Computer-aided design or Computer-aided drafting. All are functions of four angles (two incident and two scattered) and return units of 1/steradian. The bidirectional reflectance-transmittance distribution function (BRTDF) is also known as the bidirectional scattering distribution function (BSDF), which describes the way light is transmitted and reflected by a locally planar surface. (Compare with Constructive Solid Geometry.), BRTDF, BSDF The bidirectional reflectance distribution function (BRDF) is a mathematical function that describes the way light is reflected from a point on a locally planar surface. representation (B-rep) A method for representing 3D objects by their surface boundaries, which may be open or closed but do not necessarily have any relationship to one another. In three dimensions, a Bezier surface is specified by sixteen points near the desired surface patch. curve A cubic polynomial formulation whose parameters specify four points near the desired curve shape. A cubic polynomial formulation with the potential for C(2) continuity, which provides a visually smooth curve, even though it does not generally pass through any of its control points. The angle about the surface normal relative to some standard direction, such as south.
#DOES MAKE VISUALS GREAT AGAIN WORK WITH RADIANCE V MANUAL#
(See the xform manual page.) The American Standard for Character Information Interchange-the standard encoding of alphanumeric and control characters as integers between 0 and 127. transform A type of transform in which an object is repeated at multiple positions.
A primitive type that provides a rudimentary CSG subtraction operation, removing one solid from another. The usual antialiasing method used in Radiance is called supersampling. Any technique that reduces sampling artifacts in the final image, particularly "jaggies" caused by abrupt changes in scene geometry. Examples of anisotropic reflection include varnished wood with noticeable grain, brushed metal, and combed hair. (See Chapter 9 for details.) A reflection or transmission distribution function (BRTDF) that varies with rotation about the surface normal. path The sequence of view positions and directions in a walk-through animation. Scene animation occurs when the actual scene geometry, materials, and/or lighting are changing with each frame. (Compare to hemispherical fisheye perspective.) (walk-through, scene animation) A walk-through animation is a sequence of images rendered from the same scene description and lighting but from a changing view point, direction, and so on. (See the CD-ROM section on File Formats for details.) fisheye perspective A perspective view projection in which the angle from the central view direction is proportional to the distance from the center of the image. file A binary file in which indirect irradiance values and their gradients are stored for reuse in other calculations. It is more accurately referred to as a diffuse interreflection calculation. The ambient calculation in Radiance replaces this global average with local averages based on indirect irradiance computations. It is specified in SI units of watts per steradian per square meter for red, green, and blue. (value, calculation) An ambient value approximates the global average of radiance over all directions and all points of interest in a scene. The angle between a vector and the surface horizon, which is equal to 90 degrees minus the polar angle. In a Radiance scene description, an alias associates a new identifier (and possibly a new modifier) with a previously defined primitive. A method that is fully described in a procedure or computer program. An albedo of 1 means that the particles do not absorb light. An albedo of 0 means that the particles do not scatter light. The unitless ratio between the scattering coefficient and the extinction coefficient for a participating medium. sampling The automatic sending of additional samples in cases where the default number of samples is deemed inadequate to achieve the desired accuracy. In Radiance, the absorption is given separately for red, green, and blue. In SI units, this is specified as a fraction per meter. Glossary coefficient The fraction of light absorbed per unit distance in a participating medium. Glossary for Rendering with Radiance Rendering with Radiance
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