This simple tutorial demonstrates how to create a cloud effect using a combination of the standard_volume with a noise shader. It is possible to achieve a wide range of cloudy skies using this setup.

The scene can be downloaded here.

Mesh Volume

• To represent the cloud layer, we must first create an object with which we can assign a standard_volume shader. Create a sphere or cube and scale down its height.

• Increase the step_size of the sphere to around 0.1. When the step_size is positive, it turns the polymesh into a volume.

The step_size has a fixed size, therefore, the larger the container, the more steps will be taken and the longer it will take to render. Also, beware that if the step size is too small your render times will increase.

This can be done by adding an Arnold Mesh Volume Tag to the sphere.

_{Step Size in Arnold Volume parameters of sphere}

Shading

• Create a standard_volume shader and assign it to the sphere.

• Create a noise shader and connect it to the transparent_weight of the standard_volume shader. Increase the number of octaves to 8. Increase the amplitude to around 2 or 3 to get more of a cloudy appearance. Increase the scale to see more clouds (depends on the size of your object).

_{noise -> transparency of standard_volume}

Lighting

Finally, create an Arnold Sky and change Type to physical_sky. To reduce any noise in the volume, you must increase the number of volume_samples for the sky lighting.

_{physical_sky -> Environment Map}