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  • this is going to be a boring video.

  • No, not that kind of boring.

  • There we go.

  • All I'm going to do is show you how to simulate the universe on your own computer.

  • We're going to be using after effects.

  • And it doesn't really matter what version you have, as long as it's fairly recent to start with, we need some initial conditions.

  • We want to know what the universe looked like just after the Big Bang.

  • So we're gonna use the data from the W WMAP satellite, which took pictures of the cosmic microwave background.

  • You could get these images from the W A Web site, but they're in the weird, egg shaped mall vita projection, and we'd like them to be in the sequel Rectangular projection.

  • And there are ways of changing coordinates.

  • But for now, I'll provide you with a sample of CMB data.

  • Looks like this.

  • It's pretty exciting, actually.

  • You can even just use the fractal noise and after effects because that's what the CMB is.

  • Basically, it's Gaussian random noise.

  • So anyway, once we are CMB data image file, we'll create a new composition with it and immediately will pre comp it because we're gonna be using a particle plug in to start with.

  • Let's clean up this data a little bit, so I'm just gonna add some levels just to make it a bit more punchy.

  • That's within the PRI.

  • Come now, in the main composition, we need to create just a blank solid.

  • And this will rename it particles because it will continue particles and we will add particle playground, which is the basic plug in for doing particles and after effects.

  • To start with, we play.

  • We see we have this beautiful and annoying cannon, so we'll turn off the cannon.

  • Now we have nothing.

  • So we're gonna use the grid to cede our particles.

  • We want the grid to match the size of our compass.

  • So it'll be 500 by 500 say Maybe we want 25 20 particles.

  • That enough?

  • Let's go 40 by 40.

  • All right now we have particles.

  • Except if we play, we see that it creates a new particle at every position on every frame.

  • So we want a key, frame these numbers and just go to the next frame and then set them to zero so we only get one particle for each point.

  • Starting off and Albee play, they're all falling down because there's gravity now.

  • This is gravity, like a constant force in the downward direction, which isn't what we want.

  • We want particles to attract each other.

  • I'm gonna turn this off and we will go to the repel section, and we want the particles to attract, so we'll just add in a negative amount on the repel.

  • So let's do mind this 0.1 just to start with now, is he quiet?

  • Nothing happens because they're radius for the force to take effect is too small.

  • So we set this up to 50 and hopefully that will catch some nearby particles.

  • This isn't realistic.

  • Gravity is basically, either you're attracted to something if it's relatively close to you or you're not attracted to it at all.

  • If it's farther away, real gravity falls off like one of her R squared.

  • But anyway, if we play this now, we'll see that the particles are indeed attracting each other.

  • The ones in the middle don't move very much because they're pulled equal in both sides, but the ones that outside get pulled in, and as we wait, we'll see a beautiful symmetric mishmash of particles.

  • But this isn't really what we want.

  • We want the particles to attract each other based on the density of the early universe.

  • And so the bright spots on the CMB data that we used our high density and the dark spots are low density.

  • So we want to see their particles using the CMB so we can see things better.

  • I'm gonna turn off the CMB, add a white solid behind the particles and make the particles black.

  • Now we're going to set the persistent property of opacity of the particles.

  • So we're gonna use the CMB data as the source and we will map the red to opacity.

  • Now we see the places where the CMB data was brightest are dark black, and the places where it was darkest are faint turned back on, and you can see that.

  • So now if we simulate forward, we're still gonna get the same thing because all we've done is affect the opacity of the particles and other mass.

  • So to affect the mass of the particles, we go into the repel settings and we want to select using a selection map of the same the CMB data and that's all we have to d'oh.

  • Now the particles that are darker will attract more on the particles that are lighter will attract less.

  • So let's play this forward and see what happens.

  • So you can see that the particles that are darker are the ones that are attracting all the others to them on.

  • The particles that are lighter are literally lighter.

  • They're less dense.

  • Although we've got the simulation fairly well.

  • Order, How about the color to get the color nice.

  • We wanted it to be really bright, where the particles overlap and faint where they don't.

  • Because when the particles in the real universe come together, they heat up and you get bright things like stars.

  • So to do that, we actually to make these a little bit less opaque so that the brightness adds up.

  • So I'm gonna go back in here, too, are persistent property mapper and change the opacity, Max setting to something like 0.15 So now everything's gonna be very faint.

  • But that's all right.

  • That's what we want.

  • So now I'm going to go back in the project and create a new composition and call it a simulation with color and to create the color.

  • All we have to do is we'll create an adjustment layer, and the first thing we do is we add a levels to it, and that's gonna allow us to control just how dark and bright these particles are.

  • So we'll bring up the level is actually little bit to make the particles more visible.

  • Then we're gonna color, so we'll use cholera.

  • MMA.

  • Oh, that's interesting.

  • What we're gonna do is we'll just change the output cycle from none too negative as our starting point.

  • So that basically just inverts the colors and then neither white and we wanted to be a little orange to match the millennium simulation.

  • Just pick your favorite orange.

  • Okay, we have orange there.

  • And then somewhere in the near, the mid darker, and we're gonna make it a blue purple again to match the millennium simulation.

  • So now I think we've ramped our levels up a little bit too much, and one last thing I'm going to add on a fast bowler take off those hard edges of the particles.

  • Just a blurriness of one.

  • And now let's see what happens.

  • Look at this.

  • These Galaxies are these dense spots.

  • They're gonna collide, and there you have it Simulation of the large scale structure of the universe on your laptop.

this is going to be a boring video.

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教程:在After Effects中模擬宇宙 (Tutorial: Simulating the Universe in After Effects)

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    林宜悉 發佈於 2021 年 01 月 14 日
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