Putting the Light in LightWave, Part 3(b)

When we left off, we had just gotten our simple setup moved over to Layout. Today, we have just a couple of chores left to do before our scene is ready to light, and then we'll get to the much-delayed promise of setting up radiosity to help hide the fact that the scene is so gawdawful in the first place. Let's dive right back in, shall we?

Note — previous installments of this series are available from the following links:

Part 1: 3D lighting basics
Part 2: How to fake radiosity for fun and profit
Part 3(a): After faking radiosity, why not do it for real?

Fire up Layout, and open up the setup.lws scene we saved last time. Now, the first thing we have to do is to drastically dial down the grid size. If you recall, our floor plane is 1km by 1km, with the sphere and box at a mere 1m by 1m apiece, so the camera and light in our scene appear comically large. If you look on the very bottom left of the Layout window, you'll see that the grid size is a gi-normous 500m. To make this smaller, tap the [ (left bracket) key repeatedly until the grid size is down to 1m. This should make the light and camera more proportional to the sphere and cube objects, and the plane will now be the only humongous item in the scene as nature intended.

The next thing we need to do is move the camera and the default light into position. This is a relatively simple step, so I'll just give you the position and rotation settings for each. The buttons in question in Layout's interface are Move and Rotate, both of which are found under the Modify tab. Click on the light or camera (or click on the Lights or Cameras button underneath the frame slider) to select, enter in the numbers, and you'll be set. Figure 1 will hopefully sort everything out for you.

Figure 1: The buttons you'll be needing (left), and the settings to position the camera (center) and the default light (right).

Once that's all done, your Layout window should look something like Figure 2.

Figure 2

And with that, our setup is complete. Exciting stuff, to be sure. However, with the steps we took last time combined with today's efforts, we're in the ten minute range from scratch to setup. Again, since the scenario is that we have no time to really do anything, the total time involved falls into the "good" category. Now, I suppose I should return to the subject mentioned in the title of this series and talk about lighting, and see if we can't gussy this thing up using radiosity.

Let there be no light

Before we start fiddling with the lights, let's take a quick snapshot to see just how far we have to go. Hit F9 on your keyboard to do a basic render of the scene we have so far (fig. 3).

Figure 3

In a word, ick. We definitely have some work to do, but I suspect radiosity is going to help us tremendously, or else I've really painted myself into a corner. Anyway, if you recall from earlier installments, radiosity is an additive solution—the same way a tiny bit of light in the morning from outside can light an entire room (at least enough to make everything out), the mantra of radiosity is that a little goes a long way. Therefore, you're not going to get great results using radiosity if you have a zillion lights in your scene, each cranked up to 100-plus percent intensity. Come to think of it, you're probably not going to get great results lighting regular scenes that way, but that's beside the point. The point is that very few lights are required to get good results, and the ones that you do decide to place in a scene can be used sparingly (read: low intensity). In fact, you can sometimes get away with using no lights at all, and as someone who will endure great hardship to avoid an honest day's work, that sounds great to me. So as strange as this may seem, the first thing we need to do to light the scene is to turn off all the lights.

Go ahead and select the only light in the scene (either by clicking directly on it or by clicking the Lights button at the bottom of the Layout window) and then press p to bring up the Light Properties panel. Drag the Light Intensity slider down to 0 to turn off the light (we can't delete it outright since LightWave requires at least one light in every scene — I suppose this is because without that restriction, the product would only be known as Wave). Then click the Global Illumination button and turn the Ambient Intensity down to 0 as well. Figure 4 illustrates these steps.

Figure 4

You may have noticed after this step that the main viewport is now, to put it mildly, a little dark. LightWave's OpenGL previewing is great and all, but it's not tremendously helpful when there's no light in the scene. To rectify what amounts to the cover of Smell the Glove going on here, I would advise setting the rendering style of the viewport to either Wireframe or Front Face Wireframe (fig. 5) so you can at least see the outlines of the objects again.

Figure 5

Now, let's see what we can do about all this blackness. Time to turn on radiosity. If you happened to leave the Global Illumination panel active, you're all set. If not, you'll need to select the light, hit p, and then click Global Illumination again. Activate radiosity by (shockingly) clicking the Enable Radiosity button, and leave all the settings at the default. If you need a refresher as to what all these settings do, check out part 3(a) of this series through the handy-dandy link at the beginning of this article. That should be it, right? Let's hit F9 and see radiosity in all its glory (fig. 6)

Figure 6

Uhh..OK. Do not adjust your set; that is indeed an image of complete blackness. Just what in the name of all that is good and holy is going on here? The answer lies in the backdrop color of the scene. By default, LightWave sets the backdrop color to black. Since there is no light in the scene, radiosity is trying to calculate light from the only source it can find, which in this case is the backdrop color. And since that "light source" is also black, well, you get the idea. So let's fix that. At the top left of the Layout window, pull down the Window menu and select Backdrop Options. This will bring up the Backdrop portion of the Effects panel. Set the Backdrop Color to pure white (fig. 7), and then close the panel.

Figure 7

Now, hit F9 again to do a quick render, and you'll get what you see in Figure 8.

Figure 8

That's already a hundred times better than the initial render shown back in Figure 3 (not to mention infinitely better than Figure 6), but we have the problem of jaggies. This is easily remedied, however, by switching on Antialiasing in the Camera Properties panel. You can crank this way up, but remember, it will look smoother at the expense of render time. I've found that the Classic, Low setting works well with simple scenes like this. It's a 5-pass method, but it only does the edges so it won't be too bad. After enabling Antialiasing, we're left with Figure 9.

Figure 9

Antialiasing not only clears up the jaggies on the objects, but also alleviated much of the other issue, which is the pixilated nature of the shadows underneath the objects. In Figure 8, the shadows are a little rough. Antialiasing smooths these out a great deal. That, combined with bumping up the Rays Per Evaluation in the radiosity setting (again, covered in part 3a) should rid you of these types of problems completely. Remember that the higher you set any of this stuff, the longer it will take to render. As it so often is, experimentation is the order of the day.

What's next

Speaking of experimentation, I hereby turn you loose to try things out. You could implement a classic 3-point lighting setup (as talked about in part 2) and get results like Figure 10.

Figure 10

You could also bump up either the ambient intensity or the intensity of the default light to get different results. Play with the background color. Try it with a background image as your backdrop instead of a solid color. Knock yourself out, but please, not literally. The idea is that radiosity can make up for other deficiencies in your scene if you don't have the budget to do anything better, and with a total setup time bordering on fifteen minutes, I say it works pretty well. Heck, since radiosity can cut lighting time to effectively nothing in certain cases, it can be put to good use even in scenes where you don't have to hurry. Experiment, have fun, but watch out for those render times — some of 'em can be doozies. Enjoy!

Filed under: Tutorial on October 24th, 2005

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