--- ray/doc/man/man1/rtcontrib.1	2005/06/02 04:47:26	1.7
+++ ray/doc/man/man1/rtcontrib.1	2006/02/05 22:22:20	1.15
@@ -1,4 +1,4 @@
-.\" RCSid "$Id: rtcontrib.1,v 1.7 2005/06/02 04:47:26 greg Exp $"
+.\" RCSid "$Id: rtcontrib.1,v 1.15 2006/02/05 22:22:20 greg Exp $"
 .TH RTCONTRIB 1 5/25/05 RADIANCE
 .SH NAME
 rtcontrib - compute contribution coefficients in a RADIANCE scene
@@ -7,6 +7,12 @@ rtcontrib - compute contribution coefficients in a RAD
 [
 .B "\-n nprocs"
 ][
+.B \-V
+][
+.B \-fo
+|
+.B \-r
+][
 .B "\-e expr"
 ][
 .B "\-f source"
@@ -14,8 +20,13 @@ rtcontrib - compute contribution coefficients in a RAD
 .B "\-o ospec"
 ][
 .B "\-b binv"
+][
+.B "\-bn nbins"
 ]
-.B "\-m mod .."
+{
+.B "\-m mod | \-M file"
+}
+..
 [
 .B $EVAR
 ]
@@ -30,13 +41,49 @@ rtrace options
 .B "rtcontrib [ options ] \-defaults"
 .SH DESCRIPTION
 .I Rtcontrib
-computes ray contributions (i.e., color coefficients)
+computes ray coefficients
 for objects whose modifiers are named in one or more
 .I \-m
 settings.
 These modifiers are usually materials associated with
 light sources or sky domes, and must directly modify some geometric
 primitives to be considered in the output.
+A modifier list may also be read from a file using the
+.I \-M
+option.
+The RAYPATH environment variable determines directories to search for
+this file.
+(No search takes place if a file name begins with a '.', '/' or '~'
+character.)\0
+.PP
+By setting the boolean
+.I \-V
+option, you may instruct
+.I rtcontrib
+to report the contribution from each material rather than the ray
+coefficient.
+This is particularly useful for light sources with directional output
+distributions, whose value would otherwise be lost in the shuffle.
+With the default
+.I -V-
+setting, the output of rtcontrib is a coefficient that must be multiplied
+by the radiance of each material to arrive at a final contribution.
+This is more convenient for computing daylight coefficeints, or cases
+where the actual radiance is not desired.
+Use the
+.I -V+
+setting when you wish to simply sum together contributions
+(with possible adjustment factors) to obtain a final radiance value.
+Combined with the
+.I \-i
+or
+.I \-I
+option, irradiance contributions are reported by
+.I \-V+
+rather than radiance, and 
+.I \-V-
+coefficients contain an additonal factor of PI.
+.PP
 The output of
 .I rtcontrib
 has many potential uses.
@@ -51,7 +98,7 @@ systems, such as luminaires, light pipes, and shading 
 .I Rtcontrib
 calls
 .I rtrace(1)
-with the -oTW option to calculate the daughter ray
+with the -oTW (or -oTV) option to calculate the daughter ray
 contributions for each input ray, and the output tallies
 are sent to one or more destinations according to the given
 .I \-o
@@ -59,7 +106,12 @@ specification.
 If a destination begins with an exclamation mark ('!'), then
 a pipe is opened to a command and data is sent to its standard input.
 Otherwise, the destination is treated as a file.
-(An existing file of the same name is clobbered.)\0
+An existing file of the same name will not be clobbered, unless the
+.I \-fo
+option is given.
+If instead the
+.I \-r
+option is specified, data recovery is attempted on existing files.
 If an output specification contains a "%s" format, this will be
 replaced by the modifier name.
 The
@@ -70,8 +122,16 @@ this will be applied to a "%d" format in the output fi
 specification if present.
 The actual bin number is computed at run time based on ray direction
 and surface intersection, as described below.
+If the number of bins is known in advance, it should be specified with the
+.I \-bn
+option, and this is critical for output files containing multiple values
+per record.
+Since bin numbers start from 0, the bin count is always equal to
+the last bin plus 1.
+Set the this value to 0 if the bin count is unknown (the default).
 The most recent
-.I \-b
+.I \-b,
+.I \-bn
 and
 .I \-o
 options to the left of each
@@ -109,8 +169,6 @@ Unlike
 will search the RADIANCE library directories for each file given in a
 .I \-f
 option.
-(No search takes place if a file name begins with a '.', '/' or '~'
-character.)\0
 .PP
 If no
 .I \-o
@@ -191,10 +249,10 @@ pcomb -c 100 90 75 c_light1.pic -c 50 55 57 c_light2.p
 .PP
 To compute an array of illuminance contributions according to a Tregenza sky:
 .IP "" .2i
-rtcontrib -b tbin -o sky.dat -m skyglow -b 0 -o ground.dat -m groundglow
+rtcontrib -I+ -b tbin -o sky.dat -m skyglow -b 0 -o ground.dat -m groundglow
 @render.opt -f tregenza.cal scene.oct < test.dat
 .SH ENVIRONMENT
-RAYPATH		path to search for -f files
+RAYPATH		path to search for -f and -M files
 .SH AUTHOR
 Greg Ward
 .SH "SEE ALSO"