Each pass is named in krakatoa scheme and the DSO can render them in one go. This can easily be extended to suit batch processing on farm - I've done that already at work (caching uing deadline)

John was even kind enough to add a file prefix to partio4maya cache command, so there's no need to rename shapes for each pass.

So, the shortest path to useable workflow would be getting latest partio4maya and partio43delight.
I'm still ironing some wrinkles, but this should not take too long.

ps. to be clear - partio43delight can render any format supported by partio itself
BTW. there's a bug in partio itself: reading headers from realflow BINs is crashing partio...

Last edited by praetorian : 08 August 2012 at 07:52 PM.
  08 August 2012
Ah, Awesome, Hi Michal ! Glad its working for you, once you get your code to a place you're happy with, would you be interested in contributing it back to the partio project directly?

I'm glad it is working for you!

I will have a look at your export partition code, I have plans to add a "partition" tab to the partioExport GUI so I can probably base some of it on that. Another developer is also working on
code to timewarp particle caches in the visualizer to make up position data based on velocity data for in-between frames, which would be aweosme if we could all standardize on the same function in code to do that across all the render-procedurals we all are writing.

Boris, there is a compiled version that should work for windows XP and windows 7, Check the download area for the old version right now if you want to try that out again. Partio actually has a RIB export as well although its not really been tested much, so you could potentially write out your rib data that way. It will definitely be slower than using another binary file format like PRT, PDC, BGEO, BIN etc.... But you will need Michals procedural to read them.

As for the bin format header problem, if you could submit a issue on github for that with some test data that would be helpful. The problem with supporting commercial formats is they sometimes change file format versions and that could be the problem you're seeing. I'm trying to get the reallfow guys to get partio into their codebase so they can export/import any format as well.
Or at least take a look at our current format reader/writer and let us know if we need to change anything.

Let me know what else may help and I'll try to build up some partition tools soon.

talk to you later.

  09 September 2012
rendering PTC

Hey John,

I got partio4Maya running and it works fine.

In the meantime I'm on Renderman Studio. Silly question: After caching out the particles (as PTC), how do I actually render them? The visualizer is just for displaying the particles in Maya, not rendering, right?

Is there any hidden DSO that comes with Renderman to render PTCs?

Thanks again.
  09 September 2012
Its been a little while since I used Prman, but I seem to remember a way to render brickmaps, and point clouds directly.. look around the docs.. I could be delisuional.. but I'm pretty sure its possible.

are you using your own verison compiled? or my pre-compiled one?

Hopefully we'll have some more contributed DSO's for rendering soon in partio

if you have suggestions or feature requests..please post them on github in the "issues" section.
its the only way I can keep track of all the stuff people ask me for these days on so many different forums :-)

  09 September 2012
well i was dealing with something like 20.000.000 particles last week, and my best bet right know is , DONT CACHE IT Well nCache export will take LONG TIME to be cached and LONG TIME to be read at rendertime. So i prefer to put a seed by expression to keep the same behavior and render them directlty on a mutlticore machine with 3delight.

If you realy realy want a cache the RIB gen solution looks to be a clever one , as you would be able to export generic sims with different seed and blend them with a RIB box. The problem here is that RIB export take times ... i'm not a renderman expert but i'm quite sure its possible to send command at rendertime that will overide the RIB info to modify radiusPP for ex. It should be easier than creating a GTO translator.

For the GTO way well it will cost you R&D time maybe one month during this month of R&D you would have been able to render particles directly in 3Delight

I'm surprised that a big company like MPC is still using maya for his particle jobs ! Poor FX TD's i sympathize with your pain

I never try partio by the way ...

Last edited by SebKaine : 09 September 2012 at 07:34 AM.
  09 September 2012
well I have to say, this RnD is of course for my personal projects. At MPC we have a nice pipeline for caching out PTCs and render them with lots of options/customization. But for work at home I can't rely on that pipeline

@john: in the meantime I am using your partio4Maya exporter to cache out the particles. It turns out that the exporter caches out unorganized PTCs. Is there an easy way to implement organized-PTCs? That would render a lot faster

Thanks a lot..
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