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  • 32 Comments
Joined 3 years ago
Cake day: June 15th, 2023
  • AdrianTheFrog@lemmy.worldtoOpen Source@lemmy.ml•Original Apollo 11 code open-sourced by NASA — original Command Module and Lunar Module code repos are now public domain resourcesEnglish
    2·
    3 days ago

    As an amateur computer graphics person, the best way to draw accurate stars is to just pre render it onto a cubemap. But if you really need that subpixel worth of parallax to be completely accurate for every star, there are a couple ways I can think of off of the top of my head. With any you’d want to make sure you only store position, size, and color, since stars are all spheres anyways. With effort, you can be very flexible with how these are stored. (4 bits color temperature, 4 bits size, 3*32 bits coordinates maybe)

    • splat each star into the screen texture with atomics
    • some sort of tiled software rasterization thing, like in Gaussian Splatting

    Worse ideas:

    • instanced hardware rasterization
    • ray tracing

    This is not that well suited to most usual rendering techniques, because most stars are probably going to be much smaller than a pixel. Ray tracing would mean you need to just hit every star by chance (or artificially increase star size and then deal with having tons of transparency), hardware rasterization is basically the same and additionally is inefficient with small triangles. I guess you could just live with only hitting stars by chance and throw TAA at it, there’s enough stars that it doesn’t matter if you miss some. That would react badly to parallax though and defeats the purpose of rendering every star in the first place.

    It’s much more efficient to do a manual splatting thing, where for each star you look at what pixel(s) it will be in. You can also group stars together to cull out of view stars more efficiently. Subpixel occlusion will be wrong, but it probably doesn’t matter.

    This is all just for the viewport, though. Presumably there are other objects in the game besides stars, which need to have reflections on them of the stars. Then that becomes an entirely different problem.

    The real answer though is that you wouldn’t try to render all of the stars, even if you want parallax. Maybe some of the closer and larger ones as actual geometry, simplify a ton of stuff in the background, render things as volumes or 2d billboards, have a cubemap for the far distance, etc

    Edit: also ofc this presumes you know the position, scale, temperature of every star

    I also like the idea of baking all of the stars into a volume in spherical coordinates, centered around the origin

  • AdrianTheFrog@lemmy.worldtoTechnology@lemmy.world•Artemis II Astronauts Have ‘Two Microsoft Outlooks’ and Neither WorkEnglish
    1·
    14 days ago

    It’s clear that several people in charge of the youtube livestream have no idea about how to do that correctly. I think the difference is just effort. Viewership was tiny compared to Apollo 11, as was the hype leading up to it. It’s clear that NASA could provide a whole lot better footage if even some random youtuber (Everyday Astronaut) can beat them. So that aspect is, as you said, because as a society we don’t really care about the Artemis launch. SpaceX does put a fair amount of effort into their livestreams, and you can easily tell by watching them.

    For the recorded footage, film often has a lot higher dynamic range than digital cameras and usually looks a whole lot better when recording a launch up close.

    Far shots are limited by atmospheric distortion and physical limits from diffraction for a given aperture size. None of that can change.

    IDK anything about the quality of the original live broadcast of Apollo 11, so i don’t have anything to compare in that regard

  • AdrianTheFrog@lemmy.worldtoWorld News@lemmy.world•Rocket lifts off with four Artemis II astronauts on a mission to the moon and backEnglish
    102·
    16 days ago

    Falcon Heavy is quite a capable rocket, with about 60% of the SLS’s payload capacity to LEO when the side boosters are reused (although it’s almost never used for LEO, since no one actually needs that large of a payload there…).

    New Glenn can reuse it’s whole first stage, but currently has only 47% of the SLS’s payload capacity to LEO. (with plans for a larger variant)

    Starship… has been kind of a mess. At least with how their timeline has compared to their goals. They have demonstrated several successful launches, but with the reliability of their past few, I doubt anyone will trust them anytime soon.

    China seems extremely close to having a partially reusable heavy lift rocket, they have said that they’ll test it in the first half of this year (LEO payload a little bit higher than Falcon Heavy, but they plan to go to the moon with something very similar). India has some looser long-term plans.

    As a spaceflight nerd, I was thinking today about why I (and everyone else) don’t care that much about the Artemis launch. I think it’s largely because it’s not demonstrating anything new; they already did basically the same mission but without the people in it, and even more advanced missions with people in them were done in the 1960s. The rocket itself though isn’t helping, the only things it has going for it compared to other modern rockets are that it’s large and probably reliable. The technology is basically just re-used space shuttle parts, there’s nothing that seems particularly innovative, and reusing old technology hasn’t prevented it from being extremely expensive compared to basically everything else (~20x the cost of New Glenn, Falcon Heavy, or Starship per launch…). It’s also worse for the environment in basically every way (expendable, and has solid fuel boosters).

    I kind of agree with what some other people have been saying about NASA for a while now. They should probably just stick to the satellites, rovers, and technology tests, making their own launch vehicle is not really helping anyone. The usefulness of being a government funded thing is that they can do the type of science to help humanity that doesn’t turn a profit. They don’t really need their own launch vehicle to do their science, and the vehicle itself is so conservative that I’m sure they aren’t really learning anything from it. If they were actually capable of producing something economical and better than the corporations then it wouldn’t be a problem, but that will never happen with Congress pushing rocket designs that “seem like they would be cheaper” and forcing NASA to route all work through insanely inefficient military contractors.