Autodesk 12812-051462-9011 User Guide 3 - Page 1457

Near % Sets the density of the fog at the Near Range (Camera Environment Range parameter). Far % Sets the density of the fog at the Far Range (Camera Environment Range parameter). Layered group Thins and thickens the fog between an upper and lower limit. You can have multiple layers of fog by adding multiple fog entries to the list. Because you can animate all the fog parameters, you can also animate fog rising and falling, changing density and color, and add horizon on page 8005 noise. Top Sets the upper extent (in world units) of the fog layer. Bottom Sets the lower extent (in world units) of the fog layer. Density Sets the overall density of the fog. Falloff (Top/Bottom/None) Adds an exponential falloff effect so that the density is reduced to 0 at either the Top or Bottom of the fog extent. Horizon Noise Turns on the horizon noise system. Horizon Noise perturbs just the horizon of the fog layer to add realism. Size Scale factor applied to the noise. Larger scale values make the fog tendrils larger. Default=20. TIP If you want tendrils to really pop out, try making the density greater than 100. Angle Determines the affected angle off the horizon line. For example, if the angle is set to 5 (a reasonable value), then starting at 5 degrees below the horizon, the fog will begin to break up. This effect is mirrored above and below the horizon, which can produce strange results when the height of the fog layer traverses the horizon. Typically you'd want the fog to be either above or below the actual camera horizon. (You can use the horizon line in the camera parameters as an aid to help you position this.) Phase Animating this parameter animates the noise. If Phase is moving in the positive direction, then the fog tendrils will drift upward (and deform at the same time). If your fog is above the horizon you may want to animate Phase in the negative direction to make the tendrils fall downward. 6712 | Chapter 21 Effects and Environments