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Retime vs scale time DOP parameter?

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Hi guys,

I noticed a difference between using the scale time parameter of the dop network compared to using a Retime SOP after the DOP node.

Retime seems to go faster than the Scale Time parameter for the same value.

Can someone explain the difference? which one would you recommend using if you wanted to slow down your simulation?

Cheers!

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recommended would be using both, depending on your setup

unfortunately it's very generic to just say simulation, as different types have different issues, so while maybe not addressing your specific issue with unknown solver

but to keep it general,dop level scale time

- is precise as it literally computes finer steps for lower timescales

- doesn't scale everything as there is plenty of microsolvers especially that rely on global time instead of sim time especially nodes noise phases, so you can't rely on just slowing down something you have tweaked on different time scale

- can't be animated 

 

solver level timescale

- is precise as it literally computes finer steps for lower timescales

- doesn't scale any microsolvers plugged into solver, only internal ones, so external have to have linked timescale, has the same issues with pulses, etc. 

- can be animated

 

retime after sim

- it's just interpolated which can cause issues with extreme slowdowns, depending on type (volume stepping or artefacts even with advection method, particle or rbd inacurracies in interpolated samples due to subframe collisions, stepped birthing/dying of particles, etc...)

- since it interpolates already cached frames it doesnt suffer from per microsolver time inconsistencies mentioned in previous methods 

 

so I prefer simming slowmotion shots slower than realtime and then push it even slower by Retime SOP if needed, also by simming at slower time scales you can avoid having many substeps so just gain precision data without slower sim time, or you can chose to use substeps instead and cache those, but it may get tricky to deal with fractional frame numbers

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Thank you for this answer. I feel enlightened now :)

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