This is
because all the elements in the background image have shadows, but your 3D vase
does not. Shortly, you??™ll learn how to create matching shadows to finish off your
composite. But first, read on to the next section, which takes a different approach
on compositing in LightWave using foreground images.
Foreground Key and Foreground Alpha
In the next exercise, you??™ll learn about the Foreground Key. The Foreground Key is nothing
more than a color-keying system, such as the blue- and green-screen systems used by
TV meteorologists and in visual effects throughout the industry. It works by keying out, or
removing a range of colors that you specify. LightWave gives you two colors: a Low Clip
Color and a High Clip Color.
The Low Clip Color is generally the darkest, most saturated color you would want to
remove from your foreground image. The High Clip Color is the brightest, least saturated
color you??™d want to take out. Any colors between these two colors are removed from the
foreground image before it??™s pasted over the rendering. For Exercise 16.3, you??™ll take out
the sky to reveal a new background. There??™s no Adobe Photoshop involved??”it??™s all done
directly within LightWave.
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