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Hackaday Links: December 13, 2020

Our Sun is getting a bit frisky these days, and has rewarded us with perhaps the best screensaver image ever taken. The incredibly detailed photo of a sunspot was actually taken back in January by the Daniel K. Inouye Solar Telescope, a 4-meter instrument with adaptive optics that can image the sun from the near-infrared to visible wavelengths and resolve surface details down to 20 km. The photo, with a distinct “Eye of Sauron” look, shows the massive convection cells surrounding the dark sunspot; an accompanying animation shows the movement of plasmas along the tortured lines of magnetic flux that cause the sunspot to form. It’s fascinating to watch, and even more interesting to mull over the technology that went into capturing it.

With the dustup surrounding the youtube-dl DCMA takedown by GitHub fresh on the open-source community’s minds, GitHub Universe 2020 had an interesting discussion about maintaining open-source software projects that’s worth watching. They focused on the challenges that youtube-dl maintainers face in keeping the tool working, and the impact their effort has on the people and groups that rely on them. To underscore that point, they featured a researcher with Human Rights Watch who depends on youtube-dl in her work, and made it quite clear that keeping up with all the API changes that constantly break open source tools like youtube-dl make the role of the maintainers that much more critical.

Speaking of GitHub, here’s a frightening and fascinating new tool: Depix, the password de-pixelizer. Developer Sipke Mellema noticed that his company often used pixelization to obscure passwords in documentation, and wondered if he could undo the process. He wrote up an article describing the pixelization process using a linear box filter and his method for attacking it, which involves generating a De Bruijn sequence in the same font, text size, and colors as the original document and feeding a screenshot of that and the pixellated password into the tool. We suspect it’ll only work for a subset of obfuscated passwords, but it’s still pretty clever.

‘Tis the season for Advent calendars, and the folks at QEMU have posted theirs. Open each of 24 doors on the calendar and you’re rewarded with a downloadable QEMU disk image that implements something fun. Minesweeper, a ray tracer that fits into a boot loader, and of course Conway’s Game of Life. The GW-BASIC image on Day 3 caught our eye — brings back some memories.

For anyone who has ever watched a Pixar film and wondered how all that animation actually works, here’s a great lesson in making art with math. The video is by Inigo Quilez and goes through the basics of rendering images using raymarching SDFs, or signed distance functions. In the beginning, it seemed like it was going to be a little bit like drawing an owl, but his descriptions of the math involved and how each element of the animation is just another formula is fascinating. What’s more, there’s a real-time rendering tool where you can inspect the code and edit it. Alas, my changes only made things worse, but it was still fun and instructive to play with. Check out the video after the break!

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DIY Motion Control Camera Rig Produces Money Shots On A Budget

Motion control photography allows for stunning imagery, although commercial robotic MoCo rigs are hardly affordable. But what is money? Scratch-built from what used to be mechatronic junk and a hacked Canon EF-S lens, [Howard’s] DIY motion control camera rig produces cinematic footage that just blows us away.

moco_movinghead[Howard] started this project about a year ago by carrying out some targeted experiments. These would not only assess the suitability of components he gathered together from all directions, but also his own capacity in picking up enough knowledge on mechatronics to make the whole thing work. After making himself accustomed to stepper motors, Teensies and Arduinos, he converted an old moving-head disco light into a pan and tilt mount for the camera. A linear axis was added, and with more degrees of freedom, more sophisticated means of control became necessary.

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Retrotechtacular: The Early Days Of CGI

We all know what Computer-Generated Imagery (CGI) is nowadays. It’s almost impossible to get away from it in any television show or movie. It’s gotten so good, that sometimes it can be difficult to tell the difference between the real world and the computer generated world when they are mixed together on-screen. Of course, it wasn’t always like this. This 1982 clip from BBC’s Tomorrow’s World shows what the wonders of CGI were capable of in a simpler time.

In the earliest days of CGI, digital computers weren’t even really a thing. [John Whitney] was an American animator and is widely considered to be the father of computer animation. In the 1940’s, he and his brother [James] started to experiment with what they called “abstract animation”. They pieced together old analog computers and servos to make their own devices that were capable of controlling the motion of lights and lit objects. While this process may be a far cry from the CGI of today, it is still animation performed by a computer. One of [Whitney’s] best known works is the opening title sequence to [Alfred Hitchcock’s] 1958 film, Vertigo.

Later, in 1973, Westworld become the very first feature film to feature CGI. The film was a science fiction western-thriller about amusement park robots that become evil. The studio wanted footage of the robot’s “computer vision” but they would need an expert to get the job done right. They ultimately hired [John Whitney’s] son, [John Whitney Jr] to lead the project. The process first required color separating each frame of the 70mm film because [John Jr] did not have a color scanner. He then used a computer to digitally modify each image to create what we would now recognize as a “pixelated” effect. The computer processing took approximately eight hours for every ten seconds of footage. Continue reading “Retrotechtacular: The Early Days Of CGI”

How Escher’s Impossible Waterfall Was Faked

Study the image above closely. You’ll notice that physically it is an impossible object, yet this is a screenshot of full-motion video. The clip after the break shows a gentleman pouring water into the waterfall where the wheel is located. The liquid flows in a direction that appears to be uphill, then falls onto the waterwheel where it was originally poured. Ladies and Gentleman, we have the solution to the world’s energy crisis. Nope, we have a hoax and the real question is how was it done?

[David Goldman] has come up with quite the explanation. He watched the video very closely and the put together a three-dimensional diagram showing how he would build the apparatus. If you saw the movie Inception (we highly recommend you do) you will remember the infinite stair puzzle that is exposed as an optical illusion. [David’s] proposed method for debunking this hoax uses a similar build that comes in four different, precisely placed elements.

We’ve got to hand it to him. That’s a brilliant theory! Of course the first commenter on the post linked above calls this out as CGI and we’re inclined to go with that answer but that’s much less fun.

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