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

Comparing ray/doc/ray.1 (file contents):
Revision 1.8 by greg, Sun Jul 24 21:05:45 2005 UTC vs.
Revision 1.41 by greg, Wed Nov 15 18:28:09 2023 UTC

+.\" RCSid "$Id$"
+.\" Print using the -ms macro package
-<
+.DA 1/20/99
->
+.DA 11/13/2023
+.LP
-<
+.tl """Copyright \(co 2005 Regents, University of California
->
+.tl """Copyright \(co 2023 Regents, University of California
+.sp 2
+.TL
+The
+.br
+Synthetic Imaging System
+.AU
-<
+Building Technologies Program
->
+Building Technologies Department
+.br
+Lawrence Berkeley Laboratory
+.br
+.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.
+.UL Prism1
+.PP
+The prism1 material is for general light redirection from prismatic
-<
+glazings, generating secondary light sources.
->
+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
+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 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
+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 limits of the covered
-+
+spectral range in nanometers.
-+
+Subsequent real values correspond to multipliers in each wavelength band,
-+
+where the first band goes from nmA to nmA+(nmB-nmA)/N, and N is the
-+
+number of bands (i.e., the number of real arguments minus 2).
-+
+The nmA wavelength may be greater or less than the nmB wavelength,
-+
+but they may not be equal, and their ordering must correspond to
-+
+the ordering 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
-+
++ sval 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
-+
+accessible to the sval function.
-+
+This function is fed a wavelenth sample
-+
+between nmA and nmB as its only argument,
-+
+and it returns the corresponding spectral intensity.
+.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
+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 if possible.
-<
+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
+.I Rview
+is ray-tracing program for viewing a scene interactively.
+When the user specifies a new perspective,
-<
+.I rvu
->
+.I rview
+quickly displays a rough
+image on the terminal, then progressively
+increases the resolution as the user looks on.
+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
+.DS
+The Radiance Software License, Version 1.0
-<
+Copyright (c) 1990 - 2002 The Regents of the University of California,
->
+Copyright (c) 1990 - 2008 The Regents of the University of California,
+through Lawrence Berkeley National Laboratory.   All rights reserved.
+Redistribution and use in source and binary forms, with or without
+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

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Comparing ray/doc/ray.1 (file contents): Revision 1.8 by greg, Sun Jul 24 21:05:45 2005 UTC vs. Revision 1.41 by greg, Wed Nov 15 18:28:09 2023 UTC

Diff Legend

Comparing ray/doc/ray.1 (file contents):
Revision 1.8 by greg, Sun Jul 24 21:05:45 2005 UTC vs.
Revision 1.41 by greg, Wed Nov 15 18:28:09 2023 UTC