--- ray/doc/ray.html 2010/03/12 18:43:30 1.9 +++ ray/doc/ray.html 2020/09/03 15:46:32 1.29 @@ -1,7 +1,8 @@ + -The RADIANCE 4.0 Synthetic Imaging System +The RADIANCE 5.4 Synthetic Imaging System @@ -9,7 +10,7 @@ The RADIANCE 4.0 Synthetic Imaging System

-The RADIANCE 4.0 Synthetic Imaging System +The RADIANCE 5.4 Synthetic Imaging System

@@ -797,7 +798,8 @@ unless the line integrals consider enclosed geometry.

Trans2 is the anisotropic version of trans. - The string arguments are the same as for plastic2, and the real arguments are the same as for trans but with an additional roughness value. + The string arguments are the same as for plastic2, + and the real arguments are the same as for trans but with an additional roughness value. 
         mod trans2 id
@@ -809,6 +811,27 @@ unless the line integrals consider enclosed geometry.
 

 
 

+	
+	Ashik2
+	
+
+

+	Ashik2 is the anisotropic reflectance model by Ashikhmin & Shirley.
+	The string arguments are the same as for plastic2, but the real
+	arguments have additional flexibility to specify the specular color.
+	Also, rather than roughness, specular power is used, which has no
+	physical meaning other than larger numbers are equivalent to a smoother
+	surface.
+
+	mod ashik2 id
+	4+ ux uy uz funcfile transform
+	0
+	8 dred dgrn dblu sred sgrn sblu u-power v-power
+

+
+

+
+

 	
 	Dielectric
 	
@@ -1053,6 +1076,116 @@ unless the line integrals consider enclosed geometry.
 

 
 

+	
+	BSDF
+	
+
+

+	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.
+
+
+	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
+

+
+

+	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).
+

+	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.
+

+	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.
+

+	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.) 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.
+

+
+

+	
+	aBSDF
+	
+
+

+	The aBSDF material is identical to the BSDF type with two
+	important differences.  First, proxy geometry is not
+	supported, so there is no thickness parameter.  Second, an
+	aBSDF is assumed to have some specular through component
+	(the ’a’ stands for "aperture"),
+	which is treated specially during the direct calculation
+	and when viewing the material.  Based on the BSDF data, the
+	coefficient of specular transmission is determined and used
+	for modifying unscattered shadow and view rays.
+
+
+	mod aBSDF id
+	5+ BSDFfile ux uy uz funcfile transform
+	0
+	0|3|6|9
+	     rfdif gfdif bfdif
+	     rbdif gbdif bbdif
+	     rtdif gtdif btdif
+

+
+

+	If a material has no specular transmitted component, it is
+	much better to use the BSDF type with a zero thickness
+	than to use aBSDF.
+

+
+

 	
 	Antimatter
 	
@@ -1336,6 +1469,7 @@ or:
 
 
 A mixture is a blend of one or more materials or textures and patterns.
+Blended materials should not be light source types or virtual source types.
 The basic types are given below.
 
 

@@ -1408,7 +1542,6 @@ A mixfunc mixes  two  modifiers  procedurally.   It  i
 	arguments, the red, green and blue values
 	corresponding to the pixel at (u,v).
 
-
 

 
 

@@ -1710,16 +1843,10 @@ Pictures may be displayed directly under X11 using the
 or converted a standard image format using one of the following
 translators: