Dr. D's Essential Guide to Standard Material Component Maps
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"Where principle is put to work, not as a recipe or as a formula, there will always be style."—Le Corbusier
I'm always impressed with the creativity of the artists in the 3ds max community. They are constantly experimenting and inventing new processes within the max toolset to achieve their vision—creating unique visual styles in the process. Your style is built on a foundation of knowledge of the basic principles behind your use of the digital tools and techniques in max. It is a visual language all your own, and you'll create it by putting those principles into practice.
Chameleon Style
The ability to adopt and use the visual language created by an art direction team is essential to your success as a max artist. At the beginning of your career, most of the production work you do will be guided by a visual style created by someone else. As you gain experience, there will be ample opportunity to create and express your own visual language. Knowing when to be a chameleon, blending your work with the rest of the production team, and when to be an individual, freely expressing your own style, will help you gain the trust and confidence of your producer and art direction team.
One of the major creative tools in max 4 is the Material Editor. Learning how the Material Editor is organized and about its basic functions is relatively easy. But after you get beyond the basics, the incredible depth of this tool and the variety of ways that it can be used to create materials can be somewhat daunting. Understanding more about the material component maps—how they are used and what they are capable of creating—will accelerate your learning of max 4 and help you in your quest for a style of your own.
Material Component Map Basics
Every material in max has a basic set of common components, which determines its color, reflectivity, opacity, and so on. Each of the material components can be controlled by numeric values, by color changes, and by using one of max's 35 map types as a component map. In other words, you can use bitmap images, procedural noise, and falloff, among others, to affect ambient and diffuse color, opacity, specular, reflection, and so on. Figure 1 shows theMaterial Editor and the associated Maps rollout for a default standard materialusing a Blinn shader.
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Figure 1 The small box next to each material component is a Map slot, whichis linked to its counterpart in the Maps rollout. Each of max 4's 10 material types and 7 shaders has similar and unique material components.
TIP
For information that defines the material component maps discussed in this article, search for the name of the material component in the Search or Index portion of your max 4 User Reference.
The examples in the remaining sections of this article will show you the effect that material component maps can have on material appearance.
Ambient Color Component Maps
Ambient light affects every surface of an object via indirect illumination—the light reflected off the other objects and surfaces in an environment. The Ambient material component is locked to the Diffuse material component by default. Leaving them locked will work for the majority of your material needs, but sometimes you'll want the subtle effect that a map in the Ambient component can achieve.
To add a map to the Ambient color component, you must first unlock it from the Diffuse component. Then click its adjacent Map slot and choose a map from the material map browser. After the map is added, there is a parameter setting that must be adjusted so that you can actually see the map in the Material Editor and in your scene.
The Hidden Knowledge
In previous versions of max, the Global Ambient Lighting option found in the Rendering/Environment dialog box was on by default. Discreet found out that a majority of max artists didn't use the global ambient light and just turned it off when they started lighting a scene. Discreet listened to its users, and the result is that in 3ds max 4, global ambient lighting is now off by default.
That's good! However, the hidden knowledge that isn't found in the max User Reference is that global ambient light must be on to be able to see a map in the Ambient color component of a material in the Material Editor.
The Global Ambient Light settings can be changed in the Rendering/Environment dialog box. They can also be adjusted in the Material Editor. Right-click any material preview window, and choose Options from the menu. When the Material Editor Options window shown in Figure 2 opens, click the color swatch next to Ambient Light and change the HSV settings to 0,0,25; then click Apply. This gives just enough ambient light to see the map in the Material Editor and in your rendered imagery.
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Figure 2 When the lock next to Ambient Light is on, the changes that you make here will also be made in the Environment dialog box. Leave this lock on to see the Ambient component map in both the Material Editor and in the rendered scene.
Decals and Tattoos
A map in the Ambient component can be used to create a decal on the side of an object or a tattoo. The bitmap image used in the material for the alien head in Figure 3 is a simple black-and-white targa image. The effect of the Ambient component is that the high-contrast image blends in with the rest of the surface, allowing the skin texture underneath to show through.
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When the surface to which the image is applied is illuminated by direct light, the bitmap appears washed out. When seen in surfaces facing away from the light, the bitmap darkens to become its true color: black.
Figure 3 A bitmap in the Ambient color component creates a subtle painted-on look, like a stencil applied to the surface of a piece of metal or a tattoo on skin.
Diffuse Color Component Maps
Diffuse color is the color of a material seen in the surfaces that are illuminated directly by a light source. Maps added to this component are used to create variegated colors and surfaces texture. Figure 4 shows the effect of a zebra skin image added as a Diffuse component map.
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Figure 4 Diffuse component maps can be used to simulate everything from aircraft aluminum to zebra pelts. In this image, the zebra bitmap was also added to the Reflection map on the eye material, and a Cellular procedural map was added as a Bump map. Creepy!
Adjusting the Diffuse amount, as shown in Figure 5, mixes the diffuse color with the map in the Diffuse component slot. The amounts in these spinner boxes are percentages—a setting of 100 means that 100% of the map will be used as the surface color; a setting of 0 uses 100% of the component color and none of the map; and a setting of 50 creates an equal mix of the map and the diffuse color.
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Figure 5 You can use the Amount spinners next to the component maps to adjust the visual blend between the component settings and an image or procedural map in the component map slot. These spinners can also be used to adjust the intensity or effect of a procedural map such as Raytrace or Falloff.
Specular Color Component Maps
Specular color determines the color of the highlight seen in the material surface. It's determined by three factors: the color of the light source, the diffuse color of the material, and the type of material, such as painted, metal, plastic, wood, and so forth.
Specular color is not necessarily the same hue as the diffuse and ambient color. The highlights seen in surface materials take on the color of the light source and are also affected by the ambient light in the environment. You can change the specular highlight color by clicking the Specular color swatch in the Basic Parameters rollout. You can also change the specular color by adding a map.
When a map is added to the Specular color component, its image will appear wherever a specular highlight is created. Notice how the diffuse texture and color blends with the specular texture in the highlight area in the image in Figure 6.
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Figure 6 A map in the Specular color component creates texture and images that will be seen in the highlight portions of the surface. A mirror image "Area51" bitmap was added to the specular component of the alien's eye to simulate a reflection.
Specular-Level Component Maps
Specular level defines the intensity (relative brightness) of the specular highlight and is determined by the same three factors as specular color. A bitmap added to this component affects the intensity of the highlight by using the image's grayscale values. White portions of the map allow the specular level to be at full intensity. Black or darker portions of the bitmap drop the intensity to 0. The Amount spinner on this component can be adjusted higher than 100, which creates more intensity in the highlight.
Figure 7 shows the alien's eye before and after a Cellular procedural map has been added to the Specular Level component.
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Figure 7 The procedural map breaks up the highlight, creating a more complex reflection in the image. Specular Level maps can also be animated to simulate reflections of moving water seen in an eye—much faster than raytracing actual reflections.
Glossiness Component Maps
Glossiness is also affected by the factors that determine specular color and specular level. The Glossiness value controls the size of the specular highlight. Larger values focus the highlight into a smaller diameter area, and smaller values make a larger-diameter, less-focused highlighted area.
Copying the map used in the Specular Level component into the Glossiness component slot and increasing the Specular level amount to 250 produced the effect shown in Figure 8.
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Figure 8 Using the map from the Specular Level component in the Glossiness component increases the apparent depth and detail of the highlight intensity.
Self-Illumination Component Maps
Self-illumination creates the appearance of a light-emitting material, such as a light bulb, a firefly, lightning, or another glowing substance. The highest value, 100, means that the material is a 100% self-illuminating, intrinsic light source and will not be affected by other lights in the scene.
The maps added to this component use their grayscale to determine which parts of the surface will be self-illuminated. Figure 9 shows the effect that a Gradient map has when added to the Self-Illumination component.
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Figure 9 The Gradient map starts out white at the top and gradually changes to black at the bottom. The effect in the material is that the top of the alien's head is totally self-illuminated, corresponding to the white of the Gradient map. As the map gradates to black, the alien's head becomes less self-illuminated.
A Falloff map added to the Self-Illumination component creates a kind of electron microscope effect, illuminating the outer edge of the alien's head (see Figure 10).
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Figure 10 By using the grayscale of the Falloff map to determine which parts of the material will be self-illuminated, several different effects can be achieved, including the radiosity effect.
Opacity Component Maps
The Opacity component determines the transparency of a material. When a map is added to the Opacity component, the map's grayscale is used to determine which parts of the surface will be transparent and which will be opaque. White areas of the bitmap create opaque surfaces, black areas create complete transparency, and gray areas create different levels of transparency, depending on the relative value of the grayscale. Figure 11 shows this effect of copying the Falloff map from the Self-Illumination component from Figure 10 into the Opacity component.
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Figure 11 Using a Falloff map in the Opacity component creates an x-ray effect. Adding a skull and sensory organs inside the alien's head will help emphasize the x-ray imagery.
Figure 12 shows the effect of a Checker procedural map added to the Opacity component. Making the material two-sided allows you to see the inside surfaces of the head.
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Figure 12 One of the unexpected effects in this image can be seen in the veins coming out of the alien's neck. These were created procedurally, using renderable splines, which means that the tube geometry that appears in the image doesn't exist as actual mesh surfaces in the max workspace. However, when the Checker map is added to the Opacity component, it creates tube sections that appear to have a wall thickness.
Filter Color Component Maps
When light strikes a transparent material, some of it is absorbed and not allowed to pass through. A blue glass, for example, is blue because all the other colors of the light illuminating it are absorbed; only the blue is reflected and subsequently transmitted through the material. The ambient light bouncing around an environment also passes through and takes on the color of the glass. This transmitted color is defined by the Filter Color component.
The decal applied to the alien's forehead has been added to the Filter Color component. This allows the decal image to be projected onto the ground plane and determines the color and value of the light passing through the decal (see Figure 13).
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Figure 13 When used with transparent or semitransparent materials, the Filter Color component creates the effect of light passing through an object, such as a piece of glassware with an etched image on its surface. The alien's head in this image also has a Thin Wall Refraction map added to the Refraction component.
NOTE
When light passes through a piece of glass, it changes direction—bent by the refractive quality of the material. The Thin Wall Refraction map is used to simulate the refractive effect of light passing through glass, plastic, or any other thin transparent surface material.
Bump Maps
Bump maps are used to simulate the appearance of surface detail and texture. A bitmap image or procedural map used in this component will appear in the surface texture of the object. This is similar in effect to the Displacement map, except that the Bump map doesn't modify the 3D surface mesh of the object. Many of the images in this article use maps in the Bump component to create surface texture.
In a manner similar to many of the other component maps, the grayscale of the Bump component map combined with the Amount value produces the bump effect. The Amount value can be positive or negative—positive values create a texture that appears to push out from the surface; negative values push the texture into the surface. Figure 14 shows this effect.
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Figure 14 You can use an instance of the Diffuse color component map in the Bump component to create realistic natural textures such as craters, rock fissures, wood grain, and skin textures.
Reflection Component Maps
Maps used in the Reflection component slot affect the reflectivity and reflections seen in the surfaces to which the material is applied. Reflections are created by three factors: the object's form, the texture (smooth versus rough), and the environment surrounding the object.
The Raytrace material produces the most accurate reflections for organic forms. Other Reflection maps that can be used in the Reflection component are the Flat Mirror and the Reflect/Refract maps. Figure 15 shows the alien's head with a Raytrace map applied to its material. It's sitting on a reflective surface that uses the Flat Mirror map in its Reflection component.
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Figure 15 Reflections add an important touch of realism to your max scenes. They can also increase rendering times dramatically, especially if you're using the Raytrace material or a Raytrace map in a material's Reflection component. Make wise choices about the kind of Reflection map/material to use and the objects in the scene to which the materials are applied.
Refraction Component Maps
The Refraction component creates the appearance of the light-bending phenomenon known as refraction seen in glass lenses, water, marbles, crystal balls, and so forth. The IOR, or index of refraction, is a numerical value that determines the level of a material's refractivity. When light is transmitted through glass or other transparent materials, it's refracted into concentrated areas of light referred to as caustics. The refracted light caustics also change the appearance of the shadows cast by transparent objects.
Figure 16 shows the effect of a Reflect/Refract map added to the Refraction material component.
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Figure 16 Three maps can be used to achieve realistic refraction effects: Reflect/Refract, Thin Wall Refraction, and Raytrace.
Displacement Component Maps
Displacement maps are used to create complex surface details using bitmap images and procedural maps to create a 3D surface derived from the grayscale of the map. Lighter values in the image create more severe detail protrusion, and darker values create indentations in the surface.
Displacement maps can be used to create the details seen in a sculpted column, the craters on the moon, or, in this example, an elderly alien. The model for these two alien heads is exactly the same; the difference is the bitmap added to the displacement component of the elderly alien's material (see Figure 17).
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Figure 17 With some intense and time-consuming effort, you can create the wrinkly skin of the elderly alien with max's mesh-modeling tools. Using Displacement maps is a smart and viable alternative.
An important factor in creating and using displacement maps is the density of the mesh surfaces to which the map is assigned. In general, you'll need a high-density mesh to be able to use a Displacement map effectively. The art of Displacement mapping lies in the creative map images you'll create to affect the mesh surfaces.