Motion Blur for Fluids Simulations? Tweet

[brent_3d]

I would be very interested in that as well, I generated the fluids with Flip Fluids as well, but I couldn't get it to work.

This is what he showed, I don't have Flip Fluids yet and the example is in Octane v4 for blender I believe so I can't verify at the moment.

[grimm]

Ah yeah, awesome, that second image is what I was missing. Thanks!

[Phartog_1]

Hello everybody,

I have been reading this thread, because I am trying to rendera simple flip fluid, pour in cup simulation with motion blur. I enabled all the things in flip fluids ("render motion blur" and "generate motion blur vectors"). When I try to render it with octane (enable motion blur internal). What happens is that I see intersected meshes of different fluid bodies. As I understand it, flip fluids is adding shape keys to the fluid surface mesh and upon rendering this needs to be used by octane to create motion blur. But it seems octane is now rendering these as solid meshes.

In the attachment an example of what's happening. The first image is with motion blur off, and the second one when I enabled it.

Motion blur off

Motion blur on

Does anybody has any ideas how to solve this? Thanks in advance.

Patrick

[pegot]

Does anybody has any ideas how to solve this?

Set your generated FlipFluid mesh to Global in the Octane Properties tab. Unfortunately, in addition to Motion Blur, FlipFluids do not work with most settings in the Octane Properties tab.

Regarding Motion Blur: The Octane Blender Internal motion blur doesn't work but the Subframe motion blur does (in order for Subframe motion blur to render you still need to enable both Motion Blur and Generate Motion Vectors in the FlipFluid settings.

[Phartog_1]

Does anybody has any ideas how to solve this?

Set your generated FlipFluid mesh to Global in the Octane Properties tab. Unfortunately, in addition to Motion Blur, FlipFluids do not work with most settings in the Octane Properties tab.

Regarding Motion Blur: The Octane Blender Internal motion blur doesn't work but the Subframe motion blur does (in order for Subframe motion blur to render you still need to enable both Motion Blur and Generate Motion Vectors in the FlipFluid settings.

Hi pegot, thank you for the reply and explanation. I got it to work. The only problem I know experience is that in areas where the liquid is in a obstacle (a cup in this case), there's still some interference, probably because of the motion blur inside the cup (liquid still swirling around). Is there a solution or work around for this?

Also what I noticed is, that with the subframe method, you need a lot of motion samples, to have it look good. Even with 10 motion samples, I thought the motion blur didn't look very smooth.

interference with obstacle

[pegot]

To prevent liquid from going through the cup you probably have to fiddle around with the various FlipFluid controls, including making sure the cup mesh is solid enough – increasing resolution may help. There are several controls that you can experiment with, including Particle Jitter, Surface Tension, Sheeting Effects. Consult the FlipFluid documentation, they also have a good tutorial on using some of those settings, I think.

However, if some of the fluid is escaping the cup just from the different stages of the motion blur itself, I do not think there is too much you can do. None of the Subframe controls seem to work – only setting the Motion Samples seems to do anything and even at its max 32 gives very segmented results.
Would be great if the Octane Blender devs could work with the FlipFluid developer to see if this issue could be fixed. The FlipFluids motion blur does work great with Cycles though.

You can also try Blender’s own fluid simulator to see if it will work with Octane motion blur (I have not tried that yet myself).

[Phartog_1]

Hi Pegot, thanks for the reply. Maybe in the future there will be some improvement to this. I now solved it by rendering it with and without motion blur and masking the bottom part of the animation in post.

[grimm]

Another thing you could try is to have a proxy object for your container. Make it much thicker but the same size internally and run the simulation with it. Once the simulation is finished you can either delete or hide the proxy object and then use the original object in its place when you render.