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238 Chapter 18: Effects and Environments
Edge filter applied to rays emanating from object
Peri m(eter ) Alp ha —Applies the Lens Effect only
to the per imeter of an object based on its a lpha
channel. Selecting this option applies the effec t
only on the outside of an object without an y
spill on the interior. Whereas filtering by Edge
produces a spill onto the object, Perimeter Alpha
keeps all of the edges clean because it relies on the
scene alpha channel to derive its effect.
Peri m(eter )—Applies the Lens Effect only to the
perimeter of an object based on Edge interference.
Although not as precise as Perimeter Alpha, you
might n eed to use the Perimeter option at times
when the alpha channel is unavailable.
Bright—Filters the source objects based on their
brightness values. The effect is only applied to
objects with a brightness above the spinner setting
This option can be inverted by clicking the I
button next to the spinner
Hue—Filtersthesourceobjectsbytheirhue.Select
the hue by clicking the color swatch next to the
spinner. You can choose hue values from 0 to 255.
ThespinnerbesidetheHuecolorswatchletsyou
enter a variance level so that the glow can find
several different hues in the same range as the
chosen color
Additional Effects group
Additional Effects allows you to apply maps such
as Noise to your Lens Effect. You can display the
Material/Map browser by clicking the long button
next to the Apply check box.
Apply —Applies the selected map when activated.
Radial Density—Determines where and how much
you would like the additional effects applied.
Clicking the Radial D ensity button displays the
Radial De nsity dialog (page 3–256).Usingthe
Radial Density dialog you can create points on
alineandmovethosepointsalongagraphto
determine wher e the additional effect should be
placed around the light. You can also use a map
to determine where the additional effect should
be placed.
Aut o S eco nda ry Len s E f fect
Rendering menu > Effects > Environment and Effects
dialog > Effects panel > Add > Add Effect dialog > Lens
Effects > Choose Auto Secondar y, and click the (> ) arrow
button.
Adding second ary flares to the light
Secondary flares are the small circles you would
normallyseecomingoutfromthesourceofthe
lens flare along an axis relative to the camera
position. These are c aused by light refracti ng off
the different lens elements in the camera. As the