This is a screenshot of Javier’s new version of the X-15 for X-Plane 10. In this case I have hacked the rendering engine to show the specular channel* (the alpha channel) of Javier’s normal map as the texture of the airplane. In other words, that is the per pixel shininess that Javier “drew into” the normal map. there isn’t any lighting on the airplane; the bright edges are simply parts of the plane that are completely glossy.
Just look at how gnarly and detailed and full of goo it is! When you look at the plane under normal lighting conditions you simply see the regular texture. But when the sun reflects off of the plane, the reflection is messed up by this complex specularity pattern. The fact that the sun reflections change unpredictably and dynamically is what sells the illusion.
I mention this because normal maps are expensive – they aren’t compressed and can chew up 4 or 16 MB of VRAM easily – they have to be at high resolution to get the subtle bump details. As long as you’re going to have the resolution, make use of it by putting “texture” into the specular channel – it’ll make your materials seem a lot more complex.
X-Plane 10: X-Plane 10 will allow you to use a gray-scale PNG as a specular-only image, for this kind of “texture” at 1/4 of the VRAM cost, in case you don’t need the actual bump mapping.
* 3-d nerd: X-Plane’s terminology is different from what you’d see in a typical 3-d modeler materials editor. What we call “shininess” is the specular level – that is, how bright specular hilights appear to be. In a 3-d editor this is usually an RGB color, but X-Plane only gives you a single level control; the specular hilights take on the tint of the sun instead.
The “shininess ratio” or “specular exponent” you’d see in a 3-d editor isn’t available in X-Plane – it is set to a fixed exponent by the sim. The unconventional names is a historical artifact.