Export the result of numerous simulations procedurally

[Jaik]

Hi,

I'm a very new user to Houdini and sorry if this has been asked before, but I searched for everything that made sense to me and couldn't find a forum post. I may just not yet know the right Houdini vernacular to search for.

What I want to do is to be able to leave a simulation running over night, where it would repeat the simulation using a set of different params (set by a global seed for example), and output the resulting geometry. For example, maybe I want to sim a rock fracture, and I want 100 different rock fractures.

Could someone point me in the right direction for a tutorial, documentation, example file, other forum posts. Anything that could help me start. I would prefer not to have 100 copies of the sim next to one another and run them parallel because I like my computer as a not melted pool of metal. So I would like to serialize it if possible.

 

Thanks in advance!

[mestela]

'wedge' is the term you're after.

Never used it myself, this seemed like a good excuse to try, see the attached hip.

The idea is to setup your scene to write something to disk. Here I have a simple rbd setup that use a file cache sop to save the sim as a bgeo sequence.

You then create a wedge rop, and tell it which other rop it will control (the file cache sop), how many times to run (4 times), and what parameters you want changed each time it runs (the global seed on a velocity sop, so my rbd pieces get different initial velocities per wedge).

If you render the wedge rop, you'll see the sim run 4 times, and the file cache sop save the sim 4 times. If you use the filecache defaults, this will all be wasted effort, as each variation will just write to the same file location.

To fix this, you can use a $WEDGENUM variable in the file path, that will be 0 for the first run, 1 for the second, 2, 3.

That's all from me refusing to read the docs and making lots of assumptions. 

 

rbd_wedge.hipnc

[Jaik]

Ah, wedge. Another completely intuitive node name from SideFX.

Awesome, thanks so much. Appreciate the example hip too! Its a lot easier than I was expecting.

[mestela]

Well to be fair that term is used a lot in VFX, and traces back to the days of optical fx. When trying to work out what exposure you'd use for elements to do a composite, you'd shoot a wedge of multiple exposures and see what looked best. 

 

http://patrickvfx.blogspot.com/2012/01/definition-of-wedging-in-fx.html