--- ray/doc/man/man1/rtcontrib.1	2005/06/10 20:53:55	1.10
+++ ray/doc/man/man1/rtcontrib.1	2005/10/06 16:28:59	1.13
@@ -1,4 +1,4 @@
-.\" RCSid "$Id: rtcontrib.1,v 1.10 2005/06/10 20:53:55 greg Exp $"
+.\" RCSid "$Id: rtcontrib.1,v 1.13 2005/10/06 16:28:59 greg Exp $"
 .TH RTCONTRIB 1 5/25/05 RADIANCE
 .SH NAME
 rtcontrib - compute contribution coefficients in a RADIANCE scene
@@ -16,6 +16,8 @@ rtcontrib - compute contribution coefficients in a RAD
 .B "\-o ospec"
 ][
 .B "\-b binv"
+][
+.B "\-bn nbins"
 ]
 {
 .B "\-m mod | \-M file"
@@ -85,8 +87,16 @@ 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
@@ -204,7 +214,7 @@ 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 and -M files