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pmapdump.1
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.\" RCSid "$Id: pmapdump.1,v 1.9 2020/08/07 01:26:20 rschregle Exp $"
.TH PMAPDUMP 1 "$Date: 2020/08/07 01:26:20 $ $Revision: 1.9 $" RADIANCE
.SH NAME
pmapdump - generate RADIANCE scene description or point list representing
photon positions and (optionally) flux
.SH SYNOPSIS
pmapdump [\fB-a\fR [\fB-N\fR] [\fB-A\fR]] [\fB-n\fR \fInum1\fR]
[\fB-r\fR \fIradscale1\fR]
.RS
[\fB-f\fR [\fB-O\fR \fInorm1\fR]] |
[\fB-c\fR \fIrcol1\fR \fIgcol1\fR \fIbcol1\fR] \fIpmap1\fR
.br
[\fB-a\fR [\fB-N\fR] [\fB-A\fR]] [\fB-n\fR \fInum2\fR]
[\fB-r\fR \fIradscale2\fR]
.br
[\fB-f\fR [\fB-O\fR \fInorm2\fR]] |
[\fB-c\fR \fIrcol2\fR \fIgcol2\fR \fIbcol2\fR] \fIpmap2\fR ...
.RE
.SH DESCRIPTION
\fIpmapdump\fR takes one or more photon map files generated with
\fImkpmap(1)\fR as input and, by default, sends a RADIANCE scene description
of their photon distributions to the standard output. Photons are
represented as spheres of material type \fIglow\fR. These can be
visualised with e.g. \fIobjview(1)\fR, \fIrpict(1)\fR, or \fIrvu(1)\fR to
assess the location and local density of photons in relation to the scene
geometry. No additional light sources are necessary, as the spheres
representing the photons are self-luminous.
.PP
Alternatively, photons can also be output as an ASCII point list, where
each line contains a photon's position and colour.
This point list can be imported in a 3D point cloud processor/viewer
to interactively explore the photon map.
.PP
An arbitrary number of photon maps can be specified on the command line and
the respective photon type is determined automagically. Per default, the
different photon types are visualised as colour coded spheres/points
according to the following default schema:
.IP
\fIBlue\fR: global photons
.br
\fICyan\fR: precomputed global photons
.br
\fIRed\fR: caustic photons
.br
\fIGreen\fR: volume photons
.br
\fIMagenta\fR: direct photons
.br
\fIYellow\fR: contribution photons
.PP
These colours can be overridden for individual photon maps with the \fB-c\fR
option (see below). Alternatively, photons can be individually coloured
according to their actual RGB flux with the \fB-f\fR option (see below);
while this makes it difficult to discern photon types, it can be used to
quantitatively analyse colour bleeding effects, for example.
.SH OPTIONS
Options are effective for the photon map file immediately following on the
command line, and are reset to their defaults after completion of each dump.
As such they must be set individually for each photon map.
.IP "\fB-a\fR[\fB+\fR|\fB-\fR]"
Boolean switch to output photons as a point list in ASCII (text) format
instead of a RADIANCE scene.
Each output line consists of 6 tab-separated floating point values: the
X, Y, Z coordinates of the photon's position, and the R, G, B colour
channels of its flux. These values. notably the flux, are expressed in
scientific notation if necessary to accommodate their high dynamic range.
.IP
As \fIpmapdump\fR groups its options per photon map, this option must be
specified per photon map for consistent output. This prevents erroneously
dumping RADIANCE scene descriptions along with point lists, which will
fail to load in the 3D point cloud processor/viewer.
.IP "\fB-A\fR[\fB+\fR|\fB-\fR]"
Boolean switch to also output type-specific auxiliary data embedded in the
photon in conjunction with option \fB-a\fR. For most photon types this is
the unique path ID. Path IDs consist of a numeric prefix N and suffix M,
and are formatted as N:M.
.IP "\fB-c\fR \fIrcol\fR \fIgcol\fR \fIbcol\fR"
Specifies a custom sphere/point colour for the next photon map. The colour
is specified as an RGB triplet, with each component in the range (0..1].
Without this option, the default colour for the corresponding photon type
is used. This option is mutually exclusive with \fB-f\fR.
.IP "\fB-f\fR[\fB+\fR|\fB-\fR]"
Boolean switch to colour each sphere/point according to the corresponding
photon's RGB flux instead of a constant colour. The flux is adjusted for
the fraction of dumped photons to maintain the total flux contained in the
dumped photon map. Note that no exposure is applied, and as such the
resulting colours can span several orders of magnitude and may require tone
mapping with \fIpcond(1)\fR or normalisation with option \fB-O\fR (see below)
for visualisation. This option is mutually exclusive with \fB-c\fR.
.IP "\fB-n \fInum\fR"
Specifies the number of spheres or points to dump for the next photon map.
The dump is performed by random sampling with \fInum\fR as target count,
hence the number actually output will be approximate. \fINum\fR may be
suffixed by a case-insensitive multiplier for convenience, where
\fIk\fR = 10^3 and \fIm\fR = 10^6, although the latter may lead to problems
when processing the output geometry with \fIoconv(1)\fR. The default number
is 10k.
.IP "\fB-N\fR[\fB+\fR|\fB-\fR]"
Boolean switch to also output photon normals in conjunction with option
\fB-a\fR . In case of a volume or lightflow photon map, this option will
output the photon's direction.
.IP "\fB-O \fInorm\fR"
Normalise photon flux to the given value. This limits the
maximum flux in any colour channel to \fInorm\fR, which is useful for
postprocessing and visualising the photon flux within a predetermined range.
This option is only valid in conjuction with the \fB-f\fR option.
.IP "\fB-P\fR[\fB+\fR|\fB-\fR]"
Boolean option to output photon path IDs in text format. This option is
equivalent to \fB-A\fR and kept for backwards compatibility only.
.IP "\fB-r \fIradscale\fR"
Specifies a relative scale factor \fIradscale\fR for the sphere radius. The
sphere radius is determined automatically from an estimated average distance
between spheres so as to reduce clustering, assuming a uniform distribution.
In cases where the distribution is substantially nonuniform (e.g. highly
localised caustics) the radius can be manually corrected with this option.
The default value is 1.0. This option is ignored for point list output
in conjuction with \fB-a\fR.
.SH NOTES
The RADIANCE scene output may contain many overlapping spheres in areas with
high photon density, particularly in caustics. This results in inefficient
and slow octree generation with \fIoconv(1)\fR. Generally this can be
improved by reducing \fInum\fR and/or \fIradscale\fR.
.SH EXAMPLES
Visualise the distribution of global and caustic photons superimposed
on the scene geometry with 5000 pale red and 10000 pale blue spheres,
respectively:
.IP
pmapdump -n 5k -c 1 0.4 0.4 global.pm -n 10k -c 0.4 0.4 1 caustic.pm |
oconv - scene.rad > scene_pm.oct
.PP
Visualise the caustic photon distribution superimposed on the scene geometry
with 10000 spheres coloured according to the photons' respective RGB flux:
.IP
pmapdump -n 10k -f caustic.pm | oconv - scene.rad > scene_pm.oct
.PP
But Capt. B wants 'em bigger:
.IP
pmapdump -r 4.0 bonzo.pm > bonzo_bigballz.rad
.PP
RADIANCE scene dumps may also be viewed on their own by simply piping the
output of \fIpmapdump\fR directly into \fIobjview(1)\fR (using the default
number of spheres in this example):
.IP
pmapdump zombo.pm | objview
.PP
Instead of a RADIANCE scene, dump photons as a (really long) point list to
an ASCII file for import into a 3D point cloud processor/viewer:
.IP
pmapdump -a -f -n 1m lotsa.pm > lotsa_pointz.txt
.SH AUTHOR
Roland Schregle (roland.schregle@{hslu.ch,gmail.com})
.SH COPYRIGHT
(c) Fraunhofer Institute for Solar Energy Systems,
.br
(c) Lucerne University of Applied Sciences and Arts,
.br
(c) Tokyo University of Science.
.SH ACKNOWLEDGEMENTS
Development of the RADIANCE photon mapping extension was supported by:
.RS
\fIFraunhofer Institute for Solar Energy Systems\fR
funded by
the German Research Foundation (\fIDFG LU-204/10-2\fR, "Fassadenintegrierte
Regelsysteme (FARESYS)"),
\fILucerne University of Applied Sciences and Arts\fR
funded by
the Swiss National Science Foundation (\fISNSF 147053\fR, "Daylight redirecting components"),
\fITokyo University of Science\fR
funded by the JSPS Grants-in-Aid for Scientific
Research Programme (\fIKAKENHI JP19KK0115\fR, "Three-dimensional light flow").
.RE
Many thanks also to the many individuals who tested the code and provided
valuable feedback. Special greetz to Don Gregorio, PAB and Capt.\~B!
.SH "SEE ALSO"
mkpmap(1), objview(1), oconv(1), rpict(1), rvu(1),
.br
\fIThe RADIANCE Photon Map Manual\fR,
.br
\fIDevelopment and Integration of the RADIANCE Photon Map Extension:
Technical Report\fR,
.br
\fIThe RADIANCE Out-of-Core Photon Map: Technical Report\fR,
.br
\fIBonzo Daylighting Tool a.k.a. EvilDRC [TM]\fR

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