Realflow rendering

Discussions about the use of Realflow
AndyLights
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Realflow rendering

Post by AndyLights » Mon Dec 09, 2019 1:39 pm

Hello,

New user, I've looked for the answer in realflow forum and manual, as well as many vids, but can't find a concrete answer.
My question is about the full workflow from pre-sim to final render.

Once I have imported my scene from C4D into RF, set up HY things and simmed my main particles, then secondaries, At the moment I'm exporting all particles as .abc as well as the main HY mesh as .abc.
I then stitch all .abc seqs and import them into C4d. I use Octane, so I then use the scatter object to add geo to the imported particle meshes. (spheres on each point)
Taking into account that I do use octane, is this a correct workflow, speaking generally? I'm yet to reach a result that I'm happy with, I'm usually getting a fairly nice liquid mesh with lots of tiny spheres on top!

All help appreciated!
Thanks
AK

//RF:10.5.3 , standard licence + one sim node // C4D R20 // Octane V4 // Windows 10 // 32gb ram // 4 x RTX 2080 //4 x GTX 1080Ti //

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ChristianZ
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Re: Realflow rendering

Post by ChristianZ » Mon Dec 09, 2019 2:38 pm

Hi
so I then use the scatter object to add geo to the imported particle meshes. (spheres on each point)
Just to be sure we are talking about the same... you use this to render foam, right? Like on the crests of the waves?
RF10.5 standard + RFC4D3, Mac&Windows

AndyLights
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Re: Realflow rendering

Post by AndyLights » Mon Dec 09, 2019 2:56 pm

Hello!

Thanks for your reply.

Yes, secondary emitted particles (eg foam from domain). I know that octane doesn't play well with anything that isn't strictly geo so the only way I can think to render is to clone/scatter spheres onto the abc import of the foam particles, but, it always looks like sand in the liquid.

I'm wondering which ways other, more seasoned people, render these elements. Or am I correct in doing it this way, and I just need to work harder in post processes, such as motion blur etc?

I hope this makes sense! :?

Thansk!
AK

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ChristianZ
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Re: Realflow rendering

Post by ChristianZ » Tue Dec 10, 2019 8:30 am

Well, rendering the foam depends on the options that are available in a specific render engine. Personally, I am using Redshift most of the time now, have not used Octane. Redshift offers a couple of options when you use their render tag on a particles source (custom object, point instances, spheres) and most of the time you end up choosing spheres, because they can have highlights, shadows, and all the other options that allow to fine-tune the look of the particles. I liked (and would still use if I could) the Krakatoa point renderer that is somehow cool, because the look can be from crisp (with self-shadowing) to cloudy/smoke and still render billions of particles. Unfortunately, there currently are no updates for C4D R20 and higher.
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AndyLights
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Re: Realflow rendering

Post by AndyLights » Tue Dec 10, 2019 9:44 am

Hi Christian,

Yes, it's the same with octane tags to create particle geometry I think, so I will press on with that technique. It's good to know I'm not doing it totally wrong!

Is there a way to output a texture-based foam map for the liquid at all? Or would I be best trying to fiddle and make a vertex map in C4d? My thinking being I can mix the particle-based foam and a texture base, maybe.

Thank you for your help Christan, I have asked these questions on many forums and, so far, you're the only answer!

Thanks again

AK

Forester
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Re: Realflow rendering

Post by Forester » Wed Dec 11, 2019 1:38 am

Well, not wanting Christian to be all alone on a cold winter's night ........

Am not a C4D user, nor user of Octane. But I have worked on foam materials for Maxwell Render and subsurface scattering. It maybe that some of my shader settings will translate OK - they should translate to any PBR rendering engine.

The reason that I mention subsurface scattering is two-fold. First, in my various studies of foam, I see that the depth of light penetration is very, very small (as in 20.00 mm, typically). Second, the coefficient of scattering should be very high - as in something like a value of "300.00." This high an amount of scattering means that a "mass" of polygons will look like it is full of small particles ("bubbles") and there is not a need to create a jillion individual geos. So, if you create a small difference between the white color you assign for Transmittance and the color you assign for sub-surface scattering ( typically, the "Scattering Color"), it looks like you have a dense mass of tiny bubbles in the "blob."

But, I know that sometimes things go very wrong when trying to apply a dielectric material to an animated object. Depends on the stability of the renderer, I suppose.
Windows 7 Pro 64 - Realflow 10.1.2.0162 (Nov 2017 patched) Standard Version

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ChristianZ
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Re: Realflow rendering

Post by ChristianZ » Thu Dec 12, 2019 8:31 am

Well, not wanting Christian to be all alone on a cold winter's night ........
Thank you Forester :P Ideally, a forum is a place where several people come together, but this one is a little too specialized and the numbers of RF users appear to be declining.
Anyway, rendering bubbles and foam is a formidable challenge, regardless if it is done with a physics simulation or for a still image. There are also some differences regarding close-up shots of big bubbles, foam coverage of beverages, or ocean foam. In the case of hybrido foam, it is less recommended to use dielectric materials for animations as those increase render time very much. Currently, I am preparing a fresh hybrido scene with meshing and foam to test some settings. But that usually takes a couple of days.
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AndyLights
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Re: Realflow rendering

Post by AndyLights » Thu Dec 12, 2019 10:04 am

Thank you for your replies chaps, yes I have posted in the realflow forum and octanes but so far no one whats to play! So I especially appreciate your help.

I'm in the RnD phase of a project due to start early next year, basically lots of shots of a lighthouse with a stormy sea crashing into it, etc...
I was hoping to do all shots with a full simulation so make it 'real', but I think that would take far too long! So I'm thinking of using a mix of sims for the shores/ crashes, realwave and Hot4D for the open areas of water and throw in some stock effects for good measure.

I am, perhaps, over-thinking the foam. After I add wind and rain effects, motion blur et al, I'm sure A particle/sphere-based foam mixed with a texture on the mesh surface will suffice.

It's a shame that the realflow guys don't have more interaction with the users, one major factor for buying X-particles recently was that they employ a guy called Bob Warmsly who does excellent training and is in constant touch with the community. The various tutorials from Luis are a good start but they are always a section of learning, I'm yet to find a series of videos from start to finish of the pipeline. But I guess I just want someone to solve all my problems for me!

Enough complaining from me, I best go and learn!

Forester
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Re: Realflow rendering

Post by Forester » Thu Dec 12, 2019 11:58 am

Doesn't sound like you are complaining. Sounds like you have undertaken a large and complex project.
In fact, being an old blue water sailor, I'd be very interested in following along as you develop your project. Please keep us informed here.
And "Good Luck" to you!

Thanks for the information on the nature of your project. Given the scale of your scene, "foam" should be less of a problem and your proposed setup should work well.

Christian, thanks for your reply as well. You are certainly correct about the substantial differences in rendering foam at different scales. I will be very much interested in your "fresh hybrido scene" (Foam rendering should interest all of us!). Please keep us informed - maybe a different thread.

And totally tangential to AndyLights' original question - I wrote out a document yesterday about creation of translucent materials for PBR rendering engines that I hope is independent of the identity of the rendering engine. Includes how to think through the problem of making a shader for one kind of foam - "close-up view" "champagne foam." Would it help the general cause if I posted that document for download here? Maybe under a thread just called "foam shaders/materials"?
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ChristianZ
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Re: Realflow rendering

Post by ChristianZ » Thu Dec 12, 2019 2:41 pm

Would it help the general cause if I posted that document for download here? Maybe under a thread just called "foam shaders/materials"?
Of course! We will be grateful for your insights regarding rendering for any fluid-related shaders/materials :P
RF10.5 standard + RFC4D3, Mac&Windows

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