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  • What you're seeing is impossible.

  • Lasers travel at the speed of light,

  • and the only way that a blaster bolt, or a disruptor shot, or a phaser beam

  • can take this long to cross a room

  • is in science fiction, so the audience can understand what's going on.

  • But... this is real.

  • Over thereand I can't look at it

  • unless I'm wearing these incredibly-stylish laser safety goggles

  • but over there is a class 4 laser generator,

  • the sort of thing that will burn your retinas out if you treat it the wrong way.

  • But lasers can't do this.

  • They certainly can't start moving back and forth, like it's a tennis match,

  • and they absolutely can't behave like they do in Star Wars,

  • when Kylo Ren uses the Force

  • and stops one in mid-air.

  • But this is not being added by computer afterwards.

  • This is happening in-camera.

  • I can interact with this and show you.

  • So how's it being done?

  • To explain that,

  • we need to talk to the person who programmed that laser.

  • - I'm Seb Lee-Delisle, and I'm a digital artist and laserist.

  • Definitely a real job!

  • I make a lot of primarily large, outdoor installations.

  • I project onto buildings and have lots of interactions with the public

  • with musical instruments that I made.

  • This laser is a really good three-watt laser.

  • It's fairly compact, but it's got really fast scanners in.

  • The big laser is an 11-watt laser made by a company called Lightspace.

  • The scanners aren't quite as good as the ones in here,

  • but they're still perfectly acceptable and what most people use.

  • - Alright, so...

  • Can this burn me? - Yeah.

  • - Okay.

  • - You're ruining my test now. - Oh, sorry.

  • - It's actually a very simple concept,

  • and it didn't take me that long to get it working.

  • All of my code is C++.

  • In this case, I had to tweak it at a really low level

  • because there were some really fine timing adjustments that I needed to make.

  • Here's the trick,

  • and it's something you've probably seen on Science YouTube before:

  • rolling shutter.

  • See, modern cameras don't take a single frame all at the same time

  • boomphlike an old-school photograph, they scan.

  • It takes just a fraction of a second for it to go from the top,

  • all the way to the bottom of the camera,

  • and it registers each line one at a time.

  • So what we've done is we've turned the camera 90 degrees on its side,

  • so now that rolling shutter effect is going horizontally,

  • and this laser is being turned on and off incredibly quickly and incredibly precisely,

  • so that as the camera scans by for every frame,

  • the laser is on when it needs to be and off when it needs to be.

  • That takes a lot of maths and a lot of precision,

  • but the result... is this.

  • - The harder thing about programming this particular trick

  • is to start thinking in a different coordinate space...

  • Right? Because you're no longer dealing with X and Y particularly.

  • Instead, you've got one of your axes, which is the Y axis,

  • which is now time.

  • One of the things I had to take into account is obviously when you start the app,

  • when you start the camera, those things aren't gonna be in line,

  • so I had to add the capability to be able to

  • actually shift that start point at the frame backwards and forwards in time.

  • I'm certainly not the first person to exploit the rolling shutter effect

  • to make laser beam effects.

  • In fact, you can pretty much just run any traditional laser queue

  • and just start to see some weird things happening

  • if you mess around with your shutter speed and frame rate.

  • You might have seen some really good uses of it, in the past,

  • with Adam LaBay and his work with YouTube,

  • and then subsequently with Saturday Night Live.

  • What I'm doing here is a little bit different from that,

  • because we're literally taking the area of the frame in time,

  • and using that as a specific Y-position that we want something to appear in.

  • When we're all together, and we're just seeing it for the first time,

  • that was pretty special to get that surprise,

  • 'cause I've only been testing this effect out with some much smaller lasers in my studio,

  • so when we got it actually with the bigger laser in such a big space,

  • yeah, it came to life.

  • And I'm a bit surprised how it looked.

  • - Oh, what?!

  • Oh, that looks good! That looks so good!

  • - I'll be preparing a video especially with more of the behind-the-scenes stuff.

  • More of the nerdy details.

  • I'll be putting that in a separate video on my channel.

  • - I want to be clear, Seb did all the hard work here.

  • I am just the guy who went: "What if we turn the camera on its side?"

  • But while we've got all this setup, and all this equipment, and these glasses,

  • there is one effect I wanna try:

  • the bullet dodge from The Matrix.

  • Catch is... we can't do this in slow motion,

  • so I've... just gotta fake it.

  • How hard can it be?

  • That is hot. That is very hot!

What you're seeing is impossible.

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レーザービームを空中で停止させる (Stopping A Laser Beam In Mid-Air)

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    林宜悉 に公開 2021 年 01 月 14 日
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