Earth without post-processing

[blauwfilms]

Hello everyone,

For the past few years I've been making lots of Earth renders in a search for the most realistic setup.
This latest render is using my Earth Digital 3.13 project file (available on the Blauw Films website).

The planet uses a variety of 86K texture maps. The land and water shader are built up using these texture maps from chlorophyll maps to bathymetry maps. The texture maps have been manually cleaned up from the NASA image library.

The atmosphere was done with the Corona Volume and an Xpresso node setup that mathematically incorporates the Rayleigh Scattering formula into the color mixing of the volume layers. I'm playing with anisotropic direction to have the red-scattered light face the camera (sunset) and the more blue-scattered light go away from the camera (atmospheric glow). That gives the gradient of white light all the way to deep blue.

For the stars I'm using a 32-bit (hdr) star kit that we've developed for our sci-fi short film, Syntactic Labyrinths.

Would love to hear your thoughts :)

All the best, Leo

[Beanzvision]

CGI! Earth is flat! :P

[blauwfilms]

@Beanzvision as flat as a polygon ;)

[pokoy]

Looks great. You've probably compared your renders to countless images of the real thing but one thing that sticks out for me is that land/forest appears too reflective. It might be the volumetric effect of the light scattering in the atmosphere but to me it looks like there's too little difference between sea/land reflectivity.
Some examples:
https://images.t3n.de/news/wp-content/uploads/2023/01/iss_suedostasien_erde_weltall.jpeg?class=structuredData-medium
https://www.woodtv.com/wp-content/uploads/sites/51/2024/02/NASA-MICHIGAN-MITTEN.jpg

Of course it all depends on the light source angle and I might be comparing apples to oranges but I'd expect landmass to be way rougher and less reflective or the sea to be more reflective.
Another thing looking slightly off is that the landmass colors seem to be slightly too saturated.

Still, good job overall, the blue hue of the atmosphere looks great and that one is really tough to get right.

[blauwfilms]

@pokoy Thank you very much! Yes, that's a very good point. I definitely think you're right.
The land-mass has been quite tricky to get rough enough. Thanks for the references!
I'm increasing the Roughness a bit more now and I'm slightly lowering the IOR to get a stronger contrast.

The saturation is a good point too.
The images I've been using as reference have very different saturation levels. It's difficult to find a clear base-line and lots of them seem to be post-processed. I'm slightly decreasing the saturation to see what it looks like.

And thanks! The atmosphere colour was quite tricky, especially as it is created by "stacking" coloured volumes (R, G, Y, C, B, V).
With a little bit more tweaking I think I can get that "foggy" cyan in there as well.

Cheers!

[maru]

It reminded me of another "Earth with volumetric atmosphere" project from the past - https://forum.corona-renderer.com/index.php?topic=34254.0

[blauwfilms]

Very cool @maru!
Really nice to see that one.

Making planet renders is such a back-and-forth to get good looking results.
Have updated the clouds shader now for a new render.

[Beanzvision]

I started working on one of these too some time ago. I never really finished it. The atmos sucks in mine ;)

[blauwfilms]

@Beanzvision Woah!! That's epic though.

The atmosphere is always so tricky. I've attempted basing mine as much as possible on Rayleigh scattering.
I'm finishing a few updates now on the clouds. After that I will be sure to share a link to the project file.

For the atmosphere:
• I have stacked multiple spheres on top of/over each other.

• I've named them from smallest to largest: Deep Red, Red, Orange, Yellow, etc. (until Blue and UV)

• Each object got its own Volume Material

• From the smallest "wavelengths" I'm giving the volume:
— Absorption of 99% White
— Scattering of 100% Full Color
(I Used a wavelength to hex-color converter, then bracketed the color values for each corresponding volume material)
— Scattering - Texture with an Image: Atmospheric Thickness map from NASA
With a Mix mode set to Multiply, at 66%

• Then for each volume I'm changing the Directionality.
— Red at 0.75, Green at 0.25, Blue at -0.15, UV at -0.7 (Everything in between is equidistant from the surrounding values.

• The layered volumes each scatter one color of light that combines into White light. Each color of light is either scattered towards the camera (the warmer tones) or away from the camera (the colder tones). This gives "blue scattering around the planet" and "orange scattering towards the camera" effect. This also helps with getting sunset effects.

• To control their intensities + color mixing I used Xpresso.
I've attached an image of the node-tree but simply put (From Left to Right):
— A Math node Subtracts the Radius of object "Blue" from the Radius of object Earth.
The Result is the "Thickness of the Atmosphere". This is our Value1.
— Now we need a quick control for the color mixing. I made a Constant Node with a Real value of 0-1.
Dark blue: 0.1
Blue: 0.27
Cyan: 0.3
Green: 0.15
Yellow: 0.12
etc.
You want to ease-in from Deep Red to Cyan, and then ease out from the Blues into UV Blue.
These Constants are our Value2.
— I created another Constant that should be a much larger number than my planet's radius (74500 cm).
I'm using a Formula node in the next step for which I want to divide this big number by a smaller number. That will give us a Distance value for the Volume material.
I wanted there to be about 15% more "Volume" for the atmosphere. 74500/0.15 = 500000
After testing I used a value of 439576. Which became Value3.
— These values go into a Formula Node in with the following formula:
Value3/(Value1*Value2)
The Result is plugged into the Distance value from each corresponding Volume Material.
It gives a number that is big enough to always make a clear atmosphere.
Each parameter can quickly be adjusted to get more accurate color mixing.

Processing this is quite heavy. My computer is a 2017 iMac, and it's struggling quite a bit with the file.
But I'm happy to see what kind of results it gives :)

Hope this helps!

[Beanzvision]

Thanks a lot for the in depth response. It's no wonder the atmos looks so good ;) I will try to give this a go when I have some free time.

[blauwfilms]

@Beanzvision Thank you man! Would love to see your results as well :)