[nuclearsugar]

Creating astronomy visualizations often involves all sorts of fun tricks. I work in a planetarium as a 3D animator and each day has interesting unique challenges. Indeed we have to remain mindful of not pushing Maya too hard when it comes to series of scale.

We use fluids as a way to create 3D nebulae that can be flown through. https://thefulldomeblog.com/2013/08/20/the-nebula-challenge/

Or if you constrain the fluid into a sphere, then you have a dynamic volumetric sun. https://thefulldomeblog.com/2013/07/30/customizing-a-close-u...

When needing to fly through a star field, relying on particle sprites is an easy way to quickly render thousands of stars. https://thefulldomeblog.com/2013/07/03/creating-a-star-field...

Background stars are achieved by point-constraining a poly sphere to the camera. Having a poly sphere allows for easy manipulation to create realistic diurnal motion. https://thefulldomeblog.com/2013/11/13/background-stars-v2/

Flying through a galaxy field can be achieved with loads of galaxy images mapped to poly planes. For galaxies that are seen edge on, we sometimes add more detail by emitting fluid from the image colors. https://thefulldomeblog.com/2013/07/16/flying-through-a-gala...

Simulating the bands of Jupiter is tricky but I've done some experiments with 2D fluids. https://thefulldomeblog.com/2014/01/30/jupiter-bands-simulat...

And of course since the visuals are rendered for a planetarium dome, we gotta render using a fisheye camera. These days all render engines support fisheye, but 10 years ago it was a different story. https://thefulldomeblog.com/2019/09/07/exploring-render-engi... https://thefulldomeblog.com/2013/06/28/fisheye-lens-shader-o... https://thefulldomeblog.com/2013/07/23/stitching-hemicube-re...

[zlsa]

I'm sure you've heard this before, but have you checked out Space Engine[0]? It has some pretty advanced features, like path animations and cubemap rendering. I'm not sure how well it'd integrate into existing workflows, but I've used it for creating high dynamic range skyboxes for spacecraft renders.

[0]: http://spaceengine.org/

[smcameron]

> Simulating the bands of Jupiter is tricky but I've done some experiments with 2D fluids.

Nice! I've always wanted to do some fluid dynamics on the surface of a sphere, but the math is too hard for me. I found a video on youtube where someone has done some interesting things a few years ago: https://www.youtube.com/watch?v=Lzagndcx8go&t=1s but there's very little information about it. Then there was what was done for the film 2010: The year we make contact" http://2010odysseyarchive.blogspot.com/2014/12/

I've had to resort to simpler means myself, which means faking it. I use OpenSimplex noise on the surface of a sphere, and from this I can find the gradient of the noise field tangent to the surface of the sphere, rotate this vector 90 degrees about an axis passing through the center of the sphere -- which is equivalent to some kind of spherical curl of the noise field -- which gives me a non-divergent velocity field. Because incompressible fluid flows are also non-divergent, there's a strong but superficial resemblance -- it looks like fluid flow, even though it is just an arbitrary process. Into this field, I dump a bunch of colored particles and let them flow around, painting alpha blended, slowly fading trails behind them onto the surface of a cube to be used later as textures of a cubemapped sphere.

For the bands, I superimpose a simple velocity field of counter rotating bands on top of this curl-noise generated velocity field. Something like: horizontal_velocity += K x sin(5 x latitude)

Results looks like this: https://duckduckgo.com/?q=gaseous-giganticus&t=h_&iax=images...

The idea for using the curl of a noise field to mimic fluid dynamics is from a paper by Robert Bridson, et al.: https://www.cs.ubc.ca/~rbridson/docs/bridson-siggraph2007-cu...

This program is open source, it's here: https://github.com/smcameron/gaseous-giganticus