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Form

Visibility Group

The Visibility group establishes a range within which particles are visible. Distances are defined by how close or far particles are from the camera. The control can fade out near or distant particles. The units for these values are determined by After Effects' camera settings.

A diagram of how Visibility works in Form.

Far Vanish: The far distance from the camera when particles become completely invisible. Low values mean particles are farther away and become invisible. High values mean particles are closer and stay visible.

Far Vanish set low (left) and high (right).

Far Start Fade: The far distance from the camera when particles start to fade out. Low values make the fade apply itself. High values keep the fade from happening.

Far Start Fade set low (left) and high (right).

Near Start Fade: The near distance from the camera when particles start to fade out. Low values keep the fade from happening. High values make the fade apply itself. (This is the opposite of the Far Start Fade parameter.)

Near Start Fade set low (left) and high (right).

Near Vanish: The near distance from the camera when particles become completely invisible. Low values mean the particles are closer and stay visible. High values mean particles are farther away and become invisible. (This is the opposite of the Far Vanish parameter.)

Near Vanish set low (left) and high (right).

Near and Far Curves: The curve used to fade particles in the Near and Far Fade zones. The curve can use Linear or Smooth interpolation. With Smooth, the form's visibility will fade less gradually than with the Linear option.

Z Buffer: Z Buffer lets you select a 2D, comp-sized, lightness-based, linear layer to use as a z-buffer. A z-buffer contains per-pixel depth values. Typically, z-buffering stores the z axis value of each pixel. This holds information about the distance from the camera viewpoint for each pixel.

Z-buffering can be useful when particles are to be inserted into a scene from a 3D application (like Cinema 4D). The 3D app can be configured to output a z-buffer. This is also known as depth map or depth buffer.

If the Z Buffer is not anti-aliased, leaving it a bit rough on the object edges, it often won’t matter if the particles are small and moving quickly.

Z at Black: The depth (distance to camera) of a completely black pixel in the Z Buffer.

Z at White: The depth (distance to camera) of a completely white pixel in the Z Buffer.

Obscuration Layer: Since Form is applied to a 2D layer and the particles live in their own 3D world, other composition layers won't automatically obscure the particles. The Obscuration Layer provides a way to insert a 3D layer into the particles' world.

Any 3D layer in the comp can be used to obscure particles. To do this, place the Obscuration Layer below the particle layer in the timeline. Make sure its 3D switch is checked in the timeline. Then select that layer in the Obscuration pop-up.

Technical notes:

• The Obscuration Layer must have Continuous Rasterize switched off in the timeline layer switches.
• The Obscuration Layer must have 3D enabled in the timeline layer switches.
• Obscuration does not work with semi-transparent layers.
• This obscuration is not anti-aliased, so its effect can look a bit rough on the layer edges. In many cases, this issue doesn't matter because particles are small and move fast.

Before (left) and after (right) enabling Obscuration Layer.