Technique - Ring Clouds

Started by Njen, February 02, 2007, 03:24:29 pm

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Here is an example file for my method of doing ring clouds.

To start with, make a cloud layer that has a high amount of warp. You'll end up with places in the clouds that look like holes as the warped perlin makes swirly patterns. Use a Transform Shader to position a swirl to where ever you want. Note that transforming in the y direction (assuming it's near [0,0,0]) may help in positiong the swirl pattern.

Next we will create the mask using another fractal. We could use an image to mask the cloud, but this method keeps the solution all in the .tgd file. The downside is that positioning the mask can be a little fiddly, and we are at the mercy of circular shapes only. Note that you can use the Noise Stretch XYZ to make the shape more or less circular.

We now multiply the swirly clouds with the mask using a Merge Shader. Finally we clamp the output between 0 and 1.

The example file has a small and large example of the ring clouds.


(If anyone can tell me how to use the Link Inline Image feature properly, I would be most helpful!)


Thanks for posting!  This is going to be very useful. - A great Terragen resource with models, contests, galleries, and forums.


great stuff njen, thanks for the insight:D:D:D
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The world is round... so you have to use spherical projection.


Thanks for your Generosity! I'll let you know if I do anything with it.  :)

Dark Fire

Wow! These clouds are absolutely amazing! Thanks!


I think this script is a very good example of where Terragen could concentrate on improving the UI and workflow.
Its such a great tool and this is the only area (for me) that could do with substantial improvement in visualising components.

I've individually looked at all the atmos nodes in this scene and chained them through other nodes in an attempt to visualise the workflow of discovering it. I.e. What is the thought process to work this out ?
But it seems very hard to "experiment" your way through parts of the process to work out how to get this end result.

I.e. if you were 'playing' with some ideas - some parts of the workflow process are very hard to visualise and make up as you go along to slowly approach a working solution. The preview render on the left doesn't seem to be helping in some situations. Maybe we need another kind of visualisation also ?

Its only when you get to certain places in the structure that you can see the combined effect and these rely on you entering non-intuitive (to me) parameters.

As a specific example:

The "volcano rings cloud small mask" has a lead in scale of 13000 - a similar number 13300 shows up in the transform node below to get it visible in the sky. How to know this ? There's a lot of speculation involved to move something 13300 units just to be able to see it...?

So my guess at how you might go about 'discovering' this is:
- get nice looking warped clouds "volcano ring clouds small swirl"
- transform it until area of interest is in view. (looking at sky in main viewport)
  (so far this seems like nice discovery - also small thumbnail is showing useful image of density.. cool :-))
- decide to make a blob and merge the two together
  (could use image mask - projected or otherwise - but means continual fiddling if changing the viewpoint.
    so look for alternate in-system method)
- so make a blob - how big, where?
  XYZ cursor indicates area of interest is at approx (XYZ) 160000, 50000, 100000
  looking at width of area of interest. Its about 11000  (151K - 140K) in X
- so we want a roundish disk 11000 units across at that point in sky.
- so here we seem to depart from the easy path. :-)
  how do you work out the feature scale should be 15K, lead in is 13K and smallest scale is 32K
     then that coverage should be -4.
  looking at the preview we can't see the effect of these parameter changes in a way that allows us to work out what good values are and approach a good solution. (we see only corner of disk in preview and - although transform node has moved it in the preview - we have no relative scale to help us see how far in relation to our view.)
  without the transform we can't even see the blob in the sky (of course its nice to be able to scale the blob a bit in the transform node after making it - that is great).

So njen - how did you work out the blob params ?
This is a really nice tool giving excellent results. I'm really very happy :-)


This should be useful for making hurricanes and those very disc like clouds (don't remember what they are).




Thanks for the tips, there looks to be quite a bit of potential in this.


EXCELLENT example...much appreciated. I will definitely use this! :)




As this topic keeps resurfacing - and njen's cloud masks are great :-)
I thought I'd answer my own Questions above.

1. Finding useful features and looking at the the right scale is all a component of playing with the Thumbnail preview pane and its +/- zoom buttons.
     Hopefully in future these factors will be remembered on a node so as you look at various nodes and set them up for best viewing - that setting will be recalled (including rotational camera info)
     Resizing the panel next to it helps to make this view as big as possible.

2. When you are making something complex, keep manually overriding your node view by dragging nodes of interest past all the others and straight onto the planet.
   This could show you what they look more clearly than looking at them in the preview thumbnail. (then simply rewire your momentarily busted node graph again to restore that link).

3. The cursor feedback that gives you x,y,z and slope information, in either the main viewport or the preview thumbnail, is very very useful for sizing features you have made or want to make.