Optical FX Attributes

Glow Attributes

Glow Color

The color of the light’s glow. Click the color swatch to open the Color Chooser and select a color if desired.The default setting is white.

Glow Intensity

Also accessible through the material’s Special Effects attributes (see Special Effects). Controls the glow brightness. As the Glow Intensity value increases, so does the apparent size of the glow effect. A negative Glow Intensity value subtracts from other glows. (The light’s Decay Rate controls how the glow brightness decreases with distance.) The slider range is 0 to 10, but you can enter values up to infinity. The default value is 1.

Glow Spread

Controls the size of the glow effect. Negative values can have odd but sometimes useful effects. The slider range is 0 to 5. The default value is 1.

Glow Noise

Controls the strength of two-dimensional noise applied to the glow. The noise is generated on a plane centered at the location of the light and always oriented towards the camera. The slider range is 0 to 1. The default value is 0.

To create the illusion of illuminated smoke around a glowing light source, set the Glow Noise value to about 0.5 and slowly animate the Noise Uoffset and Noise Voffset values. The smoke appears to slowly drift by the light.

Tip

Generally, fog illumination is better than glow if you want to create smoke and fire effects because fog is a 3D effect (for example, glow noise cannot be occluded by objects).

The following example shows how you can create a moody night sky simply by adjusting a few Glow Attributes. The Optical FX attributes used in this example are as follows:

• Glow Type = Exponential
• Radial Frequency = 0
• Star Points= 2
• Rotation = 300
  

  Glow Radial Noise

  Randomizes the spread of the glow to simulate starburst effects and eyelashes refracting light. The slider range is 0 to 1. The default value is 0.

  Negative values of Glow Radial Noise produce thicker noise. Use the Radial Frequency attribute to control the smoothness of this effect.

  Glow Star Level

  Simulates camera star filter effects. The slider range is 0 to 4. The default value is 0. Use the Star Points attribute to set the number of points on the star. Use the Rotation attribute to rotate the star.

  Glow Opacity

  Controls the amount the light’s glow obscures objects. Think of opacity as the opposite of transparency. The slider range is 0 to 0.5. The default value is 0.

Halo Attributes

Halo Color

The color of the halo. Click the color swatch to open the Color Chooser and select another color if desired. The default setting is white.

Halo Intensity

Controls the halo brightness. As the Halo Intensity value increases, so does the apparent size of the halo effect. (The light’s Decay Rate controls how halo brightness decreases with distance.) The slider range is 0 to 5. The default value is 1.

Halo Spread

Controls the size of the halo effect. Halo size is generally larger than glow size when the Halo Spread and Glow Spread values are the same. The slider range is 0 to 5. The default value is 1.

Lens Flare Attributes

These attributes are only accessible if Lens Flare is turned on in Optical FX Attributes.

Flare Color

The color of the lens flare circles. Click the color swatch and select another color from the Color Chooser if desired. The default color is white.

Flare Intensity

Controls the flare effect’s brightness. (The light’s Decay Rate controls how the lens flare brightness decreases with distance.) The valid range is 0 to infinity. The slider range is 0 to 5. The default value is 1.

Flare Num Circles

Represents the number of circles in the lens flare effect. The valid range is 0 to infinity. The slider range is 0 to 30. The default value is 20.

If the Flare Num Circles value is very large, rendering times may be long, especially if the Flare Min Size and Flare Max Size values are large and the Flare Color is textured.

Flare Min Size, Flare Max Size

The size of the circles is randomized between these two values. The valid range is -infinity to infinity. The slider range is 0 to 5. The default value is 0.1 for Flare Min Size and 1 for Flare Max Size.

Hexagon Flare

Produces hexagonal-shaped flare elements (instead of circles).

Flare Col Spread

Controls the hue amount of individual circles randomized about the Flare Color. The Flare Col Spread value has no effect if the Flare Color is not at least partially saturated (for example, not white or grey). The slider range is 0 to 1. The default value is 0.5.

Flare Focus

Controls the circle edge sharpness. The valid range is 0 (very blurry) to 1 (totally sharp). The default value is 0.6.

Flare Vertical, Flare Horizontal

Controls the axis of the flare effect relative to the center of the image. If the light source moves, the flare appears to rotate through this point. The slider range is -1 to 1. The default value is 1.

Flare Length

Controls the flare effect length relative to the light location. If Flare Length is small, all circles overlap the light. If Flare Length is large, the circles spread out across the image. The Flare Length value has no effect if the Flare Vertical and Flare Horizontal values are both 0. The slider range is 0 to 1. The default value is 1.

Noise Attributes

See also Glow Noise.

Noise Uscale, Noise Vscale

Scales glow noise in the horizontal (Noise Uscale) and vertical (Noise Vscale) directions. The slider range is 0 to 5. The default value is 1.

Tip

You can use Noise Uscale and Noise Vscale to create layered fog or tall flames. Animate the Noise Uscale and Noise Vscale values from high to low values to make the noise appear to fly apart like an explosion.

Noise Uoffset, Noise Voffset

Offsets glow noise in the horizontal (Noise Uoffset) and vertical (Noise Voffset) directions.

For example, you can animate the Noise Uoffset and Noise Voffset values to simulate smoke, rain, or snow moving past a light. Noise repeats after an offset of 1. The slider range is 0 to 1. The default value is 1 for Noise Uoffset and 0.5 for Noise Voffset.

Noise Threshold

The cutoff value for the noise. As the Noise Threshold value approaches 0, glow noise breaks up into smaller patches. The slider range is 0 to 1. The default value is 0.5.

Tip

You can use Noise Threshold to simulate globular clusters, ejecta from explosions, snow and rain effects, especially when the Noise Uscale and Noise Vscale values are high. You can also use it to make flames and smoke more patchy.