Putting the Light in LightWave, Part 3(a)

It's been quite a while since the last installment of this series, in which I offered up some tips on faking radiosity to help add a bit of realism while cutting down on render times. But what happens if the opposite is true, and you have a project where setup time needs to be kept to a minimum and render time doesn't matter? In addition to being a beautiful, photorealistic way of rendering scenes in LightWave, radiosity can also serve as a virtual dab of Clearasil by covering up blemishes when budgets are tight.

During my year-long hiatus from the "pages" of this space, I had the chance to work on a lot of different projects, several of which called for 3D animation. But in two of those cases there was almost no budget to speak of, so there had to be shortcuts. That meant modeling, layout, keyframing, surfacing, lighting, everything had to suffer at the hands of the potent force that is a severe lack of dollars. Everything, that is, except rendering. Because render time is enormously cheaper than actual labor (at least for the way I bill projects), I could, in theory, have as much render time as I wanted. If only there was a way to smooth over all the rough edges having no time to actually put the scenes together would introduce. What to do, what to do...

What to do

Instead of trying in vain (and more than likely busting the budget) to light a scene by hand to compensate, why not give radiosity a shot? In theory, two things would be accomplished. One, there's nothing like a few soft shadows to hide ugly spots, and radiosity is renowned for those nice, gentle, realistic shadows. Two, I could effectively bring my time lighting the scene down to zero (as you'll see). Sounds great, right! Oh, it is! But before we set up a simple scene to illustrate, let me take care of some housekeeping real quick. First, if you need a review of what radiosity is, feel free to check out the previous chapter of this series. But here's a sentence swiped from that piece that should bring you up to speed:

(R)adiosity is a type of rendering solution that calculates "how light works" comparably to the way light behaves in the real world, offering extremely photorealistic results when applied correctly. Radiosity rendering bounces all the lights in a scene, even ambient lights, off of every object until the result is the nice, soft graduated lighting you're accustomed to seeing in the world around you.

I'm no physicist, but I think that's pretty much the long and short of it. With that taken care of, let's run through how to enable radiosity in LightWave before we get into our specific setup (which is another element I'll "borrow" from the last installment), and then we'll put the two together next time (hence the "a" in "Part 3(a)").

Digging down

LightWave's radiosity settings are somewhat buried, hidden beneath the Global Illumination button inside the Light Properties panel. To get there, fire up Layout, click the Lights button (in the bottom left of the main Layout window, below the timeline), click the Properties button (two buttons to the right of the Lights button) , and then click Global Illumination once the Light Properties panel opens (fig. 1).

Figure 1

The Global Illumination panel should appear in place of the Light Properties panel, and if you scan down a bit, you'll see the radiosity settings (fig. 2). I've also highlighted the ambient color and intensity portion of the panel in figure 2, but squirrel that little nugget of information away for next time. For the moment, we're going to take a quick spin around the radiosity settings.

Figure 2

For all the complexity behind the very concept of radiosity, one might expect the settings themselves to be a bit more complex. As a fan of simplicity, I'm happy to say LightWave's radiosity settings are pretty easy to figure out, which shouldn't make this part too big of a detour. Using Figure 2 for reference, here's a brief description of the settings:

Enable radiosity. I don't really have to explain this one, do I?

Type. LightWave offers three types or radiosity: Backdrop Only, Monte Carlo, and Interpolated. Backdrop Only offers the least customization, and is pretty much only good for environmental lighting, since it just bounces light off the backdrop (hence the name). Monte Carlo is the default (and should do just fine for most scenes). Interpolated is what amounts to Monte Carlo Plus, as it unlocks the tolerance and spacing settings for tweaking.

Cache Radiosity. This setting calculates radiosity once and then uses it in all the frames of an animation. Therefore, you can save a ton of render time by checking this box, but only if 1) you're rendering out an animation and 2) nothing in the scene moves except for the camera. Unless these two criteria are met, caching does you no good.

Intensity. This slider sets the amount of radiosity to calculate (kind of like how you can specify the intensity of individual lights) and can be animated over time. If you want "the full monty," so to speak, just leave this at 100%.

Rays Per Evaluation. This works just about the same way making a sphere (or ball, as i'ts specifically called) works in Modeler. A sphere's shape is defined by the number of sides and segments it has (at least in LightWave's default "Globe" method of creating a sphere). More of each equals a smoother surface, but at the expense having more polygons in the resulting sphere. The Rays Per Evaluation setting works the same way — you can dial up the resolution of the "virtual hemisphere" LightWave will use to scatter the rays, but at the expense of longer render times. Again, in many cases the default setting of 4x12 will be fine, but if you start to see garbage shadows (like when you don't have a high enough resolution Shadow Map), this setting may need to be increased.

Indirect Bounces. Once light hits an object, how many times do you want it to keep bouncing? Again, a higher number equals a potentially more realistic render, but will take longer to calculate. This setting is only available for Monte Carlo and Interpolated radiosity types.

Tolerance. The lower the tolerance, the more pixels in the image are considered in the solution, and the higher the accuracy. Dial this up to (potentially) reduce render time. This option is only available when the type is set to Interpolated.

Minimum Evaluation Spacing. The concept of evaluation setting is almost identical to the one behind tolerance, but uses scale instead of a fractional calculation. When this is smaller, the rendering is more accurate, but can take longer.

So that's it — not too much to absorb, and, of course, you're encouraged to experiment to come up with the best combo for any given scene. But for our purposes today, we're going to be using the default settings (Monte Carlo, 100% Intensity, 4x12 Rays Per Evaluation, and 1 Indirect Bounce). Ready? Good.

Right quick setup

Remember, the whole idea here is to set things up in as little time as possible, since in our hypothetical situation (as in my real ones) there's no leeway in the budget to do anything else. We're relying on radiosity to be something of a magic bullet, since render time is theoretically limitless. Obviously, the simpler your scene, the less you have to do. In the two projects I've done like this, one was a bus traveling across a map of the United States and one was a set of animated graphs. I spared no expense in modeling for both: the bus consisted of basic box shapes surfaced with photographs of an actual bus, and the charts were downright nutty by comparison, adding cylinders into the mix along with the boxes. Setup time was minimal in each case, so today we're going to keep it simple ourselves by stealing a couple of the "actors" from last time (one purple sphere and one green cube). A third piece, a plane, will serve as the floor. Let's get everything into place.

First, fire up Modeler. With the new, clean workspace you have, immediately hit the s key to save the object, and name it setup.lwo. Now, select the Create tab at the top of the Modeler window, select the Box button (in the Primitives category on the left), and then hit the n key on your keyboard to bring up the numeric entry panel. Enter the settings shown in Figure 3:

Figure 3

Once you've entered in the settings, hit the Space bar to freeze the settings and activate the plane. While we're here, let's name our plane and assign it a surface. Hit F7 to bring up the Layers window, twirl down the arrow next to setup, and double-click on (unnamed) to bring up the Layer Settings panel. Being clever, I named my layer plane; what the heck, why don't you do the same (fig. 4)?

Figure 4

Click the OK button to close the Layer Settings, and then hit F7 again to close the Layers window. Now, to assign a surface. Hit the q key to bring up the Change Surface panel and enter the following (fig. 5):

Figure 5

Click OK, and you should have a 1 km by 1 km white plane. So far, so good. Now, we're going to repeat the steps we took to create the plane to make our cube and sphere. Select layer 2 in the layer bank (that row of diagonally bisected boxes at the top right of the Modeler window), click the Box button, hit n, and enter what you see in the top portion of Figure 6 to create the box. Once that's done, select layer 3, click the Ball button, hit n again, and enter in the numbers from the bottom of Figure 6 to make the sphere.

Figure 6

If all has gone well, you'll have a 1 meter by 1 meter cube on the left and a 1 meter by 1 meter sphere on the right. They're also offset slightly on the Y axis in order to rest on top of the plane we just made (rather than the plane bisecting each in the middle). Now, as you did in the step shown in Figure 4, rename the (unnamed) layers 2 and 3 to cube and sphere, respectively. Once that's done, we're going to surface these objects as we did leading up to (and shown in) Figure 5. Select layer from the layer bank, hit the q key, and enter what you see in the top portion of Figure 7 to surface the cube. Do the same thing for layer 3, this time entering the settings from the bottom of Figure 7.

Figure 7: Remember to check the Smoothing box for the sphere (bottom)!

The last thing we'll do for today is to move things over to Layout. Save the object (just hitting the s key will do it) , and then we'll take the easy road. See that innocuous-looking little triangle at the very top right of the Modeler window (to the right of the layer bank, as circled in the top section of Figure 8)? Pull that down, select Send Object to Layout (fig. 8, bottom), and then Layout should launch itself, create a default scene, and automatically load up the object. As in Modeler, hitting the s key in Layout will compel you to save your scene, so do that now and call it setup.lws.

Figure 8

Now, if your experience was anything like mine, we're talking less than five minutes to go from diddly squat to a few arranged objects, which meshes very well with the whole "there's no time" theme going on here. And with that said, we're at a good stopping point for now. In the next installment, we're going to keyframe the objects to do a simple looping rotation, and then we'll actually get back to the topic at hand by setting up radiosity to handle all our lighting. As a bonus, I promise it won't take another year-and-a-half to get that one out, so we've already got cause to celebrate. Until next time!

Filed under: Tutorial on October 17th, 2005

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