Node Description and Purpose:
The Sunlight node is the main way of lighting your scene. It basically puts a sun in the sky. You can create as many suns as you like.
If you use the 2D Heading style compass in the 3D Preview all of the Sunlight nodes in the scene are shown as yellow dots around the outside of the compass. The position of the dot shows the Heading of the Sunlight node.
Node Type: Lighting
- Heading: This sets the direction of the sun, in degrees. 0 is North, 90 is East.
Elevation: This sets the height of the sun in the sky, in degrees. 90 is directly overhead, 0 is the horizon.
Colour: This is the colour of the sunlight.
Strength: This controls how powerful or bright the sunlight is. Larger numbers mean stronger sunlight.
Cast shadows: When enabled, shadows will be cast by this light source. Shadows are enabled by default and it is not recommended to disable them as they greatly increase realism. Shadow casting can be controlled separately for Surfaces and Atmosphere using the check boxes below. You can control the shadow casting of specific elements of the scene like a particular cloud layer using settings in the Cloud Layer v2 node itself.
Shadows of surfaces: When enabled, shadows will be cast by surfaces in the scene that are affected by this Sunlight node. Mountains will cast shadows onto nearby terrain, for example. TBC
Shadows of atmosphere: When enabled, shadows will be cast from the atmosphere elements onto each other and the terrain. This affects cloud shadow casting in particular. So for example, clouds will cast shadows both onto the terrain, as well as onto other cloud elements. This is particularly important for cloud and overall sky realism, so it is it not normally recommended to disable it. TBC
- Do soft shadows: If this is checked the shadows cast by the sun will be soft rather than hard. Soft shadows tend to be more realistic, but take longer to render. This is disabled by default. The Soft Shadow effect is controlled by the diameter and number of samples parameters below. The Diameter controls the softness or "spread" of the effect, while the Samples controls the quality.
Soft shadow diameter: This controls the softness of the shadows, measured in degrees of diameter. Larger numbers mean softer shadows. The diameter will normally correspond with the Angular Diameter of the Visible Disc below as in the real world this would be the reason for soft shadows due to angular dispersion. Note that higher Soft Shadow Diameters will probably require higher Soft Shadow Sample values to maintain quality. You can of course set them to different values to achieve different effects. TBC
Soft shadow samples: This controls the number of samples used to render the soft shadow effect. The higher the number of samples, the higher the quality of the soft shadows, but render time will also increase with higher sample numbers. Lower sample values will tend to create noisier and less precise soft shadows. The default of 9 creates a good balance between quality and render time at the default Soft Shadow Diameter of 0.5. Values above 20 are generally not recommended.
Sample jitter: This controls the randomness of soft shadow sample positions. Lower values will result in less noise, but can create banding and less realistic-looking soft shadows. However, lower values will also result in less noise, so in some cases (animation, for example) the trade-off can be worthwhile, especially where the camera is in motion and the negative effects may not be noticeable. With a jitter value of 0, soft shadow samples can be as low as 4 with the default 0.5 Soft Shadow Diameter, and still be relatively noise-free. The default value is 1 and it's generally recommended to leave it there for most scenes; values above 1 are not supported. TBC
- Glow in atmosphere: When enabled, this light source will create a glow effect in the atmosphere. The glow effect simulates the lighting of particulates in the atmosphere and in normal scenes will enhance realism. This setting is enabled by default. TBC
Specular highlights: When enabled, specular highlights will be rendered on shiny surfaces for this light source. Specular highlights are the bright reflections of a light source on a reflective object and are an important part of the realistic appearance of shiny surfaces. This setting is enabled by default. Note that this controls specular highlights for this light source only. TBC
- Visible disc: If this is checked the sun will be rendered as a visible disc or circle in the sky. This setting roughly simulates the visual effect of the sun in the real world, which appears as a "disc" in the sky when obscured by clouds for example. When disabled this light source will only be visible by the light it casts into the scene and will not be visible itself.
Angular diameter: This sets the size of the visible disc in the sky. The angular diameter describes how much of the sky the sun disc covers. The measurement is in degrees.
A single object or device in the node network which generates or modifies data and may accept input data or create output data or both, depending on its function. Nodes usually have their own settings which control the data they create or how they modify data passing through them. Nodes are connected together in a network to perform work in a network-based user interface. In Terragen 2 nodes are connected together to describe a scene.
A sample refers to a value or set of values at a point in time and/or space. The defining point of a sample is that it is a chosen value out of a continuous signal. In Terragen 2 it is usually a mathematical (procedural) function that is being sampled.