mental ray Architectural and Design Visualization Shader Library

2.5 Detailed Description of Material Parameters 21Glossiness of 1.0 (left), 0.5 (center) and 0.25 (right)The refl samples parameters defines the maximum 7 number of samples (rays) are shot tocreate the glossy reflections. Higher values renders slower but create a smoother result. Lowervalues render faster but create a grainier result. Generally 32 is enough for most cases.There are two special cases:• Since a refl gloss value of 1.0 equals a “perfect mirror” it is meaningless to shootmultiple rays for this case, hence only one reflection ray is shot.• If the refl samples value is set to 0, the reflections will be “perfect mirror” (andonly one ray shot) regardless of the actual value of refl gloss . This can be usedto boost performance for surfaces with very weak reflections. The highlight still obeysthe glossiness value.Metallic objects actually influence the color of their reflection whereas other materials do not.For example, a gold bar will have gold colored reflections, whereas a red glass orb does nothave red reflections. This is supported through the refl is metal option.• When off, the refl color parameter defines the color and reflectivity parameter(together with the BRDF settings) the intensity and colors of reflections.• When on, the diffuse parameter defines the color of reflections, and reflectivityparameter sets the “weight” between diffuse reflections and glossy (metallic) reflections.7 The actual number is adaptive and depends on reflectivity, ray importance, and many other factors.