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.\" RCSid "$Id$" |
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.\" Print using the -ms macro package |
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.DA 11/13/2023 |
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.DA 07/22/2025 |
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.LP |
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.tl """Copyright \(co 2023 Regents, University of California |
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.tl """Copyright \(co 2025 Regents, University of California |
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.sp 2 |
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.TL |
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The |
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0 |
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3 red green blue |
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.DE |
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While alternate materials that are reflective will appear as normal, |
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indirect rays will use the mirror's reflectance rather than the |
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alternate type. |
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Transmitting materials are an exception, where both transmission and |
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reflection will use the alternate type for all rays not specifically |
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targeting virtual light sources. |
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In this case, it is important that any reflections be purely specular |
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(mirror-like) and equal to the mirror's reflectivity |
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to maintain a valid result. |
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A pure diffuse reflection may be added if desired. |
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.PP |
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The mirror material type reflects light sources only from the front side |
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of a surface, regardless of any alternate material. |
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If virtual source generation is desired on both sides, two coincident |
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surfaces with opposite normal orientations may be employed to achieve |
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this effect. |
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The reflectance and alternate material type may be |
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different for the overlapped surfaces, |
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and the two sides will behave accordingly. |
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.LP |
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.UL Prism1 |
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.PP |
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8 dred dgrn dblu sred sgrn sblu u-power v-power |
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.DE |
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.LP |
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.UL WGMDfunc |
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.PP |
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WGMDfunc is a more programmable version of trans2, |
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with separate modifier paths and variables to control each component. |
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(WGMD stands for Ward-Geisler-Moroder-Duer, which is the basis for |
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this empirical model, similar to the previous ones beside Ashik2.)\0 |
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The specification of this material is given below. |
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.DS |
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mod WGMDfunc id |
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13+ rs_mod rs rs_urough rs_vrough |
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ts_mod ts ts_urough ts_vrough |
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td_mod |
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ux uy uz funcfile transform |
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0 |
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9+ rfdif gfdif bfdif |
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rbdif gbdif bbdif |
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rtdif gtdif btdif |
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A10 .. |
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.DE |
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The sum of specular reflectance ( |
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.I rs |
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), specular transmittance ( |
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.I ts |
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), diffuse reflectance ( |
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.I "rfdif gfdif bfdif" |
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for front and |
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.I "rbdif gbdif bbdif" |
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for back) |
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and diffuse transmittance ( |
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.I "rtdif gtdif btdif" |
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) should be less than 1 for each |
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channel. |
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.PP |
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Unique to this material, separate modifier channels are |
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provided for each component. |
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The main modifier is used on the diffuse reflectance, both |
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front and back. |
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The |
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.I rs_mod |
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modifier is used for specular reflectance. |
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If "void" is given for |
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.I rs_mod, |
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then the specular reflection color will be white. |
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The special "inherit" keyword may also be given, in which case |
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specular reflectance will share the main modifier. |
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This behavior is replicated for the specular transmittance modifier |
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.I ts_mod, |
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which has its own independent roughness expressions. |
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Finally, the diffuse transmittance modifier is given as |
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.I td_mod, |
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which may also be "void" or "inherit". |
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Note that any spectra or color for specular components must be |
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carried by the named modifier(s). |
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.PP |
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The main advantage to this material over BRTDfunc and |
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other programmable types described below is that the specular sampling is |
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well-defined, so that all components are fully computed. |
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.LP |
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.UL Dielectric |
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.PP |
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A dielectric material is transparent, and it refracts light |
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.I zdfname. |
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.DS |
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mod texdata id |
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8+ xfunc yfunc zfunc xdfname ydfname zdfname vfname x0 x1 .. xf |
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8+ xfunc yfunc zfunc xdfname ydfname zdfname funcfile x0 x1 .. xf |
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0 |
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n A1 A2 .. An |
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.DE |
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.DE |
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The first two real arguments indicate the extrema of the |
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spectral range in nanometers. |
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Subsequent real values correspond to multipliers in at each wavelength. |
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Subsequent real values correspond to multipliers at each wavelength. |
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The nmA wavelength may be greater or less than nmB, |
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but they may not be equal, and their ordering matches |
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the order of the spectral values. |
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pattern, similar to the colorfunc type. |
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.DS |
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mod specfunc id |
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2+ sval funcfile transform |
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2+ sfunc funcfile transform |
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0 |
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2+ nmA nmB A3 .. |
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.DE |
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Like the spectrum primitive, the wavelength range is specified |
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in the first two real arguments, and additional real values are |
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accessible to the sval function. |
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set in the evaluation context. |
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This function is fed a wavelenth sample |
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between nmA and nmB as its only argument, |
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and it returns the corresponding spectral intensity. |
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.LP |
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.UL Specdata |
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.PP |
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Specdata is like brightdata and colordata, but with more |
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than 3 specular samples. |
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.DS |
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mod specdata id |
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3+n+ |
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func datafile |
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funcfile x1 x2 .. xn transform |
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0 |
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m A1 A2 .. Am |
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.DE |
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The data file must have one more dimension than the coordinate |
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variable count, as this final dimension corresponds to the covered |
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spectrum. |
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The starting and ending wavelengths are specified in "datafile" |
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as well as the number of spectral samples. |
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The function "func" will be called with two parameters, the |
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interpolated spectral value for the current coordinate and the |
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associated wavelength. |
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If the spectrum is broken into 12 components, then 12 calls |
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will be made to "func" for the relevant ray evaluation. |
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.LP |
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.UL Specpict |
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.PP |
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Specpict is a special case of specdata, where the pattern is |
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a hyperspectral image stored in the common-exponent file format. |
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The dimensions of the image data are determined by the picture |
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just as with the colorpict primitive. |
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.DS |
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mod specpict id |
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+ |
5+ |
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func specfile |
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funcfile u v transform |
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0 |
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m A1 A2 .. Am |
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+ |
.DE |
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The function "func" is called with the interpolated pixel value |
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and the wavelength sample in nanometers, the same as specdata, |
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with as many calls made as there are components in "specfile". |
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.NH 3 |
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Mixtures |
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.PP |
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License |
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.PP |
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.DS |
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The Radiance Software License, Version 1.0 |
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The Radiance Software License, Version 2.0 |
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|
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Copyright (c) 1990 - 2008 The Regents of the University of California, |
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through Lawrence Berkeley National Laboratory. All rights reserved. |
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Radiance v6.0 Copyright (c) 1990 to 2025, The Regents of the University of |
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California, through Lawrence Berkeley National Laboratory (subject to receipt |
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of any required approvals from the U.S. Dept. of Energy). All rights reserved. |
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|
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Redistribution and use in source and binary forms, with or without |
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modification, are permitted provided that the following conditions |
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are met: |
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modification, are permitted provided that the following conditions are met: |
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|
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1. Redistributions of source code must retain the above copyright |
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notice, this list of conditions and the following disclaimer. |
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(1) Redistributions of source code must retain the above copyright notice, |
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this list of conditions and the following disclaimer. |
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|
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2. Redistributions in binary form must reproduce the above copyright |
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notice, this list of conditions and the following disclaimer in |
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the documentation and/or other materials provided with the |
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distribution. |
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(2) Redistributions in binary form must reproduce the above copyright |
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notice, this list of conditions and the following disclaimer in the |
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documentation and/or other materials provided with the distribution. |
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|
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3. The end-user documentation included with the redistribution, |
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if any, must include the following acknowledgment: |
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"This product includes Radiance software |
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(http://radsite.lbl.gov/) |
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developed by the Lawrence Berkeley National Laboratory |
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(http://www.lbl.gov/)." |
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Alternately, this acknowledgment may appear in the software itself, |
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if and wherever such third-party acknowledgments normally appear. |
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(3) Neither the name of the University of California, Lawrence Berkeley |
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National Laboratory, U.S. Dept. of Energy nor the names of its contributors |
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may be used to endorse or promote products derived from this software |
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without specific prior written permission. |
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|
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4. The names "Radiance," "Lawrence Berkeley National Laboratory" |
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and "The Regents of the University of California" must |
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not be used to endorse or promote products derived from this |
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software without prior written permission. For written |
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permission, please contact [email protected]. |
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" |
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AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
| 1740 |
> |
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
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ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE |
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> |
LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR |
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> |
CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF |
| 1744 |
> |
SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS |
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INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN |
| 1746 |
> |
CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) |
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> |
ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE |
| 1748 |
> |
POSSIBILITY OF SUCH DAMAGE. |
| 1749 |
|
|
| 1750 |
< |
5. Products derived from this software may not be called "Radiance", |
| 1751 |
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nor may "Radiance" appear in their name, without prior written |
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permission of Lawrence Berkeley National Laboratory. |
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|
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< |
THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED |
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< |
WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
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< |
OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE |
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< |
DISCLAIMED. IN NO EVENT SHALL Lawrence Berkeley National Laboratory OR |
| 1758 |
< |
ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
| 1759 |
< |
SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT |
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LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF |
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< |
USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND |
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ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, |
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< |
OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT |
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< |
OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
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SUCH DAMAGE. |
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> |
You are under no obligation whatsoever to provide any bug fixes, patches, |
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> |
or upgrades to the features, functionality or performance of the source |
| 1752 |
> |
code ("Enhancements") to anyone; however, if you choose to make your |
| 1753 |
> |
Enhancements available either publicly, or directly to Lawrence Berkeley |
| 1754 |
> |
National Laboratory, without imposing a separate written license agreement |
| 1755 |
> |
for such Enhancements, then you hereby grant the following license: a |
| 1756 |
> |
non-exclusive, royalty-free perpetual license to install, use, modify, |
| 1757 |
> |
prepare derivative works, incorporate into other computer software, |
| 1758 |
> |
distribute, and sublicense such enhancements or derivative works thereof, |
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> |
in binary and source code form. |
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.DE |
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.NH 1 |
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Acknowledgements |
