I like TrekkieMonster's idea about focused laser spotlights... as long as there's a line-of-sight available it should work.
Gosh. I'm honored. Seriously. I'm glad I could add something to the conversation. In thinking about this, and looking at orthos of other versions of the Big E, it does seem to confirm that the outside edges of the saucer extend far enough beyond the nacelles for this idea to work, although it'll be a pretty oblique angle. Still, it seems like it could create a kind of interesting effect with the wash of the light from such an angle. Of course, this same idea should also work for the pennants on the sides of the secondary hull, and at a more customary angle. I'll look forward to seeing how this might play out.
I hope the copper on the deflector returns - that feels like part of the ship's look a swell. I really like how you put the phaser banks on top and bottom of the saucer - finally the ship can fire directly above! Keep up the good work! James
Spotlighting the nacelle registry from the saucer's edge is probably your best option for a "realistic" solution, but it also has its problems. The angle is so oblique that you wind up with a very elongated oval, which is also skewed due to the elevation difference between the saucer and the nacelle. In Max, you can scale a spotlight asymmetrically to "squeeze" it so the oval is not so stretched, but it's still skewed and the result is still less than satisfactory. A way to improve that result is to use a mask texture to "shape" the beam from the spotlight so that it projects onto the nacelle the way you want it to appear. In this case, you would need more of a trapezoidal shape rather than a circle or an oval. This effect can be achieved in the real world with a device called a framing projector, also known as a "gobo," so it should be well within the capabilities of 23rd century lighting technology, even on something the scale of a starship. In software terms, you will find that you need to really crank up the brightness of your light source, especially if you're using a physically-based renderer like Mental Ray where light intensity falls off with the inverse square of the distance traveled. The oblique angle exacerbates this problem. One other issue you might run into: If your hull has any specularity (shininess) at all, there are certain complementary viewing angles from behind the ship where the light on that nacelle registry is going to flare like the sun as you catch the full force of those reflected light rays. Good luck!
I still think the above and below spotlight rows would be best in terms of realism. Having one on either side would be the next best, and if I'm visualizing correctly that might even give it the desired oval shape.
There's always the option of doing it like modern day carriers do. They have the ships registry numbers surrounded with lightbulbs, making them appear to glow at night. I found a couple of images here and here that show the effect well. Here's a closeup of the bulbs. Maybe a more futuristic version of this could look good with the letters themselves being raised above the surface, and the lights being placed behind the letters. The light would spill out from behind the letters onto the surrounding hull, while the letters would be silhouetted.
As far as making the shape "fit," well, it's not all that hard to do pretty much anything you want with the appropriate optics, given that you can "see" the place you're trying to light. Most of what's been discussed here (excepting Vektor's suggestion, above) is really "wrong" insofar as it's assuming a basic, uniform, circular-shaped spot. Instead, think of your light source as a projector, projecting a single image of film onto the surface. Perhaps the area which would be closest to the "projector" is dimmer than the region which is further away. This sort of thing is well within our current capability (custom shaped reflectors and "lens" elements for a light bulb aren't really all that complex). It'll be even easier in the future. You SHOULD be able to do what we're discussing in most rendering software packages out there today, I think. I still think that the lights for the "outside of the nacelles" banners would only be lit during "parade" activities and would normally be dimmed, if they were present at all. Nobody aboard-ship can see them, and their usefulness is pretty much nil except when in close-formation or at a dockyard. But that's not my call, so I'll leave it alone, and just hope that you don't leave them lit at all times.
I'm thinking of trying that very thing on my own version. In fact, that's the main reason I added some thickness to the lettering in the latest renderings.
Lighting the nacelle could come from the 'fins' facing down/forward onto the registry, or the red pinstriping can be raised enough to have lights facing aft and forward onto the number, or, like someone else suggested, have the numbers themselves raised and lit from the edge.
I wish this version of the Enterprise had made it into the movie instead of the one they used. It's a missed opportunity.
For those who are interested, I just posted some examples of a couple of self-illumination schemes in my Modified TOS Enterprise thread, including the back-lit/edge-lit idea. It's not bad, but I think I'm going to wind up liking the traditional method better.
Thanks gents. A return to tradition... Still wanna try out that off the saucer edge spot for the nacelle(s), but came up with this idea on my own. deg
Well that works! I think you nailed it. Looks awesome. What kind of falloff do you have on the light, just out of curiosity?