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
Open up a new Blender scene and delete the default cube.
Next put the camera onto the Y-axis facing the center of the scene. The fastest way to this is to hit ALT+G to clear the location, then ALT+R to clear the rotation, then R > X > 90 to rotate the camera 90 degrees on the X-axis and then press G > Y and move the camera backwards a little. By pressing CTRL you can constrain the motion to increments of 1 Blender Unit. For this tutorial, move the camera 6 Blender Units along the negative Y-axis.
Now go to camera view (Numpad 0) and add an icosphere. Add a Subdivision Surface modifier and set the level to at least 6 (depending on how strong your computer is you can go even higher) and set the shading to smooth.
The next step is to give the sphere a simple material. The diffuse-color should not be too saturated and have a blue tint. For this tutorial I used a Hex-Value of C1B9FF. The actual color does not matter that much since we’re going to change it later on in the compositor. Set the diffuse intensity to 1.000 and the specular intensity to 0.000. Give the material a slight emit value of 0.3 and turn on transparency. Select Z Transparency and set the alpha to 0.000.
To get parts of the sphere visible again we need a texture. Add a new texture to the 2nd texture slot. Call it “Bolts” and leave Clouds as type. In the clouds settings chose Voronoi Crackle as basis and set the size to 2.00 and the depth to 0. For the Nabla setting use 0.03. Under “Colors” chose Ramp and flip the color stops by hitting the little button with “F” on it. Next move the right stop (the one with the alpha-value of 0) to the middle (0.500). Even though it is completely transparent, the stop still has a color value assigned to it which influences the interpolation. Change it from black to fully white. Under Influence only select Alpha.
After setting the background color to black in the world settings we can have a look at our first render:
Those straight lines are of course not very exciting. That’s why we’re going to distort (or warp, how Blender calls it) them with another texture. Select the first texture slot and add another Clouds texture. Call it “Warp” and chose Voronoi F1 as a basis. Set the size to 0.45 and the depth to 5. Nabla once again 0.03. Under influence uncheck “Color” and select “Warp” with a value of 0.500. Now the lines are distorted nicely. Last thing to tweak is the Color Ramp. Choose a Hex value of C5C5C5 (a slight grey) for the right stop.
The render shows the direction where things are heading.
The last texture we’re going to add will be used to displace the sphere so it doesn’t look as perfectly round as it’s doing now. Add another texture to slot number three and once again keep the default type. Call it “Displace” and set the Size to 0.45 and the depth to 4. Nabla once again 0.03. Under influence uncheck “Color” and select “Displace” with a value of 0.543.
The cool thing now is that the warp of the first texture also influences the displace texture. The result already starts to look like the remnant of a super nova:
To add more depth and character to the remnant let’s add a second layer by adding another sphere. Select the current icosphere and name it “Icosphere.Outer”. Next duplicate the icosphere and name the new copy “Icosphere.Inner”. Now add a “Copy Scale”-Constraint to the inner sphere. To do this either use the menu in the properties panel or select the Icosphere named “Icosphere.Outer”, then Shift-select the sphere named “Icosphere.Inner” and hit CTRL+SHIFT+C. Now the inner icosphere should have a Copy Scale Constraint with “Icosphere.Outer” as the target. Set the influence to 0.900. Next select the inner sphere and scale the mesh to 0.1 by pressing S > 0.1. If everything went right, the inner sphere is now just a little smaller than the outer one. But when you scale the out sphere and make it smaller, there will be a point that both of them intersect and the outer will go inside. This will yield a very cool effect once we animate things!
Rendering shows that the distorted stripes of both spheres are rather near to each other.
That can easily be fixed by randomly rotating the outer sphere. Now we got real chaos, just like in a real super nova remnant:
Before we start animating, let’s make things look cool by applying a little compositing. So head over to the compositor (CTRL+Leftarrow). Choose “Use Nodes” and “Backdrop”. Hit SHIFT+A > Output > Viewer. Now, after pressing F12 for another render you will see the nova in the backdrop.
Add a Color Balance Node (Color > Color Balance) and connect it to the Render Layer and the Viewer. Set the values as shown in the following screenshot:
For some of the effects in this tutorial, color values >1 are needed. That’s why we’re going to add up things in the next step. Add two Mix-Nodes (Color > Mix) and set them both to “Add” with a Fac of 1.000. First mix the output of the render layer with the output of the Color Balance-Node and then the output of this operation with the output of the color balance again. Now parts of the image should have become blown-out:
Lastly let’s add a simple glow. Add a blur-node (Filter->Blur) and connect it with the output of the last Add-Node. Set the type to “Fast Gaussian” and the size to 8×8.
Add another Mix-node and set the type to “Add”. Make sure to connect the output of the last Add-node to the top of the two image-sockets at the new Add-node. Connect the output of the Blur-node to the bottom socket. This way you can use the Fac-slider to select how strongly the blurred image gets added to the original one. For this case the default of 0.5 looks good. The white might be a little too strong, though. Adjust the settings Color Balance node until there’s only very little overexposure.
This concludes the first part of the Nova-like Explosion-series. In the next part we will add animation and do more compositing.