| 60 |
|
.IP "\fB\-apC \fIfile nphotons\fR" |
| 61 |
|
Generate a contribution photon map containing approximately |
| 62 |
|
\fInphotons\fR photons, and output to file \fIfile\fR. This may then be |
| 63 |
< |
used by \fIrcontrib(1)\fR to compute light source contributions. |
| 63 |
> |
used by \fIrcontrib(1)\fR to compute light source contributions. When used |
| 64 |
> |
with \fIrtrace(1)\fR or \fIrpict(1)\fR, contribution photon maps behave as |
| 65 |
> |
regular global photon maps and yield cumulative contributions from all light |
| 66 |
> |
sources. |
| 67 |
|
.IP |
| 68 |
|
With this option, \fImkpmap\fR uses a modified photon distribution |
| 69 |
|
algorithm that ensures all light sources contribute approximately the |
| 84 |
|
photon flux; the remaining photons are discarded as their contributions |
| 85 |
|
have been accounted for. |
| 86 |
|
.IP |
| 87 |
< |
This obviates the explicit irradiance |
| 88 |
< |
evaluation by \fIrpict(1), rtrace(1)\fR and \fIrvu(1)\fR, thus providing |
| 89 |
< |
a speedup at the expense of accuracy. The resulting error is tolerable |
| 90 |
< |
if the indirect illumination has a low gradient, as is usually the case |
| 88 |
< |
with diffuse illumination. |
| 87 |
> |
This obviates the explicit irradiance evaluation by \fIrpict(1), |
| 88 |
> |
rtrace(1)\fR and \fIrvu(1)\fR, thus providing a speedup at the expense of |
| 89 |
> |
accuracy. The resulting error is tolerable if the indirect illumination has |
| 90 |
> |
a low gradient, as is usually the case with diffuse illumination. |
| 91 |
|
|
| 92 |
|
.IP "\fB\-apD \fIpredistrib\fR" |
| 93 |
|
Photon predistribution factor; this is the fraction of \fInphotons\fR |
| 95 |
|
remaining number of photons to emit in the main pass to approximately |
| 96 |
|
yield a photon map of size \fInphotons\fR. |
| 97 |
|
.IP |
| 98 |
< |
Setting this too high may |
| 99 |
< |
yield more than \fInphotons\fR in the initial pass with highly |
| 100 |
< |
reflective geometry. Note that this value may exceed 1, which may be |
| 99 |
< |
useful if the resulting photon map size greatly deviates from |
| 98 |
> |
Setting this too high may yield more than \fInphotons\fR in the initial pass |
| 99 |
> |
with highly reflective geometry. Note that this value may exceed 1, which |
| 100 |
> |
may be useful if the resulting photon map size greatly deviates from |
| 101 |
|
\fInphotons\fR with a very low average reflectance. |
| 102 |
|
|
| 103 |
< |
.IP "\fB\-apP \fIprecomp\fR" |
| 104 |
< |
Fraction of global photons to precompute in the range ]0,1] when using the |
| 105 |
< |
\fB\-app\fR option. |
| 103 |
> |
.IP "\fB\-api \fIxmin ymin zmin xmax ymax zmax\fR" |
| 104 |
> |
Define a region of interest within which to store photons exclusively; |
| 105 |
> |
photons will only be stored within the volume bounded by the given minimum |
| 106 |
> |
and maximum coordinates. Multiple instances of this option may be specified |
| 107 |
> |
with cumulative effect to define compound regions of interest. This is |
| 108 |
> |
useful for constraining photons to only the relevant regions of a scene, but |
| 109 |
> |
may increase the photon distribution time. |
| 110 |
> |
.IP |
| 111 |
> |
\fBWARNING: this is an optimisation option for advanced users (an elite |
| 112 |
> |
group collectively known as \fIZe Ekspertz\fB) and may yield biased results. |
| 113 |
> |
Use with caution!\fR |
| 114 |
|
|
| 115 |
|
.IP "\fB\-apm \fImaxbounce\fR" |
| 116 |
< |
Maximum number of bounces (scattering events) along a photon path before |
| 117 |
< |
being considered "runaway" and terminated. Photons paths are normally |
| 109 |
< |
terminated via \fIRussian Roulette\fR, depending on their albedo. With |
| 110 |
< |
unrealistically high albedos, this is not guaranteed, and this options |
| 111 |
< |
imposes a hard limit to avoid an infinite loop. |
| 116 |
> |
Synonymous with \fB\-lr\fR for backwards compatibility. May be removed in |
| 117 |
> |
future releases. |
| 118 |
|
|
| 119 |
|
.IP "\fB\-apM \fImaxprepass\fR" |
| 120 |
|
Maximum number of iterations of the distribution prepass before terminating |
| 121 |
< |
if some photon maps are still empty. This option is rarely needed as a |
| 122 |
< |
an aborted prepass indicates an anomaly in the geometry or an |
| 121 |
> |
if some photon maps are still empty. This option is rarely needed as |
| 122 |
> |
an aborted prepass may indicate an anomaly in the geometry or an |
| 123 |
|
incompatibility with the specified photon map types (see \fBNOTES\fR below). |
| 124 |
|
|
| 125 |
< |
.IP "\fB\-apo \fImod\fR" |
| 125 |
> |
.IP "\fB\-apo\fR[\fB+\fR|\fB-\fR|\fB0\fR] \fImod\fR" |
| 126 |
|
Specifies a modifier \fImod\fR to act as a \fIphoton port\fR. All |
| 127 |
|
objects using this modifier will emit photons directly in lieu of any |
| 128 |
|
light sources defined with the \fIsource\fR material. This greatly |
| 129 |
|
accelerates photon distribution in scenes where photons have to enter a |
| 130 |
|
space which separates them from the emitting light source via an |
| 131 |
< |
opening, or port. |
| 131 |
> |
aperture (e.g. fenestration, skylight) acting as a port. |
| 132 |
|
.IP |
| 133 |
< |
A typical application is daylight simulation, where a |
| 134 |
< |
fenestration acts as port to admit photons into an interior after |
| 135 |
< |
emission from an external light source. Multiple instances of this |
| 130 |
< |
option may be specified. |
| 133 |
> |
In a typical daylight simulation scenario, a fenestration acts as a port to |
| 134 |
> |
admit photons into an interior after emission from sky and solar sources. |
| 135 |
> |
Multiple instances of this option may be specified. |
| 136 |
|
.IP |
| 137 |
< |
Note that port objects must be defined with their surface normals |
| 138 |
< |
pointing \fIinside\fR as per \fImkillum\fR convention. |
| 139 |
< |
|
| 137 |
> |
By default, ports are oriented to emit in the halfspace defined |
| 138 |
> |
by their associated surface normal. This can be overridden by |
| 139 |
> |
specifying a trivalent suffix as follows: |
| 140 |
> |
.RS |
| 141 |
> |
.IP \fB+\fR: |
| 142 |
> |
Forward emission; this is equivalent to the abovementioned default behaviour. |
| 143 |
> |
.IP \fB-\fR: |
| 144 |
> |
Backward emission; the port is reversed and photons are emitted into the |
| 145 |
> |
halfspace facing away from the surface normal. |
| 146 |
> |
.IP \fB0\fR: |
| 147 |
> |
Bidirectional emission; photons are emitted from both sides of the port. |
| 148 |
> |
.RE |
| 149 |
> |
.IP |
| 150 |
> |
Some typical situations that call for a reversed photon port include, for |
| 151 |
> |
example: |
| 152 |
> |
.RS |
| 153 |
> |
.IP (a) |
| 154 |
> |
Using fenestrations as ports that were (for whatever |
| 155 |
> |
reason) defined with outward facing normals, |
| 156 |
> |
.IP (b) |
| 157 |
> |
Using a \fBmist\fR |
| 158 |
> |
primitive as a port, since this requires outward facing normals in order to |
| 159 |
> |
register the photons as having entered the volume, |
| 160 |
> |
.IP (c) |
| 161 |
> |
Reorienting a port associated with a \fBbsdf\fR modifier, since inverting |
| 162 |
> |
its normal would also reorient the BSDF and alter its behaviour. |
| 163 |
> |
.RE |
| 164 |
> |
.IP |
| 165 |
> |
Other oddball scenarios are conceivable. If in doubt, specify a |
| 166 |
> |
bidirectional port orientation for a slight performance penalty, |
| 167 |
> |
as photon emission is attempted from both sides. For well-defined |
| 168 |
> |
port geometry with inward-facing normals, just use the default; |
| 169 |
> |
doan' mess with da normalz. |
| 170 |
> |
.IP |
| 171 |
> |
Photon port geometry is discretised according to the |
| 172 |
> |
\fB\-dp\fR and \fB\-ds\fR options. These parameters aid in resolving |
| 173 |
> |
spatially and directionally varying illuminance received by the port |
| 174 |
> |
from distant light sources, e.g due to partial occlusion |
| 175 |
> |
or when using climate-based sky models. |
| 176 |
> |
|
| 177 |
|
.IP "\fB\-apO \fImodfile\fR" |
| 178 |
|
Read photon port modifiers from the file \fImodfile\fR as a more convenient |
| 179 |
|
alternative to multiple instances of \fB\-apo\fR. |
| 180 |
|
|
| 181 |
+ |
.IP "\fB\-apP \fIprecomp\fR" |
| 182 |
+ |
Fraction of global photons to precompute in the range ]0,1] when using the |
| 183 |
+ |
\fB\-app\fR option. |
| 184 |
+ |
|
| 185 |
|
.IP "\fB\-apr \fIseed\fR" |
| 186 |
< |
Seed for the random number generator. This is necessary for generating |
| 187 |
< |
different photon distributions for the same octree and photon map size. |
| 186 |
> |
Seed for the random number generator. This is useful for generating |
| 187 |
> |
different photon distributions for the same octree and photon map size, |
| 188 |
> |
notably in progressive applications. |
| 189 |
|
|
| 190 |
|
.IP "\fB\-aps \fImod\fR" |
| 191 |
|
Specifies a modifier \fImod\fR defined as \fIantimatter\fR material to act |
| 195 |
|
surface therefore does not affect the light transport and simply acts as an |
| 196 |
|
invisible photon receiver. This is useful when photon irradiance is to be |
| 197 |
|
evaluated at points which do not lie on regular geometry, e.g. at workplane |
| 198 |
< |
height with \firtrace\fR's \fB-I\fR option. Without this workaround, |
| 198 |
> |
height with \fIrtrace\fR's \fB-I\fR option. Without this workaround, |
| 199 |
|
photons would be collected from parallel but distant planes, leading to |
| 200 |
|
underestimation. Note that photons are only deposited when incident from |
| 201 |
|
the front side of the sensor surface, i.e. when entering the |
| 206 |
|
Read virtual receiver surface modifiers from the file \fImodfile\fR as a more |
| 207 |
|
convenient alternative to multiple instances of \fB\-aps\fR. |
| 208 |
|
|
| 209 |
+ |
.IP "\fB\-ae \fImod\fR" |
| 210 |
+ |
Add \fImod\fR to the ambient exclude list, so that it will be ignored by the |
| 211 |
+ |
photon map. Objects having \fImod\fR as their modifier will not have |
| 212 |
+ |
photons deposited on them. Multiple modifiers may be given, each as separate |
| 213 |
+ |
instances of this option. |
| 214 |
+ |
.IP |
| 215 |
+ |
\fBWARNING: this is an optimisation option for advanced users and may yield |
| 216 |
+ |
biased results. It may also significantly increase photon distribution |
| 217 |
+ |
times. Use with caution!\fR |
| 218 |
+ |
|
| 219 |
+ |
.IP "\fB\-aE \fIfile\fR" |
| 220 |
+ |
Same as \fI-ae\fR, except modifiers to be exluded are read from \fIfile\fR, |
| 221 |
+ |
separated by whitespace. The RAYPATH environment variable determines which |
| 222 |
+ |
directories are searched for this file. |
| 223 |
+ |
|
| 224 |
+ |
.IP "\fB\-ai \fImod\fR" |
| 225 |
+ |
Add \fImod\fR to the ambient include list, so that it will contribute to the |
| 226 |
+ |
photon map. Only objects having \fImod\fR as their modifier will have |
| 227 |
+ |
photons deposited on them. Multiple modifiers may be given, each as separate |
| 228 |
+ |
instances of this option. Note that the ambient include and exclude options |
| 229 |
+ |
are mutually exclusive. |
| 230 |
+ |
.IP |
| 231 |
+ |
\fBWARNING: this is an optimisation option for advanced users and may yield |
| 232 |
+ |
biased results. It may also significantly increase photon distribution |
| 233 |
+ |
times. Use with caution!\fR |
| 234 |
+ |
|
| 235 |
+ |
.IP "\fB\-aI \fIfile\fR" |
| 236 |
+ |
Same as \fI-ai\fR, except modifiers to be included are read from \fIfile\fR, |
| 237 |
+ |
separated by whitespace. The RAYPATH environment variable determines which |
| 238 |
+ |
directories are searched for this file. |
| 239 |
+ |
|
| 240 |
|
.IP "\fB\-bv\fR[\fB+\fR|\fB-\fR]" |
| 241 |
|
Toggles backface visibility; enabling this causes photons to be stored and |
| 242 |
|
possibly scattered if they strike the back of a surface, otherwise they |
| 243 |
|
are unconditionally absorbed and discarded. |
| 244 |
|
|
| 245 |
|
.IP "\fB\-dp \fIsampleres\fR" |
| 246 |
< |
Resolution for sampling the spatial emission distribution of a modified |
| 247 |
< |
light source (e.g. via \fIbrightfunc\fR), in samples per steradian. This |
| 248 |
< |
is required for numerically integrating the flux emitted by the light |
| 249 |
< |
source and for constructing a probability density function for photon |
| 250 |
< |
emission. The accuracy of photon emission from modified sources |
| 251 |
< |
therefore depends on this parameter. This parameter may need increasing |
| 246 |
> |
Angular resolution for sampling the spatial emission distribution of a |
| 247 |
> |
modified light source or photon port (e.g. via \fIbrightfunc\fR), in samples |
| 248 |
> |
per steradian. |
| 249 |
> |
This is required to numerically integrate the flux emitted by the light |
| 250 |
> |
source and construct a probability density function for photon emission. |
| 251 |
> |
The accuracy of photon emission from a modified source or port |
| 252 |
> |
therefore depends on this parameter. The resolution may need to be increased |
| 253 |
|
with complex emission distributions in combination with caustics. |
| 254 |
|
|
| 255 |
|
.IP "\fB\-ds \fIpartsize\fR" |
| 256 |
< |
Light source partition size ratio; a light source object is spatially |
| 257 |
< |
partitioned to distribute the photon emission over its surface. This |
| 258 |
< |
parameter specifies the ratio of the size (per dimension) of each |
| 259 |
< |
partition to the scene cube, and may need increasing for modified light |
| 260 |
< |
sources (e.g. via \fIbrightfunc\fR) with high spatial variation. |
| 256 |
> |
Light source partition size ratio; a local light source object (or photon |
| 257 |
> |
port in case of a distant source) is spatially partitioned to distribute the |
| 258 |
> |
photon emission over its surface. This parameter specifies the ratio of the |
| 259 |
> |
size (per dimension) of each partition to the scene cube, and may need |
| 260 |
> |
to be reduced for modified light sources (e.g. via \fIbrightfunc\fR) with |
| 261 |
> |
high spatial variance, or for partially occluded photon ports. |
| 262 |
|
|
| 263 |
|
.IP "\fB\-e \fIfile\fR" |
| 264 |
|
Redirect diagnostics and progress reports to \fIfile\fR instead of the |
| 270 |
|
inadvertently destroying the results of potentially lengthy photon |
| 271 |
|
mapping runs. |
| 272 |
|
|
| 273 |
< |
.IP "\fB\-i \fIinc\fR" |
| 274 |
< |
Photon heap size increment; the photon heap is enlarged by this amount |
| 275 |
< |
when storage overflows during photon distribution. No need to fiddle |
| 276 |
< |
with this under ordinary circumstances. |
| 273 |
> |
.IP "\fB\-ld \fImaxdist\fR" |
| 274 |
> |
Limit cumulative distance travelled by a photon along its path to |
| 275 |
> |
\fImaxdist\fR. Photon hits within this distance will be stored, and the |
| 276 |
> |
photon is terminated once its path length exceeds this limit. This is |
| 277 |
> |
useful for setting radial regions of interest around emitting/reflecting |
| 278 |
> |
geometry, but may increase the photon distribution time. |
| 279 |
> |
.IP |
| 280 |
> |
\fBWARNING: this is an optimisation option for advanced users (an elite |
| 281 |
> |
group collectively known as \fIZe Ekspertz\fB) and may yield biased results. |
| 282 |
> |
Use with caution!\fR |
| 283 |
|
|
| 284 |
+ |
.IP "\fB\-lr \fImaxbounce\fR" |
| 285 |
+ |
Limit number of bounces (scattering events) along a photon path to |
| 286 |
+ |
\fImaxbounce\fR before being considered "runaway" and terminated. Photons |
| 287 |
+ |
paths are normally terminated via \fIRussian Roulette\fR, depending on their |
| 288 |
+ |
albedo. With unrealistically high albedos, this is not guaranteed, and this |
| 289 |
+ |
option imposes a hard limit to avoid an infinite loop. |
| 290 |
+ |
.IP |
| 291 |
+ |
\fBWARNING: this is an optimisation option for advanced users (an elite |
| 292 |
+ |
group collectively known as \fIZe Ekspertz\fB) and may yield biased results. |
| 293 |
+ |
Use with caution!\fR |
| 294 |
+ |
|
| 295 |
|
.IP "\fB\-ma \fIralb galb balb\fR" |
| 296 |
|
Set the global scattering albedo for participating media in conjunction |
| 297 |
|
with the \fB\-apv\fR option. See \fIrpict(1)\fR for details. |
| 306 |
|
|
| 307 |
|
.IP "\fB\-n \fInproc\fR" |
| 308 |
|
Use \fInproc\fR processes for parallel photon distribution. There is no |
| 309 |
< |
benefit in specifying more than the number of physical CPU cores available. |
| 310 |
< |
This option is currently not available on Windows. |
| 309 |
> |
benefit in specifying more than the number of physical CPU cores available |
| 310 |
> |
(so doan' even try). This option is currently not available on Windows -- |
| 311 |
> |
so there, tuff luck. |
| 312 |
|
|
| 313 |
|
.IP "\fB\-t \fIinterval\fR" |
| 314 |
|
Output a progress report every \fIinterval\fR seconds. This includes |
| 346 |
|
\fB\-apM\fR option. |
| 347 |
|
|
| 348 |
|
.SS Material Support |
| 349 |
< |
The \fIplasfunc\fR, \fImetfunc\fR, \fItransfunc\fR, \fIbrtdfunc\fR, |
| 350 |
< |
\fIplasdata\fR, \fImetdata\fR and \fItransdata\fR materials are not |
| 351 |
< |
supported by the photon mapping extension. Use the newer \fIbsdf\fR material |
| 349 |
> |
Not all materials are fully supported by the photon map extension. The |
| 350 |
> |
\fIplasfunc\fR, \fImetfunc\fR, \fItransfunc\fR, \fIplasdata\fR, |
| 351 |
> |
\fImetdata\fR and \fItransdata\fR materials currently only scatter photons |
| 352 |
> |
diffusely, and will not produce caustics. The \fIbrtdfunc\fR material only |
| 353 |
> |
produces caustics via ideal (mirror) specular reflection and transmission. |
| 354 |
> |
For more realistic scattering behaviour, use the newer \fIbsdf\fR material |
| 355 |
|
instead. |
| 356 |
|
.PP |
| 357 |
|
Virtual light sources (normally enabled with the \fImirror\fR material) are |
| 380 |
|
.PP |
| 381 |
|
Generate 1 million global photons by emitting them from external light |
| 382 |
|
sources of type \fIsource\fR into a reference room via a fenestration |
| 383 |
< |
with modifier \fIglazingMat\fR: |
| 383 |
> |
with modifier \fIglazingMat\fR acting as photon port, with inward-facing |
| 384 |
> |
normal: |
| 385 |
|
.IP |
| 386 |
|
mkpmap \-apg refRoom.gpm 1m \-apo glazingMat refRoom.oct |
| 387 |
|
.PP |
| 388 |
< |
Generate a contribution photon map containing 200000 photons suitable for |
| 389 |
< |
obtaining light source contributions with \fIrcontrib(1)\fR: |
| 388 |
> |
Generate a contribution photon map containing 10 million photons to bin |
| 389 |
> |
light source contributions with \fIrcontrib(1)\fR: |
| 390 |
|
.IP |
| 391 |
< |
mkpmap \-apC bonzo-contrib.gpm 200k bonzo.oct |
| 391 |
> |
mkpmap \-apC bonzo-contrib.gpm 10m bonzo.oct |
| 392 |
|
|
| 393 |
|
.SH BUGS |
| 394 |
|
The focus of a spotlight source, as defined by the length of its direction |
| 402 |
|
Roland Schregle (roland.schregle@{hslu.ch,gmail.com}) |
| 403 |
|
|
| 404 |
|
.SH COPYRIGHT |
| 405 |
< |
(c) Fraunhofer Institute for Solar Energy Systems, Lucerne University of |
| 406 |
< |
Applied Sciences and Arts. |
| 405 |
> |
(c) Fraunhofer Institute for Solar Energy Systems, |
| 406 |
> |
.br |
| 407 |
> |
(c) Lucerne University of Applied Sciences and Arts, |
| 408 |
> |
.br |
| 409 |
> |
(c) Tokyo University of Science. |
| 410 |
|
|
| 411 |
< |
.SH ACKNOWLEDGEMENT |
| 412 |
< |
Development of the RADIANCE photon mapping extension was sponsored by the |
| 308 |
< |
German Research Foundation (DFG) and the Swiss National Science Foundation |
| 309 |
< |
(SNF). |
| 411 |
> |
.SH ACKNOWLEDGEMENTS |
| 412 |
> |
Development of the RADIANCE photon mapping extension was supported by: |
| 413 |
|
|
| 414 |
+ |
.RS |
| 415 |
+ |
\fIFraunhofer Institute for Solar Energy Systems\fR funded by |
| 416 |
+ |
the German Research Foundation (\fIDFG LU-204/10-2\fR, "Fassadenintegrierte |
| 417 |
+ |
Regelsysteme (FARESYS)"), |
| 418 |
+ |
|
| 419 |
+ |
\fILucerne University of Applied Sciences and Arts\fR funded by |
| 420 |
+ |
the Swiss National Science Foundation (\fISNSF 147053\fR, "Daylight redirecting components"), |
| 421 |
+ |
|
| 422 |
+ |
\fITokyo University of Science\fR funded by the JSPS Grants-in-Aid for Scientific |
| 423 |
+ |
Research Programme (\fIKAKENHI JP19KK0115\fR, "Three-dimensional light flow"). |
| 424 |
+ |
.RE |
| 425 |
+ |
|
| 426 |
+ |
Many thanks also to the many individuals who tested the code and provided |
| 427 |
+ |
valuable feedback. Special greetz to Don Gregorio, PAB and Capt.\~B! |
| 428 |
+ |
|
| 429 |
|
.SH "SEE ALSO" |
| 430 |
|
rpict(1), rtrace(1), rvu(1), rcontrib(1), |
| 431 |
< |
\fIThe RADIANCE Photon Map Manual\fR |
| 431 |
> |
.br |
| 432 |
> |
\fIThe RADIANCE Photon Map Manual\fR, |
| 433 |
> |
.br |
| 434 |
> |
\fIDevelopment and Integration of the RADIANCE Photon Map Extension: |
| 435 |
> |
Technical Report\fR, |
| 436 |
> |
.br |
| 437 |
> |
\fIThe RADIANCE Out-of-Core Photon Map: Technical Report\fR, |
| 438 |
> |
.br |
| 439 |
> |
\fIBonzo Daylighting Tool a.k.a. EvilDRC [TM]\fR |
| 440 |
|
|
