--- ray/doc/man/man1/rtrace.1	2005/05/31 18:01:08	1.11
+++ ray/doc/man/man1/rtrace.1	2005/06/13 20:07:55	1.12
@@ -1,4 +1,4 @@
-.\" RCSid "$Id: rtrace.1,v 1.11 2005/05/31 18:01:08 greg Exp $"
+.\" RCSid "$Id: rtrace.1,v 1.12 2005/06/13 20:07:55 greg Exp $"
 .TH RTRACE 1 10/17/97 RADIANCE
 .SH NAME
 rtrace - trace rays in RADIANCE scene
@@ -177,6 +177,12 @@ though the
 option (below) may be used to override this.
 This option is especially useful in
 conjunction with ximage(1) for computing illuminance at scene points.
+.TP
+.BR \-R
+Boolean switch to control random sampling.
+When "off", a low-discrepancy sequence is used, which reduces
+variance but can result in a brushed appearance in specular highlights.
+When "on", pure Monte Carlo sampling is used in all calculations.
 .TP
 .BR \-I
 Boolean switch to compute irradiance rather than radiance,