Cloud Layer v2
Node Description and Purpose:
The Cloud Layer node creates a planet-wide layer of clouds which may be either 2D with simulated 3D shading for faster rendering, or full volumetric 3D for maximum realism but with longer render times. Cloud layer placement is primarily defined by the height and altitude of the cloud layer. Many additional settings are provided to fine-tune the overall appearance of the cloud layer to simulate almost any real-world cloud type.
The easiest way to create new cloud layers is using the Add Cloud Layer button at the top of the Atmosphere project view. This allows you to choose from several cloud presets. Creating cloud layers automatically creates a density shader, which defines the overall shape or pattern of the clouds.
Multiple cloud layers can be used to create clouds at different altitudes, or of different types. There is no limit to the number of layers that can be added.
Node Type: Atmosphere
- Enable primary: If this is unchecked the clouds will not be visible to the camera i.e. they will not show up in renders. However if Enable secondary is turned on the clouds will still affect scene lighting and be visible in reflections.
Enable secondary: If this is unchecked the cloud layer will not influence scene lighting or be visible in reflections.
Move textures with cloud: TBC
- Cloud altitude: This parameter sets the altitude, or height, of the cloud layer.
Cloud depth: This sets the vertical thickness of the cloud layer. The depth is centred at the Cloud altitude. This means that if you have a cloud layer with an altitude of 1000m and a thickness of 200m then the bottom of the clouds will be at 900m.
This diagram shows how the cloud depth is centred at the layer altitude:
Localise: If this is checked the cloud layer is contained within a sphere that's centred at the Centre position and is the size of the Radius parameter. The cloud layer will not appear outside the sphere. Two dashed circles are drawn in preview to display localisation.
Localising a cloud layer allows you to easily control where clouds appear. For example if you wanted to create a lenticular cloud over a mountain peak you could localise a cloud layer and then position it over the peak using the Centre parameter. Set the Radius to an appropriate size and now the clouds will only appear over the mountain peak.
Centre: This sets the position of the centre of the localisation sphere.
Radius: This sets the radius of the localisation sphere.
Falloff (0..1): This parameter controls the density of the cloud from the centre out to the edge of the localisation sphere. A curve is applied to fade out the cloud as it approaches the edge. A value of 0 means there is no falloff and the clouds will have a hard edge at the sphere radius. Larger values make the clouds fade out more towards the edge of the sphere.
Value at radius (-1..0): Has its effect on the falloff area. TBC
Density shader: This parameter lets you specify a cloud density shader. The density shader is what gives the clouds their basic pattern or shape. A density shader is automatically created when adding a new cloud layer.
If you want to change the basic shape of the clouds you need to make changes to the density shader. The easiest way to do this is to select the cloud layer in the Atmosphere project view list and then click the Pattern... button underneath the list. This opens the density shader parameter view in a floating window.
Edge sharpness: TBC
Cloud density: Cloud density basically controls how "transparent" the cloud layer is. Low values make the clouds look thin. Higher values make the clouds look thicker and denser. Denser clouds look darker because less light is passing through them. See the example movie below.
Coverage adjust: This controls the coverage of the layer. Low values make it seem like there are few clouds. As you increase the value the clouds cover more of the sky. When you start to get towards a value of 2 it's the layer looks more and more overcast. See the example movie below.
Localise falloff going from 0 to 1 <mediaplayer>file:Cloud_layer_localised_falloff.mp4</mediaplayer>
Cloud density going from 0 to 0.1 <mediaplayer>file:Cloud_layer_cloud_density.mp4</mediaplayer>
Coverage adjust going from -2 to 2 <mediaplayer>file:Cloud_layer_coverage_adjust.mp4</mediaplayer>
Additional tabs for Cloud Layer v2
A shader is a program or set of instructions used in 3D computer graphics to determine the final surface properties of an object or image. This can include arbitrarily complex descriptions of light absorption and diffusion, texture mapping, reflection and refraction, shadowing, surface displacement and post-processing effects. In Terragen 2 shaders are used to construct and modify almost every element of a scene.
A parameter is an individual setting in a node parameter view which controls some aspect of the node.