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Fog

Provides fog and smoke atmospheric effects.

This plug-in provides effects such as fog that causes objects to appear to fade as they increase in distance from the camera (standard fog), or layered fog that envelops all or parts of objects in a blanket of mist.

Reference

The Fog Parameters rollout appears when you select Fog under Effects in the Environment dialog. It has the following controls:

Fog

Color: Sets the color for the fog. Click the color swatch, then select the color you want in the Color Selector dialog. You can animate the color effect by changing the fog color at a non-zero frame with the Animate button on.

Environment Color Map: This option gives you the ability to derive the fog color from a map. You can map the background and the fog color, you can animate procedural map parameters in the Track View, and you can opacity map the fog (see the next option).

The large button displays the name of the color map, or None if none is assigned. The map must use Environmental mapping coordinates (spherical, cylindrical, shrink-wrap, and screen).

To assign the map you can drag a map from a sample window or map button in the material editor (or anywhere else in 3DS MAX; for example, a projector map button) and drop it on the Environment Color Map button. A dialog asks if you want the environment map to be a copy (independent) or an instance of the source map.

Clicking Environment Color Map displays the Material/Map Browser, where you can choose a map type from the list. To adjust the environment map’s parameters, for example to assign a bitmap or change the coordinate settings, display the Material Editor and then drag the Environment Color Map button and drop it over an unused sample window.

The Use Map toggle lets you turn the effect of this map on or off.

Environment Opacity Map: Using an opacity map alters the density of the fog.

You assign the opacity map, edit it, and toggle its effect in the same way you do the Environment Color Map.

Fog Background: When this box is on (the default), the fog function is applied to the background of the scene.

Type: When Standard is selected it uses the parameters in the Standard section and when Layered is selected it uses the parameters in the Layered section.

Standard

Thins and thickens the fog based on the distance from the camera.

Exponential: When checked, density increases exponentially with distance. When unchecked, density increases linearly with distance. Check this only when you want to render transparent objects in volume fog.

Tip: If you check Exponential, increase the Step Size value to avoid banding.

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

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. Since all the fog parameters are animatable, you can animate the fog rising, falling, changing density and color, and add horizon 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. Defaults to 20.

Tip: If you want tendrils to really pop out, try making the density greater than 100.

Angle: Determines the angle off the horizon line that is affected. For example, if the angle is set to 5 (a reasonable value), then starting at 5 degrees below the horizon the fog will start 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 down.

How To

To use standard fog:

  1. Create a camera view of your scene.
  2. In the camera's creation parameters, check Show to show the Environment Ranges.
  3. Standard fog is based on the camera's environment range values.

  4. Adjust Near Range and Far Range to include the objects you want to fog in your rendering.
  5. As a general guideline, set Far Range just beyond the objects, and Near Range to intersect the object geometry closest to the camera.

  6. Choose Rendering/Environment.
  7. In the Atmosphere area of the Environment dialog, click Add.
  8. The Add Atmospheric Effect dialog appears.

  9. Choose Fog, and then click OK.
  10. Make sure that Standard is chosen as the type of fog.

To use layered fog:

  1. Create a camera or perspective view of your scene.
  2. Choose Rendering/Environment.
  3. In the Atmosphere area of the Environment dialog, click Add.
  4. The Add Atmospheric Effect dialog appears.

  5. Choose Fog, and then click OK.
  6. Choose Layered as the fog type.
  7. Set the parameters for layered fog.
  8. You can have multiple fog layers in the scene by adding multiple Fog entries to the list and making the fog Layered.