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Hackaday Links: March 31, 2024

Battlelines are being drawn in Canada over the lowly Flipper Zero, a device seen by some as an existential threat to motor vehicle owners across the Great White North. The story started a month or so ago, when someone in the government floated the idea of banning devices that could be “used to steal vehicles by copying the wireless signals for remote keyless entry.” The Flipper Zero was singled out as an example of such a nefarious device, even though relatively few vehicles on the road today can be boosted using the simple replay attack that a Flipper is capable of, and the ones that are vulnerable to this attack aren’t all that desirable — apologies to the 1993 Camry, of course. With that threat hanging in the air, the folks over at Flipper Devices started a Change.org petition to educate people about the misperceptions surrounding the Flipper Zero’s capabilities, and to urge the Canadian government to reconsider their position on devices intended to explore the RF spectrum. That last bit is important, since transmit-capable SDR devices like the HackRF could fall afoul of a broad interpretation of the proposed ban; heck, even a receive-only SDR dongle might be construed as a restricted device. We’re generally not much for petitions, but this case might represent an exception. “First they came for the Flipper Zero, but I did nothing because I don’t have a Flipper Zero…”

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Retrotechtacular: The Revolutionary Visual Effects Of King Kong

Today, it’s easy to take realistic visual effects in film and TV for granted. Computer-generated imagery (CGI) has all but done away with the traditional camera tricks and miniatures used in decades past, and has become so commonplace in modern productions that there’s a good chance you’ve watched scenes without even realizing they were created partially, or sometimes even entirely, using digital tools.

But things were quite different when King Kong was released in 1933. In her recently released short documentary King Kong: The Practical Effects Wonder, Katie Keenan explains some the groundbreaking techniques used in the legendary film. At a time when audiences were only just becoming accustomed to experiencing sound in theaters, King Kong employed stop-motion animation, matte painting, rear projection, and even primitive robotics to bring the titular character to life in a realistic way.

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Those Bullet Effects In Terminator 2 Weren’t CGI

Remember Terminator 2? Guns were nearly useless against the murderous T-1000, played by Robert Patrick. Bullets fired at the “liquid metal” robot resulted only in a chrome-looking bullet splash that momentarily staggered the killing machine. The effects were done by Stan Winston, who died in 2008, but a video and short blurb shared by the Stan Winston School of Character Arts revealed, to our surprise and delight, that the bullet impact effects were not CGI.

How was this accomplished? First of all, Winston and his team researched the correct “look” for the splash impacts by firing projectiles into mud and painstakingly working to duplicate the resulting shapes. These realistic-looking crater sculpts were then cast in some mixture of foam rubber, and given a chromed look by way of vacuum metallizing (also known as vacuum deposition) which is a way of depositing a thin layer of metal onto a surface. Vacuum deposition is similar to electroplating, but the process does not require the object being coated to have a conductive surface.

These foam rubber splash patterns — which look like metal but aren’t — were deployed using a simple mechanical system. A variety of splashes in different sizes get individually compressed into receptacles in a fiberglass chest plate. Covering each is a kind of trapdoor, each held closed by a single pin on a cable.

To trigger a bullet impact effect, a wireless remote control pulls a cable, which pulls its attached pin, and the compressed splash pattern blossoms forth in an instant, bursting through pre-scored fabric in the process. Sadly there are no photos of the device itself, but you can see it in action in the testing video shared by the Stan Winston School, embedded below.

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Obsessively Explaining The Visual Effects In Flight Of The Navigator

[Captain Disillusion] has earned a reputation on YouTube for debunking hoaxes and spreading a healthy sense of skepticism while having some of the highest production value on the platform and pretending to be some kind of inter-dimensional superhero. You’ve likely seen him give a careful explanation of how some viral video was faked alongside a generous dose of sarcastic humor and his own impressive visual effects. VFXcool is a series on his channel that takes deep dives into movies that are historically significant in the effects industry. For this installment, [Captain Disillusion]’s “intern”, [Alan], takes over to breakdown how filmmakers brought a futuristic spaceship to life in 1986’s Flight of the Navigator.

Making a movie requires hacks upon hacks, and that goes double in the era when the technology and techniques we now take for granted were being developed even as they were being put to film. The range of topics covered here is extreme: from full-scale props to models; from robotic motion control rigs to stop motion animation; from early computer graphics to the convoluted optical compositing that was necessary before digital workflows were possible. The tools themselves may be outdated, but understanding the history and the processes allows for a deeper insight into how we accomplish these kinds of effects today. And, really, it’s just so… cool.

[Captain Disillusion]’s previous VFXcool is all about the Back to the Future trilogy, and it’s a little shorter with more information on motion control rigs. We also love seeing how people make DIY effects in their own homes. LEGO actually seems like a pretty popular option for putting together whole scenes in amateur filmmaking.

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Freeze Laser Beams — Sort Of

They say a picture is worth a thousand words, and by that logic a video must be worth millions. However, from nearly the dawn of photography around 1840, photographers have made fake photographs.  In modern times, Photoshop and Deepfake make you mistrust images and videos. [Action Lab] has a great camera trick in which it looks like he can control the speed of light. You can see the video below.

You probably can guess that he can’t really do it. But he has videos where a real laser beam appears to slowly move across the screen like a laser blaster shot in a movie. You might think you only need to slow down the video speed, but light is really fast, so you probably can’t practically pull that stunt.

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Dirty Video Mixing With The Raspberry Pi Zero

Don’t get too excited now, we aren’t talking about that kind of dirty video. There’s plenty of other places on the Internet you can go to find that sort of thing. No, this video mixer is “dirty” because it combines two composite video streams into one garbled up mess that’s best viewed on an old CRT TV. Why, you may ask? Because rock and roll, that’s why.

Created by [Luke Blackford] as a visual for his band’s performances, the “Dirty Pi” is an exceptionally simple way to create some wild imagery with two Raspberry Pi Zeros. It might not be the most practical of devices, but if you want so throw some creepy looking video up on screens all over the house (say for an upcoming Halloween party), this is a fantastic way to do it on the cheap.

The idea is simple: connect the oft-forgotten composite video outputs of two Pi Zeros to a potentiometer, which then leads to the display. Play different videos on the Pis with the media player of your choice, and twiddle the potentiometer to create ghosting and interference. If you want to get that true 1980’s retro feel, put the whole thing into an old VHS cassette like [Luke] did, and you’re ready to rock.

Those who’ve been around the block a few times might recognize this trick as a variation of the [Karl Klomp] Dirty Video Mixer, and [Luke] tells us he likes this project because he was able to pull it off without writing any code or even doing any complex wiring, though he does imagine a future version where he adds some remote control functionality.

If you like your video mixers with more smarts and less dirt, we’ve covered a very slick build using the LM1881 in the past.

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Automated Doors For Theatre Effect

Door Actuator

For a theatre production, [Jason] needed a way to automatically open and close doors as a special effect. His solution, hosted on Github, lets him remotely control the doors, and put them into a ‘freak out’ mode for one scene in the play.

Two Victor 884 motor controllers are attached to an Arduino that controls the system. A custom controller lets [Jason] actuate the doors remotely, and LEDs are used to display the state of the system.

On the mechanical side, two wind shield wiper motors are used. These are connected to custom arms that were printed using a Lulzbot AO-100. The arms allow for the door to be automatically actuated, but also allow for actors to open the door manually.

The result is a neat special effect, and the 3D models that are included in the repository could be useful for other people looking to build automated doors. In the video after the break, [Jason] walks us through the system’s design and demonstrates it in action.

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