Volumetric Studies: Caustics, Godrays, Murky Water, Mist

[bdesign]

I've been doing quite a bit of experimenting and testing to come up with a method for creating volumetric atmosphere ("fog") that reacts with light, shadow, and caustics. The example renders below are:

1. Green glass scene with volumetric caustics, lit with an IES spotlight + HDRI environment.
2. Interior scene with volumetric godrays, lit with an HDRI environment.
3. Lake scene with volumetric murky water depth, lit with an HDRI environment.
4. Stone island scene with volumetric mist, lit with an HDRI environment.

For the caustics scene, the fog was rendered directly in the beauty shot; for the others, the fog was rendered in a separate pass, and composited in Photoshop with a combination of Lighten and Screen blend modes.

The basic technique is this:

1. Create a primitive cube which encompasses the scene, then split into 6 separate faces with the Geometry Editor.
2. Create a "Fog XYZ" material: Advanced type, Diffuse = 50% grey, Specular = 0, Refraction Index = 1, Diffuse Transmission = 50% grey. Connect a Color To Number node to the Opacity channel, which controls the fog opacity via the Output From value (.1 in the caustics example scene).
3. Apply a Transformation Animation node to each of the 6 faces, along their respective normal axes, moving a distance equal to the scale of the cube (either positive or negative, depending on the initial position of the face). For example, in the caustics scene, the cube has a scale of 80, so each face has a translation value of either +80 or -80 in X, Y, or Z.
4. Set the FPS in the Timeline to 1, and the duration of each of the 6 translations to 1 second.
5. Enable Motion Blur.

Once Motion Blur is enabled, you will see the volumetric atmosphere begin to build up in "slices". The longer it renders, the smoother the fog will become. It will react with light, shadow, and caustics. For the murky water and mist fog passes, only the Y plane was utilized, starting from the bottom of the lake bed and the water surface, respectively, and a Color Fade animation node was applied to the Opacity of the Fog XYZ material to fade the fog as it moves up. The mist has a Fractal (Noise) node applied to the Diffuse and Diffuse Transmission channels, with Number Fade animation nodes applied to the Scale and Falloff, to break it up a bit. Also, for the murky water scene, the Fog XYZ material has a greenish color applied to the Diffuse and Diffuse Transmission channels. For the interior, lake, and stone island scenes below, I've attached the final comp, as well as the beauty and fog passes. I'm also attaching a link to a KSP tutorial file, which includes the setup used for the green glass caustics scene. It contains the volumetric fog cube with animations, the backdrop ramp, the spotlight, and 3 spheres with Gem, Diffuse, and Flat Black materials. There are 3 Scene Sets: Beauty, Caustics, and Fog Pass. The Fog Pass has a Flat Black material applied to all geometry except for the fog planes. When rendering the Caustics scene set, Caustics and Interior Mode should be enabled under the Lighting Tab.

Link to KSP file: http://bit.ly/2gQRNf7

Interior scene from cgtrader.com
3D rock scan by MGD Films, from sketchfab.com

Cheers,
Eric

[NM-92]

Great studies Eric. You are pushing Keyshot to the limit ! That green glass scene looks fantastic.

[bdesign]

Great studies Eric. You are pushing Keyshot to the limit ! That green glass scene looks fantastic.

Thanks very much, Nico! I really appreciate the kind words 

Cheers,
Eric

[Despot]

This is way, way cool - those volume caustics are f****** awesome.

I'm in admiration of you

[TpwUK]

God rays and murky water are seriously outstanding efforts. All of them are smashing!

Martin

[LayC42]

Very amazing Eric!

[bdesign]

This is way, way cool - those volume caustics are f****** awesome.

I'm in admiration of you

Thank you so much, John! To receive a comment like this from one of the most admired artists ever in the history of keyShot is, well...f****** awesome

God rays and murky water are seriously outstanding efforts. All of them are smashing!

Martin

Thank you very kindly, Martin! I appreciate your kind words

Very amazing Eric!

Thanks very much, Marco! Very kind of you to say so

Thanks again, guys...

Cheers,
Eric

[Magnus Skogsfjord]

I'm throwing myself with John's comment. This is fantastic! Very creative usage. Loving the mood you got in these images. This will be studied further!

Great job Eric!

[bdesign]

I'm throwing myself with John's comment. This is fantastic! Very creative usage. Loving the mood you got in these images. This will be studied further!

Great job Eric!

Thank you so much, Magnus! I really appreciate your observations and comments. Please do study it further...would love to see you incorporate the technique into one of your amazing renders!

Cheers,
Eric

[Magnus Skogsfjord]

I'm throwing myself with John's comment. This is fantastic! Very creative usage. Loving the mood you got in these images. This will be studied further!

Thank you so much, Magnus! I really appreciate your observations and comments. Please do study it further...would love to see you incorporate the technique into one of your amazing renders!

You are too kind, Eric! But yes, the mood you manage to get with this lighting is fantastic. I feel the urge to test it out as soon as possible.

[bdesign]

You are too kind, Eric! But yes, the mood you manage to get with this lighting is fantastic. I feel the urge to test it out as soon as possible.

Thanks again, Magnus! Too kind?...not at all my friend...you're a brilliant artist I'm really happy that you feel inspired by this! Look forward to seeing what you come up with!

Cheers,
Eric

[Josh3D]

This is absolutely ingenious Eric. Going to put together a write up on this for the blog

[Rex]

Mind. Blown.

It is so awesome to see existing KeyShot features being utilized with such creativity! Really great stuff. Thank you for sharing!

[bdesign]

This is absolutely ingenious Eric. Going to put together a write up on this for the blog

Wow...thank you very much, Josh! That is really awesome! 

Mind. Blown.

It is so awesome to see existing KeyShot features being utilized with such creativity! Really great stuff. Thank you for sharing!

Thanks so much, Rex! Your comments really mean a lot

Cheers,
Eric

[Will Gibbons]

Holy moly! These results are really impressive. #mousedrop