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.\" RCSid "$Id" |
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.\" RCSid "$Id$" |
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.TH RTRACE 1 10/17/97 RADIANCE |
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.SH NAME |
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rtrace - trace rays in RADIANCE scene |
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.IP |
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v value (radiance) |
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.IP |
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V contribution (radiance) |
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.IP |
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w weight |
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.IP |
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W color coefficient |
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.IP |
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l effective length of ray |
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.IP |
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L first intersection distance |
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.IP |
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m modifier name |
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.IP |
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M material name |
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.IP |
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~ tilde (end of trace marker) |
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.IP |
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If the letter 't' appears in |
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.I spec, |
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then the fields following will be printed for every ray traced, |
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not just the final result. |
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If the capital letter 'T' is given instead of 't', then all rays will |
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be reported, including shadow testing rays to light sources. |
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Spawned rays are indented one tab for each level. |
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The tilde marker ('~') is a handy way of differentiating the final ray |
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value from daughter values in a traced ray tree, and usually appears |
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right before the 't' or 'T' output flags. |
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E.g., |
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.I \-ov~TmW |
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will emit a tilde followed by a tab at the end of each trace, |
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which can be easily distinguished even in binary output. |
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.IP |
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Note that there is no space between this option and its argument. |
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.TP |
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.BI -te \ mat |
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.BI -te \ mod |
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Append |
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< |
.I mat |
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.I mod |
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to the trace exclude list, |
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so that it will not be reported by the trace option |
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.I (\-o*t*). |
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Any ray striking an object having |
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.I mat |
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.I mod |
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as its modifier will not be reported to the standard output with |
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the rest of the rays being traced. |
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This option has no effect unless the 't' option has been given as |
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part of the output specifier. |
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Any number of excluded materials may be given, but each |
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This option has no effect unless either the 't' or 'T' |
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option has been given as part of the output specifier. |
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Any number of excluded modifiers may be given, but each |
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must appear in a separate option. |
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.TP |
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.BI -ti \ mat |
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.BI -ti \ mod |
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Add |
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.I mat |
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.I mod |
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to the trace include list, |
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so that it will be considered during the indirect calculation. |
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so that it will be reported by the trace option. |
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The program can use either an include list or an exclude |
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list, but not both. |
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.TP |
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.BI -tE \ file |
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Same as |
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.I \-te, |
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except read materials to be excluded from |
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except read modifiers to be excluded from |
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.I file. |
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The RAYPATH environment variable determines which directories are |
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searched for this file. |
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The material names are separated by white space in the file. |
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The modifier names are separated by white space in the file. |
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.TP |
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.BI -tI \ file |
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Same as |
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.I \-ti, |
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except read materials to be included from |
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except read modifiers to be included from |
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.I file. |
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.TP |
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.BR \-i |
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This option is especially useful in |
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conjunction with ximage(1) for computing illuminance at scene points. |
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.TP |
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.BR \-u |
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Boolean switch to control uncorrelated random sampling. |
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When "off", a low-discrepancy sequence is used, which reduces |
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variance but can result in a brushed appearance in specular highlights. |
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When "on", pure Monte Carlo sampling is used in all calculations. |
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.TP |
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.BR \-I |
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Boolean switch to compute irradiance rather than radiance, |
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with the input origin and direction interpreted instead |
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.I res. |
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The output will be flushed after every |
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.I res |
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input rays. |
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input rays if |
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.I \-y |
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is set to zero. |
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A value of one means that every ray will be flushed, whatever |
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the setting of |
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.I \-y. |
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A value of zero means that no output flushing will take place. |
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.TP |
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.BI -y \ res |
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.I \-f |
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option, above.) |
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.TP |
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.BI -n \ nproc |
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Execute in parallel on |
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.I nproc |
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local processes. |
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This option is incompatible with the |
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.I \-P |
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and |
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.I \-PP, |
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options. |
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Multiple processes also do not work properly with ray tree output |
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using any of the |
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.I \-o*t* |
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options. |
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There is no benefit from specifying more processes than there are |
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cores available on the system or the |
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.I \-x |
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setting, which forces a wait at each flush. |
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.TP |
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.BI -dj \ frac |
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Set the direct jittering to |
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.I frac. |
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.I Getinfo(1) |
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may be used to print out this information. |
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.TP |
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.BI -ae \ mat |
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.BI -ae \ mod |
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Append |
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< |
.I mat |
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> |
.I mod |
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to the ambient exclude list, |
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so that it will not be considered during the indirect calculation. |
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This is a hack for speeding the indirect computation by |
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ignoring certain objects. |
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Any object having |
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.I mat |
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.I mod |
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as its modifier will get the default ambient |
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level rather than a calculated value. |
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Any number of excluded materials may be given, but each |
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Any number of excluded modifiers may be given, but each |
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must appear in a separate option. |
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.TP |
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< |
.BI -ai \ mat |
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.BI -ai \ mod |
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Add |
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< |
.I mat |
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> |
.I mod |
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to the ambient include list, |
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so that it will be considered during the indirect calculation. |
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The program can use either an include list or an exclude |
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.BI -aE \ file |
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Same as |
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.I \-ae, |
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except read materials to be excluded from |
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except read modifiers to be excluded from |
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.I file. |
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The RAYPATH environment variable determines which directories are |
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searched for this file. |
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The material names are separated by white space in the file. |
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> |
The modifier names are separated by white space in the file. |
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.TP |
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.BI -aI \ file |
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Same as |
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.I \-ai, |
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except read materials to be included from |
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except read modifiers to be included from |
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.I file. |
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.TP |
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.BI -me " rext gext bext" |
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.TP |
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.BI -lr \ N |
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Limit reflections to a maximum of |
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.I N. |
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.I N, |
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if N is a positive integer. |
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If |
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.I N |
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is zero or negative, then Russian roulette is used for ray |
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termination, and the |
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.I -lw |
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setting (below) must be positive. |
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If N is a negative integer, then this sets the upper limit |
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of reflections past which Russian roulette will be used. |
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In scenes with dielectrics and total internal reflection, |
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a setting of 0 (no limit) may cause a stack overflow. |
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.TP |
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.BI -lw \ frac |
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Limit the weight of each ray to a minimum of |
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.I frac. |
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During ray-tracing, a record is kept of the final contribution |
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a ray would have to the image. |
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If it is less then the specified minimum, the ray is not traced. |
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During ray-tracing, a record is kept of the estimated contribution |
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(weight) a ray would have in the image. |
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If this weight is less than the specified minimum and the |
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.I -lr |
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setting (above) is positive, the ray is not traced. |
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Otherwise, Russian roulette is used to |
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continue rays with a probability equal to the ray weight |
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divided by the given |
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.I frac. |
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.TP |
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.BR -ld |
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Boolean switch to limit ray distance. |
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.SH EXAMPLES |
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To compute radiance values for the rays listed in samples.inp: |
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.IP "" .2i |
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rtrace -ov scene.oct < samples.inp > radiance.out |
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rtrace \-ov scene.oct < samples.inp > radiance.out |
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.PP |
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To compute illuminance values at locations selected with the 't' |
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command of |
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.I ximage(1): |
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.IP "" .2i |
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ximage scene.pic | rtrace -h -x 1 -i scene.oct | rcalc -e '$1=47.4*$1+120*$2+11.6*$3' |
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ximage scene.hdr | rtrace \-h \-x 1 \-i scene.oct | rcalc \-e '$1=47.4*$1+120*$2+11.6*$3' |
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.PP |
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To record the object identifier corresponding to each pixel in an image: |
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.IP "" .2i |
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vwrays -fd scene.pic | rtrace -fda `vwrays -d scene.pic` -os scene.oct |
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vwrays \-fd scene.hdr | rtrace \-fda `vwrays \-d scene.hdr` \-os scene.oct |
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.PP |
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To compute an image with an unusual view mapping: |
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.IP "" .2i |
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< |
cnt 640 480 | rcalc -e 'xr:640;yr:480' -f unusual_view.cal | rtrace |
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-x 640 -y 480 -fac scene.oct > unusual.pic |
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cnt 480 640 | rcalc \-e 'xr:640;yr:480' \-f unusual_view.cal | rtrace |
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\-x 640 \-y 480 \-fac scene.oct > unusual.hdr |
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.SH ENVIRONMENT |
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RAYPATH the directories to check for auxiliary files. |
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.SH FILES |
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/usr/tmp/rtXXXXXX common header information for picture sequence |
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/tmp/rtXXXXXX common header information for picture sequence |
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.SH DIAGNOSTICS |
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If the program terminates from an input related error, the exit status |
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will be 1. |
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Greg Ward |
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.SH "SEE ALSO" |
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getinfo(1), lookamb(1), oconv(1), pfilt(1), pinterp(1), |
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pvalue(1), rpict(1), rview(1), vwrays(1), ximage(1) |
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pvalue(1), rpict(1), rtcontrib(1), rvu(1), vwrays(1), ximage(1) |
