inteja

Celestial sphere demo (WIP) a.k.a. "My God, it's full of stars ..."

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As @Wingnut asked for a sneak peak, here's my little celestial sphere demo (very much an early work in progress).

WIP link: Celestial sphere

What's the point you ask? If you want a realistic night sky then why not just use skybox textures of the Milky Way for which NASA have some great resources like here and here?

Well I thought it'd be fun to generate it dynamically based on real star map data of the 5000 brightest stars (about the maximum visible by the naked eye from Earth under ideal conditions). The data (right ascension, declination, color, magnitude etc) is a subset of the Tycho-2 Catalogue. This gives me more control over how the stars are rendered (relative scale, brightness, color enhancement, blending with other skyboxes, star "twinkle" effect, constellation lines etc). Ultimately I'd like to get to the stage where I can dynamically generate hyper-realistic, bordering on surreal, skies similar to what you see in the best landscape astro-photography like that of Mike Taylor.

To get a good result (be able to make out clear, crisp individual stars) using skybox textures, the resolution and resulting filesize and vram requirements need to be quite large, which isn't ideal for web deployment. This dynamic generation approach means I can use one very small texture to represent a single star, but at the cost of more triangles to render. The stars always look crisp and sharp.

Ultimately I'd like to blend this with a very low-res Milky Way skybox behind, combine it with the SkyMaterial, add the moon and phases, day/night transition, geolocation and date/time support etc. I don't want a full astronomy / night sky app, just a drop-in super-realistic and dynamic sky for future projects. Ambitious I know, but I have an astronomy maths book handy and I've made some progress on that front already ...

celestial-sphere-wip.png

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Added configuration GUI - change:

  • Number of stars (up to 5000 of brightest stars)
  • Star scale
  • Celestial sphere radius
  • Star twinkle
  • Show asterisms
  • Asterism color

Thanks @Deltakosh and all other contributors for a great WebGL framework and GUI :D

celestial-sphere-wip-gui.png

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