RealFlow Official Forum

Hi.
Doing a timewarp effect using standard particles. Right now it is a three step process due to the workflow at hand:
1) import .sd from Maya and make splash simulation using the impact of the imported sd and a crown daemon
2) using retime tool timewarp the splash sim slightly to match directed action
3) in another scene, import and extend retimed sim from 2 using binary loader with time multiply of 0.10000, mesh and export.

(we need the extended x10 sim as oversampling to handle a varispeed effect which is being done in Maya)

The problem I am getting is that every 20 frames the retimed particles make a big jump. The interpolation is perfectly smooth otherwise. Obviously these jumps kinda ruin the super slow motion effect we are going for. Interpolation method doesn't matter.

Looking a little closer it seems there are particles being added every few frames, from a few hundred to a few thousand. This is happening in the original sim. I am not using a sheeter daemon and the source of the particles is a filled sphere. If anything they should be going down in number as a few are squeezing out and getting killed by kill volume. By the end of the sim the number of particles has increased 7x. That certainly helps the look of the splash but it is messing up the timewarp...

So what is adding the particles and how can I get a timewarped sim that doesn't jump because of them? Thanks!

The problem here is that the crown daemon has a built-in version of the sheeter daemon and this causes the flicker.

As a quick and dirty workaround you can simulate the scene with a 10x higher FPS output, e.g. 300 fps instead of 30. This way you'll get a smooth simulation. Don't forget to reduce the number of MAX substeps with these high settings to decrease simulation times. 30-40 substeps are enough.

Meshing should be done with OpenVDB engine in order to avoid the typical flicker you normally get with the RK mesh engine.

Ahhh, thats how it does its magic. Started thinking about making a script/graph that trickles the new particles into the sim so they do not show up in big chunks (maybe by collecting the newly birthed particles and adding them in over time) but it gave me a headache.

As far as raising the fps I was held up by the incoming .sd file which locks to frames not time; the reference objects go out of sync with the simulation. Is there a way to retime the .sd file into a new stretched out one and then use that for the splash sim? Will look into that...

Yes, you can retime the SD separately. The safe way is to create a new scene, copy the SD to its object directory and load it like any other SD. Then you do the retiming on the objects and what you get is something like animation_retimed.sd. Put this new file to the splash scene, load it and use it for the simulation.

When you retime SD files you have to be careful: in the retimer's "Input/Output settings" tab you have to check every object you want to include to the animation_retimed.sd. Only check each object's box, not the resources (abc, sd, ass, obj, etc.). At the end of this export tree you will then see that the checked objects will be added to the combined animation_retimed.sd

I hope you understand the workflow

Sure do. Thanks!

edit:
or not?

When I activate the objects from the sd file in the in/out settings they appear in the "Save animation.sd" just like you said, only there is an error of "None available" under "Source for interpolation" which prevents the retiming. Setting Interpolation to "No Iterpolation" has no effect, still an error. Neither does specifying output type (like to .sd) on the objects.

The sd is exported from Maya, has deforming geo (so I cannot use sd -> curves instead) but is nothing unusual otherwise.

???

Think I will retime the maya file and then re-export the sd instead.