Couple of Particle FX questions for short film

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  11 November 2016
Couple of Particle FX questions for short film

Hi there,

Ive started working on my first short film a couple of months ago, but atfer inital storyboarding and some concepts I got overwhelmed by my job again, so I only recently started out again.
Im currently in the process of setting up a project page on Artella to get some more people on board, because I quickly realized, that I wont get anywhere trying to do it all by myself in my spare time...

I want to focus mainly on character design and environments, but Im also planning on doing some of the FX stuff.

So in between renderings Im going to try and squeeze out some info out of you guys on how to achieve certain effects...

Here we go:

1. There will be several underwater shots. Ive done quite a few medical animations and Ive often used a very simple setup with just spawning a couple of thousands of small particles in a defined area, with those particles being a group instance of various modeled little objectsresembling sand particles or plant fibres, and then just adding some random movement with random walk or a wind force with turbulence.
This works ok, but is far from the look Im going for:

A) There is no reaction with animated objects in the scene.
B) The amount and look just doesnt feel dense enough with only 10-20.000 Particles of roughly the same size.

For the first part Im going to use Phoenix FD and the Phoenix Force op, to get a more fluid like look to the particles and not just some random movement.
For the second part Im going to try and use several Particle Flows or Events (depending on the final particle count and responsiveness in the viewport): One for the "bigger" particles that actually look like "stuff" (small sand particles, plantfibres etc.), one for smaller particles that are either just very small lowpoly spheres or boxes to catch highlights, and maybe in addition some drag particles from Phoenix FD, rendered with the pointshader.

During my past projects, where I used the simplified setup of just the bigger particles I sometimes had the problem with particles getting to close to the camera and thus looking huge and ugly in the rendering, Im not sure if Ill have to shade them properly, or If Id rather just attach a wind force to the camera to keep them at a distance.

2. There will be two or three shots where the camera needs to travel quite a distance. Just covering the whole camera path with millions of particles probably is not an option, so Im trying to figure out to get the same density, like in the previous setup. I wont be needing the realistic fluid movement, so I dont need to sim anything with Phoenix here (going without the point shaded particles) and Ill just attach a windforce to my camera to move the particles a little away from the camera as it moves through them.
I have a couple of Ideas on how to get the same density and look like in the previous setup, but Im not sure theyll work:

A) Should I just clone the camera, move the keyframes ahead 50 frames or so and then link an emitter object to that camera? And then delete them, once the camera moves past them (simple age test or big deflector linked behind the camera?).
B) Or could I somehow use the camera culling op?
Im not sure how that would work though: Woud I just create an emitter mesh to cover the whole area, emit millions of particles to get the necessary density and then let the camera culling OP reduce the amount to whats needed in the frustrum?

C) Or maybe a mix of A) and B)?

D) I dont think there is a way to get what Im after by simply doing it in post in After Effects...no reaction to objects, no 3D movement of the camera...not dense enough looking..no "closeup" particles, just fade-spheres...

Any ideas on this?
 
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