I am trying to recreate a shot from an ad breakdown where they add water drops spraying fast a subject and camera. Would this be a water sim, particle effect?
reference: https://youtu.be/aUY6gTnvWn0?si=j0o14RKrrCVhogxh @13:00
thank you!
Yeah I think you don’t need to use simulation but mostly particles effect with some animated displace so the particles don’t look like spheres…
Fluid sim is only going to slow you down here without the needed control…
First off, welcome to the community, @Quinby_Duble! Glad you are here! I think answering your question has a couple of different approaches. It is always great to let us know what you have already tried and what happened when you did that. I know I often want someone smarter than me (my wife) to tell me where to read the recipe for dinner so I don’t waste time making a bad meal. There are things to consider, though. How much time do you have? How much processing power? What quality output do you need (is this just for small screens, or 4K IMAX)?
You could use a fluid simulation, but tweaking the settings to art direct the splash just the way you want it in the fidelity you want it would be a pain. I agree with @sozap. (And not just because I spent the better part of an hour monkeying around with FLIP fluids trying to get a good looking water spray like your video…to come to the conclusion that particles would be faster and easier on my hardware for a Full HD example video.) If you have really beefy hardware and need higher fidelity, a full-blown fluid sim may be worth it. If those aren’t the case…
Particles allow you to iterate much faster. I put together a test file I can share using an emitter with some initial velocity toward the camera, using a water droplet object with some bubbles and displacement. In order to capture the feeling of the shot you shared, it is a black and white closeup in slow-mo with motion blur. I made sure to simulate the particles using a significantly slower time step (in the Integration section of the particle system properties) to get the slow-mo effect like the video. There are a few things to consider when you adjust the time step - the particles’ lifetimes probably need to be lengthened, along with pushing the emission End frame out further. I also needed to make sure to enable depth of field and set my focus distance to approximately match the reference.
This is my quick hack version:
Here’s a link to my example file on my Google Drive: https://drive.google.com/file/d/1eb_57vyznpVdatjpKJcN6BNRNxbcUbDo/view?usp=sharing It was too big to upload here. Let us know if you have any other questions!
Great stuff @Hunkadoodle !
I think you got the greatest chunk of the effect !
What they did on top of that is that they added some bits of wobbliness to some of the droplets so it looks even more liquid :
For that I think it’s doable probably with some metaballs or metaball-like behaviour and some displace.
In the meantime what you did is already super convincing ! Well done !
Metaballs were one of my original thoughts! There’s a limitation with metaballs where they aren’t static meshes, so they can’t generate motion blur. If I had more time, I would have tried to look into alternate methods (maybe vector blur? or possibly some sort of metaball baking? - I don’t know, I don’t use metaballs that much…).
Another tip for @Quinby_Duble, if you wanted to introduce more variety into the droplets, you could also create a few different variants of droplet geometry and add it to a collection and use the Pick Random option within the Render panel in the Particle System settings. Check out this section of the manual for more details:
https://docs.blender.org/manual/en/latest/physics/particles/emitter/render.html#collection
Good catch !! Indeed that makes things a bit more complicated, to keep things simple maybe the solution would be to render with eevee and accumulate frames for a motion blur effect. Basically doing it the oldschool way…
Cycles should be relatively fast for that also…
There are also filters that can do motion blur based on optical flow …
@sozap @Hunkadoodle Thank you both for the replies. I agree i think particles is the way to go, even that quick version Hunkadoodle made is like 90 percent of the way there. Metaballs seem like a great option in conjunction with vector blur for motion blur in compositing.
I did the same with FLIP fluids as well, attempting to use the built in rain feature with adjusted initial vectors, which i think could work but requires so much detail in the domain, any change was unbearably slow. will explore the particle method while adding some variation to the droplets.
Thanks again!