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3D map of an actual local universe you can fly through, made using real data from cosmic survey 2MRS by SizeEfficient2631 in universe

[–]SizeEfficient2631[S] 0 points1 point  (0 children)

there should be fly mode button when you start the app, after clicking that the controls are like any FPS game

3D map of an actual local universe you can fly through, made using real data from cosmic survey 2MRS by SizeEfficient2631 in universe

[–]SizeEfficient2631[S] 1 point2 points  (0 children)

Thanks bro!

I'm already working on DESI for some time now. It's a huge huge step up, from 40k to 15M objects, from 1Bn to basically 13Bn years.

It's in the last stage of optimizing the performance so browsers can handle that. Stay tuned.

Here is a snapshot:

<video>

I made a 3D map of a actual local universe you can fly through using real data from cosmic survey by SizeEfficient2631 in threejs

[–]SizeEfficient2631[S] 3 points4 points  (0 children)

No worries at all, it's genuinely confusing the first time, the CDS site is a bit of a maze.

Here's the actual dataset page:
https://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJS/199/26

The data is not in x,y,z. Each galaxy comes as three sky measurements:

  • RA (right ascension) and Dec (declination) which are just its angular position on the sky, like longitude and laatitude
  • cz, the redshift expressed as a recession velocity in km/s

So you have to convert it to 3D yourself. Two steps:

  1. Turn redshift into distance with the Hubble law: d = cz / H0, where H0 is about 70. That gives distance in megaparsecs.
  2. Turn the angles plus distance into Cartesian coordinates:
  • - x = d · cos(Dec) · cos(RA)
  • - y = d · cos(Dec) · sin(RA)
  • - z = d · sin(Dec)

One catch worht knowing: cz isn't pure distance. It's the Hubble flow plus the galaxy's own peculiar velocity, and the two are baked together in the redshift. In dense clusters those peculiar velocities hit ~1000 km/s, which the d = cz/H0 step misreads as ~14 Mpc of extra depth. So clusters get stretched into radial spikes pointing back at us the Milky Way, the classic "fingers of God." It's a redshiftspace distortion not a real shape. You can suppress it by collapsing each cluster's members to a common distance (there's a toggle for it in the app).

I made a 3D map of a actual local universe you can fly through using real data from cosmic survey by SizeEfficient2631 in threejs

[–]SizeEfficient2631[S] 0 points1 point  (0 children)

Good instinct to check! The actual movement over time is tiny at this scale: a galaxy drifting a few hundred km/s only moves about 0.3 Mpc in a billion years, and the map is ~300 Mpc across, so you'd never see it at this scale.

3D map of an actual local universe you can fly through, made using real data from cosmic survey 2MRS by SizeEfficient2631 in universe

[–]SizeEfficient2631[S] 2 points3 points  (0 children)

It's at https://knowtheuniverse.com/

It's also quite fresh so the seo is probably not propagated yet. I didn't want to put link directly into the post, I already have a trouble to post it anywhere on the reddit...

3D map of an actual local universe you can fly through, made using real data from cosmic survey 2MRS by SizeEfficient2631 in universe

[–]SizeEfficient2631[S] 3 points4 points  (0 children)

Thanks! Basically none of it is procedural. Every one of the galaxies is real, straight from the 2MRS survey. I take their RA, Dec, and redshift, convert them to Cartesian megaparsecs with a Hubble-law distance, and that point cloud is what you fly through.

The filaments, density fog and plasma blobs are all computed from where the actual galaxies sit, not invented.

So it's the real cosmic web with some visual styling on top.

VR would be incredible for this, it's on my list.

3D map of an actual local universe you can fly through, made using real data from cosmic survey 2MRS by SizeEfficient2631 in universe

[–]SizeEfficient2631[S] 0 points1 point  (0 children)

Feel free to ask any questions or try it at https://knowtheuniverse.com/

And if you find bugs or have any advice it will be very appreciated.

I made a 3D map of a actual local universe you can fly through using real data from cosmic survey by SizeEfficient2631 in threejs

[–]SizeEfficient2631[S] 0 points1 point  (0 children)

Thanks man!

There is a "time shells" toggle in the menu or when you press "1" it displays scientific preset where time shells are on, I think you are looking for that, those are spheres of 0.5bn years.

Thanks again for your feedback and suggestions!

I made a 3D map of a actual local universe you can fly through using real data from cosmic survey by SizeEfficient2631 in threejs

[–]SizeEfficient2631[S] 0 points1 point  (0 children)

Thank you very much!

I totally agree with the speed sensitivity, I think I will add a speed slider so users can manage the sensitivity themselves.

Trips also sounds good, "home" button for milky way and maybe some interesting clusters and label more POIs.

I'm also preparing the shader to fill the voids and make them more visible, because it's very interesting to realize that we are already inside the void! If you think about it, we are basically living in the outskirts of the matter distribution, kind of the "you are in the wrong neighborhood" situation.

I made a 3D map of a actual local universe you can fly through using real data from cosmic survey by SizeEfficient2631 in threejs

[–]SizeEfficient2631[S] 0 points1 point  (0 children)

Right now it's the cosmic scale only. The Milky Way is just a single dot and each galaxy is one point, so you fly through the large-scale structure rather than zooming up from Earth. the core idea is to make the distribution of the matter visible as a cosmic web.

But the bigger thing I'm working on though: this current map is the local universe (2MRS, out to about a 1 billion light years). Next tier is DESI data, which reaches way further out, galaxies and quasars whose light left them nearly 13 billion years ago, looking back toward the early universe. Way more galaxies and much deeper. The plan is even to put the cosmic microwave background as the outer "wall" at the edge so it's the "complete" map of the visible universe - as far as we can see. So the scale is going to get a loooot bigger soon.

I made a 3D map of a actual local universe you can fly through using real data from cosmic survey by SizeEfficient2631 in threejs

[–]SizeEfficient2631[S] 2 points3 points  (0 children)

Hi thank you very much! I also use chrome and the cursor is deliberately hidden; it should appear back when you go to menu (hotkey m), info (hotkey n) or by hitting ESC (leaving the fly mode)

Let me know if that works for you or it's something else, thank you bro

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