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Nebula Generator

With the Nebula Generator by Mark Kingsnorth we can generate a Nebula environment just by adjusting settings in the Node Editor. This product come in two varieties: 2D Nebula and 3D Nebula. This article is to provide you an overview of the generator and it’s settings.

The 2D Nebula

The 2D nebula is like an environment texture, like sky, or an HDRI. This is a leightweight nebula and doesn’t ask many resources of your computer or laptop. There are many application for it, for example: Sky box for a game (I used it in Roblox), as background in your scene while you have a real hdri on, etc. Here an overview of the settings that might come in handy when while you work on the nodes:

Mapping Nodes

Use these controls to change the position or proportions of individual parts of the nebula, such as the clouds, the stars or the large suns.

So, in this section you see 6 mapping nodes. The one on the left is for general mapping. Then from top to bottom on the right:

Cloud 1, 2 and 3.
Large Suns
Stars

For now leave, these mapping settings as is. Best is to work on other settings first. Tip for playing with the mapping settings;

Try to scale x, y, and z on at the same time.
Temporally change the rotation so you can see what you are working at. So you can see what is what!

Clouds Nodes

The main effects of the nebula is produced by overlaying a set of clouds. These clouds are produced from a series of noise nodes that are inside the NebulaCloud node. It has the following controls. Scale: The size of the overall cloud. Distortion: How distorted or distressed the cloud effect is. Overlay scale: To produce a more layered effect, an additional noise.

My tip here, is to be humble with distortions, especially for cloud 2 which seem to be the main clouds in the default setup. And if you go inside the Cloud 2 node (select the node and press TAB) you will see three Noise textures. Each of them has a roughness setting (Blender 2.83 and onwards?). So that is a new feature of blender and pretty awesome to play with here.

Now that we turned down the distortion, look around and you will see that the Nebula looks awesome from all views.

Large Suns Nodes

These nodes produce an ambient light effect on top of the nebula by adding a large noise map on top of the cloud effect, as if large nearby suns are present. The brightness and intensity are controlled by the Large Suns Color Ramp node.

My tip here: increase the roughness (relative new feature in Blender) a bit and don’t use the distortion. Another suggestion is never to use black colors, but bump it up a little bit so you have room to change the color. So that will give even more possibilities to adjust.

Stars Nodes

These customised nodes produce a star parttern. Two star nodes patterns are “Added” on top of each other to give a more random effect. The RGB Curves nodes is there to control the brightness of the stars. By adjusting the curve to be steep, the stars are brighter. Shallower curves create smaller, more subtle stars.

These nodes are very intuitive to use and doesn’t need much explanation. So you have to sets of stars and you can change their size, mix and density. Mind that if you set the colors of the stars you need to change the Mix settings under the Mix Stars settings (see later).

Mixing Clouds Nodes

Each cloud effect is added on top of each other here. This uses the Screen overlay effect which brightens each cloud layer when it is mixed. You could adjust the ‘fac’ function to change the intensity of each cloud layer.

Not much to do here, but what is interesting is to bump the black color a little bit up and give that a saturated color, like blue. (You see three Screen Mix nodes, and the first one has a color input free).

And you could here turn down the brightness of one of the clouds in case they are to bright.

Mix Large Suns Nodes

Once the cloud layers have been mixed, the ambient light effect or large nearby suns is added. This is done by selecting parts of the nebula colour using a colorramp node, and the adding Large Suns effect using the Dodge mix function.

Here its nice to play with the colorramp. Try the following: bump up the blacks a bit and change the position of the color stops in the colorramp. With this, I made my Nebula less contrasty and a bit brighter.

Cloud overlay Nodes

These nodes add an extra layer of noise effect on top of the overal nebula. The colorramp input node controls which parts of the nebula are given this effect. The other Colorramp node controls the color of the overlayed cloud effect. The texture is then added using a Dodge Overlay effect.

To see quickly what this group is about, bump up the scale very much for a moment. You see now what we are dealing with. In my case I turned down the saturation of the orange in the default setup.

Mix Stars Section

These nodes control how the star pattern is mixed in with the Nebula. The color node controls how much the star colors are affected by the color of the nebula. The colorramp node then controls which parts of the cloud have the star effect added. The effect is then added using the Dodge filter.

Other tips

So far I discussed only the 2D version of the Nebula Generator and I will review the 3D version later. Some other tips for now is to keep an eye on colormanagement (higher contrast?). And interesting is that you can bake the environment on objects! What if you can make a planet this way? I will try it out. And if anyone tried to render it out as HDRI, I am curious about it. Let me know!