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Creating a layer map (PB only)


    Layer maps are often created by painting them in an image-editing program such as Adobe Photoshop, although you can use any program that can save an image compatible with After Effects. The key to creating a good layer map is to remember that the brightness value of each pixel influences an effect property. Here are some hints and tips for creating layer maps:

    • If you want a layer map to match the shape of an image that already exists, simply use that image. For best results, create a layer map that has the same dimensions as the layer containing the image.
    • You can create a layer map by precomposing a white solid layer, a black solid layer, and a mask on the top layer that determines which areas are white and black. Increasing the mask's Mask Feather property softens the transition between black and white values.
    • In Photoshop, an easy way to create a layer map is to create a layer with a black or white background, draw a selection, and fill the selection with the opposite color. Blurring the entire layer softens the transition between black and white values.
    • You can set layer map values more precisely by painting shades of gray within a range from 0 (black) to 255 (white). This is the tonal range of an 8-bit channel. To simplify painting or drawing, see if your painting or drawing program provides or allows you to create a palette of 256 gray shades.

    Note: While images created for use as displacement maps (in other effects or programs) often map tones to values on a scale from -127 to +127, Particle Playground interprets tones of gray as values on a scale from 0.0 (black) to 1.0 (white). If you're using images created as displacement maps, use the Min and Max properties to modify the range of tones produced by the layer map. See Using Min and Max options to adjust the output range of a layer map (PB only).

    • The alpha channel in a layer map modifies the value before it's applied to the destination layer. Areas where the alpha channel is completely off (transparent areas of a layer map) have no effect on particle values. Areas where the alpha channel has a partial value (semitransparent areas of a layer map) partially affect the particle value. For example, if a layer-map pixel has a value of 10 and the layer-map alpha channel has a value of 127 (50%), the layer-map pixel is affected by 50% and its true value is 5. When you use the Persistent and Ephemeral Property Mappers, the actual value applied to a particle is also affected by the range set for the Min and Max options; see Using Min and Max options to adjust the output range of a layer map (PB only).
    • If you want to change any of the layer map's layer properties (Masks, Effects, or Transform), change them, precompose the layer, and then use the resulting composition as the layer map. Otherwise, Particle Playground ignores any property settings.
    • The contrast between adjacent pixel values determines how smoothly the values change across the surface of the layer map. To create smooth changes, paint using a soft or anti-aliased brush, or apply gradients. To create abrupt changes, avoid intermediate shades, using just a few widely spaced shades such as 50% gray, black, and white.
    • You can adjust overall edge contrast with blur or sharpen filters, if your painting or drawing program provides them.

    Note: If you want to edit individual pixels, open the layer map in the program you used to create it and make the change.