I know how much you’d love the viewport to work like a real raytracer in real time…but it’s just not going to happen …not for a few more years anyways. So comparing results between a raytracer and lighting effects and trickery is probably never going to look anything close to the same.
That being said, the display uses what is called “Normal Mapping” to achieve the bump effect…which means, it needs a “normal map” to work correctly. Inside Rhino there is a very crude mechanism that attempts to detect whether or not the “bump map” is a normal map…if it thinks it is, it leaves it alone. If it thinks it’s not dealing with a normal map, it converts what it does have into something like a normal map. However, going the other way around makes no sense… You can’t take a normal map and change it to grayscale and expect the correct results… but I digress… What I think you’re seeing then is Rhino taking your normal map that you converted to a grayscale map and converting it back into a normal map again…and obviously the results will not be the same… And I’m pretty sure Neon doesn’t do any of this…it just uses whatever map it’s given as a “bump map” …and it can do that because it’s a raytracer. The display is fixed on using Normal Mapping, and so it does whatever it can to ensure it’s dealing with normals and not different shades of gray.
Ok… with that long winded response… I will try to see why there are black spots showing up…it might be the nature of the normal map itself (I just pulled it from my inventory, not paying attention to what it’s actually supposed to be used for…but its name does indicate that it’s supposed to provide some kind of “sparkle” effect). I will see if I can either find out why this is happening or find a better noise normal map (or both). Also, since bump mapping is a lighting trick, make sure you’re using actual lights in your scene…it will not work with just the environment and Skylight…sorry, it’s just how things work currently.