topic Re: Best way to create a realistic planetary atmosphere for Earth and Mars. Thanks. in Arnold General Rendering Forum

Best way to create a realistic planetary atmosphere for Earth and Mars. Thanks.

bradybarrineau — Thu, 30 Aug 2018 00:20:25 GMT

Re: Best way to create a realistic planetary atmosphere for Earth and Mars. Thanks.

zenop — Thu, 30 Aug 2018 01:37:26 GMT

From what distance? Do you see the whole planet? Are you inside of the atmosphere? Please be more specific.

Re: Best way to create a realistic planetary atmosphere for Earth and Mars. Thanks.

lee_griggs — Thu, 30 Aug 2018 05:14:59 GMT

Yes, can you provide some more information or image examples of what you want to achieve. Which plugin you are using would also be helpful.

You could follow this tutorial.

There is also a rim lighting example here.

Re: Best way to create a realistic planetary atmosphere for Earth and Mars. Thanks.

bradybarrineau — Thu, 30 Aug 2018 20:54:01 GMT

@Lee Griggs @Zeno Pelgrims

https://www.solidangle.com/news/gravity/

I know that the shader tree for creating this realistic atmosphere must be far more complex than simple rim lighting or the Earth tutorial, I'm just wondering how the FX dept used Arnold to create such a realistic one. Thanks.

Re: Best way to create a realistic planetary atmosphere for Earth and Mars. Thanks.

lee_griggs — Fri, 31 Aug 2018 10:31:17 GMT

From the Solid Angle website:

"The rendering of the earth asset was another challenge and one of our lead shader writers, Nathan Walster, developed a volumetric approach (which raymarched the atmosphere, clouds and terrain data set) building on a variety of Framestore tools, such as our volume file format (fVox) and FX rendering tool (fMote)."

I don't remember if there was, but maybe there is also something in Cinefex about it.

Re: Best way to create a realistic planetary atmosphere for Earth and Mars. Thanks.

Slava_91 — Sat, 01 Sep 2018 12:06:51 GMT

I use aiStandardSurface Transmission Scatter for this project for atmosphere

video

Rendering one high res frame, and use them like matte paint for all sequence

Because it is easily remapping with ramp in render, for deeper values at the edges of the planet, and for tone transitions from brighter to darker blue...

This is not the best example, but the meaning should be clear, you anyway will use volume for atmosphere effect, question is just how convenient it will be do it ...
With maya fluid, or convert geometry to vdb, or maybe using polygon to volume in arnold, or transmission scatter in StandartSurface shader ...
The latter option most simple and effective for the atmosphere, but it not work, if camera move through the atmosphere.

Re: Best way to create a realistic planetary atmosphere for Earth and Mars. Thanks.

Anonymous — Thu, 17 Jan 2019 01:51:11 GMT

To build on @Slava Sych's suggestion to use a polygon as a volume in Arnold, I think that would be the simplest solution for a situation where you would need to actually enter the atmosphere or have objects moving through it. One glaring issue to this, however, is that earth's atmospheric density has an exponential falloff as you move further from the surface. Is there any way to replicate this using the Arnold Standard Volume shader? I can't seem to get a ramp connected in any way to density or figure out a solution using displacement.

Is there some sort of way to control the density via a ramp from the core to the edge of a polygon volume?

Re: Best way to create a realistic planetary atmosphere for Earth and Mars. Thanks.

Anonymous — Sun, 03 Feb 2019 10:48:00 GMT

I managed to do the density changes by getting the current shader state of the voxel being rendered in local space. I then used some math nodes with some additional information about the size of the atmosphere, and made it normalize to a 0...1 range, which I then used as uv coirdinates in a 16 bit grey scale texture, made from real density values at varying heights. I then fed this into the density with a little multiplier node attached. Works perfectly.

Here’s some pseudo math for you:

(Length(local voxel pos)-minRadiusAtmosphere) / thicknessAtmosphere

Re: Best way to create a realistic planetary atmosphere for Earth and Mars. Thanks.

ihabali — Sun, 31 Mar 2019 03:44:33 GMT

@Henrik Kragh can you elaborate more on how your setup works?