.\" RCSid "$Id: pmapdump.1,v 1.4 2019/01/10 18:29:34 rschregle Exp $"
.TH PMAPDUMP 1 "$Date: 2019/01/10 18:29:34 $ $Revision: 1.4 $" RADIANCE

.SH NAME
pmapdump - generate RADIANCE scene description of photon map distribution

.SH SYNOPSIS
pmapdump [\fB-n\fR \fInspheres1\fR] [\fB-r\fR \fIradscale1\fR] 
         [\fB-f\fR | \fB-c\fR \fIrcol1\fR \fIgcol1\fR \fIbcol1\fR] \fIpmap1\fR 
         [\fB-n\fR \fInspheres2\fR] [\fB-r\fR \fIradscale2\fR] 
         [\fB-f\fR | \fB-c\fR \fIrcol2\fR \fIgcol2\fR \fIbcol2\fR] \fIpmap2\fR 
         ...

.SH DESCRIPTION
\fIpmapdump\fR takes one or more photon map files generated with
\fImkpmap(1)\fR as input and 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
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 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.

.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 may be set individually for each photon map.

.IP "\fB-n \fInspheres\fR"
Specifies the number of spheres to dump for the next photon map.  The dump
is performed by random sampling with \fInspheres\fR as target count, hence
the number actually output will be approximate.  \fINspheres\fR may be
followed by a multiplier suffix 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 of spheres is 10k.

.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.

.IP "\fB-c\fR \fIrcol\fR \fIgcol\fR \fIbcol\fR"
Specifies a custom sphere 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"
Boolean switch to colour each sphere according to the corresponding photon's
RGB flux instead of a constant colour. Note that the resulting colours can
span several orders of magnitude and may require tone mapping with
\fIpcond(1)\fR for visualisation.  This option is mutually exclusive with
\fB-c\fR.

.SH NOTES
The 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 \fInspheres\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_pmdump.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_pmdump.oct
.PP
Dumps may also be viewed on their own by 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

.SH AUTHOR
Roland Schregle (roland.schregle@{hslu.ch,gmail.com})

.SH COPYRIGHT
(c) Fraunhofer Institute for Solar Energy Systems, Lucerne University of 
Applied Sciences and Arts.

.SH ACKNOWLEDGEMENT
Development of the RADIANCE photon mapping extension was sponsored by the 
German Research Foundation (DFG) and the Swiss National Science Foundation 
(SNF). 

.SH "SEE ALSO"
mkpmap(1), objview(1), oconv(1), rpict(1), rvu(1), 
\fIThe RADIANCE Photon Map Manual\fR