Calculating Normal Map

I'm trying to write a function that calculates a normal map from a bump 
map, and am using 
http://www.w3.org/TR/SVG/filters.html#feDiffuseLighting as a guide.  
Unfortunately, the normal calculation requires me to multiply by the 
function I(x, y), and nowhere defines what function I is.  Any ideas?  
How can I perform the Sobel gradient?  Also, why does the SVG Sobel 
calculation appear so much more complicated than other versions I google?

Mark McKay

Received on Wednesday, 3 May 2006 20:07:27 UTC