Author Topic: help making a stormy sky  (Read 658 times)

Offline eapilot

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help making a stormy sky
« on: September 07, 2017, 02:50:55 PM »
I am learning Terragen 4 strictly for making skies.  I am trying to make a stormy sky like the references below.  I just can't get it right.  I really want the feeling of volume with light peeking through the top and clear sky in the horizon.  the objective is to ultimately make it work in a 360-degree skydome.  Any recommendations?  I have some shots of shown in the correct perspective in a test map in a game engine.  My scene is pretty much made up of 3 cloud layer v3.  I am mostly adjusting feature scale in the density fractal, cloud depth, and coverage, and density. I am also moving around the three clouds a lot to find the right composition. I can't seem to get it right.  A big thanks to everyone who contributed to the forums and shared their .tgc and .tgd files over the years.  I learned mostly from reading posts and looking at files.

Offline René

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Re: help making a stormy sky
« Reply #1 on: September 08, 2017, 06:57:20 AM »

Offline eapilot

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Re: help making a stormy sky
« Reply #2 on: September 09, 2017, 01:27:44 AM »
No, I haven't checked out these older skies in the cloud library.  The dark mood looks great! I will check it out.  I will post any positive results.

Offline Dune

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Re: help making a stormy sky
« Reply #3 on: September 09, 2017, 06:10:03 AM »
I'm not much into clouds, but don't forget the altitude offset function. You can use some power fractal to push the underside of the clouds in, so you can have some sort of mammatus clouds or a wilder version of it. You need high enough clouds or the holes that are pushed up will break through.
The rain can be done with a stretched masked cloud at lower altitude, which is also warpable (for wind effects). You could even use the main cloud as mask to determine where the darkest clouds need to rain out.

So, two layers would do it, IMO.
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Offline AP

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Re: help making a stormy sky
« Reply #4 on: September 10, 2017, 12:48:12 AM »
I had made two cloud presets. If you want to use these, I can upload these presets to the File Sharing board.

Offline Dune

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Re: help making a stormy sky
« Reply #5 on: September 10, 2017, 06:00:00 AM »
Last one is very cool. Nice clean edges at the tops.
In case you still haven't seen enough of my work: www.ulco-art.nl

Offline eapilot

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Re: help making a stormy sky
« Reply #6 on: September 10, 2017, 04:14:15 PM »
@ AP, yes please!  I didn't even know there was a file sharing thread.  Btw, I have been testing and learning your past .tgc files that you have posted on the cloud library thread.  I was trying to combine elements of the mammatus clouds with larger shapes with no avail.  Either you keep the feature scale small for detail or get large shapes. I feel like I can get the large shapes that I want but not the sharp clumpiness that I want.   The vortex warp and fractal warp shaders offer lots of possibilities, although I am too much of a noob to use them effectively. 

@ Dune I have not terrain in my test scene because I would want to use Terragen for skies only so I can't use the altitude offset, right?  However, I can take a shape shader and merge it with the fractal and create a hole in the density, right?


Attached are my renders so far with not much manipulation for the .tgc files that I found in the cloud library.

Offline Oshyan

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Re: help making a stormy sky
« Reply #7 on: September 11, 2017, 05:03:02 AM »
You should be able to use a Merge Shader to blend between the mammatus shapes with larger formations in some way. If you haven't already experimented in that direction give it a try.

Also you ought to be able to use Altitude Offset referencing a terrain, if the terrain is set to not render (in Planet node for example, uncheck "render terrain"), so then you get the offset if you want it, but still no terrain rendering.

To get a hole you can use a Simple Shape Shader, or sometimes easier, just a front-projected (through camera) image map with a white circle in it (or whatever hole shape you want) used as a mask for the Density Shader or as Final Density Modulator.

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Offline Dune

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Re: help making a stormy sky
« Reply #8 on: September 11, 2017, 06:38:07 AM »
Sorry, actually, I meant the depth modulator, which works independent of terrain. Oshyan's remark made me wonder if a separate terrain line, not going into the planet, would work for altitude offset, but perhaps it would need to be calculated from the planet on backwards.
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Offline bobbystahr

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Re: help making a stormy sky
« Reply #9 on: September 11, 2017, 02:16:49 PM »
I had made two cloud presets. If you want to use these, I can upload these presets to the File Sharing board.

very nice...please do upload them to the library
something borrowed,
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Offline eapilot

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Re: help making a stormy sky
« Reply #10 on: September 11, 2017, 02:35:00 PM »
Thanks Oshyan, I have begun to experiment with the merge shader but I the operation is pretty new to me.  I don;t know the difference between merging with diffuse or displacement (or both).  I started merge with multiply, but when I tried to visualize the combined fractal result, the procedural noise was mostly black.  And there is a merge mode option of altitude.  Combing those two nodes the render time increased dramatically. Right now, I am losing some of that translucency that was in the original mammatus cloud .tgc file (from AP) and the merge operation isn;t masking the way I want yet from the larger fractal. I will keep testing.

Offline bobbystahr

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Re: help making a stormy sky
« Reply #11 on: September 11, 2017, 04:32:56 PM »
Thanks Oshyan, I have begun to experiment with the merge shader but I the operation is pretty new to me.  I don;t know the difference between merging with diffuse or displacement (or both).  I started merge with multiply, but when I tried to visualize the combined fractal result, the procedural noise was mostly black.  And there is a merge mode option of altitude.  Combing those two nodes the render time increased dramatically. Right now, I am losing some of that translucency that was in the original mammatus cloud .tgc file (from AP) and the merge operation isn;t masking the way I want yet from the larger fractal. I will keep testing.

yes do, these first 2 are quite nice even though they're not what you want apparently...keep on tweaking
something borrowed,
something Blue.
Ring out the Old.
Bring in the New

bobbystahr

Offline Oshyan

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Re: help making a stormy sky
« Reply #12 on: September 12, 2017, 05:03:31 AM »
Displacement has no effect on clouds, so don't worry about it, i.e. you want to blend in color/scalar space.

You can also just use the Mask input for any nodes that have it, to simplistically combine (i.e. subtract) one node with another.

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