Category Archives: Tutorials
I made some small additions to bring better control to the ambient rim lights around the clouds:
Before, you could just get this:
I thought it would be good to share my work on creating nebula effects in Blender and make an adjustable Blender node called “Nebula” that Blender users can download and create different effects with, seeing as I don’t have much time to create the images myself.
With the “Nebula” node you can produce a range of effects, such as:
What follows in an overview about how to use the “Nebula” Group Node and a selection of other example .blend files you can download with the group node in it. I’ve also added for upload some samples from my previous post on the subject.
The tutorial assumes that you have a working knowledge of Blender and how to install a group node in it. If you’re new to Blender, it’s all open source and is definitely worth spending the time learning it.
Here is a screenshot of the Nebula Node in Blender’s Cycles Compositor:
The node works by overlaying a series of different noise effects to produce the clouds and the stars. The clouds are produced by overlaying 3 coloured noise layers, and the ambient large “suns” are layered on top. Finally, the smaller stars are mixed in.
Here is a sample node setup that adds the nebula to the background environment in blender cycles (this is also in the sample .blend files):
The options for the Nebula Node are as follows:
The first set of options define the position of each layer. They are separated out because the key to producing a good effect is offsetting the vector (position) of the layers:
- Small Stars Vector: The position of the small background stars.
- Large Stars Vector: The position of the larger ambient stars. Note that these aren’t exactly star-like, and more produce the ambient lighting of the nebula.
- Clouds 1 Vector: position of the first cloud layer.
- Clouds 2 Vector: position of the second cloud layer.
- Clouds 3 Vector: position of the third cloud layer.
You will find that offsetting the cloud vectors using Blender’s mapping node will produce different cloud shapes and effects.
As noted, the key to getting different nebula effects is by adjusting the 3 layers of cloud noise. Each layer, labelled Cloud 1-3, has the following settings:
- Color: The individual colour of each cloud layer, mixed in by the rest by the Screen layer effect.
- Mix: How strongly mixed the cloud layer is with the overall effect (Default: 1.0)
- Scale: The size of the noise in the cloud layer.
- Distortion: The distortion effect applied to the cloud layer.
- Detail: The amount of variation in the cloud texture. Higher levels do produce more detail, but be careful not to overly distress the cloud effect.
- Detail distortion: Applies a distortion effect to the detail.
There are then some more global settings you can play with for the clouds:
- Cloud darkness: How dark a contrast the overall nebula effect is producing.
- Cloud Dark Start: The position in the noise where the dark parts of the cloud begin.
- Cloud Light Start: The position in the noise where the light parts of the cloud begin.
Sun and Star settings
The following settings control the intensity and position of the ambient light (suns) and stars.
- Large Suns Mix: The intensity of the ambient light of the nebula.
- Small Stars Mix: How much small stars shine through the nebula.
- Large Sun Scale: The size of the ambient light on the nebula.
- Large Sun Ramp Pos 1: The position where the light that brightens the nebula starts.
- Large Sun Ramp Pos 2: The position where the darker part of the ambient light tails off.
…phew! That’s it.
Below are some of the effects you can get using the Nebula Node and the associated .blend file to load into Blender:
Other Nebula Blender files
Finally, here are some .blend files of earlier effects I’ve done using the same principle but not in a group node. You might find them useful to adjust for your own projects:
And finally…. Any questions, let me know and I will do my best to respond.
I have been experimenting for some time with different ways to produce computer based nebula effects that can be animated, similar to the practical special effect of the Mutara nebula in Star Trek II The Wrath of Khan:
This was originally achieved by use of a cloud tank, where coloured dyes and other chemicals were immersed in a big glass tank of water, lit from various directions, and then photographed. This effect was used in a number of other 70s/80s films, including Indiana Jones. You can read all about it here, and there are lots of videos like this one that show you how to create your own.
An example of a cloud tank.
In the absence of a large cloud tank, I wanted to look into how to re-create this effect in 3D CGI, where you could build a cloud-like structure you could navigate around – not just a photoshop painting. Some years ago I looked at Blender’s fledgling volumetric model which showed promise. I tried recreating the tank as a 3D shape, such as a sphere, and then used 3D noise textures to influence the varying density of the cloud inside the sphere. I then lit it with different coloured lights from various directions and achieved this:
My first attempt.
At that time, you could not increase the detail beyond a certain limit, and the rendering time was quite cumbersome on a single machine (remember in 2009 public distributed computing like Amazon Web Services were still in their infancy).
I revisited the problem a number of years later in 2014. Blender had developed its Cycles system to include volume rendering, and with their nodes editor I was able to create more effects. This time I used a more straightforward cube shape and then used 3D noise and colour ramps to control the effects. I also started embedding light sources inside the cube to suggest stars which also produced some better effects.
Here are a selection of an early set of attempts, roughly in chronological order, where I did a lot more close-up shots. Remember these images are rather raw and have not had any further post-processing. Click for larger versions:
I still found drawbacks to this technique; I had a lot more power to control the effect, but rendering times were still extremely high especially on a single machine. I was experiencing times of between 1 and 6 hours for a half decent single frame render.
I therefore did one further experiment with this technique using an open source tool called Brenda and ran the process across multiple machines using Amazon Web Services. This way I could split the work up across multiple machines running simultaneously to reduce the time to render.
This nebula exists in 3D space and could be navigated in and around with a camera. This image was achieved in 40 minutes, using 8 multi-core machines in parallel – if I had ran it on a single work station, it would have taken nearly 6 hours…
I was still very impatient; Therefore I developed a system that can produce very effective results in a matter of seconds, at the sacrifice of being totally navigable – however you could simulate this using various techniques that splits the clouds up onto multiple 3D planes.
The effect was a development of a photoshop tutorial I saw online. This tutorial used more traditional painting techniques to great effect, and the key was how the artist overlaid different painted clouds over each others using the colour dodge filter. The most time consuming part was producing the clouds – so I cut that time down by using a noise texture.
I used Cycles in Blender and the node editor to overlay different noise-generated cloud effects on top of each other using the Screen filter, adding this to the world background. Because I wasn’t using volumetric rendering any more, I could produce good effects in near-realtime on a single workstation.
Here are some high resolution quality images which all took under a minute to render. Click to enlarge:
The properties can also be animated, and although you can’t quite navigate around them in the same way as using volumetric materials, the rendering time is significantly reduced – the following HD animation took 15 minutes to render on a single machine, so this effect would take even less across multiple machines. Note that the clouds move half-way through:
You can also create different effects other than the pink/purple mutara nebula effect. You could create an Eagle nebula like effect like this: