--- ray/doc/ray.html 2018/06/25 20:49:10 1.25 +++ ray/doc/ray.html 2023/12/12 20:25:22 1.37 @@ -1,8 +1,8 @@ - + -The RADIANCE 5.2 Synthetic Imaging System +The RADIANCE 6.0 Synthetic Imaging System @@ -10,7 +10,7 @@ The RADIANCE 5.2 Synthetic Imaging System

-The RADIANCE 5.2 Synthetic Imaging System +The RADIANCE 6.0 Synthetic Imaging System

@@ -83,7 +83,7 @@ The diagram in Figure 1 shows the flow between program (ovals). The central program is rpict, which produces a picture from a scene description. -Rview is a variation of rpict that computes and displays images +Rvu is a variation of rpict that computes and displays images interactively, and rtrace computes single ray values. Other programs (not shown) connect many of these elements together, such as the executive programs @@ -822,6 +822,8 @@ unless the line integrals consider enclosed geometry. Also, rather than roughness, specular power is used, which has no physical meaning other than larger numbers are equivalent to a smoother surface. + Unlike other material types, total reflectance is the sum of + diffuse and specular colors, and should be adjusted accordingly. 

 	mod ashik2 id
 	4+ ux uy uz funcfile transform
@@ -1154,22 +1156,23 @@ unless the line integrals consider enclosed geometry.
 

 
 

-	
-	sBSDF
+	
+	aBSDF
 	
 
 

-	The sBSDF material is identical to the BSDF type with two
+	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
-	sBSDF is assumed to have some specular through component,
+	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 sBSDF id
+	mod aBSDF id
 	5+ BSDFfile ux uy uz funcfile transform
 	0
 	0|3|6|9
@@ -1181,7 +1184,7 @@ unless the line integrals consider enclosed geometry.
 

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

 
 

@@ -1458,6 +1461,98 @@ or:
 	A section of text meant to  depict  a  picture, perhaps using a special purpose font such as hexbit4x1.fnt, calls for uniform  spacing.   
 	Reasonable  magnitudes  for  proportional  spacing are between 0.1 (for tightly spaced characters) and 0.3 (for wide spacing).
 
+

+
+

+	
+	Spectrum
+	
+
+

+	The spectrum primitive is the most basic type for introducing spectral
+	color to a material.
+	Since materials only provide RGB parameters, spectral patterns
+	are the only way to superimpose wavelength-dependent behavior.
+
+
+        mod spectrum id
+	0
+	0
+	5+ nmA nmB s1 s2 .. sN
+

+
+

+	The first two real arguments indicate the extrema of the
+	spectral range in nanometers.
+	Subsequent real values correspond to multipliers at each wavelength.
+	The nmA wavelength may be greater or less than nmB,
+	but they may not be equal, and their ordering matches
+	the order of the spectral values.
+	A minimum of 3 values must be given, which would act
+	more or less the same as a constant RGB multiplier.
+	As with RGB values, spectral quantities normally range between 0
+	and 1 at each wavelength, or average to 1.0 against a standard
+	sensitivity functions such as V(lambda).
+	The best results obtain when the spectral range and number
+	of samples match rendering options, though resampling will handle
+	any differences, zero-filling wavelenths outside the nmA to nmB
+	range.
+	A warning will be issued if the given wavelength range does not
+	adequately cover the visible spectrum.
+
+

+
+

+	
+	Specfile
+	
+
+

+	The specfile primitive is equivalent to the spectrum type, but
+	the wavelength range and values are contained in a 1-dimensional
+	data file.
+	This may be a more convenient way to specify a spectral color,
+	especially one corresponding to a standard illuminant such as D65
+	or a library of measured spectra.
+
+
+        mod specfile id
+	1 datafile
+	0
+	0
+

+
+

+	As with the spectrum type, rendering wavelengths outside the defined
+	range will be zero-filled.
+	Unlike the spectrum type, the file may contain non-uniform samples.
+
+

+
+

+	
+	Specfunc
+	
+
+

+	The specfunc primitive offers dynamic control over a spectral
+	pattern, similar to the colorfunc type.
+
+
+        mod specfunc id
+	2+ sfunc funcfile transform
+	0
+	2+ nmA nmB A3 ..
+

+
+

+	Like the spectrum primitive, the wavelength range is specified
+	in the first two real arguments, and additional real values are
+	set in the evaluation context.
+	This function is fed a wavelenth sample
+	between nmA and nmB as its only argument,
+	and it returns the corresponding spectral intensity.
+
 
 
 

@@ -1806,7 +1901,7 @@ The details of this process  are  not  important, but 
 directs the use of a scene description.