How do you render splash, foam and bubbles?

Discussions about the use of Realflow
Bobross
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How do you render splash, foam and bubbles?

Postby Bobross » Tue Sep 26, 2017 4:55 am

How exactly do you render these out? Bubbles are clear or "holes" in the liquid, how do you render them out in a particle state? Assign them a white material? Same with splash and foam. For instance, what material do I assign them in Maxwell?

Everything looks decent when rendering within RealFlow's version of Maxwell just assigning the "white materials. But that all goes out the window when importing the particles to Maya and assign a Maxwell material. They turn into huge blobs..


Forester
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Re: How do you render splash, foam and bubbles?

Postby Forester » Tue Sep 26, 2017 3:53 pm

Currently, there are no really appropriate Maxwell materials for foam. That is, the only existing Maxwell materials, including my own current set, are simple diffuse shaders of various white colors, maybe with a little SSS or some form of translucency thrown in. (You can find some Maxwell Render materials called "foam" in the MR Materials Library [http://www.maxwellrender.com/materials/] or a primative version I made here [http://www.expandingwave.com/product/foams-maxwell-render-materials/]) These might be good for application to RF particles and for middle distance views of foam meshes (for example, http://www.expandingwave.com/product/free-standard-sheetflow-3d-model/), but they are really not very satisfactory.

Here is what the professionals are doing to create foam shaders. (http://www.shaders.xyz/forums/topic/cha ... beer-foam/) Note that what is under development here are complex (multi-layer) shaders for high-end renderers, such as Arnold and Corona. But these are absolutely convincing - really fine work! These shader techniques make use of such things as displacement masks of bubbles of random sizes, complex layers of diffuse and translucent materials, and so forth. If you are knowledgable of shader-making, you could try your hand at development of something like this. OR, if you are using one of these render engines in Maya, you could simply copy out one of these recipes for the chosen renderer.

I've started development of a Maxwell bubble-laden material for Realflow foam meshes because it should be possible to do something like this in Maxwell (doing most of the individual layer development in Substance Designer). And this material should work in Maya and Max just fine. But I won't be able to complete this work for another few weeks due to other projects with higher priorities. Please note that the Maxwell shader I'm working on is for meshes - it would never work for application to the individual particles. There is no useful way to develop a material with bubbles for particles, since the particles are of uniform size. Not to mention that any multi-layered material would be prohibitive in render times were it to be applied to individual particles.

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ChristianZ
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Re: How do you render splash, foam and bubbles?

Postby ChristianZ » Tue Sep 26, 2017 7:47 pm

There is no useful way to develop a material with bubbles for particles, since the particles are of uniform size. Not to mention that any multi-layered material would be prohibitive in render times were it to be applied to individual particles.


Regarding particle rendering, this is possible to do in most render engines, but render times are very long indeed. There is a software that is often used for this task, Krakatoa from Thinkboxsoftware. It does not do very much (is limited with handling light and shadow), but the particle rendering as points or, better, as voxels is very fast. RealFlow standalone directly writes the ptr files for Krakatoa to be used as foam, or also for more solid materials such as snow or sand. It does not render spheres, so not useful for bubbles.
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Forester
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Re: How do you render splash, foam and bubbles?

Postby Forester » Wed Sep 27, 2017 9:39 am

Apologies, my first answer was generic, and ignorant. You must be referring to a Hybrido simulation, where "bubbles", "foam" and "splashes" are distinct RF entities and the rendering processes are using a form of volumetric rendering. However, when translated into Maya, you'll find that the "bubbles" are not really polygonal spheres as you were expecting, and so they can't be rendered out as "bubbles." I'm not sure there is a good solution for this. Sorry. :oops:


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