| 1 |
|
.\" RCSid "$Id$" |
| 2 |
< |
.TH RTCONTRIB 1 5/25/05 RADIANCE |
| 2 |
> |
.TH RCONTRIB 1 5/25/05 RADIANCE |
| 3 |
|
.SH NAME |
| 4 |
|
rcontrib - compute contribution coefficients in a RADIANCE scene |
| 5 |
|
.SH SYNOPSIS |
| 42 |
|
.br |
| 43 |
|
.B "rcontrib [ options ] \-defaults" |
| 44 |
|
.SH DESCRIPTION |
| 45 |
< |
.I Rtcontrib |
| 45 |
> |
.I Rcontrib |
| 46 |
|
computes ray coefficients |
| 47 |
|
for objects whose modifiers are named in one or more |
| 48 |
|
.I \-m |
| 61 |
|
If the |
| 62 |
|
.I \-n |
| 63 |
|
option is specified with a value greater than 1, multiple |
| 64 |
– |
.I rtrace |
| 64 |
|
processes will be used to accelerate computation on a shared |
| 65 |
|
memory machine. |
| 66 |
|
Note that there is no benefit to using more processes |
| 101 |
|
option tells |
| 102 |
|
.I rcontrib |
| 103 |
|
how many rays to accumulate for each record. |
| 104 |
< |
The default value is 1, meaning a full record will be produced for |
| 104 |
> |
The default value is one, meaning a full record will be produced for |
| 105 |
|
each input ray. |
| 106 |
< |
For values greater than 1, contributions will be averaged together |
| 106 |
> |
For values greater than one, contributions will be averaged together |
| 107 |
|
over the given number of input rays. |
| 108 |
|
If set to zero, only a single record will be produced at the very |
| 109 |
|
end, corresponding to the sum of all rays given on the input |
| 113 |
|
to sum RGB values together, but is much more efficient. |
| 114 |
|
Using this option, it is possible to reverse sampling, sending rays from |
| 115 |
|
a parallel source such as the sun to a diffuse surface, for example. |
| 116 |
< |
Note that output flushing via zero-direction rays is disabled |
| 117 |
< |
for accumulated evaluations. |
| 116 |
> |
Note that output flushing via zero-direction rays is disabled with |
| 117 |
> |
.I \-c |
| 118 |
> |
set to zero. |
| 119 |
|
.PP |
| 120 |
|
The output of |
| 121 |
|
.I rcontrib |
| 128 |
|
can be used to compute arbitrary input-output relationships in optical |
| 129 |
|
systems, such as luminaires, light pipes, and shading devices. |
| 130 |
|
.PP |
| 131 |
< |
.I Rtcontrib |
| 132 |
< |
calls |
| 133 |
< |
.I rtrace(1) |
| 134 |
< |
with the \-oTW (or \-oTV) option to calculate the daughter ray |
| 135 |
< |
contributions for each input ray, and the output tallies |
| 136 |
< |
are sent to one or more destinations according to the given |
| 131 |
> |
.I Rcontrib |
| 132 |
> |
sends the accumulated rays tallies |
| 133 |
> |
to one or more destinations according to the given |
| 134 |
|
.I \-o |
| 135 |
|
specification. |
| 136 |
|
If a destination begins with an exclamation mark ('!'), then |
| 159 |
|
specification if present. |
| 160 |
|
The actual bin number is computed at run time based on ray direction |
| 161 |
|
and surface intersection, as described below. |
| 162 |
< |
If the number of bins is known in advance, it should be specified with the |
| 162 |
> |
The number of bins must be specified in advance with the |
| 163 |
|
.I \-bn |
| 164 |
|
option, and this is critical for output files containing multiple values |
| 165 |
|
per record. |
| 169 |
|
or |
| 170 |
|
.I \-e |
| 171 |
|
option. |
| 172 |
< |
Since bin numbers start from 0, the bin count is always equal to |
| 173 |
< |
the last bin plus 1. |
| 174 |
< |
Set the this value to 0 if the bin count is unknown (the default). |
| 172 |
> |
Since bin numbers start from zero, the bin count is always equal to |
| 173 |
> |
the last bin plus one. |
| 174 |
> |
Set the this value to zero if the bin count is unknown (the default). |
| 175 |
|
The most recent |
| 176 |
|
.I \-b, |
| 177 |
|
.I \-bn |
| 186 |
|
.I \-y |
| 187 |
|
if the |
| 188 |
|
.I \-c |
| 189 |
< |
is 0, when they control the resolution string |
| 189 |
> |
is zero, when they control the resolution string |
| 190 |
|
produced in the corresponding output. |
| 191 |
|
.PP |
| 192 |
|
If a |
| 193 |
|
.I \-b |
| 194 |
|
expression is defined for a particular modifier, |
| 195 |
|
the bin number will be evaluated at run time for each |
| 196 |
< |
ray contribution from |
| 200 |
< |
.I rtrace. |
| 196 |
> |
ray contribution. |
| 197 |
|
Specifically, each ray's world intersection point will be assigned to |
| 198 |
|
the variables Px, Py, and Pz, and the normalized ray direction |
| 199 |
|
will be assigned to Dx, Dy, and Dz. |
