slow motion smoke

[sanostol]

hi, lets say I have a smoke simulation in normal time, but now I want to do the same simulation as slowmotion, so that the aniamtion has 10 times more frames, but with exactle the same animation,

how can I achieve this. setting the frames per second high, and or manipulating the scaletime parameter of the dop completely changes the simulation.

Martin

[Ratman]

Scale Time seems to divide down your temperature and buoyancy values. Scaling down time and readjusting my settings seemed to be the only way I could get slow motion smoke working.

So you'd might just have to play with it.

Though I'm sure some sort of retime tool could be build using the volume vop stuff.

[asnowcappedromance]

I might be wrong, but somehow I remember that you can write out your dop data to disk and import it into chops afterwards.

There you can rescale your sim!(wasn't there a tutorial about it in the gnomon rbd dvd ?!)

[Ratman]

You can do that easily with points, but voxel volumes are a different thing.

[sidandmj]

actually I am doing this very thing for a shot now and having great success at running the sim realtime then using the sequence blend sop to blend the

voxel data

so far it seems to work like a charm

you can also readvect density thru the blended vel fields with the time scale of the advect dop set to the new rate

i recommend not using the time scale as there are a few fields that dont respect the scale and you cant animate the scale

these issues are not present in the blending method

You can do that easily with points, but voxel volumes are a different thing.

[Ratman]

Well that's good to know, definitely gonna have to check it out now(and eat my hat )

[sanostol]

thanks guys. i tried the blend way yesterday, but for me it seemed a little bit strange, as densities are not moving between the frames they are more or less fading out on one place and fading in on the other. as I have to speed down very much it was not good enough. but I will try the sequence blend today. I did a normal blendSOP with a linear interpolation between the frames.

I also tried to upres my low and slowdowned basesim, I scaled down the velocities in the slowdown cloud and the upress extinguished the bad movement.

at the end I'm simulation 4 times more frames now, and do the timewarp in comp. but blending voxel data is very tempting

[bunker]

Have you tried to change the "timescale" for the gasAdvect nodes

in the LOWRES and UPRES solvers ? that should work if you're not using

any combustion model : just smoke

thanks guys. i tried the blend way yesterday, but for me it seemed a little bit strange, as densities are not moving between the frames they are more or less fading out on one place and fading in on the other. as I have to speed down very much it was not good enough. but I will try the sequence blend today. I did a normal blendSOP with a linear interpolation between the frames.

I also tried to upres my low and slowdowned basesim, I scaled down the velocities in the slowdown cloud and the upress extinguished the bad movement.

at the end I'm simulation 4 times more frames now, and do the timewarp in comp. but blending voxel data is very tempting

[bunker]

here is a simple smoke solver file with promoted advection speed parameter ( on the advect speed node )

advect_speed.hip

[essencevfx]

as well , if you set that timescale data to 'set always' (on the advect dops) you can actually animate that param , and time warp your smoke IN the sim ... Fun stuff

[sanostol]

thanks a lot. that sounds like fun.I will look at it. indeed sounds like fun

[reyan]

here is a simple smoke solver file with promoted advection speed parameter ( on the advect speed node )

I'm tryng to do the same in Houdini 12.5, and with Smoke Solver, inside Pyro node, and seems more complicated that before, actually. Someone know ?

[anim]

in 12.5 you can use Gas Upres DOP, it has the settings for animating the timescale, so it can be used to just retime your fluid

http://www.sidefx.com/docs/houdini12.5/examples/nodes/dop/gasupres/UpresRetime

http://forums.odforce.net/index.php?/topic/16924-dynamic-retiming-of-volume-simulation/

http://forums.odforce.net/index.php?/topic/17336-retime-large-scale-pyro/