--- ray/doc/man/man1/rpict.1	2015/06/05 08:49:01	1.20
+++ ray/doc/man/man1/rpict.1	2019/01/11 21:12:24	1.24
@@ -1,4 +1,4 @@
-.\" RCSid "$Id: rpict.1,v 1.20 2015/06/05 08:49:01 rschregle Exp $"
+.\" RCSid "$Id: rpict.1,v 1.24 2019/01/11 21:12:24 greg Exp $"
 .TH RPICT 1 2/26/99 RADIANCE
 .SH NAME
 rpict - generate a RADIANCE picture
@@ -540,7 +540,9 @@ Global photon irradiance is evaluated as part of the a
 above), caustic photon irradiance is evaluated at primary rays, and 
 indirect inscattering in 
 .I mist
-is accounted for by volume photons.
+is accounted for by volume photons. Contribution photons are treated as
+global photons by
+.I rpict.
 .IP
 Additionally specifying 
 .I bwidth2
@@ -557,7 +559,7 @@ in which case the bandwidth, if specified, is ignored,
 is invariably looked up.
 .IP
 Using direct photons replaces the direct calculation with density estimates
-for debugging and validation of photon emission.       
+for debugging and validation of photon emission.
 .TP
 .BI -am " frac"
 Maximum search radius for photon map lookups.  Without this option, an
@@ -575,6 +577,33 @@ lower if the maximum search radius contains fewer phot
 short lookups.  Setting this radius too large, on the other hand, may
 degrade performance.
 .TP
+.BI -ac " pagesize"
+Set the photon cache page size when using out-of-core photon mapping. The
+photon cache reduces disk I/O incurred by on-demand loading (paging) of
+photons, and thus increases performance. This
+is expressed as a (float) multiple of the density estimate bandwidth
+specified with
+.I \-ap
+under the assumption that photon lookups are local to a cache page. Cache
+performance is sensitive to this parameter: larger pagesizes will reduce the
+paging frequency at the expense of higher latency when paging does occur.
+Sensible values are in the range 4 (default) to 16.
+.TP
+.BI -aC " cachesize"
+Set the total number of photons cached when using out-of-core photon
+mapping, taking into account the pagesize specified by
+.I \-ac. 
+Note that this is approximate as the number of cache pages is rounded to
+the nearest prime. This allows adapting the cache to the available physical
+memory. In conjunction with the
+.I \-n
+option, this is the cache size
+.I per parallel process. 
+Cache performance is less sensitive to this parameter,
+and reasonable performance can obtained with as few as 10k photons. The
+default is 1M. This option recognises multiplier suffixes (k = 1e3, M =
+1e6), both in upper and lower case.
+.TP
 .BI -me " rext gext bext"
 Set the global medium extinction coefficient to the indicated color,
 in units of 1/distance (distance in world coordinates).
@@ -637,8 +666,8 @@ is zero, then Russian roulette is used for ray
 termination, and the
 .I -lw
 setting (below) must be positive.
-If N is a negative integer, then this sets the upper limit
-of reflections past which Russian roulette will be used.
+If N is a negative integer, then this limits the maximum
+number of reflections even with Russian roulette.
 In scenes with dielectrics and total internal reflection,
 a setting of 0 (no limit) may cause a stack overflow.
 .TP
@@ -885,4 +914,4 @@ option.
 Greg Ward
 .SH "SEE ALSO"
 getinfo(1), lookamb(1), mkpmap(1), oconv(1), pdfblur(1), pfilt(1), 
-pinterp(1), pmblur(1), printf(3), ra_rgbe(1), rad(1), rtrace(1), rvu(1)
+pinterp(1), pmblur(1), printf(3), ra_rgbe(1), rad(1), rpiece(1), rtpict(1), rtrace(1), rvu(1)