--- ray/doc/ray.html 2011/04/06 22:00:46 1.10 +++ ray/doc/ray.html 2018/10/08 20:04:09 1.27 @@ -1,7 +1,8 @@ + -The RADIANCE 4.1 Synthetic Imaging System +The RADIANCE 5.2 Synthetic Imaging System @@ -9,7 +10,7 @@ The RADIANCE 4.1 Synthetic Imaging System

-The RADIANCE 4.1 Synthetic Imaging System +The RADIANCE 5.2 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
 	
@@ -1063,7 +1086,7 @@ unless the line integrals consider enclosed geometry.
 	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.
+	surfaces and the "up" orientation for the material.
 
 
 	mod BSDF id
@@ -1076,7 +1099,7 @@ unless the line integrals consider enclosed geometry.
 

 
 

-	The first string argument is a "thickness" parameter that may be used
+	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.
@@ -1092,39 +1115,77 @@ unless the line integrals consider enclosed geometry.
 	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.
+	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.
+	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.)\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.
+	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
 	
@@ -1408,6 +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.
 
 

@@ -1480,7 +1542,6 @@ A mixfunc mixes  two  modifiers  procedurally.   It  i
 	arguments, the red, green and blue values
 	corresponding to the pixel at (u,v).
 
-
 

 
 

@@ -1782,16 +1843,10 @@ Pictures may be displayed directly under X11 using the
 or converted a standard image format using one of the following
 translators: