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Old 06-05-2013, 05:47 PM   #1
em3
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How to recreate these clouds in 3D?

On our bike ride last night, my family and I saw some very dramatic clouds in the sky. I raced off to a clear spot to grab a shot. My first thought was that there was an imminent alien attack and perhaps it was a mistake to leave my family. This thought was soon put aside by my 2nd thought which was, how can I create this in 3D?



a) displaced mesh with maybe some pflow for the 'drifters'
b) all pflow/particles
c) a and b
d) all the other ways

The scale is so huge though I would think you would have a brajillion particles/faces so's to make it virtually unrenderable. I don't work in a production environment (*edit: that calls for dramatic clouds/environments like this) but I'm certain there are tricks people use to pull this off. I know it depends on the shot but if you were going to try to remake these clouds in 3D, what would you do?
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Old 06-05-2013, 06:23 PM   #2
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Yeah I would probably do a combination of displacement, maybe with a volumetric MR or Vray shader and some particles. From the tutorials I've seen, usually clouds can be made from multiple layers of meshes or particles. Here's a decent method - http://www.youtube.com/watch?v=MubJyuvneAs

You can also add separate clouds in post too, like for some of the foggy white clouds, you can make seperate renders, and composite them, so you have more flexibility over the transparency and color.

Last edited by Ian31R : 06-05-2013 at 06:29 PM.
 
Old 06-05-2013, 09:38 PM   #3
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Thank you, Ian31R. That looks like a simple enough method and with no plugins to boot. I will give it a whack!
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Old 06-06-2013, 01:49 PM   #4
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Drop me a line if you want to beta test my latest contraption

Here's a video of an early prototype: http://vimeo.com/59950346
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Old 06-06-2013, 02:01 PM   #5
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Quote:
Originally Posted by jonadb
Drop me a line if you want to beta test my latest contraption

Here's a video of an early prototype: http://vimeo.com/59950346

That's amazing! I saw you said it was going to be a commercial script, but could you talk a little about the methodology in there? You mentioned that it uses your own light engine - does it use path tracing from the light position to define the vertex colour? And the shadows which affect that vertex colour are defined in the same way but taking into account the absorption value to define the "darkness" of it?

It looks fantastic, either way.
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Old 06-06-2013, 02:24 PM   #6
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Thx! I jsut posted it in its own thread, was going to make it commercial but I haven't found the time in the last months to do so.. so open source it is!

The tech details: Rays are cast from the a light source to each face-center of the mesh. For all the other faces the ray intersects along the way it is determined if the ray in entering or exiting the mesh volume. By adding all the distances between entry and exit points you get the total distance traveled inside the mesh, which is used as a measure for the amount of light absorption when the ray arrives at itís destination face.

So for each face center we now have a light intensity, these are averaged to the vertices and stored as vertex colors. Next, for the luminosity each vertex illuminates it surrounding neighbors within a given radius, using the distance as a measure for decay.

For the sprite generation random points on the surface are picked and a color is calculated by interpolating the vertex colors for that location. This color is then transferred to the spriteís vertex colors.

Now with a simple vertex-color map as self-illumination and a radial-gradient+falloff for opacity itís already looking like a cloud. Using cloud-puff textures will make it look even better. This all render pretty fast using scanline and itís very interactive in the viewport.
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Old 06-06-2013, 03:21 PM   #7
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Quote:
Originally Posted by jonadb
Drop me a line if you want to beta test my latest contraption

Here's a video of an early prototype: http://vimeo.com/59950346


Woah, nice utility Jonathan! I will definitely give it a go. Thanks so much!

edit: I hate to sound like a nub but, what is a 'sprite' exactly?
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Last edited by em3 : 06-06-2013 at 03:31 PM.
 
Old 06-06-2013, 05:10 PM   #8
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Quote:
Originally Posted by em3
Woah, nice utility Jonathan! I will definitely give it a go. Thanks so much!

edit: I hate to sound like a nub but, what is a 'sprite' exactly?


Thx!

sprites: https://en.wikipedia.org/wiki/Sprit...ter_graphics%29
In this case the '2d' squares that cover the mesh are the sprites.
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Old 06-06-2013, 05:10 PM   #9
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