--- ray/doc/ray.1	2010/03/12 18:43:30	1.16
+++ ray/doc/ray.1	2011/10/17 21:53:55	1.24
@@ -1,8 +1,8 @@
 .\" RCSid "$Id"
 .\" Print using the -ms macro package
-.DA 3/12/2010
+.DA 2/17/2011
 .LP
-.tl """Copyright \(co 2010 Regents, University of California
+.tl """Copyright \(co 2011 Regents, University of California
 .sp 2
 .TL
 The
@@ -865,6 +865,73 @@ mod transdata id
 6+ red green blue rspec trans tspec A7 ..
 .DE
 .LP
+.UL BSDF
+.PP
+The BSDF material type loads an XML (eXtensible Markup Language)
+file describing a bidirectional scattering distribution function.
+Real arguments to this material may define additional
+diffuse components that augment the BSDF data.
+String arguments are used to define thickness for proxied
+surfaces and the "up" orientation for the material.
+.DS
+mod BSDF id
+6+ thick BSDFfile ux uy uz funcfile transform
+0
+0|3|6|9
+     rfdif gfdif bfdif
+     rbdif gbdif bbdif
+     rtdif gtdif btdif
+.DE
+The first string argument is a "thickness" parameter that may be used
+to hide detail geometry being proxied by an aggregate BSDF material.
+If a view or shadow ray hits a BSDF proxy with non-zero thickness,
+it will pass directly through as if the surface were not there.
+Similar to the illum type, this permits direct viewing and
+shadow testing of complex geometry.
+The BSDF is used when a scattered (indirect) ray hits the surface,
+and any transmitted sample rays will be offset by the thickness amount
+to avoid the hidden geometry and gather samples from the other side.
+In this manner, BSDF surfaces can improve the results for indirect
+scattering from complex systems without sacrificing appearance or
+shadow accuracy.
+If the BSDF has transmission and back-side reflection data,
+a parallel BSDF surface may be
+placed slightly less than the given thickness away from the front surface
+to enclose the complex geometry on both sides.
+The sign of the thickness is important, as it indicates whether the
+proxied geometry is behind the BSDF surface (when thickness is positive)
+or in front (when thickness is negative).
+.LP
+The second string argument is the name of the BSDF file, which is
+found in the usual auxiliary locations.
+The following three string parameters name variables for an "up" vector,
+which together with the surface normal, define the
+local coordinate system that orients the BSDF.
+These variables, along with the thickness, are defined in a function
+file given as the next string argument.
+An optional transform is used to scale the thickness and reorient the up vector.
+.LP
+If no real arguments are given, the BSDF is used by itself to determine
+reflection and transmission.
+If there are at least 3 real arguments, the first triplet is an
+additional diffuse reflectance for the front side.
+At least 6 real arguments adds diffuse reflectance to the rear side of the surface.
+If there are 9 real arguments, the final triplet will be taken as an additional
+diffuse transmittance.
+All diffuse components as well as the non-diffuse transmission are
+modified by patterns applied to this material.
+The non-diffuse reflection from either side are unaffected.
+Textures perturb the effective surface normal in the usual way.
+.LP
+The surface normal of this type is not altered to face the incoming ray,
+so the front and back BSDF reflections may differ.
+(Transmission is identical front-to-back by physical law.)\0
+If back visibility is turned off during rendering and there is no
+transmission or back-side reflection, only then the surface will be
+invisible from behind.
+Unlike other data-driven material types, the BSDF type is fully
+supported and all parts of the distribution are properly sampled.
+.LP
 .UL Antimatter
 .PP
 Antimatter is a material that can "subtract" volumes from other volumes.
@@ -1400,16 +1467,10 @@ converts a picture to and from simpler formats.
 Pictures may be displayed directly under X11 using the program
 .I ximage,
 or converted a standard image format.
-.I Ra_avs
-converts to and from AVS image format.
-.I Ra_pict
-converts to Macintosh 32-bit PICT2 format.
+.I Ra_bmp
+converts to and from Microsoft Bitmap images.
 .I Ra_ppm
 converts to and from Poskanzer Portable Pixmap formats.
-.I Ra_pr
-converts to and from Sun 8-bit rasterfile format.
-.I Ra_pr24
-converts to and from Sun 24-bit rasterfile format.
 .I Ra_ps
 converts to PostScript color and greyscale formats.
 .I Ra_rgbe
@@ -1490,6 +1551,13 @@ the Ecole Polytechnique Federale de Lausanne (EPFL Uni
 in Lausanne, Switzerland.
 .NH 1
 References
+.LP
+Ward, G., R. Mistrick, E.S. Lee, A. McNeil, J. Jonsson,
+``Simulating the Daylight Performance of Complex Fenestration Systems
+Using Bidirectional Scattering Distribution Functions within Radiance,''
+.I "Leukos",
+7(4),
+April 2011.
 .LP
 Cater, K., A. Chalmers, G. Ward,
 ``Detail to Attention: Exploiting Visual Tasks for Selective Rendering,''