I want to gain a proper understanding of filter and transmit in layered
textures.

From the description, this is what I understand Transmit to mean.  Is this
correct?
    Picture an opaque powder sprinkled on the underlying surface.  Look
under a microscope and you'll see areas of powder and areas clear where the
undersurface shows through.  The Transmit value is the percentage of area
that the powder doesn't cover.  Mathematically, the total color is the
powder's (upper layer) color times the complement of its Transmit value,
plus the Transmit value times the color of what lies underneith.  Or is the
upper layer not multiplied by 1-Transmit?  I'd like to know details of what
POV actually does, so I can understand (and write a tutorial to share) how
this affects gamma correction and chromatisity issues in general.

As for Transmit, I don't have a clear mental model of what it does,
mathematically.  Can someone shed light on this please?

--John

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Date: 
	Tue, 16 Feb 1999 00:37:37 +0100
From: 
	Marc Schimmler <mar### [at] icauni-stuttgartde>
Newsgroups: 
	povray.general
Subject: 
	transparency gradient?
Look into that thread, I made a demo for it that pretty clearly describs the
transmit versus filter values. 



-- 
//Spider 
( spi### [at] bahnhofse ) [ http://www.bahnhof.se/~spider/ ]
#declare life = rand(seed(42))*sqrt(-1);

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