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Caching smoke pyro simulation with substeps to bgeo.sc


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Noob question about caching pyro sim to bgeo.sc after dopIO when using many substeps.

Is $F sufficient or should I be using $FF or $SF ?

Also since this is after a vdb conversion I am wondering if simply .vdb would be preferable to .bgo.sc?

My understanding is that you only need to cache substeps if you are reloading the simulation and would then use $SF.sim file format.
But after a DOP import or I/O you would use $F and .bgeo.sc since you are only concerned with whole frames at that point.

Am I correct?

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1- only cache subframes if you are planning to use them down stream, for example if you need to slow down the sim in post or if you are using smoke to source another sim with substeps (otherwise you are just generating unnecessary data)

If you are caching subframes do so use $FF.


2 - if your volume is a vdb you should cache it as .vdb only if you are planning to export to other applications. If are staying within houdiniland cache as bgeo.sc , it will be lighter and faster to load.


3 - checkpoint files or sim files. (dopnet/cache/save checkpoints or outputDOP). .sim files contain the entire data needed to carry the sim forward, so if you cache them you can restart the simulation from any frame. ( no need to resimulate the entire framerange)

In general you would use this method for heavy/slow sim in order to have a chance to retrieve them in case of failure.

Even in that scenario you would still cache the sim as regular bgeo.sc cache, and keep only the checkpoints of .sim.


Bear in mind that $SF is the simulation frame which doesn't necessarily match the $F

Ie. Your frame range is 1001-1050. and you are simming from 950 to 1050 with 2 substeps.

$FF 950 = $SF 1

$FF 950.5 = $SF 2


$FF 1049.5 = $SF 99

$FF 1050 = $SF 100


I hope I was clear enough, let me know if you have any doubt








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