Many ways to attempt this.
If you prefer working with geometry, you can create some curves and extrude
them vertically along an axis to create a wall of sorts, then animate the
curves wriggling as they travel across the sky. The extruded surface can
use a shader to control falloff. Render the geometry as separate passes
using constant shading for faster render times as well as full control over
the color. Finally, blur the passes in post before assembling.
Another route to consider is using a light, 2 bitmap textures, and a cube
with a volume shader. Essentially you'll shine a light onto the textures
which act as a mask to create light rays inside the volume of the cube. The
rays can be rendered, colored, varied and blurred.
The cube is made large enough to fill the sky and uses a constant material
with full transparency so the inside of the cube can be seen. The first
bitmap texture is a matte containing the noise pattern you want to use for
the shape of the borealis effect. The 2nd bitmap texture is a wash/gradient
to drive the effect's color. Project the textures in the XZ plane from
underneath onto the cube. Shine the light from underneath the cube to cast
rays into the cube via the volume shader. The volume shader can have most
of it's features deactivated to speed up rendering (should render really
fast). All you need is the active light list, density, and color....and
possibly raymarching step set small enough to not see aliasing. You should
not need shadow casting provided by the volume shader. Shadow falloff of
the light as well as density of the volume shader control the height of the
borealis effect, which can also be varied by inserting a noise node into the
rendertree, or by projecting another texture from the light or onto the side
of the cube to act like a matte. render the scene, then blur the results a
bit in a compositor. The advantage to this technique is it can be
completely procedural, but still leave the door wide open for you to
override that with manual control at any step of the way.
Matt
Date: Mon, 4 May 2015 11:47:45 -0400
From: Will Sharkey <[email protected]>
Subject: aurora borealis effect
To: "[email protected]"
I've been doing some research on how to achieve this effect with particles.
I was thinking sheets of particles with a bunch of turbulence and other
forces:
https://youtu.be/8NrhuBhgmjU?t=33
I'm still brainstorming, Any thoughts or approaches? Would you use
particles or animated Geo and a bunch of layered animated sequences?
Thanks in advance
