These attributes control the appearance of glows produced from light reflecting off surfaces, or from surface incandescence. Special Effects attributes are available for Anisotropic, Blinn, Lambert, Phong, and PhongE material types.
You can control the mask value for individual objects. Matte Opacity attributes are available for Anisotropic, Blinn, Lambert, Layered Shader, Phong, PhongE, Shading Map and Use Background material types.
When you select the Black Hole mode, the matte channel for the material is set to 0 (fully transparent). This creates a black hole in the alpha output where the object assigned shader renders the matte ‘knocked out’.
This value depends on which Matte Opacity Mode is selected (Opacity Gain or Solid Matte). For example, for Opacity Gain, the Matte Opacity value indicates the multiplier amount for the alpha channel. The default is 1, which means that any opaque material registers an unaffected alpha value.
The amount that light rays bend when passing through a transparent object. A Refractive Index value of 1 does not bend light rays at all, so you need to set the index value higher than 1. Refractive Index values for common materials are: glass (1.6), air (1), water (1.333), crystal (2), diamond (2.417). The valid range is 0.01 to infinity. The slider range is 0.01 to 3, but you can type in a higher value. The default setting is 1.6.
The maximum number of times the surface allows a light ray to be refracted. For example, if the Refraction Limit value is 10, the surface refracts light rays that have previously been refracted and, or reflected (off itself or off other surfaces) 9 times or less; the surface does not refract light rays that have previously been refracted and, or reflected 10 or more times. The valid range is 0 to infinity. The slider range is 0 to 10. The default value is 6. Increasing this value may significantly increase render times.
You must also consider the Render Settings window Raytracing refractions attribute too. Maya uses the lower value of the 2. For instance, if your limit is set to 9 on the material and 6 in the Render Settings window, a value of 6 is be used. See also, Reflection Limit
The physical property Total Internal Reflection (TIR) can make some transparent objects appear not to refract light. This is caused by light rays reflecting inside the thickness of the object. If this occurs, increasing Refraction Limit has no effect because the Reflection Limit is stopping light rays before they can exit the surface. However, because TIR is a real-world property, you may want to keep this effect.
The maximum number of times the surface allows a light ray to be reflected. For example, if the Reflection Limit value is 4, the surface reflects light rays previously reflected (off itself or off other surfaces) 3 times or less; the surface does not reflect light rays previously reflected 4 or more times. The valid range is 0 to infinity. The slider range is 0 to 10. The default value is 1.
Set the Reflection Limit value according to the material’s Reflectivity value. For example, if the Reflectivity value is between 0 and 0.5, set the Reflection Limit value between 1 and 2. If the Reflectivity value is between 0.5 and 1, set the Reflection Limit value between 2 and 5.
High values for Reflection Limit greatly increase rendering time. Test render the scene using various settings, and use the lowest values that give you acceptable results. Even highly reflective surfaces rarely need a Reflection Limit value as high as 10 or more.
You must also consider the Render Settings window Raytracing Reflection attribute too. Maya uses the lower value of the 2. For instance, if your limit is set to 5 on the material and 1 in the Render Settings window, a value of 1 is used. See also Reflection Limit.
Reduce this value to avoid highlight aliasing artifacts produced in reflections during raytracing because of very thin or small highlights. Maya adds Reflection Specularity to each material to control the contribution of the specular highlights in reflections. The valid range is 0 to 1. The default is 1 (full contribution).
Using Surface Thickness does not produce the same results as building a surface with actual thickness—the effect works well when the edges of the surface are not visible (for example, closed surfaces, or bounded shapes, like a car windshield).
Shadows of transparent objects are brighter in the center, simulating a light’s focus. A setting of 0 results in constant intensity shadows. The focusing increases as the parameter increases from 0 to 1. The default value is 0.5. The amount of attenuation for a given light ray depends on the angle between the light ray and the surface normal of the transparent object: the greater the angle, the greater the attenuation. To turn off the shadow attenuation completely, set shadow attenuation to 0.
Preview rendered materials and textures in the scene views. You can select specific channels to view and determine the hardware render quality. Hardware Texturing attributes are available for Anisotropic, Blinn, Lambert, Phong, and PhongE material types.
This drop-down list displays the mapped attributes for a texture-mapped material. This can be useful if you map several textures to a material and want to view them one by one. If, for example, you map a Checker texture to a Blinn material’s Color attribute, and a File texture to its Specularity attribute, you can select Color from the drop-down list to display only the Checker texture in the view. The top of a material’s Attribute Editor also provides tabs for each texture so you can select and edit the texture and watch the results in the view.
The Combined Textures option can be used to process the entire shader into one texture for hardware display purposes. It allows the entire shader to be previewed on the applied object and not just single channels, for example, color and incandescence.
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