| 11 |
|
] |
| 12 |
|
.B "{ sender.rad | - }" |
| 13 |
|
.B receivers.rad |
| 14 |
< |
.B "[ scene.rad .. ]" |
| 14 |
> |
.B "[ -i system.oct ]" |
| 15 |
> |
.B "[ system.rad .. ]" |
| 16 |
|
.SH DESCRIPTION |
| 17 |
|
.I Rfluxmtx |
| 18 |
|
samples rays uniformly over the surface given in |
| 20 |
|
and records rays arriving at surfaces in the file |
| 21 |
|
.I receivers.rad, |
| 22 |
|
producing a flux transfer matrix per receiver. |
| 23 |
< |
Additional scene surfaces are given in optional |
| 24 |
< |
.I scene.rad |
| 25 |
< |
files, which are compiled with the receivers into an octree sent to the |
| 23 |
> |
A system octree to which the receivers will be appended may be given with a |
| 24 |
> |
.I \-i |
| 25 |
> |
option following the receiver file. |
| 26 |
> |
Additional system surfaces may be given in one or more |
| 27 |
> |
.I system.rad |
| 28 |
> |
files, which are compiled before the receiver file into an octree sent to the |
| 29 |
|
.I rcontrib(1) |
| 30 |
|
program to do the actual work. |
| 31 |
|
If a single hyphen ('-') is given in place of the sender file, then |
| 68 |
|
.I vwrays(1). |
| 69 |
|
The sample count, unless set by the |
| 70 |
|
.I \-c |
| 71 |
< |
option, defaults to 10000 when a sender file is given, and 1 for pass-through mode. |
| 71 |
> |
option, defaults to 10000 when a sender file is given, or to 1 for pass-through mode. |
| 72 |
|
.SH VARIABLES |
| 73 |
|
The sender and receiver scene files given to |
| 74 |
|
.I rfluxmtx |
| 75 |
< |
contain controlling parameters in specal comments of the form: |
| 75 |
> |
contain controlling parameters in special comments of the form: |
| 76 |
|
.nf |
| 77 |
|
|
| 78 |
|
#@rfluxmtx variable=value .. |
| 85 |
|
.BI h =u |
| 86 |
|
Set hemisphere sampling to "uniform," meaning a single bin |
| 87 |
|
of (cosine-distributed) samples. |
| 88 |
< |
In the case of distant "source" primatives, this is the only |
| 88 |
> |
In the case of distant "source" primitives, this is the only |
| 89 |
|
sampling method that supports arbitrary receiver sizes. |
| 90 |
|
The other methods below require a full hemispherical source. |
| 91 |
|
.TP |
| 129 |
|
comprised of any number of subsurfaces, as in a triangle mesh or similar. |
| 130 |
|
The surface normal will be computed as the average of all the constituent |
| 131 |
|
subsurfaces. |
| 132 |
< |
The subsurfaces themselves must be planer, thus only |
| 132 |
> |
The subsurfaces themselves must be planar, thus only |
| 133 |
|
.I polygon |
| 134 |
|
and |
| 135 |
|
.I ring |
| 142 |
|
matrices) are identified by different modifier names. |
| 143 |
|
Though it may be counter-intuitive, receivers are often light sources, |
| 144 |
|
since samples end up there in a backwards ray-tracing system such as RADIANCE. |
| 145 |
+ |
When using local geometry, the overall aperture shape should be close to flat. |
| 146 |
+ |
Large displacements may give rise to errors due to a convex receiver's |
| 147 |
+ |
larger profile at low angles of incidence. |
| 148 |
|
.PP |
| 149 |
< |
Rays always eminate from the back side of the sender surface and arrive at the |
| 149 |
> |
Rays always emanate from the back side of the sender surface and arrive at the |
| 150 |
|
front side of receiver surfaces. |
| 151 |
|
In this way, a receiver surface may be reused as a sender in a subsequent |
| 152 |
|
.I rfluxmtx |
| 157 |
|
To generate a flux transfer matrix connecting input and output apertures |
| 158 |
|
on a light pipe: |
| 159 |
|
.IP "" .3i |
| 160 |
< |
rcontrib int_aperture.rad ext_aperture.rad lpipe.rad > lpipe.mtx |
| 160 |
> |
rfluxmtx int_aperture.rad ext_aperture.rad lpipe.rad > lpipe.mtx |
| 161 |
|
.SH AUTHOR |
| 162 |
|
Greg Ward |
| 163 |
|
.SH "SEE ALSO" |
