[ViewVC] Diff of: Development/ray/doc/ray.1

Comparing ray/doc/ray.1 (file contents):
Revision 1.3 by greg, Fri Mar 14 21:27:45 2003 UTC vs.
Revision 1.50 by greg, Tue Jul 22 19:43:59 2025 UTC

-<
+.\" RCSid "$Id"
->
+.\" RCSid "$Id$"
+.\" Print using the -ms macro package
-<
+.DA 1/20/99
->
+.DA 07/22/2025
+.LP
-<
+.tl """Copyright \(co 1996 Regents, University of California
->
+.tl """Copyright \(co 2025 Regents, University of California
+.sp 2
+.TL
+The
+.br
+Synthetic Imaging System
+.AU
-<
+Greg Ward
->
+Building Technologies Department
+.br
+Lawrence Berkeley Laboratory
+.br
-<
+Cyclotron Rd.
->
+Cyclotron Rd., MS 90-3111
+.br
+Berkeley, CA  94720
-–
+.br
-–
+(510) 486-4757
+.NH 1
+Introduction
+.PP
+is a variation of
+.I rpict
+that computes and displays images interactively.
-+
+Other programs (not shown) connect many of these elements together,
-+
+such as the executive programs
-+
+.I rad
-+
+and
-+
+.I ranimate,
-+
+the interactive rendering program
-+
+.I rholo,
-+
+and the animation program
-+
+.I ranimove.
-+
+The program
-+
+.I obj2mesh
-+
+acts as both a converter and scene compiler, converting a Wavefront .OBJ
-+
+file into a compiled mesh octree for efficient rendering.
+.PP
+A scene description file lists the surfaces and materials
-<
+that make up a specific environment.
-<
+The current surface types are spheres, polygons, cones,
-<
+and cylinders.
-<
+They can be made from materials such as plastic, metal,
-<
+and glass.
-<
+Light sources can be distant disks as well as local spheres, discs and
-<
+polygons.
->
+that  make up a specific environment.
->
+The current surface types are  spheres,  polygons,  cones,  and  cylinders.
->
+There is also a composite surface type, called mesh, and a pseudosurface
->
+type, called instance, which facilitates very complex geometries.
->
+Surfaces can be made from materials such as plastic, metal, and glass.
->
+Light sources can be distant disks as well as  local spheres, disks
->
+and polygons.
+.PP
+From a three-dimensional scene description and a specified view,
+.I rpict
+# comment
+modifier type identifier
-<
+n S1 S2 S3 .. Sn
->
+n S1 S2 "S 3" .. Sn
+m R1 R2 R3 .. Rm
+Thus, the same identifier may be used repeatedly, and each new
+definition will apply to the primitives following it.
+.FE
-<
+An identifier can be any string (i.e. sequence of non-blank
-<
+characters).
->
+An identifier can be any string (i.e., any sequence of non-white characters).
+The
+.I arguments
+associated with a primitive can be strings or real numbers.
+The first integer following the identifier is the number
+of string arguments, and it is followed by the arguments themselves
-<
+(separated by white space).
->
+(separated by white space or enclosed in quotes).
+The next integer is the number of integer arguments, and is followed
+by the integer arguments.
+(There are currently no primitives that use them, however.)
+A command may be continued over multiple lines using a backslash, `\\',
+to escape the newline.
+.PP
-<
+Blank space is generally ignored, except as a separator.
->
+White space is generally ignored, except as a separator.
+The exception is the newline character after a command or comment.
+Commands, comments and primitives may appear in any combination, so long
+as they are not intermingled.
+Primitive Types
+.PP
+Primitives can be surfaces, materials, textures or patterns.
-<
+Modifiers can be materials, textures or patterns.
->
+Modifiers can be materials, mixtures, textures or patterns.
+Simple surfaces must have one material in their modifier list.
+.NH 3
+Surfaces
+.LP
+.UL Cup
+.PP
-<
+A cup is an inverted cone (i.e. has an inward surface normal).
->
+A cup is an inverted cone (i.e., has an inward surface normal).
+.LP
+.UL Cylinder
+.PP
+A mesh is a compound surface, made up of many triangles and
+an octree data structure to accelerate ray intersection.
+It is typically converted from a Wavefront .OBJ file using the
-<
+obj2mesh program.
->
+.I obj2mesh
->
+program.
+.DS
+mod mesh id
++ meshfile transform
+available memory.
+In addition, the mesh primitive can have associated (u,v) coordinates
+for pattern and texture mapping.
-<
+These are made available to function files via the Lu and Lu variables.
->
+These are made available to function files via the Lu and Lv variables.
+.LP
+.UL Instance
+.PP
+.LP
+.UL Light
+.PP
-<
+Light is the basic material for self-luminous surfaces (i.e. light
->
+Light is the basic material for self-luminous surfaces (i.e., light
+sources).
+In addition to the source surface type, spheres, discs (rings with zero
+inner radius), cylinders (provided they are long enough), and
+As well as radiance, the full cone angle (in degrees)
+and orientation (output direction) vector are given.
+The length of the orientation vector is the distance
-<
+of the effective focus behind the source center (i.e. the focal length).
->
+of the effective focus behind the source center (i.e., the focal length).
+.DS
+mod spotlight id
+.LP
+.UL Mirror
+.PP
-<
+Mirror is used for planar surfaces that produce secondary
->
+Mirror is used for planar surfaces that produce virtual
+source reflections.
+This material should be used sparingly, as it may cause the light
+source calculation to blow up if it is applied to many small surfaces.
+red green blue
+.DE
-+
+While alternate materials that are reflective will appear as normal,
-+
+indirect rays will use the mirror's reflectance rather than the
-+
+alternate type.
-+
+Transmitting materials are an exception, where both transmission and
-+
+reflection will use the alternate type for all rays not specifically
-+
+targeting virtual light sources.
-+
+In this case, it is important that any reflections be purely specular
-+
+(mirror-like) and equal to the mirror's reflectivity
-+
+to maintain a valid result.
-+
+A pure diffuse reflection may be added if desired.
-+
+.PP
-+
+The mirror material type reflects light sources only from the front side
-+
+of a surface, regardless of any alternate material.
-+
+If virtual source generation is desired on both sides, two coincident
-+
+surfaces with opposite normal orientations may be employed to achieve
-+
+this effect.
-+
+The reflectance and alternate material type may be
-+
+different for the overlapped surfaces,
-+
+and the two sides will behave accordingly.
+.LP
+.UL Prism1
+.PP
+The prism1 material is for general light redirection from prismatic
-<
+glazings, generating secondary light sources.
-<
+It can only be used to modify a planar surface (i.e. a polygon or disk)
->
+glazings, generating virtual light sources.
->
+It can only be used to modify a planar surface (i.e., a polygon or disk)
+and should not result in either light concentration or scattering.
+The new direction of the ray can be on either side of the material,
+and the definitions must have the correct bidirectional properties
-<
+to work properly with secondary light sources.
->
+to work properly with virtual light sources.
+The arguments give the coefficient for the redirected light
+and its direction.
+.DS
+The scattering eccentricity parameter will likewise override the global
+setting if it is present.
+Scattering eccentricity indicates how much scattered light favors the
-<
+forward direction, as fit by the Heyney-Greenstein function:
->
+forward direction, as fit by the Henyey-Greenstein function:
+.DS
+P(theta) = (1 - g*g) / (1 + g*g - 2*g*cos(theta))^1.5
+.DE
+These three expressions (separated by white space) are evaluated in
+the context of the function file
+.I funcfile.
-<
+If no function file is required (i.e. no special variables or
->
+If no function file is required (i.e., no special variables or
+functions are required), a period (`.') may be given in its
+place.
+(See the discussion of Function Files in the Auxiliary Files section).
+red green blue spec urough vrough trans tspec
+.DE
+.LP
-+
+.UL Ashik2
-+
+.PP
-+
+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.
-+
+Unlike other material types, total reflectance is the sum of
-+
+diffuse and specular colors, and should be adjusted accordingly.
-+
+.DS
-+
+mod ashik2 id
-+
++ ux uy uz funcfile transform
-+
-+
+dred dgrn dblu sred sgrn sblu u-power v-power
-+
+.DE
-+
+.LP
-+
+.UL WGMDfunc
-+
+.PP
-+
+WGMDfunc is a more programmable version of trans2,
-+
+with separate modifier paths and variables to control each component.
-+
+(WGMD stands for Ward-Geisler-Moroder-Duer, which is the basis for
-+
+this empirical model, similar to the previous ones beside Ashik2.)\0
-+
+The specification of this material is given below.
-+
+.DS
-+
+mod WGMDfunc id
-+
++ rs_mod  rs  rs_urough rs_vrough
-+
+    ts_mod  ts  ts_urough ts_vrough
-+
+    td_mod
-+
+    ux uy uz  funcfile  transform
-+
-+
++  rfdif gfdif bfdif
-+
+    rbdif gbdif bbdif
-+
+    rtdif gtdif btdif
-+
+    A10 ..
-+
+.DE
-+
+The sum of specular reflectance (
-+
+.I rs
-+
+), specular transmittance (
-+
+.I ts
-+
+), diffuse reflectance (
-+
+.I "rfdif gfdif bfdif"
-+
+for front and
-+
+.I "rbdif gbdif bbdif"
-+
+for back)
-+
+and diffuse transmittance (
-+
+.I "rtdif gtdif btdif"
-+
+) should be less than 1 for each
-+
+channel.
-+
+.PP
-+
+Unique to this material, separate modifier channels are
-+
+provided for each component.
-+
+The main modifier is used on the diffuse reflectance, both
-+
+front and back.
-+
+The
-+
+.I rs_mod
-+
+modifier is used for specular reflectance.
-+
+If "void" is given for
-+
+.I rs_mod,
-+
+then the specular reflection color will be white.
-+
+The special "inherit" keyword may also be given, in which case
-+
+specular reflectance will share the main modifier.
-+
+This behavior is replicated for the specular transmittance modifier
-+
+.I ts_mod,
-+
+which has its own independent roughness expressions.
-+
+Finally, the diffuse transmittance modifier is given as
-+
+.I td_mod,
-+
+which may also be "void" or "inherit".
-+
+Note that any spectra or color for specular components must be
-+
+carried by the named modifier(s).
-+
+.PP
-+
+The main advantage to this material over BRTDfunc and
-+
+other programmable types described below is that the specular sampling is
-+
+well-defined, so that all components are fully computed.
-+
+.LP
+.UL Dielectric
+.PP
+A dielectric material is transparent, and it refracts light
++ 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
-+
++ thick BSDFfile ux uy uz funcfile transform
-+
-+
+|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 aBSDF
-+
+.PP
-+
+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.
-+
+.DS
-+
+mod aBSDF id
-+
++ BSDFfile ux uy uz funcfile transform
-+
-+
+|3|6|9
-+
+     rfdif gfdif bfdif
-+
+     rbdif gbdif bbdif
-+
+     rtdif gtdif btdif
-+
+.DE
-+
+.LP
-+
+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.
-+
+.LP
+.UL Antimatter
+.PP
+Antimatter is a material that can "subtract" volumes from other volumes.
+The first modifier will also be used to shade the area leaving the
+antimatter volume and entering the regular volume.
+If mod1 is void, the antimatter volume is completely invisible.
-<
+Antimatter does not work properly with the material type "trans",
-<
+and multiple antimatter surfaces should be disjoint.
->
+If shading is desired at antimatter surfaces, it is important
->
+that the related volumes are closed with outward-facing normals.
->
+Antimatter surfaces should not intersect with other antimatter boundaries,
->
+and it is unwise to use the same modifier in nested antimatter volumes.
+The viewpoint must be outside all volumes concerned for a correct
+rendering.
+.NH 3
+.I zdfname.
+.DS
+mod texdata id
-<
++ xfunc yfunc zfunc xdfname ydfname zdfname vfname x0 x1 .. xf
->
++ xfunc yfunc zfunc xdfname ydfname zdfname funcfile x0 x1 .. xf
+n A1 A2 .. An
+.DE
+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).
-+
+.LP
-+
+.UL Spectrum
-+
+.PP
-+
+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.
-+
+.DS
-+
+mod spectrum id
-+
-+
-+
++ nmA nmB s1 s2 .. sN
-+
+.DE
-+
+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.
-+
+.LP
-+
+.UL Specfile
-+
+.PP
-+
+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.
-+
+.DS
-+
+mod specfile id
-+
+datafile
-+
-+
-+
+.DE
-+
+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.
-+
+.LP
-+
+.UL Specfunc
-+
+.PP
-+
+The specfunc primitive offers dynamic control over a spectral
-+
+pattern, similar to the colorfunc type.
-+
+.DS
-+
+mod specfunc id
-+
++ sfunc funcfile transform
-+
-+
++ nmA nmB A3 ..
-+
+.DE
-+
+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.
-+
+.LP
-+
+.UL Specdata
-+
+.PP
-+
+Specdata is like brightdata and colordata, but with more
-+
+than 3 specular samples.
-+
+.DS
-+
+mod specdata id
-+
++n+
-+
+        func datafile
-+
+        funcfile x1 x2 .. xn transform
-+
-+
+m A1 A2 .. Am
-+
+.DE
-+
+The data file must have one more dimension than the coordinate
-+
+variable count, as this final dimension corresponds to the covered
-+
+spectrum.
-+
+The starting and ending wavelengths are specified in "datafile"
-+
+as well as the number of spectral samples.
-+
+The function "func" will be called with two parameters, the
-+
+interpolated spectral value for the current coordinate and the
-+
+associated wavelength.
-+
+If the spectrum is broken into 12 components, then 12 calls
-+
+will be made to "func" for the relevant ray evaluation.
-+
+.LP
-+
+.UL Specpict
-+
+.PP
-+
+Specpict is a special case of specdata, where the pattern is
-+
+a hyperspectral image stored in the common-exponent file format.
-+
+The dimensions of the image data are determined by the picture
-+
+just as with the colorpict primitive.
-+
+.DS
-+
+mod specpict id
 +
-+
+        func specfile
-+
+        funcfile u v transform
-+
-+
+m A1 A2 .. Am
-+
+.DE
-+
+The function "func" is called with the interpolated pixel value
-+
+and the wavelength sample in nanometers, the same as specdata,
-+
+with as many calls made as there are components in "specfile".
+.NH 3
+Mixtures
+.PP
+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.
+.LP
+.UL Mixfunc
+Vname is the coefficient defined in funcfile that determines the influence
+of foreground.
+The background coefficient is always (1-vname).
-–
+Since the references are not resolved until runtime, the last
-–
+definitions of the modifier id's will be used.
-–
+This can result in modifier loops, which are detected by the
-–
+renderer.
+.LP
+.UL Mixdata
+.PP
+The following variables are particularly important:
+.DS
+        Dx, Dy, Dz              - incident ray direction
-–
+        Px, Py, Pz              - intersection point
+        Nx, Ny, Nz              - surface normal at intersection point
-+
+        Px, Py, Pz              - intersection point
-+
+        T                       - distance from start
-+
+        Ts                      - single ray (shadow) distance
+        Rdot                    - cosine between ray and normal
+        arg(0)                  - number of real arguments
+        arg(i)                  - i'th real argument
+.DE
-+
+For mesh objects, the local surface coordinates are available:
-+
+.DS
-+
+        Lu, Lv                  - local (u,v) coordinates
-+
+.DE
+For BRDF types, the following variables are defined as well:
+.DS
+        NxP, NyP, NzP           - perturbed surface normal
+variables are global, a period (`.') can be given in
+place of the file name.
+It is also possible to give an expression instead of a straight
-<
+variable name in a scene file, although such expressions should
-<
+be kept simple as they cannot contain any white space.
-<
+Also, functions (requiring parameters)
->
+variable name in a scene file.
->
+Functions (requiring parameters)
+must be given as names and not as expressions.
+.PP
+Constant expressions are used as an optimization in function
+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
+.NH 1
+License
+.PP
-<
+Radiance is a registered copyright of The Regents of the University of
-<
+California ("The Regents"). The Regents grant to you a nonexclusive,
-<
+nontransferable license ("License") to use Radiance source code without fee.
-<
+You may not sell or distribute Radiance to others without the prior express
-<
+written permission of The Regents.
-<
+You may compile and use this software on any machines to which you have
-<
+personal access, and may share its use with others who have access to the
-<
+same machines.
-<
+.PP
-<
+NEITHER THE UNITED STATES NOR THE UNITED STATES DEPARTMENT OF ENERGY, NOR ANY
-<
+OF THEIR EMPLOYEES, MAKES ANY WARRANTY, EXPRESS OR IMPLIED, OR ASSUMES ANY
-<
+LEGAL LIABILITY OR RESPONSIBILITY FOR THE ACCURACY, COMPLETENESS, OR
-<
+USEFULNESS OF ANY INFORMATION, APPARATUS, PRODUCT, OR PROCESS DISCLOSED, OR
-<
+REPRESENTS THAT ITS USE WOULD NOT INFRINGE PRIVATELY OWNED RIGHTS.
-<
+By downloading, using or copying this software, you agree to abide by the
-<
+intellectual property laws and all other applicable laws of the United
-<
+States, and by the terms of this License Agreement. Ownership of the software
-<
+shall remain solely in The Regents.
-<
+The Regents shall have the right to terminate this License immediately by
-<
+written notice upon your breach of, or noncompliance with, any of its terms.
-<
+You shall be liable for any infringement or damages resulting from your
-<
+failure to abide by the terms of this License Agreement.
-<
+.PP
-<
+NOTICE: The Government is granted for itself and others acting on its behalf
-<
+a paid-up, nonexclusive irrevocable worldwide license in this data to
-<
+reproduce, prepare derivative works, and perform publicly and display
-<
+publicly. Beginning five (5) years after permission to assert copyright is
-<
+granted, subject to two possible five year renewals, the Government is
-<
+granted for itself and others acting on its behalf a paid-up, non-exclusive,
-<
+irrevocable worldwide license in this data to reproduce, prepare derivative
-<
+works, distribute copies to the public, perform publicly and display
-<
+publicly, and to permit others to do so.
->
+.DS
->
+The Radiance Software License, Version 2.0
->
->
+Radiance v6.0 Copyright (c) 1990 to 2025, The Regents of the University of
->
+California, through Lawrence Berkeley National Laboratory (subject to receipt
->
+of any required approvals from the U.S. Dept. of Energy).  All rights reserved.
->
->
+Redistribution and use in source and binary forms, with or without
->
+modification, are permitted provided that the following conditions are met:
->
->
+(1) Redistributions of source code must retain the above copyright notice,
->
+this list of conditions and the following disclaimer.
->
->
+(2) Redistributions in binary form must reproduce the above copyright
->
+notice, this list of conditions and the following disclaimer in the
->
+documentation and/or other materials provided with the distribution.
->
->
+(3) Neither the name of the University of California, Lawrence Berkeley
->
+National Laboratory, U.S. Dept. of Energy nor the names of its contributors
->
+may be used to endorse or promote products derived from this software
->
+without specific prior written permission.
->
->
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
->
+AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
->
+IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
->
+ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
->
+LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
->
+CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
->
+SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
->
+INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
->
+CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
->
+ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
->
+POSSIBILITY OF SUCH DAMAGE.
->
->
+You are under no obligation whatsoever to provide any bug fixes, patches,
->
+or upgrades to the features, functionality or performance of the source
->
+code ("Enhancements") to anyone; however, if you choose to make your
->
+Enhancements available either publicly, or directly to Lawrence Berkeley
->
+National Laboratory, without imposing a separate written license agreement
->
+for such Enhancements, then you hereby grant the following license: a
->
+non-exclusive, royalty-free perpetual license to install, use, modify,
->
+prepare derivative works, incorporate into other computer software,
->
+distribute, and sublicense such enhancements or derivative works thereof,
->
+in binary and source code form.
->
+.DE
+.NH 1
+Acknowledgements
+.PP
+in Lausanne, Switzerland.
+.NH 1
+References
-+
+.LP
-+
+Ward, Gregory J., Bruno Bueno, David Geisler-Moroder,
-+
+Lars O. Grobe, Jacob C. Jonsson, Eleanor
-+
+S. Lee, Taoning Wang, Helen Rose Wilson,
-+
+``Daylight Simulation Workflows Incorporating
-+
+Measured Bidirectional Scattering Distribution Functions,''
-+
+.I "Energy & Buildings",
-+
+Vol. 259, No. 111890, 2022.
-+
+.LP
-+
+Wang, Taoning, Gregory Ward, Eleanor Lee,
-+
+``Efficient modeling of optically-complex, non-coplanar
-+
+exterior shading: Validation of matrix algebraic methods,''
-+
+.I "Energy & Buildings",
-+
+vol. 174, pp. 464-83, Sept. 2018.
-+
+.LP
-+
+Lee, Eleanor S., David Geisler-Moroder, Gregory Ward,
-+
+``Modeling the direct sun component in buildings using matrix
-+
+algebraic approaches: Methods and validation,''
-+
+.I Solar Energy,
-+
+vol. 160, 15 January 2018, pp 380-395.
-+
+.LP
-+
+Ward, G., M. Kurt & N. Bonneel,
-+
+``Reducing Anisotropic BSDF Measurement to Common Practice,''
-+
+.I Workshop on Material Appearance Modeling,
-+
+.
-+
+.LP
-+
+McNeil, A., C.J. Jonsson, D. Appelfeld, G. Ward, E.S. Lee,
-+
+``A validation of a ray-tracing tool used to generate
-+
+bi-directional scattering distribution functions for
-+
+complex fenestration systems,''
-+
+.I "Solar Energy",
-+
+, 404-14, November 2013.
-+
+.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",
-+
+(4),
-+
+April 2011.
-+
+.LP
-+
+Cater, K., A. Chalmers, G. Ward,
-+
+``Detail to Attention: Exploiting Visual Tasks for Selective Rendering,''
-+
+.I "Eurograhics Symposium on Rendering",
-+
+June 2003.
-+
+.LP
-+
+Ward, G., Elena Eydelberg-Vileshin,
-+
+``Picture Perfect RGB Rendering Using Spectral Prefiltering and
-+
+Sharp Color Primaries,''
-+
+th Eurographics Workshop on Rendering, P. Debevec and
-+
+S. Gibson (Editors), June 2002.
-+
+.LP
-+
+Ward, G. and M. Simmons,
-+
+``The Holodeck Ray Cache: An Interactive Rendering System for Global
-+
+Illumination in Nondiffuse Environments,''
-+
+.I "ACM Transactions on Graphics,"
-+
+(4):361-98, October 1999.
-+
+.LP
-+
+Larson, G.W., H. Rushmeier, C. Piatko,
-+
+``A Visibility Matching Tone Reproduction Operator for High Dynamic
-+
+Range Scenes,''
-+
+.I "IEEE Transactions on Visualization and Computer Graphics",
-+
+(4), 291-306, December 1997.
-+
+.LP
-+
+Ward, G.,
-+
+``Making Global Illumination User Friendly,''
-+
+.I "Sixth Eurographics Workshop on Rendering",
-+
+proceedings to be published by Springer-Verlag,
-+
+Dublin, Ireland, June 1995.
-+
+.LP
-+
+Rushmeier, H., G. Ward, C. Piatko, P. Sanders, B. Rust,
-+
+``Comparing Real and Synthetic Images: Some Ideas about Metrics,''
-+
+.I "Sixth Eurographics Workshop on Rendering",
-+
+proceedings to be published by Springer-Verlag,
-+
+Dublin, Ireland, June 1995.
+.LP
+Ward, G.,
+``The Radiance Lighting Simulation and Rendering System,''

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Revision 1.3 by greg, Fri Mar 14 21:27:45 2003 UTC vs.
Revision 1.50 by greg, Tue Jul 22 19:43:59 2025 UTC