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Show HN: I was curious about spherical helix, ended up making this visualization

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Re: Show HN: I was curious about spherical helix, ended up making this visualization

#61
post #41
post #24

Awesome visualizations. The part that I was expecting to see but didn't: how can you move at a constant speed? For the original purpose of positioning objects along a path, it doesn't matter. But when moving, you can see it's moving much more slowly at the beginning and end (mostly determined by the radius). What if I want it to travel at a constant rate? Or even apply an easing function to the speed? I'm sure there'…

For constant speed you need a so-called “Euclidean parameterization” where the t value is proportional to s, the Euclidean distance traveled (and thus no matter the value of t, if you add some dt it always works out to the same ds). This is super commonly needed when animating motion along all sorts of curves, as you might guess. Unfortunately, there’s usually no closed-form solution for it, so we have to do it numer…

This pattern of stepping with different ds along a path has a lot of applications in control theory. Often we change the ds/dt ratio based on the known acceleration profile of a motor to minimize jerk and reach our destination as fast as possible.

Generally this idea is called motion profiling: https://www.motioncontroltips.com/what-is-a-motion-profile/

Re: Show HN: I was curious about spherical helix, ended up making this visualization

#62
post #21

Very cool & pretty, but I feel a little let down. There is a huge leap from the basics of 3d plotting & spheres to the crazy pattern you tease and then show at the end. I understand it as someone who kind of knows this stuff already, but I think its way too big of a leap for someone who doesn't have the background.

I think the crazy plot at the end is not intentionally constructed to be exactly that way, just an example of what you can get if you vary the parameters of cosines and sines in parametric equation setups similar to the ones shown earlier (instead of seeking to align them so they wrap a sphere exactly).

Re: Show HN: I was curious about spherical helix, ended up making this visualization

#63
post #3

These used to be super important in early oceanic navigation. It is easier to maintain a constant bearing throughout the voyage. So that's the plan sailors would try to stick close to. These led to let loxodromic curves or rhumb lines. https://en.m.wikipedia.org/wiki/Rhumb_line Mercator maps made it easier to compute what that bearing ought to be. https://en.m.wikipedia.org/wiki/Mercator_projection This configuration…

You inspired me to submit one of my 2022 projects https://observablehq.com/@jrus/spheredisksample https://news.ycombinator.com/item?id=44963521 to fit the trend of the day. People may also enjoy https://observablehq.com/@jrus/sphere-resample

Great to see you. I look forward for your comments on geometry, multivariate calculus and rotations.

Edit: fantastic graphics. You should submit the other one as an HN post too.

Re: Show HN: I was curious about spherical helix, ended up making this visualization

#64
post #60

I can't tell why, but I'm getting terrible performance on Linux/Brave. The CPU spikes immediately on visit. I'm on a powerful machine (32 GiB RAM, Intel i9 w/ 24 cores).

> I can't tell why Let's find out where this sentence goes! > Linux Would look into that. > Brave. Definitely would look into that. > 32 GiB RAM, Intel i9 w/ 24 cores This part is not relevant

You're just jealous of my 32 GiB.

Re: Show HN: I was curious about spherical helix, ended up making this visualization

#65
The animations are so fluid!

I very recently was looking to generate some complex shapes, and stumbled onto the complex problem of "disperse N points on sphere" and all its nuances.

There was a really cool / simple algorithm that was mentioned called the fibonacci-sphere that also generates a spiral around a sphere, but for the point dispersal. Here's a paper [1] on it that talks more about it.

[1] - https://arxiv.org/pdf/0912.4540

Re: Show HN: I was curious about spherical helix, ended up making this visualization

#68
post #60

Earlier quoted context omitted.

> I can't tell why Let's find out where this sentence goes! > Linux Would look into that. > Brave. Definitely would look into that. > 32 GiB RAM, Intel i9 w/ 24 cores This part is not relevant

You're just jealous of my 32 GiB.

Crying in Mac mini voice
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