TUTORIAL May 8, 2000
Light Up Your Life With Light Galleries
by Michele Bousquet
In a world crowded with competing Discreet 3D Studio MAX (www.discreet.com) plug-ins, it's refreshing to find one that boldly ventures into uncharted territory. Light Galleries, a new plug-in from Mitsubishi Electronic Research Labs (MERL, www.merl.com), is the first to tackle a fundamental problem encountered by every 3D artist: how to get the best lighting for a scene in the minimum time.
In the quest for great lighting, the artist must often render, adjust lights, render again, adjust again, on and on for what can be days or weeks, especially if the scene is complex. Light Galleries (LG) is designed to do the adjusting and rendering on its own, leaving you free to take a break or work on other projects. The plug-in tries out every possible lighting combination and renders a thumbnail for each one. From a set of thumbnails rendered over a few hours or overnight, you can get exactly the lighting you want. When the thumbnails are complete, it takes only a few minutes to choose the best one, or to mix and match to get your ideal light setup. Light Galleries then places the lights for you according to your choices, literally in half a second.
Like most well-designed plug-ins, LG's default settings work for most scenes, while its advanced features can be used to fine-tune the action.
LG is accessed from the 3D Studio MAX Utilities panel. Once the plug-in is loaded, click New to start a new LG project for the current scene. The Light Galleries window appears. Here you can set the amount of time to create thumbnails, using preset selections from one minute to 12 hours. The desired number of thumbnails is also set here, ranging from 10 to 500.
By default, thumbnails will be generated for all lights in the scene, with as many variations as possible in the time allotted. At this point, it's just a matter of clicking the big Go button on the Light Galleries window. LG will start doing its thing while you go home or get busy with something else. When your thumbnails are done, you can start on the compositing step.
Click the Viewer and Compositor buttons to open the similarly named windows. The thumbnails are displayed in the Viewer window. Scroll around to find thumbnails that have desirable lighting elements, and drag them to the Compositor window. In the Compositor, take a look at the composite image that has been generated. Click and drag up or down on any thumbnail image to increase or decrease the intensity of the light in the composite image.
Now for the magic part: When the composite image looks exactly the way you want your rendered image to look, click on Create These Lights. The lights that will produce this image are placed in your scene. Render the scene, and the final image will look identical to the thumbnail composite.
What's Going on Back There?
When you click Go, Light Galleries goes to work. The first order of business for the plug-in is generating a variations list. This list contains a description of each light configuration that will be rendered as a thumbnail. LG starts this process by looking at the Vary a Little/Vary a Lot slider for each active light to see how far to go with each variation.
LG then makes a single pass, using a random-number generator to get a series of variations. Each variation is added to the list until the total number specified is reached. Along the way, LG renders a few thumbnails and records the time needed to render one. LG calculates how much time will be needed to render the number of thumbnails requested. Ideally, there's extra time available during the render time, which LG will spend making the variations list better. LG continues generating random variations, comparing each one to those already on the list to see if it contributes more to the diversity of the thumbnail selections. If the variation does, it replaces another variation on the list. LG continues in this fashion in the available time.
Light Galleries then turns its attention to rendering thumbnails. There's nothing special about this process; LG simply goes through the variations list and renders the ones that didn't get rendered during the first phase, which is usually the majority of the thumbnails.
Asking for a particular number of thumbnails is no guarantee that they'll all get rendered. LG uses 3D Studio MAX's standard renderer to produce the thumbnails at the resolution set on the Light Galleries window. LG won't alert you if you've chosen a ridiculous quantity/time ratio for the thumbnailsit's up to you to make sure it has enough time to give you what you asked for.
In addition, LG needs a certain amount of time to create the list of light variations to be used in the thumbnails. Plan to allow two to five times the total amount of time needed to render the thumbnails themselves. This provides LG enough time to generate a large number of light configurations and to choose the ones that give you the widest variety of lighting setups. On my test scene, I got about 25 renderings for an hour's computation, which gave me the basic lighting setup. I then used the lights generated from that pass to do an overnight pass with subtle variations, and got the lights perfectly placed.
An Inside Look at Thumbnails
Each thumbnail shows the effect of one light, and each thumbnail used in the Compositor window generates a light in the scene. The light's intensities aren't varied during thumbnail creation. When you drag up or down on a thumbnail in the Compositor window, you're actually increasing or decreasing the intensity of the light interactively. The light color and intensity are displayed in a color swatch at the bottom left of the Compositor window. You have the option of clicking on the swatch to display the familiar Color Selector dialog, which can be used to change the RGB values directly.
Light Galleries uses some of the light's attributes when calculating variations, but not all of them. Only the hotspot, falloff, and position of lights and targets are varied, while parameters such as Attenuation or the shadow Size, Sample Range, and Bias are not.
When rendering thumbnails, however, LG will use most of these parameters in whatever state they were in. When you click Go!, shadows are rendered, as attenuation, projectors, and volume lights. Any hue to the light color is kept intact for thumbnails.
The only limitation that might put some users off is the lack of support for instanced lights. In the thumbnail creation process, each instanced light is treated separately, as if it were a copy. MERL representatives say that this feature will probably be added in the next version of LG.
LG has a few advanced features, such as allowing you to turn off intermittent creation of thumbnails during the variation phase for faster processing. You also have the option of editing the underlying MAXScript to customize the application.
For $99, who can resist Light Galleries? It's quick, it's solid, and it has cut my production time by 50 percent in a few situations where the lighting was critical but the time just wasn't there. Light Galleries will be especially useful to new users who know how they want the scene to look, but lack experience in placing lights. MERL is going for the market in a big way with this one (see sidebar), and I'll bet they get it.
Available from Digimation, www.maxhelp.com/lightgalleries
Michele Bousquet is an author, instructor, and writer on all things 3D Studio MAX. Her latest work is Harnessing 3D Studio MAX R3 (Autodesk Press, 2000)