art licensing question

Hopefully there are some US copyright lawyers around here ;-). I want to 
create an SVG that looks like a giraffe's patterning. Now, lets say my 
art skills suck, and the only possible way I can do this is to trace 
(NOT automated; by hand) a small section of a (presumably copyrighted 
under a restrictive license) photo of a giraffe. Given that what I'm 
tracing has the originality of tossing a giraffe pelt (which itself 
cannot be copyrighted) on a scanner (and therefore, may not qualify for 
copyright), is this OK? At what point is a photo of a non-copyrightable 
object sufficiently original to be copyrighted? Is the choice of *what* 
giraffe to photograph sufficiently "original"? (And yes, I know, the 
Best Thing To Do is to find my own giraffe to photograph, however let's 
assume that's not an option, or maybe that I'm in love with the marking 
on a particular giraffe in such a photo ;-).)

(The above is actually a real example, though one of more immediate 
concern involves a slab of granite. Again, AFAIK a slab of granite is 
not copyrightable; if I have a picture that is effectively a scan of 
said slab, is that picture subject to copyright?)

-- 
Matthew
Anonymous: I want the following [software] features:
Rex Dieter: ...and a pony. Can't forget the pony. (Ones with frickin' 
laser beams a bonus.)