Putting the Light in LightWave, Part 1

3D lighting, and "real world" lighting for that matter, is a lot like hair. Good hair can radically enhance even the plainest of faces, while a mullet (for example) tends to uglify those who might otherwise be "purty" (as some are wont to say in my neck of the woods). By the same token, good 3D lighting can make even the simplest scene beautiful, while bad 3D lighting can turn your meticulously crafted objects, pixel-perfect surfacing, and butter-smooth keyframing into a flat, uninteresting mess. But, as we'll see during the course of this series, it really doesn't take a lot to get into that good 3D lighting frame of mind. So let's start the ball rolling by going over what the art of the possible is with LightWave's lights.

Now, what I may have mentioned once or twice in my intro to character animation series I did a while back will still hold true here: I'll be using NewTek LightWave as my 3D package. But, as usual, much of the stuff we'll be going over isn't at all unique to LightWave, and probably will translate just fine to whatever 3D package you happen to be using.

The basics

Back in the day ("the day" being mid-1998, which is when I switched to LightWave as my main 3D package), LightWave 5.5 was the latest and greatest version, and lighting was all over the proverbial map. Sure, there was a lot there, but good portions of what could today be considered core lighting functionality for any 3D package were spread out between various panels and augmented by plug-ins, making for a muddled environment in which to try and light your scenes. LightWave 6 came along a while later and changed things, and now pretty much all lighting control is handled through a single, unified property panel (fig. 1). I say "unified" because both individual and global lighting properties are accessible from one panel, even though it requires an additional click to spawn the global light properties (fig. 2). If you have more than one light (which is a good idea for many projects, as we'll see in just a moment), you can also change the selected light through a drop-down menu without leaving the panel. Unfortunately, you still can't add or clone lights through the panel, which would be a good feature to have, but it's not all that hard to go into the Add menu and create new lights or clone existing ones (fig. 3).

Figure 1: LightWave's Light Properties panel.

Figure 2: The accompanying Global Illumination panel.

Figure 3: You can't add or clone lights through the Properties panel; alas, you have to use the standard Add menu.

OK, so that's the "where." What about the "what?" I'm not big on passing along generic info that is usually contained in a shipping product's manual, so I'll just list a couple salient points about LightWave's lights. First, you can set your lights to any number of light types, including distant lights (think sunlight), spotlights, point lights (think light bulbs), linear lights (think long fluorescent tube lights), or area lights (a special type of distant light). Of course, you can change the color and intensity of the lights (and animate them over time), have them cast shadows, give them lens flares, add special lighting effects like lens flares and volumetrics, and render realistically with features like caustics and radiosity. With all of those options, the sky's the limit. You can pretty closely emulate "real" lighting, from outdoor scenes to studio shots, or go for the stuff that might be a little harder to capture live, like laser beams and explosions. We'll get into all of this stuff.

A simple setup

I've seen a lot of aspiring animators' work over the years, and the one thing I see way more than I should is that some folks simply haven't bothered to use any light other than the single default light most 3D programs give you in a new scene. Multiple lights are the spice of life, and if you've done any prior research into lighting for either 3D or the real world, you've doubtless come across some sort of discussion on three-point lighting. In a nutshell, you've got one main light, called the key light, which will provide most of the light in the scene. Then you've got the fill light, which generally is softer than the key light and placed on the opposite side as the key light. Then you've got the back light, which is soft like the fill light and generally adds some depth between your subject and the background.

Figure 4 shows a render of a very simple three-point lighting setup. It's just a yellow plane and a white sphere (the stuff from which countless bad demo reels are made), with the key light coming in from the left, the fill light coming in from the right, and a back light coming in from the -- you guessed it -- back. Pretty basic, but pretty important as well. Usually, I'll start with this base three-point lighting setup on all of my projects, and then move the lights around, adjust the intensity and color, add lights, subtract lights, change light types, etc. until the look I want comes out. A lot of times I'll also add a null object to the scene and parent all the lights to that, so I have a single "handle" to move all the lights in the scene at once, or do a quick rotation of the null to tweak how the lights collectively fall. The bottom line is that while three-point lighting originated in the real world, the concept is invaluable in the virtual one. Starting out with some variation of a three-point setup as the foundation of your overall lighting scheme and working up from there is an extraordinarily simple but very healthy habit to adopt in your 3D scenes.

Figure 4: A pretty basic three-point lighting setup.

The last thing I'll mention here is that there are countless lighting guides for the film and television industry available, and even though most weren't really written with 3D lighting in mind, they're nonetheless great resources for how to approach lighting your 3D scene. Personally, I recommend Film Lighting by Kris Malkiewicz. Even though the copy I have is quite dated, it's a great resource because it combines a nice set of reference material with interviews with various cinematographers and gaffers, ultimately presenting a good mix of the theoretical and the practical. Anyway, there are countless other guides as well; any number of which could prove extremely useful as you start to think more and more about 3D lighting. And in these days of in-house coffee shops and comfy lounge chairs at most book store chains, an afternoon of browsing might very well be a worthwhile activity.

Start real, get unreal

Keep in mind that while many parts of a 3D animation package have concepts firmly rooted in the real world, you're quite able to do things that defy these real-world concepts, and lighting is definitely no exception. I feel one of my world-famous bullet point roundup list coming on:

Negative lighting. In LightWave, you can set the intensity of a light to a negative number, in effect, "sucking" light away from a scene and creating reverse shadows (fig. 5). This also works great with colored lights to remove a certain color from a scene in strategic spots.

Figure 5: The fill light has been set to a negative intensity, effectively subtracting light from the scene.

Projection images. You can designate an image to serve as a gel that the light gets passed through (fig. 6). This effect, of course, mimics real-world lighting tricks, but the twist here is that you can also use this effect with image sequences (or QuickTime movies), as well as use grayscale or color images as your gel.

Figure 6: Projection images can add some ambiance to your lighting setup.

Animated color and intensity. Adding an envelope to light color and intensity can be useful in a lot of situations, from disco lighting to explosions

Unreal shadows. Want to get away from "normal" shadows? Change the color (fig. 7) or use LightWave's Shadow Map feature to soften the edges.

Figure 7: Red shadows to the left, green shadows to the right. You're not stuck with basic black.

Selective application. If you don't like the way a certain light falls on a certain object, you can instruct the light to ignore the object or the object to ignore the light (fig. 8), which would be very hard to pull off in the real world. You can also set a variety of shadow options on an object-by-object basis (fig. 9).

Figure 8: Whether you use the Object panel (top left) or the Light panel (top right), you can instruct items in your scene to ignore other items. In this case, the lights are all affecting the ground plane but the fill and back lights are ignoring the sphere.

Figure 9: You're in control over whether or how each object casts and receives shadows.

Realistic results

Regardless of whether you're going for real or unreal with your lighting, LightWave has some extras that can add some very nice touches to the final product. Before I launch yet again into another bullet point list of said features, it's worth noting that with the exception of lens flares, these can add significantly to rendering time:

Lens flares. Perfect for sunlight, candlelight, or explosions, lens flares can be attached to any light and pack a bunch of options (fig. 10).

Figure 10: A lens flare (and the lens flare control panel) in action.

Volumetric lighting. This is light that you can actually see, rather than just see the effects of (fig. 11). Flashlights, headlights, you get the idea. You can also add texture to the light beams, meaning that you can simulate fog underneath a streetlamp, for example.

Figure 11: Volumetric lighting at work. Notice how the underside of the sphere "cuts" into the beam of light.

Radiosity. Rather than being something you apply directly to lights, radiosity is a rendering solution that calculates how the light in a scene diffuses, or, in effect, bounces, off of the objects in the scene. Ultimately, you get that softer, diffused lighting that occurs in the real world. Radiosity rendering can dramatically add to the realism of your scene, but at a price -- it typically takes waaaaayyyy longer to render a scene with radiosity turned on. Figure 12 shows the setup as originally seen in Figure 4 rendered with radiosity turned on. There's an unseen, luminous half-dome over the entire scene that helps contain all the light, so it all gets bounced back on the stage. The fact that it's luminous means that it actually adds ambient light to the scene when radiosity is applied, so as a result, I've turned the intensity of each light in the scene down by 50%, and set the ambient light to 0%. But, when compared to Figure 4, the interplay of the light across the sphere is much more realistic and really integrates the sphere in with the plane in a realistic way.

Figure 12: The basic three-point lighting setup optimized for and rendered with radiosity.

Caustics. Caustics, like radiosity, is a rendering choice that mainly affects transparent surfaces. You know that distinctively watery pattern you see at the bottom of a swimming pool, or the distortion of the light passing through a glass object? That's caustics in action. Figure 13 shows that our usual white sphere has been replaced with a glass one, and has been rendered with caustics on. Notice the distortion in the shadows where the light has passed through the glass sphere. Them's good caustics!

Figure 13: Caustics give you those realistic distorted light interactions with transparent objects.

I can't emphasize enough that radiosity and caustics (but especially radiosity) really, really, really, really, really, REALLY add dramatically to your rendering times. The best advice I can give, especially if you're planning on animating your scene (read: more than a single frame), is plan to not use either unless you just can't get the look you want otherwise. There are plenty of things you can do short of turning these rendering options on, which I'll get into in a later article in this series.

In conclusion...

Well, let's see now. We've learned how LightWave controls its lights, where the light properties panel lives, the advantages of starting with three-point lighting in your scene, and some of the realistic and hyper-realistic things you can do with your lights. You've also hopefully gotten a sense of just what's possible with lights in your 3D scene, which is probably the most important aspect of all of this. Lastly, and no less crucially, you've been reminded of how horrible mullets are. Looking ahead, many of the things I've mentioned so far will get their own article as this series unfolds, so stay tuned!

Filed under: Tutorial on November 12th, 2003

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