NAME

       dctimestep - compute annual simulation time-step via matrix multiplication

SYNOPSIS

       dctimestep DCspec [ skyvec ]
       dctimestep Vspec Tbsdf.xml Dmat.dat [ skyvec ]

DESCRIPTION

       Dctimestep  has  two  invocation  forms.   In  the first form, dctimestep is given a daylight coefficient
       specification and an optional sky vector, which may be read from the standard input if unspecified.   The
       daylight  coefficients  are  multiplied  against  this vector and the results are written to the standard
       output.  This may be a list of color values or a combined Radiance image, as explained below.

       In the second form, dctimestep takes four input files, forming a matrix expression.  The  first  argument
       is  the  View matrix file that specifies how window output directions are related to some set of measured
       values, such as an  array  of  illuminance  points  or  images.   This  matrix  is  usually  computed  by
       rtcontrib(1)  for  a  particular  set of windows or skylight openings.  The second argument is the window
       transmission matrix, or BSDF, given as a standard XML description.  The third argument  is  the  Daylight
       matrix file that defines how sky patches relate to input directions on the same opening.  This is usually
       computed  using  genklemsamp(1) with rtcontrib in a separate run for each window or skylight orientation.
       The final input is the sky contribution vector, usually computed by genskyvec(1), which may be passed  on
       the  standard  input.  This data must be in ASCII format, whereas the View and Daylight matrices are more
       efficiently represented as binary float data if machine byte-order is not an issue.

       Sent to the standard output of dctimestep is either an ASCII color vector with as many  RGB  triplets  as
       there  are  rows in the View matrix, or a combined Radiance picture.  Which output is produced depends on
       the first argument.  A regular file name will be loaded and interpreted as a matrix to generate  a  color
       results  vector.   A  file specification containing a '%d' format string will be interpreted as a list of
       Radiance component pictures, which will be summed according to the computed vector.

EXAMPLES

       To compute workplane illuminances at 3:30pm on Feb 10th:

         gensky 2 10 15:30 | genskyvec | dctimestep workplaneDC.dmx > Ill_02-10-1530.dat

       To compute an image at 10am on the equinox from a set of component images:

         gensky 3 21 10 | genskyvec | dctimestep viewc%03d.hdr > view_03-21-10.hdr

       To compute a set of illuminance contributions for Window 1 on the Winter solstice at 2pm:

         gensky 12 21 14 | genskyvec | dctimestep IllPts.vmx Blinds20.xml Window1.dmx > Ill_12-21-14.dat

       To compute Window2's contribution to an interior view at 12 noon on the Summer solstice:

         gensky 6 21 12 | genskyvec | dctimestep view%03d.hdr Blinds30.xml Window2.dmx > view_6-21-12.hdr

AUTHOR

       Greg Ward

SEE ALSO

       genklemsamp(1), genskyvec(1), mkillum(1), rtcontrib(1), rtrace(1), vwrays(1)

RADIANCE                                            12/09/09                                       DCTIMESTEP(1)