47 lines
1.6 KiB
TeX
47 lines
1.6 KiB
TeX
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\subsection{Surface scattering models}
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Surface scattering models describe the way in which light reflects
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from surfaces in the scene. Even slight adjustments to such a description
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can significantly change the appearance of a rendering.
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To achieve realistic results, Mitsuba comes with a library of
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both general-purpose models (smooth or rough glass, metal, plastic, ..) and
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more specialized models (woven cloth, masks, ..).
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Throughout the documentation and within the scene description language,
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the word \emph{BSDF} is used synonymously with the term ``surface
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scattering model''. This is an abbreviation for
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\emph{Bidirectional Scattering Distribution Function}, a more
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precise technical description of the model's properties.
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In Mitsuba, BSDFs are assigned to \emph{shapes}, which
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describe the visible surfaces in the scene. In the scene
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description language, this assignment must
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either be performed by nesting BSDFs within shapes,
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or they can be named and then later referenced
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by by name.
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The following fragment shows an example of both kinds of usages:
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\begin{xml}
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<scene>
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<!-- Creating a named BSDF for later use -->
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<bsdf type=".. BSDF type .." id="myNamedMaterial">
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<!-- BSDF parameters go here -->
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</bsdf>
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<shape type="sphere">
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<!-- Example of referencing a named material -->
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<ref id="myNamedMaterial"/>
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</shape>
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<shape type="sphere">
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<!-- Example of using an unnamed material -->
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<bsdf type=".. BSDF type ..">
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<!-- BSDF parameters go here -->
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</bsdf>
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</shape>
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</scene>
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\end{xml}
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It is generally more economical to use named BSDFs when they
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are used in several places, since this reduces Mitsuba's internal
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memory usage.
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