Sky textures

Sky Environment Parameters

Total_bright.

The overall brightness of the environment. The valid range is 0 to infinity. The slider range is 0 to 5. The default value is 1.

Sun Parameters

Sun_bright.

The color and brightness of the sun. The default color Value is 0.5.

Halo_bright.

The color and brightness of the halo around the sun. The default color value is 0.1.

Elevation

The angle (in degrees) of elevation of the sun relative to the floor. The valid range is -10000 to 10000. The slider range is 0 (sunrise/sunset) to 90 (midday). The default value is 45.

Azimuth

The angle (in degrees) of the sun in the sky about a vertical vector. The valid range is -10000 to 10000. The slider range is 0 to 360. The default value is 145.

Size

The size (radius) of the sun. The valid range is 0 to 10000. The slider range is 0 to 20. The default value is 0.531.

Blur

The size (radius) of the halo around the sun. The valid range is 0 to 1000. The slider range is 0 to 20. The default value is 1.

Atmospheric Settings

Sky_bright.

A scaling factor applied to the sky color. The default color Value is 0.5.

Air_density

The density of the air in the atmosphere. The denser the air, the more light will be scattered. Think of air density in terms of low and high altitudes. High altitude skies are almost black straight up and blue near the horizon (the Air_density value less than 1). Low altitude skies are blue straight up and white near the horizon (the Air_density value greater than 1). The slider range is 0 to 3. The default value is 1.

Dust_density

The density of dust in the atmosphere. The slider range is 0 to 3. The default value is 0.

Sky_thickness

The thickness of the atmosphere. The valid range is 0 to infinity. The slider range is 0 to 10000. The default value is 1000.

Sky_radius

The outer radius of the sky as a multiple of Sky_thickness. The Sky_thickness and Sky_radius values determine the planet radius, and planet radius influences the appearance of sunsets. A planet with a large radius will have very red (and very dark) sunsets (you can adjust Sky_bright to compensate for sunsets that are too dark).

For example, if Sky_thickness is 1000 and Sky_radius is 50, the outer radius of the sky is 1000 x 50 = 50 000 units, and the radius of the planet is (1000 x 50) - (1000 x 1) = 49 000 units.

The valid range is 0 to infinity. The slider range is 0.01 to 300. The default value is 50.

Floor Parameters

The Floor Parameters control the appearance of the environment’s planet surface.

Has_floor

Toggles the floor ON or OFF. If Has_floor is OFF, the environment below the horizon is a mirror image of the environment above the horizon.

Floor_texture

The color or texture of the floor. The default color value is 0.392.

Cloud Parameters

Cloud texture

The texture that determines cloud distribution in the sky. For example, the Fractal texture creates very realistic clouds. By default, there is no cloud texture map (and no clouds).

Cloud_bright.

The brightness and color of cloud illumination from ambient scattered light in the atmosphere. (The amount of ambient light depends on the Elevation value.) The default color Value is 0.5.

Sunset_bright.

The brightness and color of cloud illumination when the sun is below the horizon and the clouds are front lit (for example, when the sun’s Elevation value is 0 and its Azimuth value is 180). This is a very subtle effect and occurs only briefly in nature during a sunrise or sunset. The effect is more noticeable with high altitude clouds. The default color Value is 1.

Density

The density of individual clouds. The valid range is 0 to infinity. The slider range is 0 (no clouds) to 5 (heavy clouds). The default value is 1.

Threshold

A threshold value for the Cloud texture that controls how much of the sky is covered with cloud. As the Threshold value increases, darker areas of the texture do not produce clouds. The valid range is 0 to infinity. The slider range is 0 (entire sky is cloudy) to 1 (no clouds). The default value is 0.5.

Power

The clouds are scaled and positioned by adjusting the Power option. The cloud density is achieved by subtracting the Threshold from the pixel value clipping to 0, then multiplying the result with Density. To control the amount of unfocusing of the Cloud_texture, adjust the Blur value (under Sun Parameters). The valid range is 0 to infinity. The slider range is 0 to 1. The default value is 1.

Altitude

The height of the clouds. The Altitude value does not greatly affect the position of the clouds. Instead, it determines how much the atmosphere obscures the clouds near the horizon. Low altitude clouds disappear into haze much more slowly than high altitude clouds. The valid/slider range is 0 to 1. The default value is 0.2.

Halo_Size

The size (radius) of cloud illumination from direct back lighting by the sun (for example, when the sun’s Azimuth value is 0). Direct back lighting is most noticeable near the edges of thick clouds or through thin clouds. The valid range is 0 to infinity. The slider range is 0 to 50. The default value is 20.

Calculation Quality

The calculations required for curved atmospheres are expensive. The Calculation Quality parameters do not greatly affect the appearance of the sky, but do affect the speed at which the calculations are computed.

Sky_samples

The number of samples used above the cloud layer. Set the Sky_samples value to 1 for maximum speed. The valid range is 0 to 20. The slider range is 0 to 3. The default value is 5.

Floor_samples

The number of samples used by the atmosphere between the eye and the horizon. Increasing the Floor_samples value increases the effect of the atmosphere along the floor. At 0, there is no atmosphere between the eye and horizon. The valid range is 0 to 20. The slider range is 0 to 3. The default value is 1.

Cloud_samples

The number of samples used below the cloud layer. At 0, clouds do not fade to mist at the horizon. The valid range is 0 to 20. The slider range is 0 to 3. The default value is 5.