| 13 |
|
][ |
| 14 |
|
.B "\-t pctcull" |
| 15 |
|
][ |
| 16 |
+ |
.B "\-n nss" |
| 17 |
+ |
][ |
| 18 |
+ |
.B "\-s thresh" |
| 19 |
+ |
][ |
| 20 |
|
.B "\-l maxlobes" |
| 21 |
< |
] |
| 18 |
< |
[ |
| 21 |
> |
][ |
| 22 |
|
.B "bsdf.sir .." |
| 23 |
|
] |
| 24 |
|
.br |
| 35 |
|
][ |
| 36 |
|
.B "\-t pctcull" |
| 37 |
|
][ |
| 38 |
+ |
.B "\-n nss" |
| 39 |
+ |
][ |
| 40 |
+ |
.B "\-s thresh" |
| 41 |
+ |
][ |
| 42 |
|
.B "{+|-}forward" |
| 43 |
|
][ |
| 44 |
|
.B "{+|-}backward" |
| 66 |
|
The |
| 67 |
|
.I \-a |
| 68 |
|
option turns off reciprocity averaging for isotropic scattering or anisotropic reflection. |
| 69 |
< |
Normally on (+a), this ensures that the tensor BRDF obeys Helmholtz reciprocity. |
| 70 |
< |
However, in certain rare cases, reciprocity averaging can cause unwanted noise in the output. |
| 69 |
> |
Normally on (+a), this ensures that each tensor-tree hemisphere follows symmetry |
| 70 |
> |
implied by Helmholtz reciprocity, and is designed to reduce noise in measured data. |
| 71 |
> |
However, for some data, reciprocity averaging can actually make the output worse. |
| 72 |
|
.PP |
| 73 |
|
The maximum resolution of the tensor tree may be controlled by the |
| 74 |
|
.I \-g |
| 85 |
|
Setting this parameter to -1 turns culling off entirely, which may be |
| 86 |
|
useful for comparisons. |
| 87 |
|
.PP |
| 88 |
+ |
The |
| 89 |
+ |
.I \-n |
| 90 |
+ |
option controls the number of super-samples to send in patches whose |
| 91 |
+ |
difference to its neighbors exceeds some threshold. |
| 92 |
+ |
The default number of super-samples is 256. |
| 93 |
+ |
The difference threshold for super-sampling is controlled by the |
| 94 |
+ |
.I \-s |
| 95 |
+ |
option, and defaults to 0.35. |
| 96 |
+ |
.PP |
| 97 |
|
The first invocation form takes a intermediate scattering representation |
| 98 |
|
as produced by |
| 99 |
|
.I pabopto2bsdf(1) |
| 109 |
|
interpolated radial basis function. |
| 110 |
|
The default value is 15000, which generally keeps the interpolation tractable. |
| 111 |
|
Setting the value to 0 turns off this limit. |
| 112 |
+ |
Parameter options may be altered between input files, in case a different |
| 113 |
+ |
resolution or culling percentage is indicated for transmission versus |
| 114 |
+ |
reflection for example. |
| 115 |
|
.PP |
| 116 |
|
In the second invocation form, |
| 117 |
|
.I bsdf2ttree |
| 138 |
|
options, and should obey both Helmholtz reciprocity and |
| 139 |
|
integrate to less than 1 over each projected incident hemisphere |
| 140 |
|
for energy conservation. |
| 141 |
+ |
The variable and function definitions in each |
| 142 |
+ |
.I \-f source |
| 143 |
+ |
file are read and compiled from the RADIANCE library where it is found. |
| 144 |
|
If the |
| 145 |
|
.I \-t3 |
| 146 |
|
option is specified, the defined function is assumed to be isotropic. |
| 165 |
|
is recommended when rays will be impinging from either side. |
| 166 |
|
.SH EXAMPLE |
| 167 |
|
To take two components of an intermediate BSDF representation and create |
| 168 |
< |
a high-resolution tensor tree with 85% culling: |
| 168 |
> |
a high-resolution tensor tree with 85% culling on transmission and 95% |
| 169 |
> |
culling on reflection: |
| 170 |
|
.IP "" .2i |
| 171 |
< |
bsdf2ttree -g 7 -t 85 transmitted.sir reflected.sir > combined.xml |
| 171 |
> |
bsdf2ttree -g 7 -t 85 transmitted.sir -t 95 reflected.sir > combined.xml |
| 172 |
|
.PP |
| 173 |
|
To create a low-res BSDF corresponding to a one-sided, |
| 174 |
|
isotropic Phong distribution: |
| 175 |
|
.IP "" .2i |
| 176 |
|
bsdf2ttree -g 5 -t3 -e 'phong(ix,iy,iz,ox,oy,oz) = if(iz, .1+((iz+oz)/sqrt((ix+ox)^2+(iy+oy)^2+(iz+oz)^2))^50, 0)' phong > phong.xml |
| 177 |
+ |
.SH ENVIRONMENT |
| 178 |
+ |
RAYPATH the directories to check for auxiliary files. |
| 179 |
|
.SH AUTHOR |
| 180 |
|
Greg Ward |
| 181 |
|
.SH "SEE ALSO" |
| 182 |
< |
bsdf2klems(1), icalc(1), genBSDF(1), pkgBSDF(1), rcontrib(1), |
| 183 |
< |
rfluxmtx(1), wrapBSDF(1) |
| 182 |
> |
bsdf2klems(1), icalc(1), genBSDF(1), pabopto2bsdf(1), pabopto2xyz(1), |
| 183 |
> |
pkgBSDF(1), rcontrib(1), rfluxmtx(1), wrapBSDF(1) |
