pkgbsdf(1) [minix man page]
PKGBSDF(1) General Commands Manual PKGBSDF(1) NAME
pkgBSDF - package BSDFs provided as XML for Radiance SYNOPSIS
pkgBSDF [ -i ][ -s ] bsdf.xml .. DESCRIPTION
PkgBSDF takes one or more XML files, each describing the bidirectional scattering distribution function of a surface or geometric system, and packages them into RADIANCE scene descriptions. If the input file(s) do not begin with a '.' or '/', the directories in the RAYPATH environment variable will be searched. One rectangle is produced for each BSDF that has no detail geometry and/or no rear-side reflectance distribution. If both front and back reflectance distributions are present with detail geometry, then two rectangles will be used to sand- wich the geometry extracted from the BSDF file. The front surface will always be centered just in front of the origin facing the positive Z-direction, with "up" in the positive Y-direction. The back surface, if present, will parallel the front surface at a distance slightly greater than the BSDF system thickness. Scene units will always be in meters. The -i option causes pkgBSDF to produce frozen octree instances for any detail geometry, which may reduce memory requirements in scenes with many references to the same complex BSDF object. Normally, pkgBSDF produces one RADIANCE scene file for each XML input, replacing the required '.xml' suffix with '.rad' in the same direc- tory. The -s option sends the RADIANCE scene description to the standard output rather than writing it to a file, but only works for a single XML input. Any instance octree is still written out to a file generated by replacing the '.xml' suffix with '.oct' in the same directory. EXAMPLE
Package all the XML files in the current directory as Radiance scene files, employing frozen octree instances for any detail geometry: pkgBSDF -i *.xml AUTHOR
Greg Ward SEE ALSO
genBSDF(1), oconv(1), xform(1) RADIANCE
6/23/2011 PKGBSDF(1)
Check Out this Related Man Page
GENBSDF(1) General Commands Manual GENBSDF(1) NAME
genBSDF - generate BSDF description from Radiance or MGF input SYNOPSIS
genBSDF [ -c Nsamp ][ -n Nproc ][ -r 'rtcontrib opts...' ][ -t{3|4} Nlog2 ][ {+|-}forward ][ {+|-}backward ][ {+|-}mgf ][ {+|-}geom unit ][ -dim Xmin Xmax Ymin Ymax Zmin Zmax ] [ geom .. ] DESCRIPTION
GenBSDF computes a bidirectional scattering distribution function from a Radiance or MGF scene description given on the input. The program assumes the input is in Radiance format unless the +mgf option is specified. The output conforms to the LBNL Window 6 XML standard for BSDF data, and will include an MGF representation of the input geometry if the +geom option is given, followed by one of "meter," "foot," "inch," "centimeter," or "millimeter," depending on the scene units. The default is to include the provided geometry, which is assumed to be in meters. Geometry output can be supressed with the -geom option, which must also be followed by one of the above length units. Normally, genBSDF computes components needed by a backwards ray-tracing process, +backward. If both forward and backward (front and back) distributions are needed, the +forward option may be given. To turn off backward components, use the -backward option. Computing both components takes about twice as long as one component. The geometry must fit a rectangular profile, whose width is along the X-axis, height is in the Y-axis, and depth is in the Z-axis. The positive Z-axis points into the room, and the input geometry should not extend into the room. (I.e., it should not contain any positive Z values, since the putative emitting surface is assumed to lie at Z=0.) The entire window system should be modeled, including sills and edge geometry anticipated in the final installation, otherwise accuracy will be impaired. Similarly, materials in the description should be carefully measured. Normally, the input geometry will be positioned according to its actual bounding box, but this may be overridden with the -dim option. Use this in cases where the fenestration system is designed to fit a smaller (or larger) opening or is offset somehow. The variance in the results may be reduced by increasing the number of samples per incident direction using the -c option. This value defaults to 2000 samples distributed over the incoming plane for each of the 145 Klems hemisphere directions. In some cases, the processing time may be reduced by the -n option, which specifies the number of simultaneous rtrace(1) processes to run in rtcontrib(1). The -r option may be used to specify a set of quoted arguments to be included on the rtcontrib command line. The -t4 mode computes a non-uniform BSDF represented as a rank 4 tensor tree, suitable for use in the Radiance rendering tools. The param- eter given to this option is the log to the base 2 of the sampling resolution in each dimension, and must be an integer. The -c setting should be adjusted so that an appropriate number of samples lands in each region. A -t4 parameter of 5 corresponds to 32x32 or 1024 output regions, so a -c setting of 10240 would provide 10 samples per region on average. Increasing the resolution to 6 corresponds to 64x64 or 4096 regions, so the -c setting would need to be increased by a factor of 4 to provide the same accuracy in each region. The -t3 mode is similar to -t4 but computes a rank 3 tensor tree rather than rank 4. This provides a much faster computation, but only works in special circumstances. Specifically, do NOT use this option if the system is not in fact isotropic. I.e., only use -t3 when you are certain that the system has a high degree of radial symmetry. Again, the parameter to this option sets the maximum resolution as a power of 2 in each dimension, but in this case there is one less dimension being sampled. EXAMPLE
To create a BSDF description including geometry from a set of venetian blinds: genblinds blind_white blind1 .07 3 1.5 30 40 | xform -rz -90 -rx 90 > blind1.rad genBSDF -r @rtc.opt blind_white.mat glazing.rad blind1.rad > blind1.xml To create a non-uniform, anisotropic BSDF distribution with a maximum resolution of 128x128 from the same description: genBSDF -r @rtc.opt -t4 7 -c 160000 blind_white.mat glazing.rad blind1.rad > blind12.xml NOTES
The variable resolution (tensor tree) BSDF representation is not supported by all software and applicatons, and should be used with cau- tion. It provides practical, high-resolution data for use in the Radiance rendering programs, but does not work in the matrix formulation of the daylight coefficient method for example. Also, third party tools generally expect or require a fixed number of sample directions using the Klems directions or similar. AUTHOR
Greg Ward SEE ALSO
dctimestep(1), genklemsamp(1), genskyvec(1), mkillum(1), pkgBSDF(1), rtcontrib(1), rtrace(1) RADIANCE
9/3/2010 GENBSDF(1)