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.\" RCSid "$Id$" |
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.TH RPIECE 1 5/25/05 RADIANCE |
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.TH RTCONTRIB 1 5/25/05 RADIANCE |
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.SH NAME |
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rtcontrib - compute contributions in a RADIANCE scene |
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rtcontrib - compute contribution coefficients in a RADIANCE scene |
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.SH SYNOPSIS |
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.B rtcontrib |
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[ |
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rtrace options |
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] |
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.B octree |
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.br |
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.B "rtcontrib [ options ] \-defaults" |
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.SH DESCRIPTION |
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.I Rtcontrib |
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computes ray contributions (i.e., color coefficients) |
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These modifiers are usually materials associated with |
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light sources or sky domes, and must directly modify some geometric |
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primitives to be considered in the output. |
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The computed contributions can then be used in linear combination to |
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The output of |
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.I rtcontrib |
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has many potential uses. |
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Source contributions can be used as components in linear combination to |
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reproduce any desired variation, e.g., simulating lighting controls or |
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changing sky conditions via daylight coefficients. |
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More generally, |
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.I rtcontrib |
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may be used to compute input-output relationships in optical |
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systems, such as light pipes and shading devices. |
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can be used to compute arbitrary input-output relationships in optical |
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systems, such as luminaires, light pipes, and shading devices. |
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.PP |
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.I Rtcontrib |
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calls |
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.I rtrace(1) |
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to calculate the contributions for each input ray, |
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and the output tallies are sent to one or more files according to the |
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with the -oTW option to calculate the daughter ray |
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contributions for each input ray, and the output tallies |
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are sent to one or more files according to the given |
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.I \-o |
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specification. |
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If an output specification contains a "%s" format, this will be |
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a "bin number" within each object if finer resolution is needed, and |
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this will be applied to a "%d" format in the output file |
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specification if present. |
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(The actual bin number is computed at run time based on ray direction |
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and surface intersection, as described below.)\0 |
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The actual bin number is computed at run time based on ray direction |
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and surface intersection, as described below. |
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The most recent |
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.I \-b |
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and |
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will be assigned to Dx, Dy, and Dz. |
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These parameters may be combined with definitions given in |
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.I \-e |
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options and files read in |
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arguments and files read using the |
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.I \-f |
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options, to compute the bin, which will be |
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option. |
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The computed bin value will be |
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rounded to the nearest whole number. |
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This mechanism allows the user to define precise regions or directions |
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they wish to accumulate, such as the Tregenza sky discretization, |
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which would be otherwise impossible to specify |
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as a set of RADIANCE primitives. |
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The rules and predefined functions available for these expressions are |
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described in the |
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.I rcalc(1) |
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man page. |
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Unlike |
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.I rcalc, |
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.I rtcontrib |
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will search the RADIANCE library directories for each file given in a |
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.I \-f |
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option. |
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(No search takes place if a file name begins with a '.', '/' or '~' |
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character.)\0 |
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.PP |
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If no |
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.I \-o |
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.IP "" .2i |
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rtcontrib -b tbin -o sky.dat -m skyglow -b 0 -o ground.dat -m groundglow |
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@render.opt -f tregenza.cal scene.oct < test.dat |
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.SH ENVIRONMENT |
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RAYPATH path to search for -f files |
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.SH AUTHOR |
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Greg Ward |
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.SH "SEE ALSO" |
