View Full Version : shadow only object?

07-28-2005, 03:22 PM
I have a character walking on the ground, but I want to render the shadow that's falling on the ground, but not the ground plane itself. For compositing, I want an object that only catches shadows. How do I do this?
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07-28-2005, 04:06 PM
If I'm reading you right, then for your ground surface, select the Advanced tab in the surface editor and switch "Alpha Channel" to Shadow Density.


07-30-2005, 12:53 PM
In addition to the Shadow Alpha setting on the object, I use Front Projection quite a bit for the "ground plane" object. When you have a background sequence / plate, setting its Surface to be a Front-Projection texture and specifying the background sequence / plate as the image will cause LW to move pixels from the background to the object suface in the render.

Be sure to set Mipmap Quality to "OFF" for the background.

Also, I use a home-grown Image Filter plug-in to do the final compositing in situ. It reads the alpha channel produced by LW from the objects and the Shadow Alpha, and moves pixels from the background plate into the final image based upon the alpha value.

If you're interested, the plug-in is attached. The caveat is that the background image size must match your rendering size...I didn't want to mess with stretching/compressing the image.