Guest Author: Gottfried Hoffman
This written tutorial shows how to create a cool and stylized Nova-like explosion all inside Blender.
A Supernova is something mankind can’t watch too often, and there are only a few recordings of such deep-space happenings. What you can see from the Earth is mostly the remnants. The stylized nova you are about to create was inspired by the famous remnant Tycho, which is just beautiful, and a few computer simulations released by NASA over time.
Nasa Simulation Reference
3-Dimensional Flash Center simulation of the deflagration phase of a Type Ia supernovae.
Lets get started
For the last and final part we will be adding the volumetric cloud that adds the unique style to our nova.
First add an object that will use the volume material. Go to a frame 200 in the timeline and add a cube. Next, go into Edit Mode and scale it by 1.2. If you scale it in Object Mode, the mapping of the 3D texture we’re going to use later on will be off. Since the cube is concealing the nova sphere set it’s display type to “Wire” in the object properties.
Next add a volume material to it by adding a new material and then choosing the “Volume” type. Set the density to 0.000 (we will control the density by a texture) and the density scale to 8.000. In the shading section set the scattering to 4.000 and change the reflection color to D31343.
Moving on, let’s add a “Point Density” texture to the material.
Point Density textures use the position of points in 3D space for the influence of material parameters. They can be used with point cloud data, particle system or the vertices of objects. We’ll choose the latter option and use the vertices of the inner sphere as source. Go to the section titled “Point Density”, select “Object Vertices” and select the Icosphere.Inner. The Radius of 0.300 Blender units of course is way too much considering that the outer sphere has a maximum radius of 1.000 Blender units so reduce the radius to 0.100.
Now that the source of the Point Density is set we need to define what property of the volume material gets influenced by the texture. Go to the influence panel and only select density.
A render at this point might look a little weird.
That’s because there is just one lamp in the scene and the volume needs lights to penetrate it. Add one area lamp with white light and an energy of 1.000 that’s shining slightly from the top-left. Use a value of 5.000 for the distance such that the light ends right inside the nova sphere.
When rendering, there’s volume around nearly all of the nova but it’s still looking rather weird.
To fix that, you need to change the integration in the settings of the volume material. The “Step Size” tells how fine the volume is calculated. Lower values yield better results but take longer to render. Set the value to 0.010.
Now the volume is looking like it should, no more noise and the light penetrates it as it should:
It’s just not looking right because the nova seems to be superimposed over the nebula. That’s because the nebula is currently on layer two where the star field is also located. To fix this move the cube and the area lamp to layer 3.
Use the steps from part three of this tutorial to create a third Renderlayer for the nebula. Use an AlphaOver node to get the nebula over the nova.
The nova now has a nebula, but it’s looking perfectly spherical. To get a more realistic shape Blender offers the ability to distort the result of a point density texture with another 3D texture. You can find that in the section “Turbulence” under the settings of the point density texture. Enable it and set the size to 0.200, the Depth to 5 and the strength to 2.000
Now the result is starting to look really cool!
Let’s use some compositing to improve the looks a little more. Add an RGB Curves node between the Render Layer of the nebula and the AlphaOver and change the curve like in the following figure to get some custom contrast:
Now the only things left are some final brush-ups in the form of a glow. Use the setup from part one of this tutorial that uses a blur node and an mix node set to “Add” (you can just copy the two nodes from farther left in the noodles) but use 16 pixels for the blur.
The only problem is that now the entire scene glows. You might want to have only the extra glow for the nova part. To easily fix this add another RGB curves node before the blur node. Use it to selectively remove darker parts from the blur.
Congratulations! Things are ready for the final render now!