Volumetric clouds lighting from space view

Development Rendering
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1

Hi,

I’ve been working on a stylized planet generator, but now that I’m trying to add some volumetric clouds, they don’t seem to interact with light correctly! They are being lit up as if they are all positioned on the north pole!

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Judging by this example from the documentation, it should be possible to achieve this:

DirectionalLight_OpaqueShadowsOnClouds
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Is there something that I’m missing?

2

Your clouds looks good to be honest. Could you share what you changed to volumetric clouds look good on planetary scale ?

3

@sajedn You will need to use the more expensive Use per Sample Atmospheric Light Transmittance on the cloud material. Be aware that we still ahve the ambient lighting that is not spatialized, currently simply taken from the skylight position.

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4

Exactly, It doesn’t look good (especially because it doesn’t respect the ground shadow cast on clouds from far away), and as you mentioned, it’s expensive.

Is there any way to prevent directional light from affecting clouds altogether? Then using the light direction it might be possible to light them manually.

5

Happy to hear it, just follow this tutorial:

Then apply these changes:

  • Replace all 2D textures with volumetric textures.
  • Set Tracing Start Distance on VolumeticCloud Actor to something high (For my use case 2000 was enough since my planet’s radius was 1850km)
  • Play with Cloud material settings especially scale to achieve what you like. You might need to use multiple Volumetric textures with different scales to achieve a material that looks good far away and in closer shots.
6

Use per Sample Atmospheric Light Transmittance should look great. Otherwise you have to tweak your atmospehre and cloud layer altitude, parameters.

sky light contribution: you can fully occlude this using ambiant occlusion input on root node. Then you can do any custom lighting yourself through emissive.

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7

Thanks, Fully occluding clouds and setting cloud scattered luminance scale to black completely removed lighting from clouds.