Raytrace material is a material that creates fully raytraced reflections and refractions. The reflections and refractions it generates are more accurate than those produced by the Reflect/Refract map. Rendering raytraced objects is slower than using Reflect/Refract. On the other hand, Raytrace is optimized for rendering 3DS MAX scenes, and you can further optimize it for your scene by excluding specific objects from raytracing.
Note: You can also use the Raytrace map, which uses the same raytracer to generate accurate, raytraced reflections and refractions. Raytrace Map and Raytrace material have the same name because they use the same raytracer and share global parameters.
The colors in the basic parameters Raytrace material behave differently from colors in standard materials. In effect, standard material colors use the model of painting – they apply arbitrary colors to the surface of an object. Raytracing, on the other hand, is a way of modeling the action of light rays in a scene. The Raytrace material color components behave more like their physical counterparts. In Raytrace material, Diffuse is the color that the surface reflects without specular reflection, while Reflect controls the amount of specular reflection – these two material components are interdependent. If the material is completely reflective, no diffuse color is visible. If the material is completely nonreflective, only the diffuse color is visible.
The Dynamics Properties rollout for the Raytrace material contains the same controls as the dynamics properties for a standard material.
Raytrace material has a large user interface with lots of controls. In general, if you are using Raytrace to create reflections and refractions, the controls in the Basic Parameters rollout are the only ones you need to adjust. The Extended Parameters rollout for Raytrace has controls for special effects, and the Raytracer Controls rollout affects the raytracer itself. In general, you should use the Raytracer Controls if your scene is very large or very complicated, and you are concerned about performance.
The basic parameters in this rollout are similar to the basic parameters for standard materials, but the color components of a Raytrace material behave differently.
As with standard materials, you can use a map for Raytrace color components and various other parameters. The small buttons to the right of the color swatches and parameters take you to the Material/Map Browser to select a map of corresponding type. These are shortcuts that also have corresponding buttons in the Maps rollout. If you have assigned a map to one of these colors, the button displays the letter “M.” An uppercase M means that the corresponding map is assigned and active. A lowercase “m” means that the map is assigned and inactive (turned off).
Shading: Same as for standard materials: can be Phong, Blinn, Constant, or Metal.
Constant shading for Raytrace material uses a Phong highlight model on a faceted object.
2 Sided: Same as for standard materials. When on, shades and raytraces both sides of faces. By default, objects are one-sided in order to speed up rendering.
If you have a 2 sided, reflective and refractive object, the raytracer runs until it hits the maximum recursion level. This can
Wire: Same as for standard materials. When on, renders the material in wireframe mode. You can specify the wrie size in the Extended Parameters rollout.
With pixels, wires maintains the same apparent thickness regardless of the scale of the geometry or how near or far the object is positioned. With units, the wires appear thinner at a distance and thicker at close range, as if they were modeled in the geometry.
Face Map: Applies the material to the faces of the geometry. If the material is a mapped material, it requires no mapping coordinates. The map is automatically applied to each facet of the object.
Super Sample: Super-sampling reduces aliasing in specular highlights and bump maps. It does this by calling the shader five times rather than once, using a quincunx pattern (the five on a domino), then averaging the results. Naturally, this slows down rendering time. Turn this on only if you are having trouble with aliasing in specular highlights or bump maps.
Ambient: This is NOT the same as the standard ambient color. For Raytrace material, this controls an ambient absorbtion factor. Because raytracing accurately models the environment, it doesn’t make sense for a raytraced material to have an ambient color independent of the environment. Instead, this color controls how much the material absorbs ambient light. Setting Ambient to white is the same as locking the ambient and diffuse colors in a standard material. Default = black.
Diffuse: This is similar to the standard diffuse color, but it is not quite the same. The diffuse color is the color that the object reflects, without specular reflection. It is interdependent with the Reflect color. When Reflect is 100% (pure white), the diffuse color has no effect (this differs from the standard material). Default = 50% gray.
When rendered, the appearance of the diffuse color depends on the angle between the light source and the surface normals of the object’s faces. [SHOULD WE SAY MORE ABOUT THIS HERE?]
Reflect: The specular reflection color. This is the color that the reflected environment (that is, the rest of the scene) is filtered through. The color’s Value controls the amount of reflection. If your reflect color is saturated and the diffuse color is black, the effect is like colored chrome (for example, colored Christmas tree balls). This component uses the raytracer -- if the raytracer is turned off, it still respects the environment color or map or the map in the Raytrace material’s Environment component. Default = black –- no reflection.
If raytracing is turned off (in the Raytracer Controls rollout), the object still reflects the environment mapping, but ignores other objects in the scene.
Note: Raytrace reflects and transmits the IDs in material effects channel (G-buffer), so it can create glowing reflections, and so on.
Luminosity: Similar to the standard material's self illumination component, except that it does not depend on the diffuse color. You can have a blue diffuse object with red luminosity. Default = black.
Transparency: Similar to the standard material’s filter color for transmitted light, combined with the standard material’s opacity controls. This color filters scene elements that are behind the object with Raytrace material. Black is opaque, white is fully transparent, and any value in between filters objects behind the raytraced object. A fully saturated color in both the diffuse and transparency components gives the effect of tinted glass. If you want more of an opaque look, pick the color you want as a transparent color, copy it to the diffuse color, make the diffuse color fully saturated, and then adjust the transparency to get the effect you want. Default = black – no transparency.
If raytracing is turned off (in the Raytracer Controls rollout), the object still refracts the environment mapping, but ignores other objects in the scene.
Note: By separating the diffuse, reflect, and transparency components, Raytrace material gives you a great deal of control over how the object reacts to its environment. For example, an object might diffusely reflect red, specularly reflect green, and transmit blue
-- this is not a real-world effect, but it can be useful.
Index of Refr. (Refraction): The index of refraction (IOR) controls how severely the material refracts transmitted light. Left at 1.0, the IOR of air, the object behind the transparent object does not distort. At 1.5 the object behind distorts greatly – like a glass marble. At an IOR slightly less than 1.0, the object reflects along its the edges -- like a bubble seen from under water. Default = 1.0.
Common IOR's (assuming the camera is in air or a vacuum) are:
Air
1.0
Water
1.333
Glass
1.5 to 1.7
Diamond
2.419
In the physical world, the IOR results from the relative densities of the transparent material and the medium the eye or the camera is in. In general, the higher the IOR, the denser the object.
You can also use a map to control the index of refraction. IOR maps always interpolate between 1.0 (the IOR of air) and the setting in the IOR parameter. For example, if the IOR is set to 3.55 and you use a black-and-white Noise map to control IOR, the IORs rendered on the object will be set to values between 1.0 and 3.55 -- the object will appear denser than air. If, on the other hand, your IOR is set to 0.5, then the same map values will render between 0.5 and 1.0 -- as if the camera were under water and the object was less dense than the water.
The controls in this area affect the appearance of specular highlights. Specular highlights simulate the surface of the raytraced object reflecting the lights in the scene. Changing the color or intensity of lights in the scene can change the appearance of specular highlights.
As in standard materials, as you adjust the values in this area, the highlight curve at the right changes to give you an idea of the effect. The material preview in the sample window also updates.
Color: This is the color of specular highlights, assuming white lights in the scene.
Click the color swatch to display a Color Selector and change the highlight color.
Shininess: As in standard materials, this is the tightness (or spread) of specular highlights.
Shininess Strength: As in standard materials, this is the intensity of specular highlights. You can set Shininess Strength to a very high value so you can get very strong, tight highlights.
Soften: As in standard materials, lets you soften the effect of highlights formed by glancing light. This is useful because the algorithms for generating specular highlights don’t work at very glancing angles.
You can also use Soften for special effects. Unlike standard materials, you can set Raytrace Soften to values greater than one. High values of Soften with very large, soft specular highlights can give a good rubbery effect.
Environment: Lets you specify an environment map that overrides the global environment map. Both Reflect and Transparency use the scene-wide environment map unless you use this button to specify another map. With this control, you can use different environment maps on a per-object basis, or provide an environment to specified objects when the scene as a whole has none.
This map overrides the scene-wide environment for both reflection and refraction. To override for refraction alone, see the Transparency Environment control in the Extended Parameters rollout.
Use the check box to enable or disable this map.
Tip: You can use any map as the Raytrace environment -- including the Reflect/Refract map. Reflect/Refract map is often adequate for getting the required look, and it renders more quickly than raytracing the entire scene, especially if the Raytrace material is transparent. If you are using Raytrace material just to get the glass to look right on a car's headlight or on a lightbulb hanging in the middle of a room, turn off the raytracer and use an environment map instead.
Bump: This is the same as a standard material's bump map. Click the button to assign the map. Use the spinner to change the bump Amount.
Except for the wireframe controls, the controls in the Extended Parameters rollout for Raytrace material are specific to the Raytrace material.
The controls in this area are special effects. They are powerful, but you might need to use some experimentation to use them effectively.
Extra Lighting: Adds light that shines only on objects with the Raytrace material. You can view this as an ambient lighting color that you can control on a per-material basis, but don’t confuse it with the ambient absorbtion from the Basic Parameters rollout. By mapping this parameter, you can simulate radiosity -- the ambient light that results from reflected light in a scene.
You can also use a map for Extra Lighting to simulate the color bleeding that can result from radiosity. For example, in strong light a white shirt next to an orange wall will show a reflected orange color.
Translucency: Creates a translucent effect. The Translucency color is a non-directional diffuse reflection. The diffuse color on an object depends upon the angle between the surface normal and the position of the light source. Translucency doesn't care about the alignment of the surface normal. Because of this, the Translucency color appears as a back light. For thin objects, think of this as shining a light on the back of a piece of rice paper. You can cast shadows onto the back of the paper and see them projected through the paper – this works well with a projector light. On thicker objects, you can get some good wax effects.
Tip: A slight amount of Translucency can add to the realism of skin and eyes.
Fluorescence and Fluor. Bias: Create an effect similar to black light on a black light poster. The light from a black light is largely ultraviolet, outside the visible spectrum. Under black light, fluorescent paints flare or glow. The fluorescence in Raytrace material takes whatever light it sees in the scene, applies a bias curve to it, and then, regardless of the color of the lights in the scene, it illuminates the fluorescent material as if it were lit by white light. [PRECEDING SENTENCE NEEDS TO BE CLEARER – WHAT IS THE PURPOSE OF THE BIAS IF THE COLOR IS THEN IGNORED? I DON’T THINK SCOTT WROTE WHAT HE MEANT]
At 0.5, The Bias makes Fluorescence behave just like diffuse coloring. Bias values higher than 0.5 increase the flourescent effect. Bias values lower than 0.5 make the lighting in the scene have a lesser effect than it does on the diffuse color -- you can get some chromatic shifting effects with this. [FIRST ½ OF PREVIOUS SENTENCE MAKES NO SENSE AT ALL]
Tips: Full saturation and value for the Flourescence color help give the effect of commercial flourescent paints. Also, the Fluorescence color interacts with the Diffuse color, unless Diffuse is a neutral gray.
Size: Sets the size of the wire in wireframe mode. You can set either pixels (the default) or current units.
The controls in this area let you further tune transparency effects.
Transp. Environment (Transparency Environment): Similar to the environment map in Basic Parameters, but overrides the scene’s environment map for transparency (refraction) only. Transparent objects refract this map, while reflections still reflect the scene (or the Basic Parameters Environment map, if one is chosen).
Click the button to choose the Transparency Environment map. Use the check box to toggle the effect of the map.
The density controls are for transparent and translucent materials. If the material is opaque (the default), they have no effect.
Color: This is a transmission color based on thickness. While filter (Transparency) color tints objects behind the transparent object, the density color gives the appearance of color within the object itself, like tinted glass.
To use, first make sure the object is transparent. Click the color swatch to display the Color Selector and choose a color, then turn on the check box.
The Amount controls the amount of density color. It can range from zero to 1.0. Reducing this value reduces the density color effect. Default = 1.0.
A thin piece of tinted glass is mainly clear, while a thick piece of the same glass has more color. The Start and End controls help you simulate this effect. They are expressed in world units. Start is the position in the object where the density color begins to appear (default = 0.0). End is the position in the object where the density color reaches its full Amount value. To have a lighter effect, increase the End value. To have a heavier effect, reduce the End value.
The object must be at least as thick as the Start value before the density color is visible.
You can map this color component.
Fog: Density fog is also a thickness-based effect. It fills the object with a fog that is both opaque and self illuminated. The effect is like smoke trapped in a glass, or wax at the tip of a candle. Colored fog in tubular objects can resemble neon tubes.
To use, first make sure the object is transparent. Click the color swatch to display the Color Selector and choose a color, then turn on the check box.
The Amount controls the amount of density fog. It can range from zero to 1.0. Reducing this value reduces the density fog effect and makes the fog translucent. Default = 1.0.
The Start and End controls let you adjust the fog effect based on the object’s dimensions. They are expressed in world units. Start is the position in the object where the density fog begins to appear (default = 0.0). End is the position in the object where the density fog reaches its full Amount value. To have a lighter effect, increase the End value. To have a heavier effect, reduce the End value.
You can map this color component.
The controls in this rollout affect the operation of the raytracer itself. They can help you improve rendering performance.
These two toggles enable or disable raytracing of reflections or refractions for this material. If you are using the Raytrace material only for one purpose or the other, turning off the one you aren’t using can improve rendering time.
Raytrace Reflections: Turns raytracing of reflective objects on or off. Default = on.
Raytrace Refractions: Turns raytracing of transparent objects on or off. Default = on.
Reflect Falloff: Reflection falloff dims reflections to black at this distance. Default = 100.0.
Refract Falloff: Refraction falloff dims refractions to black at this distance. Default = 100.0.
Options: Click to display the Raytracer Options dialog.
The Raytracer Options dialog has a number of toggles that enable or disable raytrace features at the global or the local level.
Note: Use this dialog to enable antialiasing.
Global Parameters: Click to display the Global Raytracer Settings dialog.
This dialog controls recursion level, global antialiasing, and renderer acceleration.
Global Exclude: Click to display the global Exclude/Include dialog.
An object that is excluded globally is excluded from the raytracer for the entire scene. That is, it is excluded by all Raytrace materials and Raytrace maps in the scene.
Local Exclude: Click to display the local Exclude/Include dialog.
An object that is excluded locally is excluded from this material only.
Tip: Using exclusion lists is one of the best and simplest ways to speed up the raytracer.
The remaining controls in the Raytracer Controls rollout affect antialiasing, including blurring and defocusing. By default, these controls are disabled and the raytracer uses global, scene-wide settings.
Basically, you have four options for antialiasing.
The adaptive antialiaser can get pretty slow in cases where it has to do a lot of work, but by putting the time into it, it will produce some really nice, hyper-real stills.
Override Global Settings: The remainder of the Raytrace Controls rollout is disabled unless you turn on this toggle. Default = off.
Note: Regardless of the settings here, blurring, defocusing, and antialiasing will not work if the the antialiaser is turned off in the Raytracer Options dialog.
Copy Antialias Parameters: Let you copy antialiasing parameters from the global to the local level, or vice versa.
Global -> Local: Copies global antialiasing parameters to the local, material level.
Local -> Global: Copies the material’s local antialiasing parameters to the global, scene level.
Adaptive: Enables the adaptive anti-aliaser for this Raytrace material. Default = on.
Initial Rays: This is the initial number of rays cast per pixel. Default = 4.
Threshold: This determines the sensitivity of the adaption algorithm. It can range from 0 to 1, where 0 always casts the maximum number of rays and 1 always casts only the minimum number of rays. Default = 0.1.
Max. Rays (Maximum Rays): This is the maximum number of rays the algorithm will cast.
Blur Offset is similar to blur offset for Bitmap materials, while defocus is based on distance.
Blur Offset: Affects the sharpness or blurriness of the bitmap without regard to its distance from the view. You can use Blur Offset to soften or defocus the details of a reflection or refraction. The value is specified in pixels. Default = 0.0.
See Blur/Blur Offset for more information.
Blur Aspect: This is an aspect ratio that changes the shape of the blur. Usually you will not need to change it. Default = 1.0.
Blur Map: This lets you use a map to apply the blur offset value. That is, where the map is white, blur offset is fully applied, and where it is black, it is ignored. For example, if the map is a Checker map, blur offset is applied only in every other square. Values between black and white cause less blur.
Click the button to assign a blur offset map. Use the check box to enable or disable the map.
Defocusing: Defocusing is a blur based on distance. With Defocus, objects near the surface are not blurred, but objects farther away are blurred. The rays cast are spread as they leave the Raytrace material object's surface. Default = 0.0.
Defocus Aspect: This is an aspect ratio that changes the shape of the defocusing. Usually you will not need to change it. Default = 1.0.
Defocus Map: This lets you use a map to apply the defocus value. That is, where the map is white, defocus is fully applied, and where it is black, it is ignored. For example, if the map is a Checker map, defocus is applied only in every other square. Values between black and white cause less defocusing.
Click the button to assign a blur offset map. Use the check box to enable or disable the map.
As with a standard material, this rollout contains map buttons for mappable components of the Raytrace material.
The check box at the left enables or disables the map, and the Amount value controls the strength of the map in this material.
This rollout shows information about the creators of the Raytrace material, and the material’s version number.