Mastering Naturalistic Lighting

Naturalistic lighting is not dependent on a particular number of lights. Instead, the technique strives to match the lighting of the real world, whatever it might be. Every naturalistic lighting setup is different. Therefore, specific steps for achieving good naturalistic lighting cannot be written in stone. Nevertheless, some general guidelines are appropriate: a

First, identify the strongest source of light and determine its origin. Is the light coming from a recognizable object, such as a lamp? Is the light actually reflected from a floor, wall, or ceiling? If you’re lighting a 3D scene that doesn’t actually exist, think of a location in the real world that is a relatively close match. Once you’ve determined what the source is, place a key light that replicates its quality. For example, sunlight is best replicated with a directional light, a flashlight is best replicated with a spot light, reflected light from a large wall is best replicated with an area light, and so on.

Shadows offer clues to the nature of the light source. For example, if a row of windows is shadowed and the shadows are hard-edged and all in parallel, the source is direct sunlight. If the shadows are fairly distinct but are skewed, the source is an artificial light fairly close by. If shadows are extremely soft and diffuse, the source either is very broad or consists wholly of reflected light. If you are lighting a scene that has a particular time of day or specific interior location, make sure your shadows match accordingly.

(Left) Sunlight creates parallel shadows of windows on a floor. (Middle) An artificial light creates heavily skewed shadows of a fence. (Right) A photographer’s light umbrella creates a broad source of light and thus an extremely soft shadow.

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Maya Lighting

         Light shapes the world by showing us what we see. It creates a sense of depth, it initiates the perception of c olor, and it allows us to distinguish shape and form. For a scene to be successful in CG, these realities of light need to be reproduced as faithfully as possible. The trick is learning to see light and its astonishing effects on the world around us.

Basic Lighting Concepts

It’s no surprise that Maya’s lighting resembles actual direct-lighting techniques used in photography and filmmaking. Lights of various types are placed around a scene to illuminate the subjects as they would for a still life or a portrait. Your scene and what’s init dictate, to some degree at least, which lights you put where. The type of lights you use depends on the desired effect. At the basic level, you want your lights to illuminate the scene. Without lights, your cameras have nothing to capture. Although it seems rather easy to throw your lights in, turn them all on, and render a scene, that couldn’t be further from the truth Lighting is the backbone of CG. Although it’s technically easy to insert and configurelights, it’s ow you light that will make or break your scene. Knowing how to do that eally only comes with a good deal of experience and experimentation, as well as a good ye and some patience.eiques of lighting a scene in Maya

and start you on the road to finding out more.

Learning to See

There are many nuances to the real-world lighting around us that we take for granted. We intuitively understand what we see and how it’s lit, and we infer a tremendous amount of visual information without much consideration. With CG lighting, you must re-create these nuances for your scene. That amounts to all the work of lighting. The most valuable thing you can do to improve your lighting technique is to relearn how you see your environment. Simply put, refuse to take for granted what you see. Question why things look the way they do, and you’ll find that the answers almost always come around to lighting. Take note of the distinction between light and dark in the room you’re in now. Notice the difference in the brightness of highlights and how they dissipate into diffused light and then into shadow. When you start understanding how real light affects objects, you’ll be much better equipped to generate your own light. After all, the key to good lighting starts with the desire to create an interesting image.

What Your Scene Needs

Ideally, your scene needs areas of highlight and shadow. Overlighting a scene flattens everything and diminishes details. This is perhaps the number-one mistake of beginners. Shows a still life with too many bright lights that only flatten the image and remove any sense of color and depth. Similarly, underlighting your scene makes it muddy, gray, and rather lifeless, and it covers your details in darkness and flattens the entire frame. Shows the still life underlit. The bumps and curves of the mesh are hardly noticeable.

Finding a good middle ground to lighting yourscene is key. Like a photographer, you want your image

to have the full range of exposure. You want the richest acks to the brightest whites in your frame to create a

deep sense of detail. Even though you may not have an bsolute black to white in the rendered image, the concept s appealing. As in Figure 10.3, light and shadow omplement each other and work to show the featuresof your surface.

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Edit Connections in Autodesk Maya 2013

The proses of tweaking the various animation curves hat are part of the rig willrequire seleting a lot of nodes that are connected already via a set-driven key but also spread out among the various panels of Autodesk Maya 2013.Autodesk Maya a number of ways to view connected nodes. One of the newest additions to the tool set is the Node Editor , which in some ways, is like the older  Hypergraph but slightly more elegant. As the next few steps demonstrate, you can use this editor to easily select the nodes you have already connected and even get rid of some nodes that have been created along the way  that aren’t really needed.

1.       In the viewport window, choose  Panels c Layout  c Three  Panes Split Top.  Use

the Panel menu  in each pane to set the top-left  viewport to Node  Editor, he top right  view to Persp, and the bottom view to Graph Editor.

2.       In Persp view, select the lightControlHandle so that  it turns  green. In the Node Editor, click the icon for input  and output connectionconnected nodes

3.       Hold  the Alt key while RMB dragging in the Node  Editor  to zoom  in on the node  boxes;  take a look  at the animation curve nodes.  By selecting the anima- tion curve nodes,  you will see the animation curves appear in the Graph Editor

There  are quite  a few animation curve nodes.  Several of them were created  when you used a set-driven key to drive the ramp’s  color  position; as a result,  a few animation curves were added  that  don’t  really improve the scene.

4.       In the Node  Editor, select the node  named  neonLight_colorEntryList_1_colorB, and press the Delete key to remove  it from the scene.

5.       Use the same process  to delete the following nodes.  These are keyframes that have been set on the colors  of the ramp, but you need only animation curves for the position of the ramp  colors,  not the color  values themselves.  Delete the fol- lowing  nodes:

neonLight_colorEntryList_1_colorR neonLight_colorEntryList_1_colorG neonLight_colorEntryList_0_colorR neonLight_colorEntryList_0_colorG neonLight_colorEntryList_0_colorB neonLight_colorEntryList_0_Position

6.       In the Node  Editor, select the neonLight_colorEntryList_1_Position node,  and

Shift+select the motionPath1_uValue node.  You’ll see the animation curves appear on the Graph Editor  below.  Drag  a selection  around both  curves, and press F to focus the view on the curves.

7.       Press the Linear  Tangents button to make  both  curves straight, which  removes the easing in and out of the animation

The animation curves on the graph  indicate how the animation of the attributes is tied to the Translate x values of the lightControlHandle node.  The x axis values correspond to the Translate x value of lightControlHandle, the Y axis values correspond to the values of neonLight_colorEntryList_1_Position and motionPath1_uValue, both  of which  range  between 0 and 1. To make  the anima- tions  a bit more  in sync, you should  edit the curves so that  they match, as in the following steps.

8.       Select the lower  keyframe on the far right,  which  is the starting value of motion- Path1_uValue. Press W to switch  to move mode,  and drag the key upward on the Graph Editor  so that  it matches  the starting point  of neonLight_colorEntryL- ist_1_Position

9.       Play the animation; you should  see that  the position of the locator is more closely aligned  with  the leading  edge of the color  of the ramp  as it moves along the tube.  You can continue to tweak  the position of the keyframes on the Graph Editor  to refine the animation if you like.

10.    Next  you can edit the animation of the emitter  rate.  In the Node  Editor, select the emitter1_rate node.  The animation curve appears on the Graph Editor  at the bottom of the window. Press F to focus on the curve.

The graph  shows  that  the rate starts  at 0 when  the lightControlHandle is all the way on the left. The rate gradually increases  as the lightControlHandle moves to the right.  It would  most likely look  better  if the emitter  started at a higher  rate, increased, and then dropped off sharply  as the lightControlHandle reaches  the right  side.

11.    e the Insert  Key function and the Move  Key function to add keyframes near the front  and the end of the curve. Use the Move  Keyframe  tool to edit the keys on the Graph Editor  so that  they resemble  This doesn’t  have to be an exact  match;  in fact, there  are opportunities to create  variations on the look of the particle  effect through editing  this curve. Just make  sure you keep the start  and end points  at the same place so that  the emitter  is off when  the light- ControlHandle is at either  end of the lightControl.

12.    Rewind and play the animation.

13.    To make  the nParticles behave  more  like sparks, open  the Outliner window, and select the nParticle1 node.  Open  its Attribute Editor  to the nPartcle1Shape tab, and set LifeSpanMode to Random Range.  Set LifeSpan to 0.35  and Lifespan Random to 0.1. This means  the nParticles will live for 0.35*1 seconds  plus or minus  0.1 seconds  (see left image in

14.    Switch to the nucleus1 tab,  and set the Gravity  slider to 1 so that  the nParticles don’t  fall quite  as quickly

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