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.\" RCSid "$Id: pmapdump.1,v 1.4 2019/01/10 18:29:34 rschregle Exp $" |
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.TH PMAPDUMP 1 "$Date: 2019/01/10 18:29:34 $ $Revision: 1.4 $" RADIANCE |
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|
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.SH NAME |
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pmapdump - generate RADIANCE scene description or point list representing |
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photon positions and (optionally) flux |
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|
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.SH SYNOPSIS |
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pmapdump [\fB-a\fR] [\fB-n\fR \fInum1\fR] [\fB-r\fR \fIradscale1\fR] |
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[\fB-f\fR | \fB-c\fR \fIrcol1\fR \fIgcol1\fR \fIbcol1\fR] |
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\fIpmap1\fR |
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[\fB-a\fR] [\fB-n\fR \fInum2\fR] [\fB-r\fR \fIradscale2\fR] |
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[\fB-f\fR | \fB-c\fR \fIrcol2\fR \fIgcol2\fR \fIbcol2\fR] |
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\fIpmap2\fR ... |
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|
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.SH DESCRIPTION |
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\fIpmapdump\fR takes one or more photon map files generated with |
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\fImkpmap(1)\fR as input and, by default, sends a RADIANCE scene description |
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of their photon distributions to the standard output. Photons are |
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represented as spheres of material type \fIglow\fR. These can be |
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visualised with e.g. \fIobjview(1)\fR, \fIrpict(1)\fR, or \fIrvu(1)\fR to |
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assess the location and local density of photons in relation to the scene |
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geometry. No additional light sources are necessary, as the spheres |
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representing the photons are self-luminous. |
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.PP |
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Alternatively, photons can also be output as an ASCII point list, where |
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each line contains a photon's position and colour. |
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This point list can be imported in a 3D point cloud processor/viewer |
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to interactively explore the photon map. |
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.PP |
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An arbitrary number of photon maps can be specified on the command line and |
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the respective photon type is determined automagically.Per default, the |
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different photon types are visualised as colour coded spheres/points |
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according to the following default schema: |
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.IP |
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\fIBlue\fR: global photons |
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.br |
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\fICyan\fR: precomputed global photons |
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.br |
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\fIRed\fR: caustic photons |
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.br |
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\fIGreen\fR: volume photons |
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.br |
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\fIMagenta\fR: direct photons |
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.br |
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\fIYellow\fR: contribution photons |
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.PP |
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These colours can be overridden for individual photon maps with the \fB-c\fR |
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option (see below). Alternatively, photons can be individually coloured |
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according to their actual RGB flux with the \fB-f\fR option (see below); |
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while this makes it difficult to discern photon types, it can be used to |
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quantitatively analyse colour bleeding effects, for example. |
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|
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.SH OPTIONS |
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Options are effective for the photon map file immediately following on the |
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command line, and are reset to their defaults after completion of each dump. |
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As such they may be set individually for each photon map. |
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|
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.IP "\fB-a\fR" |
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Boolean switch to output photons as a point list in ASCII (text) format |
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instead of a RADIANCE scene. |
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Each output line consists of 6 tab-separated floating point values: the |
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X, Y, Z coordinates of the photon's position, and the R, G, B colour |
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channels of its flux. These values. notably the flux, may be expressed |
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in scientific notation to accommodate their high dynamic range. |
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|
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.IP "\fB-f\fR" |
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Boolean switch to colour each sphere/point according to the corresponding |
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photon's RGB flux instead of a constant colour. Note that no exposure is |
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applied, and as such the resulting colours can span several orders of |
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magnitude and may require tone mapping with \fIpcond(1)\fR for |
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visualisation. This option is mutually exclusive with \fB-c\fR. |
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|
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.IP "\fB-c\fR \fIrcol\fR \fIgcol\fR \fIbcol\fR" |
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Specifies a custom sphere/point colour for the next photon map. The colour |
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is specified as an RGB triplet, with each component in the range (0..1]. |
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Without this option, the default colour for the corresponding photon type |
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is used. This option is mutually exclusive with \fB-f\fR. |
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|
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.IP "\fB-n \fInum\fR" |
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Specifies the number of spheres or points to dump for the next photon map. |
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The dump is performed by random sampling with \fInum\fR as target count, |
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hence the number actually output will be approximate. \fINum\fR may be |
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suffixed by a case-insensitive multiplier for convenience, where |
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\fIk\fR = 10^3 and \fIm\fR = 10^6, although the latter may lead to problems |
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when processing the output geometry with \fIoconv(1)\fR. The default number |
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is 10k. |
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|
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.IP "\fB-r \fIradscale\fR" |
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Specifies a relative scale factor \fIradscale\fR for the sphere radius. The |
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sphere radius is determined automatically from an estimated average distance |
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between spheres so as to reduce clustering, assuming a uniform distribution. |
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In cases where the distribution is substantially nonuniform (e.g. highly |
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localised caustics) the radius can be manually corrected with this option. |
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The default value is 1.0. This option is ignored for point list output |
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in conjuction with \fB-a\fR. |
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|
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.SH NOTES |
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The RADIANCE scene output may contain many overlapping spheres in areas with |
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high photon density, particularly in caustics. This results in inefficient |
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and slow octree generation with \fIoconv(1)\fR. Generally this can be |
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improved by reducing \fInum\fR and/or \fIradscale\fR. |
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|
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.SH EXAMPLES |
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Visualise the distribution of global and caustic photons superimposed |
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on the scene geometry with 5000 pale red and 10000 pale blue spheres, |
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respectively: |
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.IP |
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pmapdump -n 5k -c 1 0.4 0.4 global.pm -n 10k -c 0.4 0.4 1 caustic.pm | |
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oconv - scene.rad > scene_pm.oct |
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.PP |
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Visualise the caustic photon distribution superimposed on the scene geometry |
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with 10000 spheres coloured according to the photons' respective RGB flux: |
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.IP |
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pmapdump -n 10k -f caustic.pm | oconv - scene.rad > scene_pm.oct |
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.PP |
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RADIANCE scene dumps may also be viewed on their own by simply piping the |
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output of \fIpmapdump\fR directly into \fIobjview(1)\fR (using the default |
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number of spheres in this example): |
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.IP |
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pmapdump zombo.pm | objview |
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.PP |
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Dump photons as a (really long) point list to an ASCII file for import in |
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a 3D point cloud viewer: |
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.IP |
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pmapdump -a -f -n 1m lotsa.pm > lotsa-pointz.txt |
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.PP |
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Capt. B. wants 'em bigger: |
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.IP |
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pmapdump -r 4.0 bonzo.pm > bigbonzo-pm.rad |
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|
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.SH AUTHOR |
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Roland Schregle (roland.schregle@{hslu.ch,gmail.com}) |
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|
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.SH COPYRIGHT |
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(c) Fraunhofer Institute for Solar Energy Systems, Lucerne University of |
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Applied Sciences and Arts. |
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|
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.SH ACKNOWLEDGEMENT |
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Development of the RADIANCE photon mapping extension was sponsored by the |
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German Research Foundation (DFG) and the Swiss National Science Foundation |
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(SNF). |
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|
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.SH "SEE ALSO" |
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mkpmap(1), objview(1), oconv(1), rpict(1), rvu(1), |
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\fIThe RADIANCE Photon Map Manual\fR, |
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\fIBonzo Daylighting Tool [TM]\fR |
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