For some reason I found that posted image hilarious… this is the only industry where such an image would be accepted as ‘normal’ (no pun intended).
Interesting results… I don’t see much use in DeriveNormalZ if you’re using TC_NormalMap compression unless I’m missing something. Perhaps it is useful if you’re combining lots of normal maps in the material, but just using the R and G channels and getting the overall B channel.