1 |
<html> |
2 |
<head> |
3 |
<title> |
4 |
The RADIANCE 3.5 Synthetic Imaging System |
5 |
</title> |
6 |
</head> |
7 |
<body> |
8 |
|
9 |
Copyright � 2003 Regents, University of California |
10 |
|
11 |
<p> |
12 |
|
13 |
<h1> |
14 |
The RADIANCE 3.5 Synthetic Imaging System |
15 |
</h1> |
16 |
|
17 |
<p> |
18 |
|
19 |
Building Technologies Department<br> |
20 |
Lawrence Berkeley National Laboratory<br> |
21 |
1 Cyclotron Rd., 90-3111<br> |
22 |
Berkeley, CA 94720<br> |
23 |
<a HREF="http://radsite.lbl.gov/radiance"</a> |
24 |
http://radsite.lbl.gov/radiance<br> |
25 |
|
26 |
<p> |
27 |
<hr> |
28 |
|
29 |
<h2> |
30 |
<a NAME="Overview">Overview</a> |
31 |
</h2> |
32 |
<ol> |
33 |
<li><a HREF="#Intro">Introduction</a><!P> |
34 |
<li><a HREF="#Scene">Scene Description</a><!P> |
35 |
<ol> |
36 |
<li><a HREF="#Primitive"> Primitive Types</a> |
37 |
<ol> |
38 |
<li><a HREF="#Surfaces">Surfaces</a> |
39 |
<li><a HREF="#Materials">Materials</a> |
40 |
<li><a HREF="#Textures">Textures</a> |
41 |
<li><a HREF="#Patterns">Patterns</a> |
42 |
<li><a HREF="#Mixtures">Mixtures</a> |
43 |
</ol><!P> |
44 |
<li><a HREF="#Auxiliary">Auxiliary Files</a> |
45 |
<ol> |
46 |
<li><a HREF="#Function">Function Files</a> |
47 |
<li><a HREF="#Data">Data Files</a> |
48 |
<li><a HREF="#Font">Font Files</a> |
49 |
</ol><!P> |
50 |
<li><a HREF="#Generators">Generators</a> |
51 |
</ol><!P> |
52 |
<li><a HREF="#Image">Image Generation</a><!P> |
53 |
<li><a HREF="#License">License</a><!P> |
54 |
<li><a HREF="#Ack">Acknowledgements</a><!P> |
55 |
<li><a HREF="#Ref">References</a><!P> |
56 |
<li><a HREF="#Index">Types Index</a><!P> |
57 |
</ol> |
58 |
|
59 |
<p> |
60 |
<hr> |
61 |
|
62 |
<h2> |
63 |
<a NAME="Intro">1. Introduction</a> |
64 |
</h2> |
65 |
|
66 |
RADIANCE was developed as a research tool for predicting |
67 |
the distribution of visible radiation in illuminated spaces. |
68 |
It takes as input a three-dimensional geometric model |
69 |
of the physical environment, and produces a map of |
70 |
spectral radiance values in a color image. |
71 |
The technique of ray-tracing follows light backwards |
72 |
from the image plane to the source(s). |
73 |
Because it can produce realistic images from a |
74 |
simple description, RADIANCE has a wide range of applications |
75 |
in graphic arts, lighting design, |
76 |
computer-aided engineering and architecture. |
77 |
|
78 |
<p> |
79 |
<img SRC="diagram1.gif"> |
80 |
<p> |
81 |
Figure 1 |
82 |
<p> |
83 |
The diagram in Figure 1 shows the flow between programs (boxes) and data |
84 |
(ovals). |
85 |
The central program is <i>rpict</i>, which produces a picture from a scene |
86 |
description. |
87 |
<i>Rview</i> is a variation of rpict that computes and displays images |
88 |
interactively, and rtrace computes single ray values. |
89 |
Other programs (not shown) connect many of these elements together, |
90 |
such as the executive programs |
91 |
<i>rad</i> |
92 |
and |
93 |
<i>ranimate</i>, |
94 |
the interactive rendering program |
95 |
<i>rholo</i>, |
96 |
and the animation program |
97 |
<i>ranimove</i>. |
98 |
The program |
99 |
<i>obj2mesh</i> |
100 |
acts as both a converter and scene compiler, converting a Wavefront .OBJ |
101 |
file into a compiled mesh octree for efficient rendering. |
102 |
|
103 |
<p> |
104 |
A scene description file lists the surfaces and materials |
105 |
that make up a specific environment. |
106 |
The current surface types are spheres, polygons, cones, and cylinders. |
107 |
There is also a composite surface type, called mesh, and a pseudosurface |
108 |
type, called instance, which facilitates very complex geometries. |
109 |
Surfaces can be made from materials such as plastic, metal, and glass. |
110 |
Light sources can be distant disks as well as local spheres, disks |
111 |
and polygons. |
112 |
|
113 |
<p> |
114 |
From a three-dimensional scene description and a specified view, |
115 |
<i>rpict</i> produces a two-dimensional image. |
116 |
A picture file is a compressed binary representation of the |
117 |
pixels in the image. |
118 |
This picture can be scaled in size and brightness, |
119 |
anti-aliased, and sent to a graphics output device. |
120 |
|
121 |
<p> |
122 |
A header in each picture file lists the program(s) |
123 |
and parameters that produced it. |
124 |
This is useful for identifying a picture without having to display it. |
125 |
The information can be read by the program <i>getinfo</i>. |
126 |
|
127 |
<p> |
128 |
<hr> |
129 |
|
130 |
<h2> |
131 |
<a name="Scene">2. Scene Description</a> |
132 |
</h2> |
133 |
|
134 |
A scene description file represents a three-dimensional physical environment in Cartesian (rectilinear) world coordinates. |
135 |
It is stored as ASCII text, with the following basic format: |
136 |
|
137 |
<pre> |
138 |
# comment |
139 |
|
140 |
modifier type identifier |
141 |
n S1 S2 "S 3" .. Sn |
142 |
0 |
143 |
m R1 R2 R3 .. Rm |
144 |
|
145 |
modifier alias identifier reference |
146 |
|
147 |
! command |
148 |
|
149 |
... |
150 |
</pre> |
151 |
|
152 |
A comment line begins with a pound sign, `#'. |
153 |
|
154 |
<p> |
155 |
The <a NAME="scene_desc">scene description primitives</a> |
156 |
all have the same general format, and can be either surfaces or modifiers. |
157 |
A primitive has a modifier, a type, and an identifier. |
158 |
<p> |
159 |
A <a NAME="modifier"><b>modifier</b></a> is either the |
160 |
identifier of a previously defined primitive, or "void". |
161 |
<br> |
162 |
[ The most recent definition of a modifier is the |
163 |
one used, and later definitions do not cause relinking |
164 |
of loaded primitives. |
165 |
Thus, the same identifier may be used repeatedly, |
166 |
and each new definition will apply to the primitives following it. ] |
167 |
<p> |
168 |
An <a NAME="identifier"><b>identifier</b></a> can be any string |
169 |
(i.e., any sequence of non-white characters). |
170 |
<p> |
171 |
The arguments associated with a primitive can be strings or real numbers. |
172 |
<ul> |
173 |
<li> The first integer following the identifier is the number of <b>string arguments</b>, |
174 |
and it is followed by the arguments themselves (separated by white space or enclosed in quotes). |
175 |
<li> The next integer is the number of integer arguments, and is followed by the <b>integer arguments</b>. |
176 |
(There are currently no primitives that use them, however.) |
177 |
<li> The next integer is the real argument count, and it is followed by the <b>real arguments</b>. |
178 |
</ul> |
179 |
|
180 |
<p> |
181 |
An <a NAME="alias"><b>alias</b></a> gets its type and arguments from |
182 |
a previously defined primitive. |
183 |
This is useful when the same material is |
184 |
used with a different modifier, or as a convenient naming mechanism. |
185 |
The reserved modifier name "inherit" may be used to specificy that |
186 |
an alias will inherit its modifier from the original. |
187 |
Surfaces cannot be aliased. |
188 |
|
189 |
<p> |
190 |
A line beginning with an exclamation point, `!', |
191 |
is interpreted as a command. |
192 |
It is executed by the shell, and its output is read as input to the program. |
193 |
The command must not try to read from its standard input, or confusion |
194 |
will result. |
195 |
A command may be continued over multiple lines using a |
196 |
backslash, `\', to escape the newline. |
197 |
|
198 |
<p> |
199 |
White space is generally ignored, except as a separator. |
200 |
The exception is the newline character after a command or comment. |
201 |
Commands, comments and primitives may appear in any |
202 |
combination, so long as they are not intermingled. |
203 |
|
204 |
<p> |
205 |
<hr> |
206 |
|
207 |
<h3> |
208 |
<a NAME="Primitive">2.1. Primitive Types</a> |
209 |
</h3> |
210 |
|
211 |
Primitives can be <a HREF="#Surfaces">surfaces</a>, |
212 |
<a HREF="#Materials">materials</a>, |
213 |
<a HREF="#Textures">textures</a> or |
214 |
<a HREF="#Patterns">patterns</a>. |
215 |
Modifiers can be <a HREF="#Materials">materials</a>, |
216 |
<a HREF="#Mixtures">mixtures</a>, |
217 |
<a HREF="#Textures">textures</a> or <a HREF="#Patterns">patterns</a>. |
218 |
Simple surfaces must have one material in their modifier list. |
219 |
|
220 |
<p> |
221 |
<hr> |
222 |
|
223 |
<h4> |
224 |
<a NAME="Surfaces">2.1.1. Surfaces</a> |
225 |
</h4> |
226 |
<dl> |
227 |
|
228 |
A scene description will consist mostly of surfaces. |
229 |
The basic types are given below. |
230 |
|
231 |
<p> |
232 |
|
233 |
<dt> |
234 |
<a NAME="Source"> |
235 |
<b>Source </b> |
236 |
</a> |
237 |
<dd> |
238 |
A source is not really a surface, but a solid angle. |
239 |
It is used for specifying light sources that are very distant. |
240 |
The direction to the center of the source and the number of degrees subtended by its disk are given as follows: |
241 |
|
242 |
<pre> |
243 |
mod source id |
244 |
0 |
245 |
0 |
246 |
4 xdir ydir zdir angle |
247 |
</pre> |
248 |
|
249 |
<p> |
250 |
|
251 |
<dt> |
252 |
<a NAME="Sphere"> |
253 |
<b>Sphere</b> |
254 |
</a> |
255 |
<dd> |
256 |
A sphere is given by its center and radius: |
257 |
|
258 |
<pre> |
259 |
mod sphere id |
260 |
0 |
261 |
0 |
262 |
4 xcent ycent zcent radius |
263 |
</pre> |
264 |
|
265 |
<p> |
266 |
|
267 |
<dt> |
268 |
<a NAME="Bubble"> |
269 |
<b>Bubble</b> |
270 |
</a> |
271 |
|
272 |
<dd> |
273 |
A bubble is simply a sphere whose surface normal points inward. |
274 |
|
275 |
<p> |
276 |
|
277 |
<dt> |
278 |
<a NAME="Polygon"> |
279 |
<b>Polygon</b> |
280 |
</a> |
281 |
<dd> |
282 |
A polygon is given by a list of three-dimensional vertices, |
283 |
which are ordered counter-clockwise as viewed from the |
284 |
front side (into the surface normal). |
285 |
The last vertex is automatically connected to the first. |
286 |
Holes are represented in polygons as interior vertices |
287 |
connected to the outer perimeter by coincident edges (seams). |
288 |
|
289 |
<pre> |
290 |
mod polygon id |
291 |
0 |
292 |
0 |
293 |
3n |
294 |
x1 y1 z1 |
295 |
x2 y2 z2 |
296 |
... |
297 |
xn yn zn |
298 |
</pre> |
299 |
|
300 |
<p> |
301 |
|
302 |
<dt> |
303 |
<a NAME="Cone"> |
304 |
<b>Cone</b> |
305 |
</a> |
306 |
<dd> |
307 |
A cone is a megaphone-shaped object. |
308 |
It is truncated by two planes perpendicular to its axis, |
309 |
and one of its ends may come to a point. |
310 |
It is given as two axis endpoints, and the starting and ending radii: |
311 |
|
312 |
<pre> |
313 |
mod cone id |
314 |
0 |
315 |
0 |
316 |
8 |
317 |
x0 y0 z0 |
318 |
x1 y1 z1 |
319 |
r0 r1 |
320 |
</pre> |
321 |
|
322 |
<p> |
323 |
|
324 |
<dt> |
325 |
<a NAME="Cup"> |
326 |
<b>Cup</b> |
327 |
</a> |
328 |
<dd> |
329 |
A cup is an inverted <a HREF="#Cone">cone</a> (i.e., has an |
330 |
inward surface normal). |
331 |
|
332 |
<p> |
333 |
|
334 |
<dt> |
335 |
<a NAME="Cylinder"> |
336 |
<b>Cylinder</b> |
337 |
</a> |
338 |
<dd> |
339 |
A cylinder is like a <a HREF="#Cone">cone</a>, but its |
340 |
starting and ending radii are equal. |
341 |
|
342 |
<pre> |
343 |
mod cylinder id |
344 |
0 |
345 |
0 |
346 |
7 |
347 |
x0 y0 z0 |
348 |
x1 y1 z1 |
349 |
rad |
350 |
</pre> |
351 |
|
352 |
<p> |
353 |
|
354 |
<dt> |
355 |
<a NAME="Tube"> |
356 |
<b>Tube</b> |
357 |
</a> |
358 |
<dd> |
359 |
A tube is an inverted <a HREF="#Cylinder">cylinder</a>. |
360 |
|
361 |
<p> |
362 |
|
363 |
<dt> |
364 |
<a NAME="Ring"> |
365 |
<b>Ring</b> |
366 |
</a> |
367 |
<dd> |
368 |
A ring is a circular disk given by its center, |
369 |
surface normal, and inner and outer radii: |
370 |
|
371 |
<pre> |
372 |
mod ring id |
373 |
0 |
374 |
0 |
375 |
8 |
376 |
xcent ycent zcent |
377 |
xdir ydir zdir |
378 |
r0 r1 |
379 |
</pre> |
380 |
|
381 |
<p> |
382 |
|
383 |
<dt> |
384 |
<a NAME="Instance"> |
385 |
<b>Instance</b> |
386 |
</a> |
387 |
<dd> |
388 |
An instance is a compound surface, given |
389 |
by the contents of an octree file (created by oconv). |
390 |
|
391 |
<pre> |
392 |
mod instance id |
393 |
1+ octree transform |
394 |
0 |
395 |
0 |
396 |
</pre> |
397 |
|
398 |
If the modifier is "void", then surfaces will |
399 |
use the modifiers given in the original description. |
400 |
Otherwise, the modifier specified is used in their place. |
401 |
The transform moves the octree to the desired location in the scene. |
402 |
Multiple instances using the same octree take |
403 |
little extra memory, hence very complex |
404 |
descriptions can be rendered using this primitive. |
405 |
|
406 |
<p> |
407 |
There are a number of important limitations to be aware of |
408 |
when using instances. |
409 |
First, the scene description used to generate the octree must |
410 |
stand on its own, without referring to modifiers in the |
411 |
parent description. |
412 |
This is necessary for oconv to create the octree. |
413 |
Second, light sources in the octree will not be |
414 |
incorporated correctly in the calculation, |
415 |
and they are not recommended. |
416 |
Finally, there is no advantage (other than |
417 |
convenience) to using a single instance of an octree, |
418 |
or an octree containing only a few surfaces. |
419 |
An <a HREF="../man_html/xform.1.html">xform</a> command |
420 |
on the subordinate description is prefered in such cases. |
421 |
</dl> |
422 |
|
423 |
<p> |
424 |
|
425 |
<dt> |
426 |
<a NAME="Mesh"> |
427 |
<b>Mesh</b> |
428 |
</a> |
429 |
<dd> |
430 |
A mesh is a compound surface, made up of many triangles and |
431 |
an octree data structure to accelerate ray intersection. |
432 |
It is typically converted from a Wavefront .OBJ file using the |
433 |
<i>obj2mesh</i> program. |
434 |
|
435 |
<pre> |
436 |
mod mesh id |
437 |
1+ meshfile transform |
438 |
0 |
439 |
0 |
440 |
</pre> |
441 |
|
442 |
If the modifier is "void", then surfaces will |
443 |
use the modifiers given in the original mesh description. |
444 |
Otherwise, the modifier specified is used in their place. |
445 |
The transform moves the mesh to the desired location in the scene. |
446 |
Multiple instances using the same meshfile take little extra memory, |
447 |
and the compiled mesh itself takes much less space than individual |
448 |
polygons would. |
449 |
In the case of an unsmoothed mesh, using the mesh primitive reduces |
450 |
memory requirements by a factor of 30 relative to individual triangles. |
451 |
If a mesh has smoothed surfaces, we save a factor of 50 or more, |
452 |
permitting very detailed geometries that would otherwise exhaust the |
453 |
available memory. |
454 |
In addition, the mesh primitive can have associated (u,v) coordinates |
455 |
for pattern and texture mapping. |
456 |
These are made available to function files via the Lu and Lv variables. |
457 |
|
458 |
</dl> |
459 |
|
460 |
<p> |
461 |
<hr> |
462 |
|
463 |
<h4> |
464 |
<a NAME="Materials">2.1.2. Materials</a> |
465 |
</h4> |
466 |
|
467 |
A material defines the way light interacts with a surface. The basic types are given below. |
468 |
|
469 |
<p> |
470 |
|
471 |
<dl> |
472 |
|
473 |
<dt> |
474 |
<a NAME="Light"> |
475 |
<b>Light</b> |
476 |
</a> |
477 |
<dd> |
478 |
Light is the basic material for self-luminous surfaces (i.e., |
479 |
light sources). |
480 |
In addition to the <a HREF="#Source">source</a> surface type, |
481 |
<a HREF="#Sphere">spheres</a>, |
482 |
discs (<a HREF="#Ring">rings</a> with zero inner radius), |
483 |
<a HREF="#Cylinder">cylinders</a> (provided they are long enough), and <a HREF="#Polygon">polygons</a> can act as light sources. |
484 |
Polygons work best when they are rectangular. |
485 |
Cones cannot be used at this time. |
486 |
A pattern may be used to specify a light output distribution. |
487 |
Light is defined simply as a RGB radiance value (watts/steradian/m2): |
488 |
|
489 |
<pre> |
490 |
mod light id |
491 |
0 |
492 |
0 |
493 |
3 red green blue |
494 |
</pre> |
495 |
|
496 |
<p> |
497 |
|
498 |
<dt> |
499 |
<a NAME="Illum"> |
500 |
<b>Illum</b> |
501 |
</a> |
502 |
|
503 |
<dd> |
504 |
Illum is used for secondary light sources with broad distributions. |
505 |
A secondary light source is treated like any other light source, except when viewed directly. |
506 |
It then acts like it is made of a different material (indicated by |
507 |
the string argument), or becomes invisible (if no string argument is given, |
508 |
or the argument is "void"). |
509 |
Secondary sources are useful when modeling windows or brightly illuminated surfaces. |
510 |
|
511 |
<pre> |
512 |
mod illum id |
513 |
1 material |
514 |
0 |
515 |
3 red green blue |
516 |
</pre> |
517 |
|
518 |
<p> |
519 |
|
520 |
<dt> |
521 |
<a NAME="Glow"> |
522 |
<b>Glow</b> |
523 |
</a> |
524 |
|
525 |
<dd> |
526 |
Glow is used for surfaces that are self-luminous, but limited in their effect. |
527 |
In addition to the radiance value, a maximum radius for shadow testing is given: |
528 |
|
529 |
<pre> |
530 |
mod glow id |
531 |
0 |
532 |
0 |
533 |
4 red green blue maxrad |
534 |
</pre> |
535 |
|
536 |
If maxrad is zero, then the surface will never be tested for shadow, although it may participate in an interreflection calculation. |
537 |
If maxrad is negative, then the surface will never contribute to scene illumination. |
538 |
Glow sources will never illuminate objects on the other side of an illum surface. |
539 |
This provides a convenient way to illuminate local light fixture geometry without overlighting nearby objects. |
540 |
|
541 |
<p> |
542 |
|
543 |
<dt> |
544 |
<a NAME="Spotlight"> |
545 |
<b>Spotlight</b> |
546 |
</a> |
547 |
|
548 |
<dd> |
549 |
Spotlight is used for self-luminous surfaces having directed output. |
550 |
As well as radiance, the full cone angle (in degrees) and orientation (output direction) vector are given. |
551 |
The length of the orientation vector is the distance of the effective |
552 |
focus behind the source center (i.e., the focal length). |
553 |
|
554 |
<pre> |
555 |
mod spotlight id |
556 |
0 |
557 |
0 |
558 |
7 red green blue angle xdir ydir zdir |
559 |
</pre> |
560 |
|
561 |
<p> |
562 |
|
563 |
<dt> |
564 |
<a NAME="Mirror"> |
565 |
<b>Mirror</b> |
566 |
</a> |
567 |
|
568 |
<dd> |
569 |
Mirror is used for planar surfaces that produce secondary source reflections. |
570 |
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. |
571 |
This material is only supported for flat surfaces such as <a HREF="#Polygon">polygons</a> and <a HREF="#Ring">rings</a>. |
572 |
The arguments are simply the RGB reflectance values, which should be between 0 and 1. |
573 |
An optional string argument may be used like the illum type to specify a different material to be used for shading non-source rays. |
574 |
If this alternate material is given as "void", then the mirror surface will be invisible. |
575 |
This is only appropriate if the surface hides other (more detailed) geometry with the same overall reflectance. |
576 |
|
577 |
<pre> |
578 |
mod mirror id |
579 |
1 material |
580 |
0 |
581 |
3 red green blue |
582 |
</pre> |
583 |
|
584 |
<p> |
585 |
|
586 |
<dt> |
587 |
<a NAME="Prism1"> |
588 |
<b>Prism1</b> |
589 |
</a> |
590 |
|
591 |
<dd> |
592 |
The prism1 material is for general light redirection from prismatic glazings, generating secondary light sources. |
593 |
It can only be used to modify a planar surface |
594 |
(i.e., a <a HREF="#Polygon">polygon</a> or <a HREF="#Ring">disk</a>) |
595 |
and should not result in either light concentration or scattering. |
596 |
The new direction of the ray can be on either side of the material, |
597 |
and the definitions must have the correct bidirectional properties to work properly with secondary light sources. |
598 |
The arguments give the coefficient for the redirected light and its direction. |
599 |
|
600 |
<pre> |
601 |
mod prism1 id |
602 |
5+ coef dx dy dz funcfile transform |
603 |
0 |
604 |
n A1 A2 .. An |
605 |
</pre> |
606 |
|
607 |
The new direction variables dx, dy and dz need not produce a normalized vector. |
608 |
For convenience, the variables DxA, DyA and DzA are defined as the normalized direction to the target light source. |
609 |
See <a HREF="#Function">section 2.2.1</a> on function files for further information. |
610 |
|
611 |
<p> |
612 |
|
613 |
<dt> |
614 |
<a NAME="Prism2"> |
615 |
<b>Prism2</b> |
616 |
</a> |
617 |
|
618 |
<dd> |
619 |
The material prism2 is identical to <a HREF="#Prism1">prism1</a> except that it provides for two ray redirections rather than one. |
620 |
|
621 |
<pre> |
622 |
mod prism2 id |
623 |
9+ coef1 dx1 dy1 dz1 coef2 dx2 dy2 dz2 funcfile transform |
624 |
0 |
625 |
n A1 A2 .. An |
626 |
</pre> |
627 |
|
628 |
<p> |
629 |
|
630 |
<dt> |
631 |
<a NAME="Mist"> |
632 |
<b>Mist</b> |
633 |
</a> |
634 |
|
635 |
<dd> |
636 |
Mist is a virtual material used to delineate a volume |
637 |
of participating atmosphere. |
638 |
A list of important light sources may be given, along with an |
639 |
extinction coefficient, scattering albedo and scattering eccentricity |
640 |
parameter. |
641 |
The light sources named by the string argument list |
642 |
will be tested for scattering within the volume. |
643 |
Sources are identified by name, and virtual light sources may be indicated |
644 |
by giving the relaying object followed by '>' followed by the source, i.e: |
645 |
|
646 |
<pre> |
647 |
3 source1 mirror1>source10 mirror2>mirror1>source3 |
648 |
</pre> |
649 |
|
650 |
Normally, only one source is given per mist material, and there is an |
651 |
upper limit of 32 to the total number of active scattering sources. |
652 |
The extinction coefficient, if given, is added the the global |
653 |
coefficient set on the command line. |
654 |
Extinction is in units of 1/distance (distance based on the world coordinates), |
655 |
and indicates the proportional loss of radiance over one unit distance. |
656 |
The scattering albedo, if present, will override the global setting within |
657 |
the volume. |
658 |
An albedo of 0 0 0 means a perfectly absorbing medium, and an albedo of |
659 |
1 1 1 means |
660 |
a perfectly scattering medium (no absorption). |
661 |
The scattering eccentricity parameter will likewise override the global |
662 |
setting if it is present. |
663 |
Scattering eccentricity indicates how much scattered light favors the |
664 |
forward direction, as fit by the Heyney-Greenstein function: |
665 |
|
666 |
<pre> |
667 |
P(theta) = (1 - g*g) / (1 + g*g - 2*g*cos(theta))^1.5 |
668 |
</pre> |
669 |
|
670 |
A perfectly isotropic scattering medium has a g parameter of 0, and |
671 |
a highly directional material has a g parameter close to 1. |
672 |
Fits to the g parameter may be found along with typical extinction |
673 |
coefficients and scattering albedos for various atmospheres and |
674 |
cloud types in USGS meteorological tables. |
675 |
(A pattern will be applied to the extinction values.) |
676 |
|
677 |
<pre> |
678 |
mod mist id |
679 |
N src1 src2 .. srcN |
680 |
0 |
681 |
0|3|6|7 [ rext gext bext [ ralb galb balb [ g ] ] ] |
682 |
</pre> |
683 |
|
684 |
There are two usual uses of the mist type. |
685 |
One is to surround a beam from a spotlight or laser so that it is |
686 |
visible during rendering. |
687 |
For this application, it is important to use a <a HREF="#Cone">cone</a> |
688 |
(or <a HREF="#Cylinder">cylinder</a>) that |
689 |
is long enough and wide enough to contain the important visible portion. |
690 |
Light source photometry and intervening objects will have the desired |
691 |
effect, and crossing beams will result in additive scattering. |
692 |
For this application, it is best to leave off the real arguments, and |
693 |
use the global rendering parameters to control the atmosphere. |
694 |
The second application is to model clouds or other localized media. |
695 |
Complex boundary geometry may be used to give shape to a uniform medium, |
696 |
so long as the boundary encloses a proper volume. |
697 |
Alternatively, a pattern may be used to set the line integral value |
698 |
through the cloud for a ray entering or exiting a point in a given |
699 |
direction. |
700 |
For this application, it is best if cloud volumes do not overlap each other, |
701 |
and opaque objects contained within them may not be illuminated correctly |
702 |
unless the line integrals consider enclosed geometry. |
703 |
|
704 |
<dt> |
705 |
<a NAME="Plastic"> |
706 |
<b>Plastic</b> |
707 |
</a> |
708 |
|
709 |
<dd> |
710 |
Plastic is a material with uncolored highlights. |
711 |
It is given by its RGB reflectance, its fraction of specularity, and its roughness value. |
712 |
Roughness is specified as the rms slope of surface facets. |
713 |
A value of 0 corresponds to a perfectly smooth surface, and a value of 1 would be a very rough surface. |
714 |
Specularity fractions greater than 0.1 and roughness values greater than 0.2 are not very realistic. |
715 |
(A pattern modifying plastic will affect the material color.) |
716 |
|
717 |
<pre> |
718 |
mod plastic id |
719 |
0 |
720 |
0 |
721 |
5 red green blue spec rough |
722 |
</pre> |
723 |
|
724 |
<p> |
725 |
|
726 |
<dt> |
727 |
<a NAME="Metal"> |
728 |
<b>Metal</b> |
729 |
</a> |
730 |
|
731 |
<dd> |
732 |
Metal is similar to <a HREF="#Plastic">plastic</a>, but specular highlights are modified by the material color. |
733 |
Specularity of metals is usually .9 or greater. |
734 |
As for plastic, roughness values above .2 are uncommon. |
735 |
|
736 |
<p> |
737 |
|
738 |
<dt> |
739 |
<a NAME="Trans"> |
740 |
<b>Trans</b> |
741 |
</a> |
742 |
|
743 |
<dd> |
744 |
Trans is a translucent material, similar to <a HREF="#Plastic">plastic</a>. |
745 |
The transmissivity is the fraction of penetrating light that travels all the way through the material. |
746 |
The transmitted specular component is the fraction of transmitted light that is not diffusely scattered. |
747 |
Transmitted and diffusely reflected light is modified by the material color. |
748 |
Translucent objects are infinitely thin. |
749 |
|
750 |
<pre> |
751 |
mod trans id |
752 |
0 |
753 |
0 |
754 |
7 red green blue spec rough trans tspec |
755 |
</pre> |
756 |
|
757 |
<p> |
758 |
|
759 |
<dt> |
760 |
<a NAME="Plastic2"> |
761 |
<b>Plastic2</b> |
762 |
</a> |
763 |
|
764 |
<dd> |
765 |
Plastic2 is similar to <a HREF="#Plastic">plastic</a>, but with anisotropic roughness. |
766 |
This means that highlights in the surface will appear elliptical rather than round. |
767 |
The orientation of the anisotropy is determined by the unnormalized direction vector ux uy uz. |
768 |
These three expressions (separated by white space) are evaluated in the context of the function file funcfile. |
769 |
If no function file is required (i.e., no special variables or functions are required), a period (`.') may be given in its place. |
770 |
(See the discussion of <a HREF="#Function">Function Files</a> in the Auxiliary Files section). |
771 |
The urough value defines the roughness along the u vector given projected onto the surface. |
772 |
The vrough value defines the roughness perpendicular to this vector. |
773 |
Note that the highlight will be narrower in the direction of the smaller roughness value. |
774 |
Roughness values of zero are not allowed for efficiency reasons since the behavior would be the same as regular plastic in that case. |
775 |
|
776 |
<pre> |
777 |
mod plastic2 id |
778 |
4+ ux uy uz funcfile transform |
779 |
0 |
780 |
6 red green blue spec urough vrough |
781 |
</pre> |
782 |
|
783 |
<p> |
784 |
|
785 |
<dt> |
786 |
<a NAME="Metal2"> |
787 |
<b>Metal2</b> |
788 |
</a> |
789 |
|
790 |
<dd> |
791 |
Metal2 is the same as <a HREF="#Plastic2">plastic2</a>, except that the highlights are modified by the material color. |
792 |
|
793 |
<p> |
794 |
|
795 |
<dt> |
796 |
<a NAME="Trans2"> |
797 |
<b>Trans2</b> |
798 |
</a> |
799 |
|
800 |
<dd> |
801 |
Trans2 is the anisotropic version of <a HREF="#Trans">trans</a>. |
802 |
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. |
803 |
|
804 |
<pre> |
805 |
mod trans2 id |
806 |
4+ ux uy uz funcfile transform |
807 |
0 |
808 |
8 red green blue spec urough vrough trans tspec |
809 |
</pre> |
810 |
|
811 |
<p> |
812 |
|
813 |
<dt> |
814 |
<a NAME="Dielectric"> |
815 |
<b>Dielectric</b> |
816 |
</a> |
817 |
|
818 |
<dd> |
819 |
A dielectric material is transparent, and it refracts light as well as reflecting it. |
820 |
Its behavior is determined by the index of refraction and transmission coefficient in each wavelength band per unit length. |
821 |
Common glass has a index of refraction (n) around 1.5, and a transmission coefficient of roughly 0.92 over an inch. |
822 |
An additional number, the Hartmann constant, describes how the index of refraction changes as a function of wavelength. |
823 |
It is usually zero. (A <a HREF="#Patterns">pattern</a> modifies only the refracted value.) |
824 |
|
825 |
<pre> |
826 |
mod dielectric id |
827 |
0 |
828 |
0 |
829 |
5 rtn gtn btn n hc |
830 |
</pre> |
831 |
|
832 |
<p> |
833 |
|
834 |
<dt> |
835 |
<a NAME="Interface"> |
836 |
<b>Interface</b> |
837 |
</a> |
838 |
|
839 |
<dd> |
840 |
An interface is a boundary between two dielectrics. |
841 |
The first transmission coefficient and refractive index are for the inside; the second ones are for the outside. |
842 |
Ordinary dielectrics are surrounded by a vacuum (1 1 1 1). |
843 |
|
844 |
<pre> |
845 |
mod interface id |
846 |
0 |
847 |
0 |
848 |
8 rtn1 gtn1 btn1 n1 rtn2 gtn2 btn2 n2 |
849 |
</pre> |
850 |
|
851 |
<p> |
852 |
|
853 |
<dt> |
854 |
<a NAME="Glass"> |
855 |
<b>Glass</b> |
856 |
</a> |
857 |
|
858 |
<dd> |
859 |
Glass is similar to <a HREF="#Dielectric">dielectric</a>, but it is optimized for thin glass surfaces (n = 1.52). |
860 |
One transmitted ray and one reflected ray is produced. |
861 |
By using a single surface is in place of two, internal reflections are avoided. |
862 |
The surface orientation is irrelevant, as it is for <a HREF="#Plastic">plastic</a>, <a HREF="#Metal">metal</a>, and <a HREF="#Trans">trans</a>. |
863 |
The only specification required is the transmissivity at normal incidence. |
864 |
(Transmissivity is the amount of light not absorbed in one traversal |
865 |
of the material. |
866 |
Transmittance -- the value usually measured -- is the total light |
867 |
transmitted through the pane including multiple reflections.) |
868 |
To compute transmissivity (tn) from transmittance (Tn) use: |
869 |
|
870 |
<pre> |
871 |
tn = (sqrt(.8402528435+.0072522239*Tn*Tn)-.9166530661)/.0036261119/Tn |
872 |
</pre> |
873 |
|
874 |
Standard 88% transmittance glass has a transmissivity of 0.96. |
875 |
(A <a HREF="#Patterns">pattern</a> modifying glass will affect the transmissivity.) |
876 |
If a fourth real argument is given, it is interpreted as the index of refraction to use instead of 1.52. |
877 |
|
878 |
<pre> |
879 |
mod glass id |
880 |
0 |
881 |
0 |
882 |
3 rtn gtn btn |
883 |
</pre> |
884 |
|
885 |
<p> |
886 |
|
887 |
<dt> |
888 |
<a NAME="Plasfunc"> |
889 |
<b>Plasfunc</b> |
890 |
</a> |
891 |
|
892 |
<dd> |
893 |
Plasfunc in used for the procedural definition of plastic-like materials |
894 |
with arbitrary bidirectional reflectance distribution functions (BRDF's). |
895 |
The arguments to this material include the color and specularity, |
896 |
as well as the function defining the specular distribution and the auxiliary file where it may be found. |
897 |
|
898 |
<pre> |
899 |
mod plasfunc id |
900 |
2+ refl funcfile transform |
901 |
0 |
902 |
4+ red green blue spec A5 .. |
903 |
</pre> |
904 |
|
905 |
The function refl takes four arguments, the x, y and z |
906 |
direction towards the incident light, and the solid angle |
907 |
subtended by the source. |
908 |
The solid angle is provided to facilitate averaging, and is usually |
909 |
ignored. |
910 |
The refl function should integrate to 1 over |
911 |
the projected hemisphere to maintain energy balance. |
912 |
At least four real arguments must be given, and these are made available along with any additional values to the reflectance function. |
913 |
Currently, only the contribution from direct light sources is considered in the specular calculation. |
914 |
As in most material types, the surface normal is always altered to face the incoming ray. |
915 |
|
916 |
<p> |
917 |
|
918 |
<dt> |
919 |
<a NAME="Metfunc"> |
920 |
<b>Metfunc</b> |
921 |
</a> |
922 |
|
923 |
<dd> |
924 |
Metfunc is identical to <a HREF="#Plasfunc">plasfunc</a> and takes the same arguments, |
925 |
but the specular component is multiplied also by the material color. |
926 |
|
927 |
<p> |
928 |
|
929 |
<dt> |
930 |
<a NAME="Transfunc"> |
931 |
<b>Transfunc</b> |
932 |
</a> |
933 |
|
934 |
<dd> |
935 |
Transfunc is similar to <a HREF="#Plasfunc">plasfunc</a> but with an arbitrary bidirectional transmittance distribution |
936 |
as well as a reflectance distribution. |
937 |
Both reflectance and transmittance are specified with the same function. |
938 |
|
939 |
<pre> |
940 |
mod transfunc id |
941 |
2+ brtd funcfile transform |
942 |
0 |
943 |
6+ red green blue rspec trans tspec A7 .. |
944 |
</pre> |
945 |
|
946 |
Where trans is the total light transmitted and tspec is the non-Lambertian fraction of transmitted light. |
947 |
The function brtd should integrate to 1 over each projected hemisphere. |
948 |
|
949 |
<p> |
950 |
|
951 |
<dt> |
952 |
<a NAME="BRTDfunc"> |
953 |
<b>BRTDfunc</b> |
954 |
</a> |
955 |
|
956 |
<dd> |
957 |
The material BRTDfunc gives the maximum flexibility over surface reflectance and transmittance, |
958 |
providing for spectrally-dependent specular rays and reflectance and transmittance distribution functions. |
959 |
|
960 |
<pre> |
961 |
mod BRTDfunc id |
962 |
10+ rrefl grefl brefl |
963 |
rtrns gtrns btrns |
964 |
rbrtd gbrtd bbrtd |
965 |
funcfile transform |
966 |
0 |
967 |
9+ rfdif gfdif bfdif |
968 |
rbdif gbdif bbdif |
969 |
rtdif gtdif btdif |
970 |
A10 .. |
971 |
</pre> |
972 |
|
973 |
The variables rrefl, grefl and brefl specify the color coefficients for the ideal specular (mirror) reflection of the surface. |
974 |
The variables rtrns, gtrns and btrns specify the color coefficients for the ideal specular transmission. |
975 |
The functions rbrtd, gbrtd and bbrtd take the direction to the incident light (and its solid angle) and |
976 |
compute the color coefficients for the directional diffuse part of reflection and transmission. |
977 |
As a special case, three identical values of '0' may be given in place of these function names to indicate no directional diffuse component. |
978 |
|
979 |
<p> |
980 |
Unlike most other material types, the surface normal is not altered to face the incoming ray. |
981 |
Thus, functions and variables must pay attention to the orientation of the surface and make adjustments appropriately. |
982 |
However, the special variables for the perturbed dot product and surface normal, RdotP, NxP, NyP and NzP are reoriented |
983 |
as if the ray hit the front surface for convenience. |
984 |
|
985 |
<p> |
986 |
A diffuse reflection component may be given for the front side with rfdif, gfdif and bfdif for the front side of the surface |
987 |
or rbdif, gbdif and bbdif for the back side. |
988 |
The diffuse transmittance (must be the same for both sides by physical law) is given by rtdif, gtdif and btdif. |
989 |
A pattern will modify these diffuse scattering values, and will be available through the special variables CrP, CgP and CbP. |
990 |
|
991 |
<p> |
992 |
Care must be taken when using this material type to produce a physically valid reflection model. |
993 |
The reflectance functions should be bidirectional, and under no circumstances should the sum of reflected diffuse, |
994 |
transmitted diffuse, reflected specular, transmitted specular and the integrated directional diffuse component be greater than one. |
995 |
|
996 |
<p> |
997 |
|
998 |
<dt> |
999 |
<a NAME="Plasdata"> |
1000 |
<b>Plasdata</b> |
1001 |
</a> |
1002 |
|
1003 |
<dd> |
1004 |
Plasdata is used for arbitrary BRDF's that are most conveniently given as interpolated data. |
1005 |
The arguments to this material are the <a HREF="#Data">data file</a> and coordinate index functions, |
1006 |
as well as a function to optionally modify the data values. |
1007 |
|
1008 |
<pre> |
1009 |
mod plasdata id |
1010 |
3+n+ |
1011 |
func datafile |
1012 |
funcfile x1 x2 .. xn transform |
1013 |
0 |
1014 |
4+ red green blue spec A5 .. |
1015 |
</pre> |
1016 |
|
1017 |
The coordinate indices (x1, x2, etc.) are themselves functions of the x, y and z direction to the incident light, plus the solid angle |
1018 |
subtended by the light source (usually ignored). |
1019 |
The data function (func) takes five variables, the |
1020 |
interpolated value from the n-dimensional data file, followed by the |
1021 |
x, y and z direction to the incident light and the solid angle of the source. |
1022 |
The light source direction and size may of course be ignored by the function. |
1023 |
|
1024 |
<p> |
1025 |
|
1026 |
<dt> |
1027 |
<a NAME="Metdata"> |
1028 |
<b>Metdata</b> |
1029 |
</a> |
1030 |
|
1031 |
<dd> |
1032 |
As metfunc is to plasfunc, metdata is to <a HREF="#Plasdata">plasdata</a>. |
1033 |
Metdata takes the same arguments as plasdata, but the specular component is modified by the given material color. |
1034 |
|
1035 |
<p> |
1036 |
|
1037 |
<dt> |
1038 |
<a NAME="Transdata"> |
1039 |
<b>Transdata</b> |
1040 |
</a> |
1041 |
|
1042 |
<dd> |
1043 |
Transdata is like <a HREF="#Plasdata">plasdata</a> but the specification includes transmittance as well as reflectance. |
1044 |
The parameters are as follows. |
1045 |
|
1046 |
<pre> |
1047 |
mod transdata id |
1048 |
3+n+ |
1049 |
func datafile |
1050 |
funcfile x1 x2 .. xn transform |
1051 |
0 |
1052 |
6+ red green blue rspec trans tspec A7 .. |
1053 |
</pre> |
1054 |
|
1055 |
<p> |
1056 |
|
1057 |
<dt> |
1058 |
<a NAME="Antimatter"> |
1059 |
<b>Antimatter</b> |
1060 |
</a> |
1061 |
|
1062 |
<dd> |
1063 |
Antimatter is a material that can "subtract" volumes from other volumes. |
1064 |
A ray passing into an antimatter object becomes blind to all the specified modifiers: |
1065 |
|
1066 |
<pre> |
1067 |
mod antimatter id |
1068 |
N mod1 mod2 .. modN |
1069 |
0 |
1070 |
0 |
1071 |
</pre> |
1072 |
|
1073 |
The first modifier will also be used to shade the area leaving the antimatter volume and entering the regular volume. |
1074 |
If mod1 is void, the antimatter volume is completely invisible. |
1075 |
Antimatter does not work properly with the material type <a HREF="#Trans">"trans"</a>, |
1076 |
and multiple antimatter surfaces should be disjoint. |
1077 |
The viewpoint must be outside all volumes concerned for a correct rendering. |
1078 |
|
1079 |
</dl> |
1080 |
|
1081 |
<p> |
1082 |
<hr> |
1083 |
|
1084 |
<h4> |
1085 |
<a NAME="Textures">2.1.3. Textures</a> |
1086 |
</h4> |
1087 |
|
1088 |
A texture is a perturbation of the surface normal, and is given by either a function or data. |
1089 |
|
1090 |
<p> |
1091 |
|
1092 |
<dl> |
1093 |
|
1094 |
<dt> |
1095 |
<a NAME="Texfunc"> |
1096 |
<b>Texfunc</b> |
1097 |
</a> |
1098 |
|
1099 |
<dd> |
1100 |
A texfunc uses an auxiliary function file to specify a procedural texture: |
1101 |
|
1102 |
<pre> |
1103 |
mod texfunc id |
1104 |
4+ xpert ypert zpert funcfile transform |
1105 |
0 |
1106 |
n A1 A2 .. An |
1107 |
</pre> |
1108 |
|
1109 |
<p> |
1110 |
|
1111 |
<dt> |
1112 |
<a NAME="Texdata"> |
1113 |
<b>Texdata</b> |
1114 |
</a> |
1115 |
|
1116 |
<dd> |
1117 |
A texdata texture uses three data files to get the surface normal perturbations. |
1118 |
The variables xfunc, yfunc and zfunc take three arguments each from the interpolated values in xdfname, ydfname and zdfname. |
1119 |
|
1120 |
<pre> |
1121 |
mod texdata id |
1122 |
8+ xfunc yfunc zfunc xdfname ydfname zdfname vfname x0 x1 .. xf |
1123 |
0 |
1124 |
n A1 A2 .. An |
1125 |
</pre> |
1126 |
|
1127 |
</dl> |
1128 |
|
1129 |
<p> |
1130 |
<hr> |
1131 |
|
1132 |
<h4> |
1133 |
<a NAME="Patterns">2.1.4. Patterns</a> |
1134 |
</h4> |
1135 |
|
1136 |
Patterns are used to modify the reflectance of materials. The basic types are given below. |
1137 |
|
1138 |
<p> |
1139 |
|
1140 |
<dl> |
1141 |
|
1142 |
<dt> |
1143 |
<a NAME="Colorfunc"> |
1144 |
<b>Colorfunc</b> |
1145 |
</a> |
1146 |
|
1147 |
<dd> |
1148 |
A colorfunc is a procedurally defined color pattern. It is specified as follows: |
1149 |
|
1150 |
<pre> |
1151 |
mod colorfunc id |
1152 |
4+ red green blue funcfile transform |
1153 |
0 |
1154 |
n A1 A2 .. An |
1155 |
</pre> |
1156 |
|
1157 |
<p> |
1158 |
|
1159 |
<dt> |
1160 |
<a NAME="Brightfunc"> |
1161 |
<b>Brightfunc</b> |
1162 |
</a> |
1163 |
|
1164 |
<dd> |
1165 |
A brightfunc is the same as a colorfunc, except it is monochromatic. |
1166 |
|
1167 |
<pre> |
1168 |
mod brightfunc id |
1169 |
2+ refl funcfile transform |
1170 |
0 |
1171 |
n A1 A2 .. An |
1172 |
</pre> |
1173 |
|
1174 |
<p> |
1175 |
|
1176 |
<dt> |
1177 |
<a NAME="Colordata"> |
1178 |
<b>Colordata</b> |
1179 |
</a> |
1180 |
|
1181 |
<dd> |
1182 |
Colordata uses an interpolated data map to modify a material's color. |
1183 |
The map is n-dimensional, and is stored in three auxiliary files, one for each color. |
1184 |
The coordinates used to look up and interpolate the data are defined in another auxiliary file. |
1185 |
The interpolated data values are modified by functions of one or three variables. |
1186 |
If the functions are of one variable, then they are passed the corresponding color component (red or green or blue). |
1187 |
If the functions are of three variables, then they are passed the original red, green, and blue values as parameters. |
1188 |
|
1189 |
<pre> |
1190 |
mod colordata id |
1191 |
7+n+ |
1192 |
rfunc gfunc bfunc rdatafile gdatafile bdatafile |
1193 |
funcfile x1 x2 .. xn transform |
1194 |
0 |
1195 |
m A1 A2 .. Am |
1196 |
</pre> |
1197 |
|
1198 |
<p> |
1199 |
|
1200 |
<dt> |
1201 |
<a NAME="Brightdata"> |
1202 |
<b>Brightdata</b> |
1203 |
</a> |
1204 |
|
1205 |
<dd> |
1206 |
Brightdata is like colordata, except monochromatic. |
1207 |
|
1208 |
<pre> |
1209 |
mod brightdata id |
1210 |
3+n+ |
1211 |
func datafile |
1212 |
funcfile x1 x2 .. xn transform |
1213 |
0 |
1214 |
m A1 A2 .. Am |
1215 |
</pre> |
1216 |
|
1217 |
<p> |
1218 |
|
1219 |
<dt> |
1220 |
<a NAME="Colorpict"> |
1221 |
<b>Colorpict</b> |
1222 |
</a> |
1223 |
|
1224 |
<dd> |
1225 |
Colorpict is a special case of colordata, where the pattern is a two-dimensional image stored in the RADIANCE picture format. |
1226 |
The dimensions of the image data are determined by the picture such that the smaller dimension is always 1, |
1227 |
and the other is the ratio between the larger and the smaller. |
1228 |
For example, a 500x338 picture would have coordinates (u,v) in the rectangle between (0,0) and (1.48,1). |
1229 |
|
1230 |
<pre> |
1231 |
mod colorpict id |
1232 |
7+ |
1233 |
rfunc gfunc bfunc pictfile |
1234 |
funcfile u v transform |
1235 |
0 |
1236 |
m A1 A2 .. Am |
1237 |
</pre> |
1238 |
|
1239 |
<p> |
1240 |
|
1241 |
<dt> |
1242 |
<a NAME="Colortext"> |
1243 |
<b>Colortext</b> |
1244 |
</a> |
1245 |
|
1246 |
<dd> |
1247 |
Colortext is dichromatic writing in a polygonal font. |
1248 |
The font is defined in an auxiliary file, such as helvet.fnt. |
1249 |
The text itself is also specified in a separate file, or can be part of the material arguments. |
1250 |
The character size, orientation, aspect ratio and slant is determined by right and down motion vectors. |
1251 |
The upper left origin for the text block as well as the foreground and background colors must also be given. |
1252 |
|
1253 |
<pre> |
1254 |
mod colortext id |
1255 |
2 fontfile textfile |
1256 |
0 |
1257 |
15+ |
1258 |
Ox Oy Oz |
1259 |
Rx Ry Rz |
1260 |
Dx Dy Dz |
1261 |
rfore gfore bfore |
1262 |
rback gback bback |
1263 |
[spacing] |
1264 |
</pre> |
1265 |
|
1266 |
or: |
1267 |
|
1268 |
<pre> |
1269 |
mod colortext id |
1270 |
2+N fontfile . This is a line with N words ... |
1271 |
0 |
1272 |
15+ |
1273 |
Ox Oy Oz |
1274 |
Rx Ry Rz |
1275 |
Dx Dy Dz |
1276 |
rfore gfore bfore |
1277 |
rback gback bback |
1278 |
[spacing] |
1279 |
</pre> |
1280 |
|
1281 |
<p> |
1282 |
|
1283 |
<dt> |
1284 |
<a NAME="Brighttext"> |
1285 |
<b>Brighttext</b> |
1286 |
</a> |
1287 |
|
1288 |
<dd> |
1289 |
Brighttext is like colortext, but the writing is monochromatic. |
1290 |
|
1291 |
<pre> |
1292 |
mod brighttext id |
1293 |
2 fontfile textfile |
1294 |
0 |
1295 |
11+ |
1296 |
Ox Oy Oz |
1297 |
Rx Ry Rz |
1298 |
Dx Dy Dz |
1299 |
foreground background |
1300 |
[spacing] |
1301 |
</pre> |
1302 |
|
1303 |
or: |
1304 |
|
1305 |
<pre> |
1306 |
mod brighttext id |
1307 |
2+N fontfile . This is a line with N words ... |
1308 |
0 |
1309 |
11+ |
1310 |
Ox Oy Oz |
1311 |
Rx Ry Rz |
1312 |
Dx Dy Dz |
1313 |
foreground background |
1314 |
[spacing] |
1315 |
</pre> |
1316 |
|
1317 |
<p> |
1318 |
|
1319 |
By default, a uniform spacing algorithm is used that guarantees every character will appear in a precisely determined position. |
1320 |
Unfortunately, such a scheme results in rather unattractive and difficult to read text with most fonts. |
1321 |
The optional spacing value defines the distance between characters for proportional spacing. |
1322 |
A positive value selects a spacing algorithm that preserves right margins and indentation, |
1323 |
but does not provide the ultimate in proportionally spaced text. |
1324 |
A negative value insures that characters are properly spaced, but the placement of words then varies unpredictably. |
1325 |
The choice depends on the relative importance of spacing versus formatting. |
1326 |
When presenting a section of formatted text, a positive spacing value is usually preferred. |
1327 |
A single line of text will often be accompanied by a negative spacing value. |
1328 |
A section of text meant to depict a picture, perhaps using a special purpose font such as hexbit4x1.fnt, calls for uniform spacing. |
1329 |
Reasonable magnitudes for proportional spacing are between 0.1 (for tightly spaced characters) and 0.3 (for wide spacing). |
1330 |
|
1331 |
</dl> |
1332 |
|
1333 |
<p> |
1334 |
<hr> |
1335 |
|
1336 |
<h4> |
1337 |
<a NAME="Mixtures">2.1.5. Mixtures</a> |
1338 |
</h4> |
1339 |
|
1340 |
A mixture is a blend of one or more materials or textures and patterns. |
1341 |
The basic types are given below. |
1342 |
|
1343 |
<p> |
1344 |
|
1345 |
<dl> |
1346 |
|
1347 |
<dt> |
1348 |
<a NAME="Mixfunc"> |
1349 |
<b>Mixfunc</b> |
1350 |
</a> |
1351 |
|
1352 |
<dd> |
1353 |
A mixfunc mixes two modifiers procedurally. It is specified as follows: |
1354 |
|
1355 |
<pre> |
1356 |
mod mixfunc id |
1357 |
4+ foreground background vname funcfile transform |
1358 |
0 |
1359 |
n A1 A2 .. An |
1360 |
</pre> |
1361 |
|
1362 |
Foreground and background are modifier names that must be |
1363 |
defined earlier in the scene description. |
1364 |
If one of these is a material, then |
1365 |
the modifier of the mixfunc must be "void". |
1366 |
(Either the foreground or background modifier may be "void", |
1367 |
which serves as a form of opacity control when used with a material.) |
1368 |
Vname is the coefficient defined in funcfile that determines the influence of foreground. |
1369 |
The background coefficient is always (1-vname). |
1370 |
Since the references are not resolved until run-time, the last definitions of the modifier id's will be used. |
1371 |
This can result in modifier loops, which are detected by the renderer. |
1372 |
|
1373 |
<p> |
1374 |
|
1375 |
<dt> |
1376 |
<a NAME="Mixdata"> |
1377 |
<b>Mixdata</b> |
1378 |
</a> |
1379 |
|
1380 |
<dd> |
1381 |
Mixdata combines two modifiers using an auxiliary data file: |
1382 |
|
1383 |
<pre> |
1384 |
mod mixdata id |
1385 |
5+n+ |
1386 |
foreground background func datafile |
1387 |
funcfile x1 x2 .. xn transform |
1388 |
0 |
1389 |
m A1 A2 .. Am |
1390 |
</pre> |
1391 |
|
1392 |
<dt> |
1393 |
<a NAME="Mixpict"> |
1394 |
<b>Mixpict</b> |
1395 |
</a> |
1396 |
|
1397 |
<dd> |
1398 |
Mixpict combines two modifiers based on a picture: |
1399 |
|
1400 |
<pre> |
1401 |
mod mixpict id |
1402 |
7+ |
1403 |
foreground background func pictfile |
1404 |
funcfile u v transform |
1405 |
0 |
1406 |
m A1 A2 .. Am |
1407 |
</pre> |
1408 |
|
1409 |
<p> |
1410 |
|
1411 |
The mixing coefficient function "func" takes three |
1412 |
arguments, the red, green and blue values |
1413 |
corresponding to the pixel at (u,v). |
1414 |
|
1415 |
</dl> |
1416 |
<p> |
1417 |
|
1418 |
<dt> |
1419 |
<a NAME="Mixtext"> |
1420 |
<b>Mixtext</b> |
1421 |
</a> |
1422 |
|
1423 |
<dd> |
1424 |
Mixtext uses one modifier for the text foreground, and one for the background: |
1425 |
|
1426 |
<pre> |
1427 |
mod mixtext id |
1428 |
4 foreground background fontfile textfile |
1429 |
0 |
1430 |
9+ |
1431 |
Ox Oy Oz |
1432 |
Rx Ry Rz |
1433 |
Dx Dy Dz |
1434 |
[spacing] |
1435 |
</pre> |
1436 |
|
1437 |
or: |
1438 |
|
1439 |
<pre> |
1440 |
mod mixtext id |
1441 |
4+N |
1442 |
foreground background fontfile . |
1443 |
This is a line with N words ... |
1444 |
0 |
1445 |
9+ |
1446 |
Ox Oy Oz |
1447 |
Rx Ry Rz |
1448 |
Dx Dy Dz |
1449 |
[spacing] |
1450 |
</pre> |
1451 |
|
1452 |
</dl> |
1453 |
|
1454 |
<p> |
1455 |
<hr> |
1456 |
|
1457 |
<h3> |
1458 |
<a NAME="Auxiliary">2.2. Auxiliary Files</a> |
1459 |
</h3> |
1460 |
|
1461 |
Auxiliary files used in <a HREF="#Textures">textures</a> and <a HREF="#Patterns">patterns</a> |
1462 |
are accessed by the programs during image generation. |
1463 |
These files may be located in the working directory, or in a library directory. |
1464 |
The environment variable RAYPATH can be assigned an alternate set of search directories. |
1465 |
Following is a brief description of some common file types. |
1466 |
|
1467 |
<p> |
1468 |
|
1469 |
<h4> |
1470 |
<a NAME="Function">12.2.1. Function Files</a> |
1471 |
</h4> |
1472 |
|
1473 |
A function file contains the definitions of variables, functions and constants used by a primitive. |
1474 |
The transformation that accompanies the file name contains the necessary rotations, translations and scalings |
1475 |
to bring the coordinates of the function file into agreement with the world coordinates. |
1476 |
The transformation specification is the same as for the <a HREF="#Generators">xform</a> command. |
1477 |
An example function file is given below: |
1478 |
|
1479 |
<pre> |
1480 |
{ |
1481 |
This is a comment, enclosed in curly braces. |
1482 |
{Comments can be nested.} |
1483 |
} |
1484 |
{ standard expressions use +,-,*,/,^,(,) } |
1485 |
vname = Ny * func(A1) ; |
1486 |
{ constants are defined with a colon } |
1487 |
const : sqrt(PI/2) ; |
1488 |
{ user-defined functions add to library } |
1489 |
func(x) = 5 + A1*sin(x/3) ; |
1490 |
{ functions may be passed and recursive } |
1491 |
rfunc(f,x) = if(x,f(x),f(-x)*rfunc(f,x+1)) ; |
1492 |
{ constant functions may also be defined } |
1493 |
cfunc(x) : 10*x / sqrt(x) ; |
1494 |
</pre> |
1495 |
|
1496 |
Many variables and functions are already defined by the program, and they are listed in the file rayinit.cal. |
1497 |
The following variables are particularly important: |
1498 |
|
1499 |
<pre> |
1500 |
Dx, Dy, Dz - incident ray direction |
1501 |
Nx, Ny, Nz - surface normal at intersection point |
1502 |
Px, Py, Pz - intersection point |
1503 |
T - distance from start |
1504 |
Ts - single ray (shadow) distance |
1505 |
Rdot - cosine between ray and normal |
1506 |
arg(0) - number of real arguments |
1507 |
arg(i) - i'th real argument |
1508 |
</pre> |
1509 |
|
1510 |
For mesh objects, the local surface coordinates are available: |
1511 |
|
1512 |
<pre> |
1513 |
Lu, Lv - local (u,v) coordinates |
1514 |
</pre> |
1515 |
|
1516 |
For BRDF types, the following variables are defined as well: |
1517 |
|
1518 |
<pre> |
1519 |
NxP, NyP, NzP - perturbed surface normal |
1520 |
RdotP - perturbed dot product |
1521 |
CrP, CgP, CbP - perturbed material color |
1522 |
</pre> |
1523 |
|
1524 |
A unique context is set up for each file so |
1525 |
that the same variable may appear in different |
1526 |
function files without conflict. |
1527 |
The variables listed above and any others defined in |
1528 |
rayinit.cal are available globally. |
1529 |
If no file is needed by a given primitive because all |
1530 |
the required variables are global, |
1531 |
a period (`.') can be given in place of the file name. |
1532 |
It is also possible to give an expression instead |
1533 |
of a straight variable name in a scene file, |
1534 |
although such expressions should be kept |
1535 |
simple if possible. |
1536 |
Also, functions (requiring parameters) must be given |
1537 |
as names and not as expressions. |
1538 |
|
1539 |
<p> |
1540 |
Constant expressions are used as an optimization in function files. |
1541 |
They are replaced wherever they occur in an expression by their value. |
1542 |
Constant expressions are evaluated only once, so they must not contain any variables or values that can change, |
1543 |
such as the ray variables Px and Ny or the primitive argument function arg(). |
1544 |
All the math library functions such as sqrt() and cos() have the constant attribute, |
1545 |
so they will be replaced by immediate values whenever they are given constant arguments. |
1546 |
Thus, the subexpression cos(PI*sqrt(2)) is immediately replaced by its value, -.266255342, |
1547 |
and does not cause any additional overhead in the calculation. |
1548 |
|
1549 |
<p> |
1550 |
It is generally a good idea to define constants and variables before they are referred to in a function file. |
1551 |
Although evaluation does not take place until later, the interpreter does variable scoping and |
1552 |
constant subexpression evaluation based on what it has compiled already. |
1553 |
For example, a variable that is defined globally in rayinit.cal |
1554 |
then referenced in the local context of a function file |
1555 |
cannot subsequently be redefined in the same file |
1556 |
because the compiler has already determined the scope of the referenced variable as global. |
1557 |
To avoid such conflicts, one can state the scope of a variable explicitly by |
1558 |
preceding the variable name with a context mark (a back-quote) for a local variable, |
1559 |
or following the name with a context mark for a global variable. |
1560 |
|
1561 |
<p> |
1562 |
|
1563 |
<h4> |
1564 |
<a NAME="Data">2.2.2. Data Files</a> |
1565 |
</h4> |
1566 |
|
1567 |
Data files contain n-dimensional arrays of real numbers used for interpolation. |
1568 |
Typically, definitions in a function file determine how to index and use interpolated data values. |
1569 |
The basic data file format is as follows: |
1570 |
|
1571 |
<pre> |
1572 |
N |
1573 |
beg1 end1 m1 |
1574 |
0 0 m2 x2.1 x2.2 x2.3 x2.4 .. x2.m2 |
1575 |
... |
1576 |
begN endN mN |
1577 |
DATA, later dimensions changing faster. |
1578 |
</pre> |
1579 |
|
1580 |
N is the number of dimensions. |
1581 |
For each dimension, the beginning and ending coordinate values and the dimension size is given. |
1582 |
Alternatively, individual coordinate values can be given when the points are not evenly spaced. |
1583 |
These values must either be increasing or decreasing monotonically. |
1584 |
The data is m1*m2*...*mN real numbers in ASCII form. |
1585 |
Comments may appear anywhere in the file, beginning with a pound |
1586 |
sign ('#') and continuing to the end of line. |
1587 |
|
1588 |
<p> |
1589 |
|
1590 |
<h4> |
1591 |
<a NAME="Font">2.2.3. Font Files</a> |
1592 |
</h4> |
1593 |
|
1594 |
A font file lists the polygons which make up a character set. |
1595 |
Comments may appear anywhere in the file, beginning with a pound |
1596 |
sign ('#') and continuing to the end of line. |
1597 |
All numbers are decimal integers: |
1598 |
|
1599 |
<pre> |
1600 |
code n |
1601 |
x0 y0 |
1602 |
x1 y1 |
1603 |
... |
1604 |
xn yn |
1605 |
... |
1606 |
</pre> |
1607 |
|
1608 |
The ASCII codes can appear in any order. N is the number of vertices, and the last is automatically connected to the first. |
1609 |
Separate polygonal sections are joined by coincident sides. |
1610 |
The character coordinate system is a square with lower left corner at (0,0), lower right at (255,0) and upper right at (255,255). |
1611 |
|
1612 |
<p> |
1613 |
|
1614 |
<hr> |
1615 |
|
1616 |
<h3> |
1617 |
<a NAME="Generators">2.3. Generators</a> |
1618 |
</h3> |
1619 |
|
1620 |
A generator is any program that produces a scene description as its output. |
1621 |
They usually appear as commands in a scene description file. |
1622 |
An example of a simple generator is genbox. |
1623 |
|
1624 |
<ul> |
1625 |
|
1626 |
<li> |
1627 |
<a NAME="Genbox" HREF="../man_html/genbox.1.html"> |
1628 |
<b>Genbox</b> |
1629 |
</a> |
1630 |
takes the arguments of width, height and depth to produce a parallelepiped description. |
1631 |
<li> |
1632 |
<a NAME="Genprism" HREF="../man_html/genprism.1.html"> |
1633 |
<b>Genprism</b> |
1634 |
</a> |
1635 |
takes a list of 2-dimensional coordinates and extrudes them along a vector to |
1636 |
produce a 3-dimensional prism. |
1637 |
<li> |
1638 |
<a NAME="Genrev" HREF="../man_html/genrev.1.html"> |
1639 |
<b>Genrev</b> |
1640 |
</a> |
1641 |
is a more sophisticated generator that produces an object of rotation from parametric functions for radius and axis position. |
1642 |
<li> |
1643 |
<a NAME="Gensurf" HREF="../man_html/gensurf.1.html"> |
1644 |
<b>Gensurf</b> |
1645 |
</a> |
1646 |
tessellates a surface defined by the parametric functions x(s,t), y(s,t), and z(s,t). |
1647 |
<li> |
1648 |
<a NAME="Genworm" HREF="../man_html/genworm.1.html"> |
1649 |
<b>Genworm</b> |
1650 |
</a> |
1651 |
links cylinders and spheres along a curve. |
1652 |
<li> |
1653 |
<a NAME="Gensky" HREF="../man_html/gensky.1.html"> |
1654 |
<b>Gensky</b> |
1655 |
</a> |
1656 |
produces a sun and sky distribution corresponding to a given time and date. |
1657 |
<li> |
1658 |
<a NAME="Xform" HREF="../man_html/xform.1.html"> |
1659 |
<b>Xform</b> |
1660 |
</a> |
1661 |
is a program that transforms a scene description from one coordinate space to another. |
1662 |
Xform does rotation, translation, scaling, and mirroring. |
1663 |
|
1664 |
</ul> |
1665 |
|
1666 |
<p> |
1667 |
<hr> |
1668 |
|
1669 |
<h2> |
1670 |
<a NAME="Image">3. Image Generation</a> |
1671 |
</h2> |
1672 |
|
1673 |
Once the scene has been described in three-dimensions, it is possible to generate a two-dimensional image from a given perspective. |
1674 |
|
1675 |
<p> |
1676 |
The image generating programs use an <a NAME="octree"><b>octree</b></a> to efficiently trace rays through the scene. |
1677 |
An octree subdivides space into nested octants which contain sets of surfaces. |
1678 |
In RADIANCE, an octree is created from a scene description by <a NAME="oconv1" HREF="../man_html/oconv.1.html"><b>oconv</b></a>. |
1679 |
The details of this process are not important, but the octree will serve as input to the ray-tracing programs and |
1680 |
directs the use of a scene description. |
1681 |
<ul> |
1682 |
<li> |
1683 |
<a NAME="rview" HREF="../man_html/rview.1.html"><b>Rview</b></a> is ray-tracing program for viewing a scene interactively. |
1684 |
When the user specifies a new perspective, rview quickly displays a rough image on the terminal, |
1685 |
then progressively increases the resolution as the user looks on. |
1686 |
He can select a particular section of the image to improve, or move to a different view and start over. |
1687 |
This mode of interaction is useful for debugging scenes as well as determining the best view for a final image. |
1688 |
|
1689 |
<li> |
1690 |
<a NAME="rpict" HREF="../man_html/rpict.1.html"><b>Rpict</b></a> produces a high-resolution picture of a scene from a particular perspective. |
1691 |
This program features adaptive sampling, crash recovery and progress reporting, all of which are important for time-consuming images. |
1692 |
</ul> |
1693 |
<p> |
1694 |
A number of <a NAME="filters"><b>filters</b></a> are available for manipulating picture files: |
1695 |
<ul> |
1696 |
<li> <a HREF="../man_html/pfilt.1.html"><b>Pfilt</b></a> |
1697 |
sets the exposure and performs antialiasing. |
1698 |
<li> <a HREF="../man_html/pcompos.1.html"><b>Pcompos</b></a> |
1699 |
composites (cuts and pastes) pictures. |
1700 |
<li> <a HREF="../man_html/pcomb.1.html"><b>Pcomb</b></a> |
1701 |
performs arbitrary math on one or more pictures. |
1702 |
<li> <a HREF="../man_html/pcond.1.html"><b>Pcond</b></a> |
1703 |
conditions a picture for a specific display device. |
1704 |
<li> <a HREF="../man_html/protate.1.html"><b>Protate</b></a> |
1705 |
rotates a picture 90 degrees clockwise. |
1706 |
<li> <a HREF="../man_html/pflip.1.html"><b>Pflip</b></a> |
1707 |
flips a picture horizontally, vertically, or both |
1708 |
(180 degree rotation). |
1709 |
<li> <a HREF="../man_html/pvalue.1.html"><b>Pvalue</b></a> |
1710 |
converts a picture to and from simpler formats. |
1711 |
</ul> |
1712 |
|
1713 |
<p> |
1714 |
Pictures may be displayed directly under X11 using the program |
1715 |
<a HREF="../man_html/ximage.1.html">ximage</a>, |
1716 |
or converted a standard image format using one of the following |
1717 |
<b>translators</b>: |
1718 |
<ul> |
1719 |
<li> <b>Ra_avs</b> |
1720 |
converts to and from AVS image format. |
1721 |
<li> <a HREF="../man_html/ra_pict.1.html"><b>Ra_pict</b></a> |
1722 |
converts to Macintosh 32-bit PICT2 format. |
1723 |
<li> <a HREF="../man_html/ra_ppm.1.html"><b>Ra_ppm</b></a> |
1724 |
converts to and from Poskanzer Portable Pixmap formats. |
1725 |
<li> <a HREF="../man_html/ra_pr.1.html"><b>Ra_pr</b></a> |
1726 |
converts to and from Sun 8-bit rasterfile format. |
1727 |
<li> <a HREF="../man_html/ra_pr24.1.html"><b>Ra_pr24</b></a> |
1728 |
converts to and from Sun 24-bit rasterfile format. |
1729 |
<li> <a HREF="../man_html/ra_ps.1.html"><b>Ra_ps</b></a> |
1730 |
converts to PostScript color and greyscale formats. |
1731 |
<li> <a HREF="../man_html/ra_rgbe.1.html"><b>Ra_rgbe</b></a> |
1732 |
converts to and from Radiance uncompressed picture format. |
1733 |
<li> <a HREF="../man_html/ra_t16.1.html"><b>Ra_t16</b></a> |
1734 |
converts to and from Targa 16 and 24-bit image formats. |
1735 |
<li> <a HREF="../man_html/ra_t8.1.html"><b>Ra_t8</b></a> |
1736 |
converts to and from Targa 8-bit image format. |
1737 |
<li> <a HREF="../man_html/ra_tiff.1.html"><b>Ra_tiff</b></a> |
1738 |
converts to and from TIFF. |
1739 |
<li> <a HREF="../man_html/ra_xyze.1.html"><b>Ra_xyze</b></a> |
1740 |
converts to and from Radiance CIE picture format. |
1741 |
</ul> |
1742 |
|
1743 |
<p> |
1744 |
|
1745 |
<hr> |
1746 |
|
1747 |
<h2> |
1748 |
<a NAME="License">4. License</a> |
1749 |
</h2> |
1750 |
|
1751 |
<pre> |
1752 |
The Radiance Software License, Version 1.0 |
1753 |
|
1754 |
Copyright (c) 1990 - 2002 The Regents of the University of California, |
1755 |
through Lawrence Berkeley National Laboratory. All rights reserved. |
1756 |
|
1757 |
Redistribution and use in source and binary forms, with or without |
1758 |
modification, are permitted provided that the following conditions |
1759 |
are met: |
1760 |
|
1761 |
1. Redistributions of source code must retain the above copyright |
1762 |
notice, this list of conditions and the following disclaimer. |
1763 |
|
1764 |
2. Redistributions in binary form must reproduce the above copyright |
1765 |
notice, this list of conditions and the following disclaimer in |
1766 |
the documentation and/or other materials provided with the |
1767 |
distribution. |
1768 |
|
1769 |
3. The end-user documentation included with the redistribution, |
1770 |
if any, must include the following acknowledgment: |
1771 |
"This product includes Radiance software |
1772 |
(<a HREF="http://radsite.lbl.gov/">http://radsite.lbl.gov/</a>) |
1773 |
developed by the Lawrence Berkeley National Laboratory |
1774 |
(<a HREF="http://www.lbl.gov/">http://www.lbl.gov/</a>)." |
1775 |
Alternately, this acknowledgment may appear in the software itself, |
1776 |
if and wherever such third-party acknowledgments normally appear. |
1777 |
|
1778 |
4. The names "Radiance," "Lawrence Berkeley National Laboratory" |
1779 |
and "The Regents of the University of California" must |
1780 |
not be used to endorse or promote products derived from this |
1781 |
software without prior written permission. For written |
1782 |
permission, please contact [email protected]. |
1783 |
|
1784 |
5. Products derived from this software may not be called "Radiance", |
1785 |
nor may "Radiance" appear in their name, without prior written |
1786 |
permission of Lawrence Berkeley National Laboratory. |
1787 |
|
1788 |
THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED |
1789 |
WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
1790 |
OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE |
1791 |
DISCLAIMED. IN NO EVENT SHALL Lawrence Berkeley National Laboratory OR |
1792 |
ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
1793 |
SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT |
1794 |
LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF |
1795 |
USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND |
1796 |
ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, |
1797 |
OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT |
1798 |
OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
1799 |
SUCH DAMAGE. |
1800 |
</pre> |
1801 |
|
1802 |
<hr> |
1803 |
|
1804 |
<h2> |
1805 |
<a NAME="Ack">5. Acknowledgements</a> |
1806 |
</h2> |
1807 |
|
1808 |
This work was supported by the Assistant Secretary of Conservation and Renewable Energy, |
1809 |
Office of Building Energy Research and Development, |
1810 |
Buildings Equipment Division of the U.S. Department of Energy under Contract No. DE-AC03-76SF00098. |
1811 |
|
1812 |
<p> |
1813 |
Additional work was sponsored by the Swiss federal government |
1814 |
under the Swiss LUMEN Project and was carried out in the |
1815 |
Laboratoire d'Energie Solaire (LESO Group) at the |
1816 |
Ecole Polytechnique Federale de Lausanne (EPFL University) in Lausanne, Switzerland. |
1817 |
|
1818 |
<p> |
1819 |
|
1820 |
<hr> |
1821 |
|
1822 |
<h2> |
1823 |
<a NAME="Ref">6.</a> References |
1824 |
</h2> |
1825 |
<p> |
1826 |
<ul> |
1827 |
<li>Ward, Greg, Elena Eydelberg-Vileshin, |
1828 |
``<a HREF="http://viz.cs.berkeley.edu/~gwlarson/papers/egwr02/index.html">Picture Perfect RGB |
1829 |
Rendering Using Spectral Prefiltering and Sharp Color Primaries</a>,'' |
1830 |
Thirteenth Eurographics Workshop on Rendering (2002), |
1831 |
P. Debevec and S. Gibson (Editors), June 2002. |
1832 |
<li>Ward, Gregory, |
1833 |
``<a HREF="http://viz.cs.berkeley.edu/~gwlarson/papers/cic01.pdf">High Dynamic Range Imaging</a>,'' |
1834 |
Proceedings of the Ninth Color Imaging Conference, November 2001. |
1835 |
<li>Ward, Gregory and Maryann Simmons, |
1836 |
``<a HREF="http://viz.cs.berkeley.edu/~gwlarson/papers/tog99.pdf"> |
1837 |
The Holodeck Ray Cache: An Interactive Rendering System for Global Illumination in Nondiffuse |
1838 |
Environments</a>,'' ACM Transactions on Graphics, 18(4):361-98, October 1999. |
1839 |
<li>Larson, G.W., ``<a HREF="http://viz.cs.berkeley.edu/~gwlarson/papers/ewp98.pdf">The Holodeck: A Parallel |
1840 |
Ray-caching Rendering System</a>,'' Proceedings of the Second |
1841 |
Eurographics Workshop on Parallel Graphics and Visualisation, |
1842 |
September 1998. |
1843 |
<li>Larson, G.W. and R.A. Shakespeare, |
1844 |
<a HREF="http://radsite.lbl.gov/radiance/book/index.html"><em>Rendering with Radiance: |
1845 |
the Art and Science of Lighting Visualization</em></a>, |
1846 |
Morgan Kaufmann Publishers, 1998. |
1847 |
<li>Larson, G.W., H. Rushmeier, C. Piatko, |
1848 |
``<a HREF="http://radsite.lbl.gov/radiance/papers/lbnl39882/tonemap.pdf">A Visibility |
1849 |
Matching Tone Reproduction Operator for |
1850 |
High Dynamic Range Scenes</a>,'' LBNL Technical Report 39882, |
1851 |
January 1997. |
1852 |
<li>Ward, G., ``<a HREF="http://radsite.lbl.gov/radiance/papers/erw95.1/paper.html">Making |
1853 |
Global Illumination User-Friendly</a>,'' Sixth |
1854 |
Eurographics Workshop on Rendering, Springer-Verlag, |
1855 |
Dublin, Ireland, June 1995.</li> |
1856 |
<li>Rushmeier, H., G. Ward, C. Piatko, P. Sanders, B. Rust, |
1857 |
``<a HREF="http://radsite.lbl.gov/mgf/compare.html"> |
1858 |
Comparing Real and Synthetic Images: Some Ideas about |
1859 |
Metrics</a>,'' Sixth Eurographics Workshop on Rendering, |
1860 |
Springer-Verlag, Dublin, Ireland, June 1995.</li> |
1861 |
<li>Ward, G., ``<a HREF="http://radsite.lbl.gov/radiance/papers/sg94.1/paper.html">The RADIANCE |
1862 |
Lighting Simulation and Rendering System</a>,'' <em>Computer |
1863 |
Graphics</em>, July 1994.</li> |
1864 |
<li>Rushmeier, H., G. Ward, ``<a HREF="http://radsite.lbl.gov/radiance/papers/sg94.2/energy.html">Energy |
1865 |
Preserving Non-Linear Filters</a>,'' <em>Computer |
1866 |
Graphics</em>, July 1994.</li> |
1867 |
<li>Ward, G., ``A Contrast-Based Scalefactor for Luminance |
1868 |
Display,'' <em>Graphics Gems IV</em>, Edited by Paul Heckbert, |
1869 |
Academic Press 1994.</li> |
1870 |
<li>Ward, G., ``<a HREF="http://radsite.lbl.gov/radiance/papers/sg92/paper.html">Measuring and |
1871 |
Modeling Anisotropic Reflection</a>,'' <em>Computer |
1872 |
Graphics</em>, Vol. 26, No. 2, July 1992. </li> |
1873 |
<li>Ward, G., P. Heckbert, ``<a HREF="http://radsite.lbl.gov/radiance/papers/erw92/paper.html">Irradiance |
1874 |
Gradients</a>,'' Third Annual Eurographics Workshop on |
1875 |
Rendering, Springer-Verlag, May 1992. </li> |
1876 |
<li>Ward, G., ``<a HREF="http://radsite.lbl.gov/radiance/papers/erw91/erw91.html">Adaptive Shadow |
1877 |
Testing for Ray Tracing</a>'' Photorealistic Rendering in |
1878 |
Computer Graphics, proceedings of 1991 Eurographics |
1879 |
Rendering Workshop, edited by P. Brunet and F.W. Jansen, |
1880 |
Springer-Verlag. </li> |
1881 |
<li>Ward, G., ``Visualization,'' <em>Lighting Design and |
1882 |
Application</em>, Vol. 20, No. 6, June 1990. </li> |
1883 |
<li>Ward, G., F. Rubinstein, R. Clear, ``<a HREF="http://radsite.lbl.gov/radiance/papers/sg88/paper.html">A Ray Tracing Solution for |
1884 |
Diffuse Interreflection</a>,'' <em>Computer Graphics</em>, |
1885 |
Vol. 22, No. 4, August 1988. </li> |
1886 |
<li>Ward, G., F. Rubinstein, ``A New Technique for Computer |
1887 |
Simulation of Illuminated Spaces,'' <em>Journal of the |
1888 |
Illuminating Engineering Society</em>, Vol. 17, No. 1, |
1889 |
Winter 1988. </li> |
1890 |
</ul> |
1891 |
<p> |
1892 |
See the <a HREF="index.html">RADIANCE Reference Materials</a> page |
1893 |
for additional information. |
1894 |
<hr> |
1895 |
|
1896 |
<a NAME="Index"><h2>7. Types Index</h2></a> |
1897 |
|
1898 |
<pre> |
1899 |
<h4> |
1900 |
SURFACES MATERIALS TEXTURES PATTERNS MIXTURES</h4> |
1901 |
<a HREF="#Source">Source</a> <a HREF="#Light">Light</a> <a HREF="#Texfunc">Texfunc</a> <a HREF="#Colorfunc">Colorfunc</a> <a HREF="#Mixfunc">Mixfunc</a> |
1902 |
<a HREF="#Sphere">Sphere</a> <a HREF="#Illum">Illum</a> <a HREF="#Texdata">Texdata</a> <a HREF="#Brightfunc">Brightfunc</a> <a HREF="#Mixdata">Mixdata</a> |
1903 |
<a HREF="#Bubble">Bubble</a> <a HREF="#Glow">Glow</a> <a HREF="#Colordata">Colordata</a> <a HREF="#Mixtext">Mixtext</a> |
1904 |
<a HREF="#Polygon">Polygon</a> <a HREF="#Spotlight">Spotlight</a> <a HREF="#Brightdata">Brightdata</a> |
1905 |
<a HREF="#Cone">Cone</a> <a HREF="#Mirror">Mirror</a> <a HREF="#Colorpict">Colorpict</a> |
1906 |
<a HREF="#Cup">Cup</a> <a HREF="#Prism1">Prism1</a> <a HREF="#Colortext">Colortext</a> |
1907 |
<a HREF="#Cylinder">Cylinder</a> <a HREF="#Prism2">Prism2</a> <a HREF="#Brighttext">Brighttext</a> |
1908 |
<a HREF="#Tube">Tube</a> <a HREF="#Plastic">Plastic</a> |
1909 |
<a HREF="#Ring">Ring</a> <a HREF="#Metal">Metal</a> |
1910 |
<a HREF="#Instance">Instance</a> <a HREF="#Trans">Trans</a> |
1911 |
<a HREF="#Mesh">Mesh</a> <a HREF="#Plastic2">Plastic2</a> |
1912 |
<a HREF="#Metal2">Metal2</a> |
1913 |
<a HREF="#Trans2">Trans2</a> |
1914 |
<a HREF="#Mist">Mist</a> |
1915 |
<a HREF="#Dielectric">Dielectric</a> |
1916 |
<a HREF="#Interface">Interface</a> |
1917 |
<a HREF="#Glass">Glass</a> |
1918 |
<a HREF="#Plasfunc">Plasfunc</a> |
1919 |
<a HREF="#Metfunc">Metfunc</a> |
1920 |
<a HREF="#Transfunc">Transfunc</a> |
1921 |
<a HREF="#BRTDfunc">BRTDfunc</a> |
1922 |
<a HREF="#Plasdata">Plasdata</a> |
1923 |
<a HREF="#Metdata">Metdata</a> |
1924 |
<a HREF="#Transdata">Transdata</a> |
1925 |
<a HREF="#Antimatter">Antimatter</a> |
1926 |
|
1927 |
</pre> |
1928 |
|
1929 |
<p> |
1930 |
|
1931 |
|
1932 |
<hr> |
1933 |
<center>Last Update: October 22, 1997</center> |
1934 |
</body> |
1935 |
</html> |
1936 |
|