Ken's Academy Award: Noise and Turbulence

Ah, I wondered why it felt like Perlin noise had been around for way longer than 1997.

I've always loved the demoscene stuff I've seen. How would you recommend getting into it? Both the community and creation

Is that what they use in Metal Gear Rising to simulate the texture in the inside of objects?

Man, that's a super interesting use of it. Controlling randomness shows up in so many - often unexpected - places when dealing with aesthetics.

I wrote a detailed explanation last year which might also help some: http://eastfarthing.com/blog/2015-04-21-noise/

That's kind of like saying the random() function made a billion dollars for Notch, though. What made the money was the whole game, not just one algorithm used.

My brother wrote a rather nice clojure library that does 4D texture generation

https://github.com/mikera/clisk

My simple gamer (ie every texture is 2D) brain had a bit of trouble coming to terms with continuous 4D textures, and I think it was talking about how Perlin noise could be continuous that made the idea stick eventually.

Your description is accurate, but the most important part to know is that the random values on the lattice are used as the derivatives of the noise function. The noise function itself is then an itegral of those derivates. By putting the derivatives at the lattice points, the grid structure underneath becomes far less visible. If you used the random values directly, and just interpolated those using a spline, you get a 0-value derivative at exactly every lattice point, and you end up seeing the grid structure in the result, it becomes glaringly apparent. Using Perlin noise, the minima and maxima are offset randomly from the grid, making the overall function feel much more natural.

It's useful any time you need some natural looking randomness in a texture. Perlin noise is standard in pretty much all 3d rendering software for films, and it's becoming quite common for games.

The turbulence part of this is when you take a whole stack of Perlin noises at different frequencies, i.e., different grid sizes, and sum them. It's more expensive of course, but this is how to get extremely realistic feeling noise, it gives you medium and high frequencies. And it further hides any grid artifacts.

I used Perlin noise as a wind function to animate bushes & trees in the animated movie Madagascar. Perlin actually works really well for windy looking motion because of the way it's derviatives work. I tried a whole bunch of other noise functions, and Perlin was the only one that worked well.

Another fun application of Perlin noise is fake fluid dynamics. If you take the curl of a Perlin noise field, you get a nice turbulence function that has no divergence. Fluids are usually approximated as being incompressible, and that's part of what makes fluids look fluid. Curl of Perlin can give you a nice fluid-looking turbulence. Curl of any noise is divergence-free, of course, but Perlin works well and looks better than others.

Perlin noise is actually more expensive to evaluate than a real fluid simulation. The fun/important part is that Perlin is static, so there's no simulation and you can render your frames out of order and in parallel. With a fluid simulation, each sim frame depends on the previous one. Fake curly noise is also easier to set up and tune than a fluid sim.

I and others have used this technique on lots of films for quick turbulent smoke, fog, and particulate effects.

Thanks for the link(s)!

Awesome stuff

I've found most stories headlined "How something did something else" tell you nothing about how.

I guess "how" is American (or headline-ese) for why'

He has written a couple of lines above the code.

Agreed: "It seems that my techniques found their way into the various software packages" leaves the how completely to the imagination :)

you need to scroll up...

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In 1997 I received a Technical Achievement Award from the Academy of Motion Picture Arts and Sciences for work I had done on procedural texture. For example, the NYU Torch on the right is made entirely from procedural textures (except for the text along the bottom). The flame, background, and metal and marble handle are not actually 3D models - they are all entirely faked with textures. A hi-res image of a marble vase I made using this technique can be found here. A bunch of other texture images I created can be found here.

I then improved it, and wrote a paper about that. You can play with interactive demos of the improved version here.

You can play with designing noise-based textures yourself with a really nice interactive Java Applet created by Justin Legakis. Also, the interactive fractal planet demo on my home page is made using these techniques.

It seems that my techniques found their way into the various software packages, such as Autodesk Maya, SoftImage, 3D Studio Max, Dynamation, RenderMan, etc., that folks use to make the effects for feature films, which is way cool. Movies look better now, and I guess that makes me a good American.

Here's what the award actually says:

To Ken Perlin for the development of Perlin Noise, a technique used to produce natural appearing textures on computer generated surfaces for motion picture visual effects. The development of Perlin Noise has allowed computer graphics artists to better represent the complexity of natural phenomena in visual effects for the motion picture industry.

Needless to say, my Mom was very happy.

Thanks, we removed the anchor from the link.