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!

16 thoughts on “Hackaday Links: December 13, 2020

  1. Note: The QEMU Advent Calander Day-3 GW-BASIC download will land you a QEMU .qcow2 disk image. A Linux .sh shell script is provided to use it, but no info about using it in Windows. A QEMU image may load on a MAC, dunno much about that, but isn’t MAC OS just a hijacked version of FreeBSD at its core?

  2. From now on, if I want to obscure a password, or an address, or any other text in a picture, I will replace it with a pixelization of “cheaters never prosper”, or maybe something nastier.

      1. He’s not leaving any information, he’s completely replacing it all with something that decodes to an unrelated nasty message for the hacker who tries.

        They might well accidentally mess up the process, and without blackout it might be easy to think you redacted when you didn’t, but you could make the same mistake with blackout if you accidentally use 0.99 opacity.

        I’d stick with solid color to be extra safe though.

  3. The article for the sunspot picture says, “The image is about 16,000 kilometres (10,000 miles) across, and Earth, with its diameter of 12,742 kilometres, could fit comfortably inside the sunspot, the researchers said.” Well, as comfortably as one can do anything while being on the surface of the Sun.

  4. I had a look at that githubuniverse page. To be more precise, at its source code (would /you/ run javascript dished out by Microsoft on /your/ computer?).

    Without javascript enabled, it’s just one of those Web Black Holes (TM).

    As expected, an inward-pointing link farm. But I could get at the abstract thingie. Microsoft wielding “Human Rights Watch” as a weapon against Google. That’s why they shelled out $7B for Github.

    This is abject. This is disgusting.

    Don’t get me wrong. Google is, in my eyes, as nasty as Microsoft. They’re both too big to be good for our society. They reap the advantages of a (barely) civilised world without contributing back what would be needed to make the whole business sustainable.

    As far as I am concerned, they can fight each other out of existence. Mozilla vs. King Kong. No sympathy for any of them.

    But taking free software projects which happen to be hosted at Github as weapons in this fight… ugh.

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