Photon Paint: The Art of Lighting

Lighting Basics

"What good are computers? They can only give you answers." - Pablo Picasso

Picasso's quote suggests that the ability to ask questions is the important thing, not the answers. Indeed, it is our curiosity and ability to form relevant questions that elevates us above the mighty digital tools at our disposal. The important question is, "Light we must, but what kind of lighting?"

At the end of this chapter, you'll have completed the lighting, materials, animation, layer rendering, and compositing for Sc-01—your first complete scene for Area51.avi. This section, "Lighting Basics," focuses on helping you understand the different kinds of lights in max and how each one can be used in your scenes. You'll also learn how to adjust the parameters controlling the attributes common to all lighting, such as color, shadow casting, and so on.

Up to this point, you have created three max files: Area51_Animatic.max, Sc-01.max, and Sc-01_Clouds.max. You'll be accessing all three files to finish the scene.

Start by opening Sc-01.max. This file contains the cooling tower models and the camera that you created in Chapter 3, "Giving Form to Feeling: The Art of Modeling." When max opens, click the Create command panel and select the Lights icon . 3ds max 4 provides three standard types of lights to work with. Two of them, Spot and Direct, also have a target version (see Figure 5.2).

Figure 5.2 The basic light types in max have unique capabilities and lighting effects modeled after their real-world counterparts.

Until you create your first light in a scene, max uses an invisible default lighting system to temporarily illuminate your models. Max's default lighting is the equivalent of one or two omni lights set in front and to the left of the scene and behind and to the right of your objects in the workspace. These omni lights turn off when you create your first light in max, so they won't interfere with your lighting process.

Although each standard type of light in max has its own unique properties and effect, they share some common attributes and controls. An understanding of which light to use and when to use it will come as you experiment with each type of light. The following section provides an overview of max lights and some generalized rules of thumb to guide how they are used in your scenes.

Direct, Omni, Spot: Which One to Use?

Sc-01 takes place outside. Its key light source is the sun, which sits low on the horizon shining through the ominous clouds roiling overhead. Because the sun is shining through the clouds, its light isn't constantly illuminating the cooling tower, and the shadows cast by the clouds can be seen moving across the front face of the tower. In consideration of these factors, a Target Direct Light was chosen as the light source in this scene.

Direct Lights: Coherent Light

I use direct lights almost exclusively for simulation of any type of outside light source, including sunlight and moonlight. The light rays from a direct light source are coherent, meaning they travel in the same direction parallel to each other. This simulates the way light rays from an extremely large and distant light source, such as the moon or sun, travel and illuminate the objects in their paths (see Figure 5.3).

Figure 5.3 A direct light can also be used to create the light from laser beams and powerful focused flashlights and spotlights.

Omni Lights: Incoherent Light

The light from an omni light is incoherent and radiates spherically in all directions. The light from a normal light bulb is a good example of an omni light application and incoherent light. I use omni lights mostly as fill lights—they are especially good at creating the kind of fake radiosity and soft, glowing ambient light needed to simulate night shots. The shot created in 3D Studio MAX 3.0 Workshop used 17 omni lights at one point to achieve the correct radiosity (see Figure 5.4 and Figure CP.12 in the color section).

Figure 5.4 Use omni lights as fill lights and to help simulate radiosity and ambient light in your scene.

Spotlights: Coherent Incoherency

Spotlights work well for simulating artificial lighting such as street lamps, work lights, vehicle headlights, and so on. Spotlights are used for interior lighting in most cases and also in conjunction with omni lights to achieve the appearance of radiosity.

The light rays from a spotlight are emitted in a cone-shaped pattern. The light rays aren't parallel but they are semicoherent—contained within the cone angle of the light specified in the lighting falloff parameters (see Figure 5.5).

Whatever lights you choose to use, give yourself time to experiment, and when you have found a combination that works, refine it and see whether you can achieve the same effect with fewer lights. Sometimes that is impossible and, fortunately for those of us who love lights, max doesn't limit the number of lights you can use in your scene.

Figure 5.5 Use spotlights to create the light from artificial light sources.

Ambient Light: Global Illumination

Ambient light is another type of lighting effect that is an important element for achieving the effect of radiosity in your scenes.

Creating the appearance of radiosity in your lighting requires that you simulate how an object's reflected light illuminates other objects in the environment. Ambient light can be thought of as the sum total of all that reflected light bouncing around your scene. The lighter or more reflective a surface is, the more light energy it contributes to the total ambient light in your shot. Ambient light uniformly illuminates an environment; you can't tell where it's coming from, and it doesn't have an identifiable direction. There are two specific ways to add ambient light into your scene. You can add more lights into the environment or you can use the max global ambient light setting, which is turned off by default in max4.

I prefer to use additional lights to create ambient radiosity and rarely use the global ambient light setting in max. However, it does work well when trying to create the diffused light effects seen in mist or fog in broad daylight, such as the foggy morning shown in Figure 5.6. Ambient light also works well when trying to create special effects, such as a flash of lightning that washes out the scene with an arc of bright white illumination. Think of using the ambient setting for experimental and special effects, and keep it turned off completely when you begin lighting in max (see Figure CP.13 in the color section).

Figure 5.6 Ambient light is created when light is reflected and scattered uniformly by the fog in this environment. The ambient light bouncing around an environment is the reason shadows are not really black and the ground shadows on a bright snowy morning are deep blue.

Start in the Dark

A watercolorist begins the painting process by preserving and using the white of the paper and then painting with transparent color washes, building layer upon layer to create increasingly darker areas of the composition; in other words, the artist paints light to dark.

Lighting in max is exactly the opposite. You start with all the lights turned off, completely in the dark, and build up the lighting layer by layer; color by color; brighter and brighter—you'll light the scene (paint with light) dark to light, until you've achieved the desired atmosphere and mood.

In Sc-01, you are trying to create an ominous alien environment. The first step is to establish the main or key light of the shot—in this case, the sun at the horizon. The next step is to fake the radiosity effect by modifying the cooling tower material to add some of the sky color into its surfaces. Adding sky color into materials in daylight shots helps objects match the color and atmosphere of the other composited layers.

The Anatomy of a Target Direct Light

When you are finished with this part of the lighting, your cooling tower will look like the image for Sc-01 (see Figure CP.11 in the color section). You can also find the image on the CD in MAXWorkshop\Area51Final Targas\Sc-01. Target Direct Lights and Target Spotlights have three component parts: the light object, the target object, and the line that connects the two. Creating a Target Direct Light is similar in process to the camera you created in Chapter 4. You'll choose the kind of light you want to create and drag in the viewport. The initial point of the drag defines the location of the light, and the point where you release the mouse establishes the location of the target object. The following steps create the Target Direct Light for Sc-01:

1. Change to Right view and maximize your viewport. Zoom out from the tower and camera so that you have some room to create the light (see Figure 5.7). Click the Lights icon in the Create command panel and select Target Direct.

2. Click in the viewport to the left and slightly above the cooling tower model, and drag the mouse to the right at a slight downward angle. Release the mouse to define the target position in the center of the cooling tower just below the top section. Your viewport should look like Figure 5.7.

Figure 5.7 The Target Direct Light for Sc-01 is slightly above the tower and its light is coming from the horizon just as the sun's light would be at dusk.

3. Change to Top view and click the line that connects the light and its target. Select Move from the right-click Quad Menu and move the sunlight and its target using the X-axis. Center it over the cooling tower, as shown in Figure 5.8.

To see how the light is currently affecting your cooling tower, press C and Shift+Q to change to Camera view and render your scene. The light illuminates the front of the tower, creating a hotspot of light in its middle. The bottom and sides of the tower fade off into darkness. After a light is created and positioned correctly, the next step is to adjust the general parameters that create its color, shadows, and so on.

Figure 5.8 Selecting the line that connects the target to the light will simultaneously select both elements. The same holds true for Target Cameras.

Adjusting General Lighting Parameters

All lights in max use the same general parameters to control how the light affects the scene. With your light selected, click the Modify command panel and change the name of this light to Sun Light. Then look at the General Parameters rollout, as shown in Figure 5.9.

When I started using max it took a long time to learn how each of these interrelated parameters affected the lighting design I was creating. It's important to take the time and experiment with all the settings to discover exactly what they do, and a brief overview of the parameters will help you begin the process of discovery. As you read about the parameters, change the settings for the Sun Light as listed in the following sections.

Figure 5.9 General Parameters control the basic parameters common to every type of max light object. These parameters are often misunderstood and therefore underused. Learning the function of each of these parameters will help you use the lights in your scene more effectively.

Type List

The Type list contains all the light types available in max. If you want to change the light type of a light you are modifying, just select the new light type from this list. Leave this setting as is for the lighting in this scene.

Exclude/Include List

Max gives you the capability to exclude and include specific objects from light and/or shadows cast by any light in the scene. This is especially important when you are trying to achieve the appearance of radiosity in your scene. Including an object is equivalent to excluding all the other objects in the scene; and, conversely, excluding objects is equivalent to including the remaining objects.

Light and Cast Shadows On/Off Check Boxes

When both of these boxes are checked, the light is on and it will cast shadows. When Cast Shadows is unchecked, the light won't cast shadows in the scene. When an unattenuated light doesn't cast shadows, it lights up all the objects in its path regardless of whether the object is sitting behind another object. When a light is turned off, its wireframe image turns black in your viewport and no shadows are cast regardless of the on/off status of the Cast Shadows check box. Max lights are on and Cast Shadows are off by default. The Sun Light in Sc-01 will cast shadows, so check the Cast Shadows box to turn it on.

Light Color Controls

There are three ways to adjust the color of your lights in max. You can click the color swatch next to the On check box and adjust the color using the color selector dialog box, you can change the RGB values, or you can change the HSV values.

HSV is another way of describing color, and its values and spinners are interdependent with the RGB settings. HSV controls the hue, saturation, and value of a light's color. Hue is another name for the color—red, green, and so on. Saturation determines how much of the pure hue is present in the color. Value determines the brightness of the color. Adjust the Value setting to make a color darker in value without diminishing its saturation. Change the HSV value of this light to 105,199,199 to add a green tint to the light to go with the sky gradient.

Multiplier Setting

Adjusting the Multiplier value enables you to increase or decrease the brightness of a light beyond its normal range. The max default Multiplier setting is 1.0. Increasing the Multiplier value above the default setting intensifies the brightness of the light, tending to create glare and washed-out images. Decreasing the Multiplier to values less than 1.0 diminishes the intensity of the light. Negative multiplier values create dark areas in the shot as if the light is removing light from the surfaces in its path. This comes in handy when you are trying to consciously create more contrast by darkening specific areas in your composition. Using a negative light value also changes the color of the light to its complementary color. When creating the projector map for the cloud shadows, which you will do in moment, the Sun Light needed more intensity to be able to "burn" through the clouds. So, change the Sun Light Multiplier value to 2.0.

Affect Surfaces Section

The controls in this section enable you to specify the specific part of a material's ambient, diffuse, and specular components that will be affected by the selected light. In general, I prefer to soften the blend between the diffuse and ambient material components by increasing the Soften Diff. Edge value to its maximum setting of 100. Leave the Diffuse and Specular check boxes as they are for now.

Sun Light General Parameters Recap

Here's a recap of the General Parameters settings for the Sun Light. Type: Target Direct Light; Light and Cast Shadows: On; Exclude: None; HSV Values: 105,199,199; Multiplier: 2.0; Affect Surfaces: Soften Diff. Edge: 100. The General Parameters rollout for the Sun Light should look like Figure 5.10.

Figure 5.10 Adjusting a light's General Parameters is just the tip of the lighting iceberg. Understanding how these parameters affect your lighting lays an important foundation for adjusting the deeper lighting controls in the other rollouts.

Adjusting Directional Parameters

The controls in the next rollout specify how your light appears in the scene. You can specify the shape of the light, its hotspot, and Falloff amount, and add projector maps; a great feature that you'll use for the animating cloud shadows (see Figure 5.11).

Figure 5.11 Directional Parameters allow you to fine-tune the display, appearance, and effect of the lights in your scene.

Light Cone Settings

The settings in the Light Cone section of the Directional Parameters rollout control how the light is displayed in the scene and how it affects the environment it's placed in. The Projector Map section enables you to use a special light effect called projector map. As you read these definitions, make the indicated adjustments to this rollout:

• Show Cone—When the box next to Show Cone is checked, the light cone, determined by the falloff size, always appears in your scene. When it's unchecked, the cone appears only when the light is selected. Check this box to display the cone of the Sun Light.

• Overshoot—When Overshoot is checked, a light casts light in all directions like an omni light. However, the light's projection maps and shadows occur only within the light's cone. Leave Overshoot unchecked.

• Hotspot and Falloff—Falloff is the diameter of the cone of the light that determines how big an area of light will illuminate. The size of the hotspot relative to the falloff controls how soft the edge of the falloff diameter appears in the scene. The size of the hotspot determines how intense a highlight the light creates on the surfaces of the objects it's illuminating. Change the Falloff amount for the Sun Light to 82 and the Hotspot amount to 35.

Figure 5.12 shows the effect that changing the relative value of the Hotspot will have on the appearance of the falloff. A direct light with a Falloff amount of 70 lights all three spheres.

• Circle/Rectangle—The falloff shape of spotlights and direct lights can be a circle or a rectangle. The rectangular shape is useful for light and shadows created by doors, windows, or the flat surfaces of buildings. Leave the Sun Light set to Circle.

• Aspect/Bitmap Fit—When you select Rectangle for your light shape, you can adjust its width-to-height proportion by using the Aspect spinner. An aspect value of 1.0 creates a rectangle whose height is equal to the width. A value of .5 means that the rectangle is half as high as it is wide. Bitmap Fit is used to match the aspect ratio of a rectangular spotlight or direct light to the aspect ratio of the bitmap image used as a projector map. This ensures that the projection appears correctly in the scene. These controls don't work with the Circle selection.

• Target Distance—Shows you the distance from the light to its target.

Sun Light Directional Parameters Recap

The Directional Parameter settings for the Sun Light are as follows: Show Cone: On; Overshoot: Off; Hotspot: 35; Falloff: 82; Circle is the selected light shape; leave the rest of the parameters as they are. Your Directional Parameters rollout should look like Figure 5.13.

The Sun Light in Sc-01 isn't attenuated, so the Workshop at this point will skip Attenuation and move on to the Shadow Parameters rollout. For a complete explanation of Attenuation, visit the max User Reference. After you learn about shadow parameters, you'll return to the projector map and create the animating map used to simulate the clouds passing in front of the sun.

Figure 5.12 The relationship of the Hotspot amount to the Falloff amount determines how soft the edge of the area illuminated by the light will be.

Figure 5.13 The Directional Parameters settings for the Sun Light were chosen to create a softer falloff edge without a strong highlight.

Adjusting Shadow and Shadow Map Parameters

Scroll down in the Command Panel and open the Shadow Parameters rollout. This rollout has two sections that control the general parameters of object and atmospheric shadows cast by your max lights (see Figure 5.14).

Figure 5.14 The parameter settings in this rollout will be fine-tuned in the Shadow Map Parameters rollout.

Cast Shadows is already turned on for Sun Light in the General Parameters rollout. The On check box in this rollout and the Cast Shadows check box in the General Parameters rollout are linked—turning off shadows here will turn them off there, and vice versa.

Shadow Map and Raytraced Shadows

Two types of shadows can be created in 3ds max 4: Shadow Map and Raytrace. Raytraced shadows take longer to render, and with some creative adjustment, Shadow Map shadows can achieve the look of Raytraced shadows. Both shadow types can be used in your scenes because the shadow type for every light can be set independently. Common shadow parameters can also be applied to several lights at the same time using the Global settings.

You can mix shadow types according to where the shadow appears in the composition: Raytraced shadows in the foreground to emphasize detail and Shadow Map shadows in the imagery far away from the camera where a low level of detail is required. It's important to experiment with both types of shadows to learn their limitations and how each one affects scene imagery and rendering time. Figure 5.15 shows the difference between Raytraced shadows and Shadow Map shadows set at their default max settings. You can leave the shadow type for the Sun Light set to Shadow Map; its quality is sufficient for Sc-01.

Figure 5.15 Raytraced shadows create accurate shadows of a high quality. The only downside is that they can take longer to render. Furthermore, Raytraced shadows only accurately simulate shadows of harsh lighting conditions, giving the shadow a sharp edge. Shadow Map shadows allow for feathered shadow edges—thus, it is in combination that reality can be replicated.

The Shadow Map shadows took 47 seconds to render; the Raytraced shadows were rendered in 54 seconds. That doesn't seem like too big of a difference, but the more complex a scene, the greater the differential will be between the two rendering times.

Using Shadow Map shadows for the Sun Light shadows in Sc-01 produced a rendering time of 36 seconds per frame; Raytraced shadows were rendered in 50 seconds per frame. The difference between the two is just 14 seconds. However, when you multiply the difference by the scene length of 288 frames, the total rendering time difference is over 65 minutes. That's not insignificant. Using multiple lights following the advice given by Dave Campbell can help you optimize your rendering times. Keep these factors in mind as you design the lighting for your scenes.

A good way to get around this problem is to fool the audience into thinking that a scene is raytraced (both shadows and reflections) by putting a Raytraced image layer in the extreme foreground. The eye sees the higher image quality and fools the mind into thinking that the entire scene is raytraced also. This is especially effective in shots using animated cameras. Figure 5.16 shows an image that uses this cheap trick.

Global Settings

The Use Global Settings check box allows lights in a scene to use the same shadow and Shadow Map parameters. When this box is checked, you can control the shadows of all lights that also have this box checked using one set of parameters. Changing the parameters of one light in the global settings group changes all the rest. When global settings are used, the Shadow Map Parameters rollout changes to show the parameters for all lights that are using global settings.

Adjusting Shadow Color and Density

The color swatch next to Color and the Density amount (the Dens. box) are used to specify the color and intensity of the shadows cast by your lights. When you click the color swatch, the Color Selector dialog box opens for you to specify the RGB or HSV values of your shadow color. The Sun Light shadow color can remain set to black. Color will be added into the shadows in another way later in this chapter.

Figure 5.16 Use Raytraced reflections and shadows wisely by creating limited Raytraced layers that can fool the eye into thinking the entire scene is raytraced. The color version of this image can be seen in Figure CP.7 in the color section of this book.

Density controls the value of the shadow. The default Dens. amount is 1.0, which creates the darkest value of shadow possible. Lower values create less dense or lighter shadow values and allow the color of the object material that the shadow is being cast on to show through. Leave the Sun Light shadow Density value set at 1.0 for now.

Shadow Parameter's Map Option

When a bitmap image or procedural map is put into the Map slot, it will be seen in the shadow cast by the light. This can result in some really interesting effects that allow you to create patterned and animating shadows images (see Figure 5.17).

Light Affects Shadow Color Parameter and Atmosphere Shadows Section

The Light Affects Shadow Color parameter is another feature of max lighting that helps simulate radiosity in your scenes. Under realistic lighting conditions, shadows are never truly black. Their color is created by three factors: the intensity and color of the light creating the shadow, the color and surface properties (reflective and nonreflective) of the material the shadow is being cast on, and the intensity and color of the ambient light bouncing around in the scene.

Figure 5.17 Adding bitmap and procedural maps to the Map slot of the Shadow Parameters creates images and effects inside cast shadows.

Allowing the light to affect the color of the shadows will essentially blend the light color with the shadow color. This simulates the way shadows look in the real world. Later in this chapter, you'll adjust the cooling tower material to create a fake radiosity effect. This will negate most of the effect that using the Light Affects Shadow Color will have in the imagery, so leave this box unchecked.

Adjusting Shadow Map Parameters

Shadow Map parameter settings are used to fine-tune the quality of the shadows cast by your lights. In Figure 5.15, shown previously, the Shadow Map shadows appeared a bit rough around the edges because of the default settings shown in Figure 5.18.

Figure 5.18 Shadow Map Parameters fine-tune the location and quality of Shadow Map shadows.

Map Bias controls how close the shadow is to the shadow-casting object. Higher Bias values can result in shadows that don't look like they are attached to the object correctly. A map Bias of less then 1.0 creates a shadow that looks correctly attached to the object.

Map Size determines the quality of the shadow image. Lower values create jaggy edges. Higher values create near-raytrace-quality shadow maps.

Sample Range determines how soft the edge of the shadow is. Higher values produce softer edges that simulate diffraction. Lower values create hard shadow edges. Figures 5.19 and 5.20 show two images rendered with different shadow bias, map size, and sample range settings.

Raytraced shadows use two parameters to control their appearance: Bias and Max Quadtree Depth. Raytrace Bias functions in a similar manner to the Bias setting for Shadow Map shadows. Higher values move the shadow away from the shadow-casting object, and lower values create a more correct connected shadow. Raytraced shadows always have a hard-defined edge.

Figure 5.19 High bias values make shadows appear disconnected from the shadow-casting objects. Low map sizes reduce the quality of the shadow map and, coupled with low sample ranges, create jagged shadow edges.

Figure 5.20 Bias values less than 1.0 generally make shadows appear correctly connected to the shadow-casting objects. High map size improves the quality of the shadow map and, coupled with high sample ranges, create near-raytrace-quality imagery; however, it takes just about the same time to render.

Figure 5.21 shows Raytraced shadow using a Raytrace Bias of .5 and a Max Quadtree Depth of 10. This resulted in a rendering time of 43 seconds—an acceptable rendering time comparable to 42 seconds for Shadow Map images of similar quality.

Figure 5.21 The choice between Shadow Map shadows and the crisp, realistic Raytraced shadows shown in this image becomes a matter decided by the needs of the scene, the visual language of the production, and the production schedule.

Projector Map: Creating Animated Cloud Shadows

The clouds you created in Chapter 4 for Sc-01 are not real 3D volumes of simulated water vapor and can't cast shadows or be realistically lit in their current form. Real clouds passing in front of the sun sitting low on the horizon would cast shadows into the environment the sun is illuminating. And the light illuminating them would light up the surfaces of the clouds closest to the sun. To create the shadows of the clouds that are moving across the face of the cooling tower, you'll make a Noise map similar to the one you used to create the overhead clouds and use it as a projector map.

Creating the Cloud Shadow Projector Map

Follow these steps to create the projector map:

1. Press M to open the Material Editor and position it in your viewport just to the left of the Command Panels.

2. Select the Sun Light and click the Modify command panel. Scroll down to the Directional Parameters rollout and click the Map slot marked None in the Projector Map section.

3. When the Material/Map Browser opens, double-click Noise to close the browser and add the Noise map into your Projector map slot.

4. Drag the Noise map and drop it onto an empty material preview window in the Material Editor. Select Instance as the Clone type when the Clone/Copy dialog box appears, and click OK. Your Material Editor and Directional Parameters rollout should look like Figure 5.22.

Figure 5.22 The drag-and-drop process is the same one you used to create the BG Gradient map in Chapter 3.

5. Change the name of the Noise map to Cloud_Shadows and scroll down to the Noise Parameters rollout in the Material Editor.

6. Change the Noise Parameters to the following: Noise Type: Fractal; Noise Threshold—High: 0.6; Low: 0.4; Levels: 3.0; Size: 50.0 (see Figure 5.23).

Figure 5.23 The settings for the projector map were developed through a lot of experimentation with the look of the cloud shadows and how they animated across the face of the cooling tower.

7. Scroll down and open the Output rollout and click Invert; leave the rest of the output parameters set to their default values, as shown in Figure 5.24.

Figure 5.24 Every map created in the Material Editor has an Output rollout, which gives you control over the major factors affecting the appearance of the map in your scene. It's a fun and powerful set of parameters that can be used to affect subtle and intense changes to basic bitmap and procedural map imagery.

As you did with the cloud plane in Chapter 4, you'll be using the X- and Y-axis Offset in the Coordinates rollout to animate the cloud shadows.

Animating the Cloud_Shadows Projector Map

Clouds are found almost exclusively in the troposphere, which starts at sea level and extends up to approximately 15 kilometers above the earth's surface. Because of their enormous size and distance from our earthbound POV, the speed at which clouds move is difficult to gauge by eye. The one way to gauge their speed accurately is by measuring the ground speed of the shadows the clouds cast on the ground. Visually the shadows and the clouds will appear to travel at different speeds—a type of parallax effect created by relative distance of the clouds, which are far away, and their shadows, which are very near.

To create realistic-looking animating shadows on the cooling towers, and taking the parallax effect into account, the shadows moving across the face of the cooling tower will move faster than the clouds seen in the cloud plane. The cloud shadows also need to move up and to the right over the face of the tower to relate to the movement of the cloud layer:

1. Scroll up to the Coordinates rollout and click the Animate button to enter Animate mode. Move the time slider to frame number 287 at the end of the Track Bar.

2. Change the X Offset value in the Coordinate rollout to –400 and the Y Offset value to –200. Click the Animate button to exit Animate mode, save your file, and render the Camera view to see the shadows cast by the projector map. Your Coordinates rollout should look like Figure 5.25.

Figure 5.25 When you are designing your effects animation, consider the power of animating materials to create the imagery you are trying to achieve.

After you have modified the cooling tower material and created the camera animation, you'll render the sequential images of the cloud shadows on the cooling tower. The images will be composited with the cloud layer you created in Chapter 4 and the BG Sky from Chapter 3.

Faking Ambient Radiosity

The technical director at our studio, Dave Otte, and I have a lot of discussions about lighting, material development, scene complexity, and so on. Technical directors like Dave are excellent artists who also have expertise in the more technical aspects of modeling, lighting, animation, scene development, and production rendering. Their job is to work with the art director to establish the visual language and invent the processes that implement the visual language into the production pipeline.

Achieving the look and feel of radiosity in production imagery without having to resort to dozens of lights or radiosity rendering plug-ins has been an ongoing project of Dave's. He's come up with several techniques that are fun, easy to use, and creative. You'll be learning about one of the techniques in this scene.

Adding a Falloff Map

The following steps will show you how to use a Falloff map to fake radiosity in the cooling tower material:

1. Click the Cooling_Tower_Master material preview window in your Material Editor. Scroll down in the editor until you see the Maps rollout (see Figure 5.26).

2. Click the Map slot next to Extra Lighting and select Falloff from the Material/Map Browser. Click OK to load the Falloff map into the Extra Lighting map slot.

Using this map allows you to specify a color for all the shadows seen on the cooling tower form, including those cast by the Sun Light and its projector map.

Adjusting the Falloff Map

When you add the Falloff map into the Map slot, the Maps rollout window changes to the Falloff Parameters window shown in Figure 5.27.

Figure 5.26 The Maps rollout provides a comprehensive list of all the Map slots in a material and the maps assigned to them.

Figure 5.27 Falloff maps can be used to control reflection, material color, transparency, and so on. A Falloff map can be used in any of the material Map slots.

Finding the right combination of falloff settings, background gradient color, cloud layer color, and cooling tower material color was accomplished with a lot of test renders and experimental failures. Here are the settings that worked with the lighting scheme created for Sc-01. If you are trying a lighting and color scheme of your own, experiment with the settings until you get the look you want:

1. Click Falloff Type and select Shadow/Light from the list. This is the type of falloff that enables you to create a different color or even material for the surfaces of an object that are illuminated and those in shadow.

2. Click the black color swatch under Shaded:Lit in the top-left corner of the rollout. Change the color values to HSV: 150,191,100. This specifies that the color seen in the shadows of the material will be a deep blue. This color was chosen to go with the color scheme of the scene and to fake radiosity by creating shadows that aren't black.

3. Scroll down to the Mix Curve rollout and drag the point on the left down about halfway in the graph window (see Figure 5.28).

Figure 5.28 The Mix Curve graph controls the gradient produced by the falloff. The gradient bar below the graph shows the result of the adjustments you make to the curve.

4. Open the Output rollout and change the value in Output Amount to 2.0. This intensifies the color seen in the shadows. Close the Material Editor when you're finished.

When you render your scene, you can see the dark blue color specified by the Falloff map in the shadows of the cooling tower. This color will blend perfectly with the rest of the finishing touches you'll make to complete the scene.