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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Animate the Effect Using the Custom Rig

The rig is essentially  complete, but for the animation to behave  the way the director wants, you’ll need to fine-tune  the animation curves created  by the set-driven key. This way, the position of the spark  is in line with  the color  of the ramp, and the rate of the spark  emission  is a little more  elegant.

Keep in mind  that  the director will want  to tweak  the look  of the effect quite  a bit; the rig is designed  to reduce  the amount of work  it takes  to change  the animation in the future. The rig takes  a few more  steps to set up, but the payoff  comes later when you have to constantly change  the animation to match  the director’s vision.

1.     shot requires that  the light on the sign start  on frame  320 and end around frame  360.  Set the Time Slider to frame  320.  Move  the lightControlHandle all the way to the left. Hold  the mouse  over the Translate x channel  in the Channel Box; right-click and choose  Key Selected.

2.    Move  the Time Slider to 360,  move the lightControlHandle all the way to the right,  and set a second  keyframe.

3.     Switch to the ShotCam camera  in the viewport. Rewind and play the scene. It’s   a bit lackluster at the moment, so it’s time to do some tweaking.

4.    Switch to Perpective view in the viewport, and zoom in on the sign. Set the Time Slider Range so that it starts at 300 and ends at 380; thisway,you don’t have to sit through whole animation the whole animation every time yaou review it.

5.    It many be bit hard to see the emiter’s position and progression of the red color as it moves along the length of the glass tube. You can make things a bit easier by simply constraining a locator to the Outliner, select spark Emitter, and CTRL+ select locator1. Switch to the Animation menu set, and choose Contrain c Point c Options. In the Outliner,

6.    Scrub along the Timeline. You should see the locator move along the curve. To fis the timing, you can work with the Graph Editor

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Tutorial Autodesk Maya Lighting

Here’s where  the fun begins. To create  the effect of the light traveling along  the length of the neon  tube,  you’ll attach a ramp  to the incandescence channel  of a Blinn shader.

1.     Open  the Hypershade to find the shader  named  neonGlassBlinn. This is a simple

shader  that  has already  been set up to create  the look  of the neon  glass. Select the shader, and MMB  drag it on top of the vacancyNeonGeo in the Perspective view.

2.    In the Hypershade, select the neonGlassBlinn shader, and open  its settings  in the Attribute Editor. Click the checkered box to the right  of the Incandescence chan- nel to open  the Create  Texture Node  panel.

3.    Select the 2D Textures category on the left side of the panel,  and click Ramp  to create  a ramp  node  (see Figure 1.5).  Hold  the mouse  pointer over the Perspective view, and press the 6 hotkey  to switch  to textured view. Make  sure that  the Renderer panel  in the viewport window is set to High  Quality Rendering; otherwise, you won’t  see the ramp  texture update properly as it’s applied  to the geometry.

In Perspective  view, the rainbow pattern of the ramp  appears on the neon  tube, but it is a repeating pattern that  looks  more  festive than  demonic. To fix this, you can adjust  the UVs of the vacancyNeonGeo node.

Figure 1.5   Use the Create Render node panel to attach a ramp                                      texture to the Incandescence channel of the neon-

                                                                                                    GlassBlinn material.

4.     Select the vacancyNeonGeo node,  and choose  Window c UV Texture Editor.

If you zoom  out (waaaaay out),  you’ll see that  the UVs are a long vertical  strip. In the UV Texture Editor’s  menu  panel,  expand the Textures menu,  and select vacancyNeonGeo|blinn2SG|ramp1 so that  the ramp  appears in the UV Texture Editor.

As you can see, the rainbow colors  of the ramp  appear in the upper  quadrant of the UV Texture Editor. What  you don’t  see is that  outside  of this area,  the ramp texture repeats  over and over to infinity,  which  is what  the colors  on the neon tube continually repeat;  the UVs for the tube continue well outside  of that  upper quadrant (see Figure 1.6).

Figure 1.6   The UV Texture Editor shows that the UV texture coordinates of the neon sign geometry go well beyond the upper quadrant of the texture space. The result is that the ramp texture repeats along the length of the glass tube.

5.   Right-click the UVs, and select UV from the marking menu.   Select some of the UV coordinates in the editor  (the selected coordinates will be highlighted in green). Hold  the Ctrl key, right-click again  above  the selected UVs, and choose To Shell from the marking menu.  This selects all of the connected UVs of the glass tube geometry.

6.    From  within  the UV Texture Editor, choose  Polygons  c Normalize. This forces the UVs to fit within  the upper-right quadrant of the UV texture space. Now  the ramp  is no longer  repeating. The UV coordinates will look  fairly dense in the

UV Texture Editor, but in Perspective  view, you’ll see that  the ramp  goes from red to green to blue across  the length  of the sign.

7.   Select the ramp1 node  on the Textures tab of Hypershade, and open  its settings in the Attribute Editor.

8.   Click the x at the top of the ramp  to delete the blue color  at the top of the ramp.         Set the middle  color  to black;  then set Interpolation to None.

9.   Set the bottom color  to a devilish shade  of red.

10.  Try dragging the circle for the black  color  up and down;  you’ll see the light move

      along  the neon  tube (see Figure 1.7).  Name  the ramp  node  neonLight.

Figure 1.7   Move the black color of the ramp up and down; the color updates on the tube geometry in Perspective view.

To make  the sign easier to read,  you can apply  a separate dark  shader  to the parts  of the tube that  connect  the letters.  This replicates the way actual  neon signs are constructed in the real world, adding  an extra  touch  of realism.

11.     Right-click the vacancyNeonGeo geometry in Perspective  view, and choose Face. Carefully select the individual faces connecting the V and the A. Once they are selected,  switch  to the Rendering menu  set, and choose  Lighting/ Shading  c Assign Favorite Material c Lambert. This creates  a new Lambert shader  and applies  it to the selected faces. Do the same for the other  parts  of the sign. Assign the same Lambert shader  to these selected faces (you can use

Lighting/Shading c Assign Existing  Material to do this easily). Figure 1.8 shows the result.

Figure 1.8

12.     Select sparkEmitter in the Outliner. In the Set Driven  Key panel,  click Load

Driven.  lightControlHandle should  still be loaded  as the driver.

13.     Use the Set Driven  Key panel  to keyframe the emitter  so that  when  lightControl- Handle is all the way to the left, the Rate attribute of the emitter  is 0, and when lightControlHandle is all the way to the right,  the emitter’s  Rate attribute is 100. You can use the same technique that  you used in steps 9 and 10 to do this.

14.     This is probably a good  point  at which  to save your  scene file.

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