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Hi there, 

 

I've been asked to create a simulation of a large scale oil spill as seen from a high altitude. I'm currently trying to use RealFlow and then bringing in those meshes with a thin film shader, and then applying displacement in After Effects. Is there some way I could apply a highly detailed turbulent displacement that would respect the direction and speed of the realflow meshes? Attached are some examples of the sort of image the client is looking for. Any ideas on how to approach recreating this with convincing dynamic motion, shifting iridescent colors, and a good amount of fine detail, whether in cinema, after effects or any platform would be very much appreciated. 

 

 

ussarizonatears.jpg

uss-arizona-oil-slick-930891.jpg

BPDX1091-M.jpg

Oil spill - great image image_preview.jpeg

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natevplas    12

Wow, that's a tough one!  I've always thought that oil on water has a cool look to it with that iridescent shine, but never thought too deeply about why it looks like that.  Good ol' Google to the rescue: http://www.hk-phy.org/iq/oil_rainbow/oil_rainbow_e.html

Apparently the difference in reflected color is due to the varying thickness of the oil layer and how the top and underside of the oil reflects/bends light.  I wonder if you take your RealFlow sim and add a Displacer Effector which only pushes polys in the Y direction.  Then create a shader with various noises to displace the sim.  I haven't tried it myself (and I don't use RF), but see if this produces interesting results with your thin film shader (or maybe a simple fresnel with the rainbow colors would work in the Reflection channel?).  Not knowing how long the shot is or more about what the client needs, it seems like you could get away with not having much animation in C4D.  Then take it into AE and apply some instances of the Liquify effect to animate a subtle swirling flow.

That's just my two cents.  I'd be happy to hear how other people might tackle this!

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harrymihalis    2
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  • Hi natevplas thanks so much for your many good suggestions I will certainly be trying them out. Cinema's Thin Film shader already has a built in function to map noise or other shaders to the thickness of the oil film, and i'm getting some good results in terms of the material now using a GGX reflection layer with additive transparency and some high IOR numbers. I will certainly be using After Effects to add in extra detail and was testing with turbulent displacement but your suggestion of animating the liquify effect is much better. 

     

    I'm not having much luck with RealFlow and am finding the simulation times and filesizes pretty unmanageable as unfortunately I don't have access to a super computer, although I was considering looking into houdini as I managed to unearth this code for up-resing fluid simulations.  http://www.tkim.graphics/CPT/

    Unfortunately I'm on Windows and it seems like this code is only compatible with Mac/Linux, and I have no idea how to use Houdini.

     

    Anyway thanks for your input! 

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    natevplas    12

    Yeah, I can imagine having a lot of trouble getting RF to do this.  You'd probably be better off painting a matte for an alpha channel on a plane- or using a turbulent gradient to get those wavy edges to it.

    Would love to see what you came up with!

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    harrymihalis    2
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  • Hi natevplas, 

     

    I'm making good progress with realflow now. I found an old tutorial for realflow and Maya on making lava flows which details a technique for pinning a texture to the mesh which is then deformed along with the particle movement and adapted it to work in c4d. This then bakes out to UVs that can be used to drive the transparency of the thinfilm effect in c4d. In terms of the natural motion I ended up using a grey scale version of the large scale oil spill and mapping the roughness and stickyness parameters of my collision surface to that so the fluid kind of traces the formation of densities and flows in the image, but then moves on and gradually evolves its own shape. That speed information also comes out as a vertex map which I can use to drive the variation of the thin film, along with a little animation of my sky hdr and a bump map from the realflow UVs to add some detail. 

     

    I'm still figuring out how to handle exporting the number of frames the client needs (2,250), but feel im definitely on the right track at last. Many thanks for your input!

     

    H

     

     

    SurfaceCloseUp1.JPG

    Mat1_0370.jpg

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    natevplas    12

    Cool!  Sounds like a really interesting solution- not sure I totally get it, but glad you figured that out!  In the second pic, are you planning to show those edges to the RF mesh?  They look a bit blobby.

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    harrymihalis    2
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  • Yeah I don't really understand it either to be honest. I got some tips from a RealFlow veteran who told me I was doing several things wrong, so starting again armed with a better understanding of the parameters. 

     

    The final render will be a close up of the central portion of the mesh, so those blobby edges won't be on show. 

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