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root/radiance/ray/src/util/trad.hlp
Revision: 2.15
Committed: Thu Sep 28 14:11:45 1995 UTC (28 years, 6 months ago) by greg
Branch: MAIN
Changes since 2.14: +4 -1 lines
Log Message:
added color PostScript output

File Contents

# Content
1 $Id$
2
3 This help file is associated with the trad interface to the Radiance
4 rad(1) program. Trad consists of trad.wsh and one do_*.tcl file for
5 each screen. There are currently seven such screens: File, Scene,
6 Zone, Views, Options, Action and Results.
7
8 .Trad.Intro
9
10 Trad is a graphical user interface (GUI) to the
11 rad(1) program, which controls the operation of the basic
12 Radiance scene compiling, rendering and picture filtering programs.
13 Trad also includes links to a few utilities for displaying and
14 converting results, but most of what it does can be done by editing a
15 small text file, called the "rad input file".
16 Scene creation still requires the use of a text or graphical editor,
17 or translation from some external CAD format.
18
19 Trad interaction is broken into seven screens.
20 Each screen is accessed by pressing its associated radio
21 button along the right-hand side of the main window.
22 If trad is started with no file name, the File screen is displayed,
23 and you must pick a valid rad input file before any other screen may
24 be accessed.
25 If a name is given for a file that doesn't exist, trad goes to the
26 Scene screen and prompts you to enter the names of one or more
27 Radiance scene description files.
28 If a rad input file exists already, trad determines if there are
29 renderings still to be done or if everything is finished.
30 If there is still work to be done, trad opens first with the Action
31 screen.
32 If all renderings are complete and up-to-date, trad opens right to
33 Results screen.
34
35 For additional guidance on Radiance in general, consult the Radiance
36 Tutorial, Reference Manual, and man pages.
37 In particular, it is a good idea to read through the rad(1) man page
38 before using this interface.
39
40 To find out how to get more help, press the "Next" button to the
41 right.
42
43 .Trad.Help
44
45 If you have specific questions about trad, search through the
46 category and topic menus on this help window, or press and release
47 the left mouse button while holding the control key over the object of
48 curiosity in the main trad window.
49 (In general, only active windows are given help file links -- click
50 on these rather than the text labels.)
51 Additional search capabilities are available over all topics using
52 the "Grep" button.
53
54 For help on the help facility itself, Control-click on the problem
55 help widget or on the window title in the upper right corner for
56 more general information.
57 (To get back to trad-specific help, press the "HELP" button in the
58 main trad window or Control-click on a trad widget.)
59
60 .Trad.Messages
61
62 Informative messages, commands executed by rad, and errors
63 appear in the message window at the bottom of the trad frame.
64 Growing the trad window means growing this message window, and
65 not much else.
66 This is not really necessary, since the window will be grown
67 automatically if the message requires it.
68
69 Serious errors will be accompanied by the sounding of the bell.
70
71 .Trad.Quit
72
73 To quit the trad application, press the "Quit" button at any time.
74 If you have made changes to the rad input variables, you will be
75 asked prior to program exit if you want to save your changes first.
76
77 Any batch process running in the background will continue to run,
78 and the associated error messages will be viewable by
79 trad later when you open the same rad input file.
80
81 .File.Intro
82
83 This button selects the trad File screen, which allows rad input
84 files to be loaded and saved, and new files to be created.
85
86 .File.Load
87
88 This button loads the selected file into trad.
89 If the current file has been changed and these changes have not been
90 saved, you will be given first the opportunity to save your changes.
91
92 The actual load operation may take several seconds or even minutes,
93 depending on the status of the rendering process.
94 This is because the rad program itself is used to interpret the
95 input file, and if there is no up-to-date octree associated with the
96 file, it is necessary to run getbbox on the entire scene
97 before the variable values can be set.
98 It is possible to eliminate this delay in future loads by going to
99 the Action screen and running oconv.
100
101 If the opened file has read-only mode set (see chmod(1)), then the
102 "Read Only" check box will be lit.
103 Unchecking this box means that it will be possible to save the file
104 later, though the actual mode on the file will not be changed until
105 it is saved.
106 Loading a writable file always clears the "Read Only" check box.
107
108 If an error is encountered while trying to load the file, a message
109 will be printed in the box at the bottom.
110
111 .File.Save
112
113 The "Save" button in the File screen saves any changes to the
114 current file.
115 This information is saved in the original file by default, but may
116 be saved in another file by entering a new name in the "File" field.
117 If this new file already exists, a dialogue box will ask if you really
118 want to overwrite it.
119 If the file name is different than the original
120 one loaded, the "Read Only" check box will be ignored.
121
122 .File.New
123
124 The "New" button clears all rad variables in preparation for
125 writing a new rad input file.
126 If the file selected already exists, a warning box will ask if you
127 really want to ignore the previous file contents.
128 If you agree, then no warning will be given when the file is later
129 overwritten.
130
131 .File.ReadOnly
132
133 The "Read Only" check box permits you to indicate that the opened
134 file should not be overwritten.
135 This box will be checked automatically if the permissions on the
136 edited file do not allow writing by the user.
137 If the box is subsequently unchecked, trad will attempt to change
138 permissions and write to the file when a save is requested.
139 If this fails, an error message will indicate the problem.
140
141 .Scene.Intro
142
143 This button selects the trad Scene screen.
144 On this screen, you may enter the octree file and the scene files
145 that go into it, as well as any mkillum or other files on which the
146 scene depends.
147 These files are generally produced by hand in a text editor or by
148 conversion from an external CAD format, such as DXF.
149 (See the Radiance Reference Manual and Radiance Tutorial for details on the
150 information contained in these files.)
151
152 To enter a file of a particular type, press the corresponding button
153 to get a dialogue box that allows you to pick existing files from any
154 directory.
155
156 Use the "Discard" button to remove one or more files from a specific
157 list.
158 The actual file is untouched.
159
160 .Scene.Octree
161
162 The "Octree" entry in the Scene screen names the octree file to be
163 compiled by oconv from the materials and scene files.
164 (See the oconv(1) man page for more details.)
165
166 If make(1) is being used to build the octree, you should leave all
167 other windows on this screen empty.
168 The octree can still be rebuilt from trad by pressing the "oconv"
169 or "Force" buttons on the Action screen, but normally it is
170 expected to be current.
171 In particular, an unsupported octree must exist before loading
172 a rad input file on which it depends.
173
174 The default octree name is the root name from the render input file
175 plus ".oct".
176 If mkillum is being used (i.e. one or more illum files is given),
177 then two additional octrees will be created, named the same except
178 for an additional "0" or "1" immediately before the file suffix
179 (normally ".oct").
180
181 To delete the named octree, and therefore force the scene to be
182 recompiled and all the pictures to be rerendered, use the "Delete"
183 button next to the octree window.
184
185 .Scene.OctDelete
186
187 The "Delete" button next to the octree window removes the named
188 octree from the filesystem, forcing the scene to be later recompiled
189 and all the pictures to be rerendered (if desired).
190 This is appropriate if you add or remove materials, scene or illum
191 files from one or more lists, or make some change to a materials file
192 that requires the octree to be rebuilt (such as adding or removing
193 individual materials).
194
195 Verification is required before the octree will be deleted.
196
197 You can achieve the same effect as manually removing the octree by
198 pressing the "Force" button on the scene compilation section
199 of the Action screen.
200 (See the "Force" topic under the "Action" help category for more
201 information.)
202
203 .Scene.Materials
204
205 Materials files generally contain Radiance material descriptions
206 only, not geometry.
207 The purpose of listing them separately is so that minor changes to
208 material parameters will not force the octree to be rebuilt,
209 incurring an additional delay that is unnecessary.
210
211 The "Materials" button is used to add materials files to the list.
212 A dialogue box appears when you press this button and allows you to
213 select files to be included.
214 Each new selection is added to the end of the materials list.
215 The default matching pattern for material files is "*.mat".
216 This may of course be reassigned within the file selection window.
217
218 The list box showing the current materials may be edited in three
219 ways besides the dialogue for adding files.
220 First, entries may be removed from the list
221 using the "Discard" button.
222 Second, entries may be moved within the box by selecting them with
223 the left mouse button and clicking the middle mouse button over the
224 entry you wish to place the selected items above.
225 If you wish to put the selected items at the very end of the list,
226 click the middle mouse button below the last entry.
227 Third, entries may be moved from other windows by
228 selecting them and pressing the middle button.
229 This works for the list boxes on this screen as well as selections
230 in other windows on the display.
231
232 The order of materials files is usually unimportant, but sometimes
233 there are definitions in later files that depend on prerequisites in
234 earlier files.
235 An example of this is a window illum source that depends on a sky
236 description file, which must appear before it.
237 The order of files shown in the list is the order they will be given
238 to oconv and therefore to the rendering programs.
239
240 .Scene.Illum
241
242 Illum files are Radiance scene descriptions that contain surfaces
243 to be converted into illum sources by mkillum(1).
244 Please consult the manual page for mkillum and understand the
245 Radiance Tutorial before using this box, since these files differ slightly
246 from standard Radiance scene descriptions.
247
248 The "Illum" button is used to add illum files to the list.
249 A dialogue box appears when you press this button and allows you to
250 select files to be included.
251 Each new selection is added to the end of the illum list.
252 The default matching pattern for material files is "*.rad".
253 This may of course be reassigned within the file selection window.
254
255 The list box showing the current illum files may be edited in three
256 ways besides the dialogue for adding files.
257 First, entries may be removed from the list
258 using the "Discard" button.
259 Second, entries may be moved within the box by selecting them with
260 the left mouse button and clicking the middle mouse button over the
261 entry you wish to place the selected items above.
262 If you wish to put the selected items at the very end of the list,
263 click the middle mouse button below the last entry.
264 Third, entries may be moved from other windows by
265 selecting them and pressing the middle button.
266 This works for the list boxes on this screen as well as selections
267 in other windows on the display.
268
269 .Scene.Scene
270
271 Scene files give the geometry and (perhaps) some of the materials
272 used in a particular Radiance model.
273 These files are given to oconv(1) in the order specified.
274 The ordering of files is usually not important, unless some later
275 files use materials or other modifiers defined in earlier files.
276
277 The "Scene" button is used to add scene files to the list.
278 A dialogue box appears when you press this button and allows you to
279 select files to be included.
280 Each new selection is added to the end of the scene list.
281 The default matching pattern for material files is "*.rad".
282 This may of course be reassigned within the file selection window.
283
284 The list box showing the current scene files may be edited in three
285 ways besides the dialogue for adding files.
286 First, entries may be removed from the list
287 using the "Discard" button.
288 Second, entries may be moved within the box by selecting them with
289 the left mouse button and clicking the middle mouse button over the
290 entry you wish to place the selected items above.
291 If you wish to put the selected items at the very end of the list,
292 click the middle mouse button below the last entry.
293 Third, entries may be moved from other windows by
294 selecting them and pressing the middle button.
295 This works for the list boxes on this screen as well as selections
296 in other windows on the display.
297
298 .Scene.Objects
299
300 Object files are files on which the given octree depends, but which
301 are not included directly on the oconv command line.
302 If any of these files is modified, then it is assumed that the
303 octree must be rebuilt.
304
305 To automatically determine which files in the working directory
306 affect the octree, press the "Auto" button just below the "Objects"
307 button.
308 Note that this will only add files to the object list.
309 If you wish to completely replace what is already there, you must
310 therefore select all the files and use the "Discard" button before
311 pressing "Auto".
312
313 .Scene.Discard
314
315 The "Discard" button removes the selected file names from a list.
316 The actual files are untouched, of course.
317 (Some care should be taken here, since there is no undo
318 function associated with this window other than reloading the
319 original information with the "Revert" button.)
320
321 .Scene.Edit
322
323 Use the "Edit" button to open a text editor on the selected file(s).
324 This is a convenient way to look at and change the contents of the
325 Radiance input files.
326
327 .Scene.Copy
328
329 The "Copy" button may be used to selectively copy the scene file
330 information from another rad input file.
331 Specifically, the variables "OCTREE, materials, illum, scene and
332 objects" will be read in to replace the current values.
333
334 All other variables will be unaffected.
335
336 .Scene.Revert
337
338 The "Revert" button is a convenient way to revert to the original
339 values in the rad input file.
340 Only the variables on the Scene screen will be affected, but any changes
341 to these variables since the last save will be lost.
342
343 .Zone.Intro
344
345 This button selects the trad Zone screen.
346 On this screen, the user should enter the maximum and minimum
347 coordinates of the zone of interest for this set of renderings.
348 This zone need not correspond exactly to any interior or exterior
349 walls, as it is used primarily to set rendering parameters and
350 standard viewpoints.
351
352 An interior zone means that standard viewpoints will be selected
353 from the inside of this box.
354 An exterior zone means that standard viewpoints will be selected
355 from the outside of this box.
356 The default zone is an exterior one computed from the bounding box
357 of the entire scene.
358 (Note that this is not usually desirable.)
359
360 In addition to the ZONE variable, this screen offers the ability
361 to set four other rad variables that are generally associated with a
362 particular scene and a particular zone.
363 These are the rad DETAIL, INDIRECT, VARIABILITY and EXPOSURE
364 variables.
365 For more information on these topics, use the Topic menu or consult
366 the rad manual page.
367
368 .Zone.Type
369
370 There are two types of zones understood by rad, "Interior" and
371 "Exterior".
372 An interior zone is indicated when renderings generally take place
373 inside a specified 3-d box.
374 A typical example might be a single room or auditorium.
375 An exterior zone is indicated when renderings generally take place
376 outside a specified 3-d box, which is the focus of attention.
377 A typical example might be a building exterior or a single object,
378 such as a chair.
379
380 .Zone.Zone
381
382 A zone is specified by six real numbers, corresponding to the world
383 coordinates of the box's corners.
384 Zone boxes are always axis-aligned, therefore one need only specify
385 the minimum and maximum X, Y, and Z coordinates.
386
387 The exact values of these coordinates is not terribly important, as
388 they are only used to guide the setting of certain rendering
389 parameters and standard view positions.
390 It does not matter for instance whether the values lie on the inside
391 or the outside of walls, or if there are non-rectilinear geometries
392 defining the space perimeter.
393 In fact, the whole space may not even be aligned with the X, Y, and Z
394 axes, and a very approximate box may be given.
395 In this case, the standard views may not be very intelligent or
396 useful, but the rendering parameters will still be satisfactory so
397 long as the overall size of the given box is close to the overall
398 size of the space.
399
400 The Zone entry windows may be manipulated in the following ways.
401 Control-U clears the current window.
402 Control-V pastes the contents of the current selection at the
403 insertion point.
404 Return moves the focus to the next window in the chain.
405
406 .Zone.Detail
407
408 The "Detail" setting indicates the relative level
409 of geometric detail in this zone.
410 If the zone is empty except for a few large pieces of furniture, a
411 "Low" setting is indicated.
412 (For an exterior zone, low detail would mean that the object is
413 relatively simple.)
414 If the zone contains a usual amount of furniture and clutter, a
415 "Medium" setting is appropriate.
416 If the zone contains a great many small objects or protrusions, a
417 setting of "High" is indicated.
418
419 This variable is used by rad to set rendering parameters that are
420 affected by the sizes of objects relative to the overall size of the
421 space.
422
423 .Zone.Indirect
424
425 The "Indirect" setting indicates how important indirect illumination
426 is in this space.
427 A setting of "0" means that most light falls directly on visible
428 surfaces, and this setting can be used in most cases.
429 A setting of "1" means that most objects are not directly
430 illuminated by light sources, but receive light only after it has
431 bounced once off some other surface, such as the ceiling.
432 Likewise, a setting of "2" means that light must reflect twice off
433 other surfaces before reaching most objects of interest.
434
435 Keep in mind that the rendering calculation increases substantially
436 with each increment to this variable, so it is a good idea to use
437 the smallest reasonable value.
438
439 .Zone.Variability
440
441 The "Variability" setting gives a qualitative indication of how
442 light varies in magnitude over surfaces in this zone.
443 In a typical direct or indirect lighting situation, this variable
444 would be set to "Low", indicating that light is fairly uniform
445 throughout the space.
446 If there are some areas that are much better lit than others, such
447 as desks with powerful tasks lights in a room with dimmer ambient
448 lighting, a "Medium" setting is appropriate.
449 If there is direct sunlight entering the room, casting bright
450 patches on some surfaces and not others, then a setting of "High" is
451 indicated.
452
453 Note that this variable speaks to the magnitude of light variations
454 more than the patterns of light.
455 It may well be that the light is casting interesting patterns such
456 as scallops on the walls or something, but as long as the variations
457 in brightness are less than an order of magnitude or so, it is a low
458 variability situation.
459 The high variability
460 example given above of direct sun entering a space corresponds to a
461 a variation in brightness of about three orders of magnitude, or
462 1,000 to 1!
463
464 .Zone.Exposure
465
466 The "Exposure" setting gives the multiplier between the initial
467 radiance values at each pixel (in watts/steradian/meter^2) to the
468 display pixel values (in the range of 0-1, where 0 is black and 1 is
469 the maximum monitor output).
470 This setting also determines the average "ambient level," which is
471 an important parameter for rendering accuracy.
472
473 There are two basic ways to compute the exposure value.
474 The first is by trial and error, where the value is adjusted up and
475 down within rview using the "e = value" command.
476 Though it sounds flaky, this is the most reliable way to set the
477 exposure (and ambient level) in general lighting situations.
478
479 The second method is using a zonal cavity approximation.
480 For this, you must estimate the total light flux entering the zone
481 from light sources and windows, and the total illuminated area.
482 (This applies to interior zones, only. For exterior zones, use the
483 value suggested by gensky in its output.)
484 In addition, you must approximate the area-weighted average
485 reflectance of the illuminated surfaces.
486 The formula then for the exposure multiplier using this information
487 is: pi*tot_area*(1-avg_refl)/(2*tot_flux*avg_refl)
488 where pi is 3.1416, tot_area is given in square meters and
489 tot_flux is given in watts.
490 (Divide total lumens by 179 lumens/watt to get watts.)
491
492 The exposure value may either be given as a positive real value, or
493 as a real value preceeded by a '+' or '-' indicating a positive or
494 negative number of f-stops (powers of two) from the original value.
495
496 If no exposure is given, pfilt will automatically compute the
497 average for each image, and a default ambient level of 10 will be
498 used for exterior zones and 0.01 for interior zones.
499
500 .Zone.Copy
501
502 The "Copy" button on the Zone screen takes all values for this
503 screen from another rad input file, replacing the current values.
504 Specifically, the rad variables "ZONE, DETAIL, INDIRECT,
505 VARIABILITY and EXPOSURE" will be copied from the named file.
506
507 All other variables will be left untouched.
508
509 .Zone.Revert
510
511 The "Revert" button is a convenient way to revert to the original
512 values in the rad input file.
513 Only the variables on the Zone screen will be affected, but any changes
514 to these variables since the last save will be lost.
515
516 .Views.Intro
517
518 This button selects the trad Views screen.
519 This screen provides a means of setting the multi-valued
520 "view" variable.
521 Each view setting is listed by name, or by number if no name has
522 been assigned.
523 To add a new view, enter a unique name and specify the view
524 options,
525 then press the "Add" or "Set Default" button.
526 If a view with the same name already exists, it is unconditionally
527 overwritten.
528 To modify a particular view, simply select it, change its name
529 and/or parameters, and press the "Change" button.
530 To remove an unwanted view, select it and press the "Delete" button.
531 To undo this action, simply press the "Add" button again.
532
533 The first view in the list is the default given to rview during
534 interactive rendering, and is the first view rendered in a batch run.
535 To change the default view, select the newly desired view and press
536 the "Set Default" button.
537 This button also acts like the "Add" button inasmuch as a new view
538 may be entered and this button will add it and make it the default
539 at the same time.
540
541 The Views screen also allows the standard view up vector to be
542 changed, as well as the root picture name and the output resolution.
543
544 .Views.List
545
546 The list box on the far left of the Views screen shows the
547 currently defined view names.
548 Clicking on any of these with the left mouse button shows the view
549 parameters and allows the view to be edited.
550
551 To change the name or options, edit the "Name" or "Options"
552 entry and click on the "Change" button.
553
554 Use the "Add" button to add a new view, which may be modified from
555 an old one by changing the name and options.
556
557 Use the "Delete" button to delete the selected view from the list.
558
559 Views are listed in the order in which they appear in
560 the rad input file.
561
562 The standard view is "X" is used if no views are specified.
563
564 .Views.Name
565
566 Each view has a unique name, which may be chosen at the user's
567 discretion or taken from a list of standard views, described below.
568 An invented name should be kept as short as possible, since it is
569 added to the picture file name along with the standard ".pic" suffix.
570
571 The standard views are specified by strings of the form
572 "[Xx]?[Yy]?[Zz]?[vlahc]?".
573 (That is, an optional upper or lower case X followed by an optional
574 upper or lower case Y followed by an optional upper or lower case Z
575 followed by an optional lower case V, L, A, H or C.)
576 The letters indicate the desired view position, where upper case "X"
577 means maximum X, lower case "y" means minimum Y and so on.
578 The final letter is the view type, where 'v' is perspective (the
579 default), 'l' is parallel, 'a' is angular fisheye, 'h' is
580 hemispherical fisheye and 'c' is for cylindrical panorama.
581 A perspective view from maximum X, minimum Y would be "Xy" or
582 "Xyv".
583 A parallel view from maximum Z would be "Zl".
584 If "ZONE" is an interior zone, the standard views will
585 be inside the perimeter.
586 If it is an exterior zone, the standard views will be outside.
587 Note that the standard views are best used as starting points,
588 and additional arguments may be given after the
589 identifier to modify a standard view to suit a particular model.
590
591 .Views.Options
592
593 The "Options" entry window is where the Radiance view
594 corresponding to the selected name is given.
595 If the view is one of the standard names (described in the "Views
596 Name" section), then the options are truly optional, and will
597 modify the standard view.
598 Otherwise, it is usually necessary to specify a set of options to
599 define a view.
600
601 The simplest view specification is of the form "-vf viewfile", where
602 "viewfile" is a file created with the rview "view" command, or a
603 Radiance picture.
604 This method of naming views, although convenient, is not the best
605 since it is difficult to know exactly where such a view is by
606 seeing only its file name.
607 Also, the file may change or be moved or removed, and then the view
608 may be different than expected or gone altogether.
609
610 To add view options selected from another X11 window, select the
611 text from another window in the normal fashion, use the left mouse
612 button to click on the insertion point in the options string, then
613 use Control-V to insert the text at that point.
614 For convenience, the middle mouse button has been made
615 equivalent to Control-V in this window, but it is not the normal
616 interaction mode for trad.
617
618 Consult the rpict(1) manual page for a full description of the various
619 view options, all of which begin with "-v".
620 Just briefly, the "-vt?" option sets the view type, where "?" is
621 replaced by one of the letters "v, l, a, h or c", corresponding to
622 perspective, parallel, angular fisheye, hemispherical fisheye
623 and cylindrical panorama, respectively.
624 The "-vp x y z" option sets the view position (eyepoint), where "x y z"
625 is replaced by the position in 3-space.
626 The "-vd xd yd zd" option sets the view direction, where "xd yd zd"
627 is a vector pointing in the desired direction.
628 (To compute this direction from a "look-at" point, simply subtract
629 the eyepoint from the look-at point. Vector normalization is
630 unnecessary.)
631 The "-vh horiz" and "-vv vert" options set the horizontal and
632 vertical view sizes, respectively.
633 For perspective views, these correspond to full camera angles in
634 degrees.
635 For parallel views (using the "-vtl" option), they correspond to
636 image plane size in world coordinates.
637 The lesser used "-vu xd yd zd", "-vs vs" and "-vl vl" options
638 will not be discussed here.
639
640 The order of the view options is irrelevant, unless the same option
641 is given twice, in which case the last one is used.
642 Trad does not check the syntax of the view options strings, so be
643 careful!
644 In particular, make sure that each option and each argument has a
645 space between it and whatever follows.
646
647 Hitting return in the "Options" window is equivalent to pressing the
648 "Add" button followed by the "Clear" button.
649
650 .Views.Add
651
652 The view "Add" button takes the currently defined view given by the
653 "Name" and "Options" windows and appends it to the list of views.
654 If another view by the same name exists, it is removed first.
655
656 Since the view is added to the end of the "Views" list, the "Add"
657 button is a convenient way to move views to a lower-priority
658 position.
659 Simply select the view you wish to be last and press "Add".
660
661 To add a view as the first (i.e. the default) view instead of the
662 last, use the "Set Default" button.
663
664 .Views.Change
665
666 The view "Change" button deletes the currently selected view and
667 adds the currently defined view in its place, changing the name
668 and/or view options in the process.
669
670 .Views.Delete
671
672 The view "Delete" button removes the currently selected view from
673 the view list.
674
675 To undo this action, simply press the "Add" button immediately
676 afterwards, while the deleted view is still present in the edit
677 window.
678
679 .Views.Clear
680
681 The "Clear" button simply clears the "Name" and "Options" windows
682 for the convenience of entering a new view.
683 It has no effect on the rad input variables.
684
685 Note that Control-U will always clear an entry box whose cursor is
686 active.
687
688 .Views.Default
689
690 The "Set Default" button may be used to make the selected view the
691 default view for rendering.
692 This simply moves the view to the top of the list in the rad input file.
693 The default view will be the one normally rendered by rview when rad
694 is started interactively, and is the first view rendered in a batch
695 process.
696
697 A new view may be added as the default view by pressing the "Set
698 Default" button rather than the "Add" button.
699 It is never necessary to press both.
700
701 If the selected view is already the default, this button will be
702 disabled and will read "Is Default" instead of "Set Default".
703
704 .Views.Up
705
706 The standard view up vector may be set to the positive X axis (+X),
707 the positive Y axis (+Y), the positive Z axis (+Z), the negative
708 X axis (-X), the negative Y axis (-Y), or the negative Z axis (-Z).
709
710 This setting may always be overriden by the "-vu xd yd zd" option,
711 and will be altered for a particular view if it happens to be
712 parallel to the view direction.
713
714 .Views.Picture
715
716 The root picture file name is given in the "Picture" entry window.
717 To this will be added an underscore, followed by the name of
718 the particular view being rendered, followed by the ".pic" suffix.
719
720 To render pictures into a different directory than the one
721 containing the rad input file, simply precede the file name by a
722 relative or absolute directory.
723 (Do not use the tilde shorthand for home directories,
724 as it is not guaranteed to work on all systems.)
725
726 The default picture name is the root name of the rad input file.
727
728 .Views.Resolution
729
730 The final picture resolution is set in the "Resolution" entry
731 window.
732 The first entry is the X resolution (in pixels), and the second
733 (optional) entry is the Y resolution.
734 If there is only one entry, the maximum X and Y resolution will be
735 equal.
736 If a third entry is given, it is taken as the aspect ratio of the
737 destination pixels.
738 A number greater than one means that the pixels on the destination
739 device are taller than they are wide (and therefore there are more
740 of them horizontally than vertically spanning a like distance), and
741 a number less than one means the opposite.
742 An aspect ratio of zero means that the exact given X and Y
743 dimensions are to be honored, whatever the resulting pixel ratio.
744 Normally, either the X or the Y resolution is reduced as necessary
745 to maintain a specific pixel aspect ratio (1 by default).
746
747 The default value for this variable is "512".
748
749 .Views.Rawfile
750
751 The "Rawfile" entry window determines if and where the raw output picture
752 from rpict will be saved.
753 If the entry is empty, the file will be removed after rendering and
754 filtering.
755 This is the normal action, since the raw file
756 takes up disk space and is not generally useful.
757 However, if you wish to perform some special filtering function,
758 this file can be renamed instead of removed by giving a
759 root file name in this entry window.
760 The final name in this case will be the given root plus and
761 underscore plus the view name followed by a ".pic" suffix.
762
763 In the special case when the raw file name and picture file name are
764 the same, the raw file is saved and no filtering takes place.
765
766 .Views.Zfile
767
768 The "Zfile" entry window gives the root name of the file in which to
769 store the raw (binary floating point) distances to pixels in the
770 original generated image.
771 If this entry is empty, then no z-file will be saved.
772
773 The final z-file name will be the given root plus an underscore plus
774 the view name plus a ".zbf" suffix.
775
776 To convert this image to human-readable form, the program "od" will
777 work on some systems, or the Radiance "pvalue" program may be used
778 to first convert it to a greyscale Radiance picture using the
779 options "-r -h -b -df `getinfo -d < pictname`" where "pictname" is
780 replaced by the raw picture file name.
781 (Getinfo simply gets the original image dimensions, which are not
782 stored in the z-file.)
783
784 .Views.Copy
785
786 The "Copy" button in the Views screen permits those variables
787 represented on this screen to be copied from another rad input file.
788 Specifically, the affected variables are "view, UP, PICTURE, and
789 RESOLUTION".
790
791 The original values will be lost, and all other variables will be
792 untouched.
793
794 .Views.Revert
795
796 The "Revert" button is a convenient way to revert to the original
797 values in the rad input file.
798 Only the variables on the Views screen will be affected, but any changes
799 to these variables since the last save will be lost.
800
801 .Options.Intro
802
803 This button selects the trad Options screen.
804 This screen allows the setting of various options for
805 controlling the rendering process.
806 The most general option is rendering "Quality", which determines the
807 overall accuracy and beauty of the pictures produced.
808 A separate "Penumbras" option indicates the importance of soft
809 shadows in this scene.
810 The "Ambfile" variable allows you to specify a file for sharing
811 ambient files between runs, and it is recommended that you set
812 this variable for high quality renderings.
813 The "Optfile" variable allows you to specify a separate file for
814 storing rendering options, which reduces the size of the command
815 line and makes it easier to run programs such as rtrace(1).
816 The "Report" variable may be used to specify a time interval (in
817 minutes) between progress reports.
818
819 Other windows allow the user to customize the options to oconv(1),
820 mkillum(1), rview(1) and rpict(1), and pfilt(1).
821
822 .Options.Quality
823
824 The "Quality" setting affects the overall accuracy and beauty of the
825 renderings produced.
826
827 A "Low" setting is appropriate for quick checks of scene geometry and
828 crude lighting studies.
829 No interreflection calculation will take place, regardless of the
830 setting of the "INDIRECT" variable, and other options are tuned for
831 speed over accuracy.
832 The computed picture size will exactly equal the final picture
833 size, thus some aliasing may be apparent.
834
835 A "Medium" quality setting is most often used for draft renderings, as
836 it provides a good balance between rendering time and accuracy.
837 The number of interreflections calculated will be equal to the
838 setting of the "INDIRECT" variable.
839 The computed picture size will be twice the final size, for a modest
840 degree of anti-aliasing.
841
842 A "High" quality setting is usually reserved for final renderings.
843 The number of interreflections computed will equal the value of the
844 "INDIRECT" variable plus one, to guarantee accuracy.
845 The computed picture size will be three times the final size, so
846 aliasing artifacts should be negligible.
847
848 When increasing the value of the "Quality" setting, it is usually a
849 good idea to delete the old "Ambfile", if there is one.
850 (See the "AmbDelete" topic under the current help category for
851 details.)
852
853 .Options.Penumbras
854
855 The "Penumbras" setting determines whether or not Radiance will
856 make a special effort to generate soft shadows from area light sources.
857 Since this is a potentially expensive calculation, penumbras should
858 only be switched "On" when they are really needed.
859
860 Leaving this setting "Off" does not mean that area light sources
861 will be treated as points.
862 It only means that some accuracy and possibly some smoothness
863 will be traded for speed in the shadow calculations.
864
865 .Options.Ambfile
866
867 The "Ambfile" is the file used to store Radiance ambient values for
868 later reuse in other renderings.
869 This can greatly reduce the time required to generate multiple
870 views, as well as improve the quality of a single view whenever
871 interreflections are computed.
872
873 It is strongly recommended that the user set this variable, especially
874 when the "QUALITY" variable is set to "High".
875 The usual convention is to use the root name of the rad input file,
876 followed with the ".amb" suffix.
877 It is generally not a good idea to share ambient files between
878 different zones, as the placement and accuracy of these values will
879 vary according to the location and characteristics of each zone.
880
881 .Options.AmbDelete
882
883 The "Delete" button next to the "Ambfile" window on the Options
884 screens allows you to remove the named ambient file.
885 This is usually done when a change to one or more rad variables
886 casts doubt on the accuracy of the values stored in this file.
887 In particular, increases in the variables, "DETAIL, INDIRECT,
888 VARIABILITY, EXPOSURE or QUALITY" generally invalidate this file.
889
890 If the ambient file is not empty, you will be asked to verify this
891 operation since the values may represent a significant computational
892 effort.
893
894 .Options.Optfile
895
896 The "Optfile" setting assigns a file to hold rendering options,
897 which may be a convenience when these options are reused for
898 rtrace(1) or rpiece(1), or manual invocations of rview or rpict.
899 Using an options file also reduces the size of the command line,
900 making it a little easier on the eye.
901
902 To assure that the "Optfile" contents are up-to-date, you should press
903 the "oconv" or "Script" button on the Action screen.
904
905 .Options.Report
906
907 The "Report" setting indicates the time interval (in minutes)
908 between rpict progress reports.
909 Normally, rpict runs silently, but it is often nice to know how far
910 a given rendering has progressed.
911 Normally, progress reports and errors during batch renderings
912 are sent to the error file given by the root of the rad input
913 file name followed by the ".err" suffix.
914 (See the "CheckErr" topic under the "Action" screen category.)
915 If you wish these reports and errors to be directed to a different
916 file, follow the time interval by a space and a file name.
917
918 No setting on this variable means do not report rendering progress.
919 A zero setting means the same thing, and may be used when a
920 separate error file is desired but progress reports are not.
921
922 .Options.Oconv
923
924 The "oconv opts" window may be used to specify any additional
925 options to the oconv(1) command used to compile the scene
926 description.
927
928 In particular, the "-f" option for creating a "frozen" octree may
929 speed rendering start-up substantially, although it makes it
930 impossible to change even material properties without
931 recompiling the scene again.
932 (The "-f" option is technically incompatible with naming
933 "materials" files on the Scene screen.)
934
935 If oconv generates a "set overflow" error, it may mean that the "-r
936 res" option is needed to increase the octree resolution.
937 See the oconv(1) man page for details.
938
939 The "-i octree" option should be used with extreme caution, as incremental
940 building of octrees is not very well supported by rad.
941 You may do it this way if you specify the input octree as one of the
942 "Objects" files on the Scene screen, but it is preferable to use the
943 UNIX make(1) utility to incrementally build the octree instead, and
944 indicate this by not specifying any illum or scene files.
945
946 .Options.Mkillum
947
948 The "mkillum opts" window may be used to specify options to the
949 mkillum(1) command, whose options are actually passed to rtrace(1).
950 These options apply only if there are one or more "Illum" files
951 named on the Scene screen.
952
953 It is very important to set mkillum options sensibly,
954 since rad does not have the intelligence to do it for you.
955
956 .Options.Render
957
958 The "render opts" window is used to specify additional options to
959 the rview(1) and rpict(1) rendering programs.
960 Most of the important parameters are computed by rad, so this
961 window is usually used to override specific parameters or to give
962 additional information, such as which materials to exclude from the
963 interreflection calculation.
964
965 .Options.Pfilt
966
967 The "pfilt opts" window is used to specify additional options to
968 the pfilt(1) picture filtering program.
969
970 Note that the "-e expval", "-x xres" and "-y yres" options are
971 already dictated by the settings of the "EXPOSURE" and "RESOLUTION"
972 variables, and should therefore be used with caution.
973
974 Also note that the setting of some pfilt options require a
975 two-pass filtering process, rather than the default single pass.
976 If no "EXPOSURE" setting is given, this is not a problem, but if a
977 value for the "EXPOSURE" variable is set as recommended, then it is
978 necessary to manually specify the "-2" option to pfilt, followed by
979 an exposure that undoes the "EXPOSURE" setting.
980 An equivalent workaround is to unset the EXPOSURE variable and
981 manually set the render option "-av V V V", where "V" is equal to
982 0.5/old_EXPOSURE.
983
984 .Options.Copy
985
986 The "Copy" button in the Options screen permits those variables
987 represented on this screen to be copied from another rad input file.
988 Specifically, the affected variables are "QUALITY, PENUMBRAS,
989 AMBFILE, OPTFILE, REPORT, oconv, mkillum, render and pfilt".
990
991 The original values will be lost, and all other variables will be
992 untouched.
993
994 .Options.Revert
995
996 The "Revert" button is a convenient way to revert to the original values
997 in the rad input file.
998 Only the variables on the Options screen will be affected, but any changes
999 to these variables since the last save will be lost.
1000
1001 .Action.Intro
1002
1003 This button selects the trad Action screen.
1004 This screen is where the actual Radiance programs are
1005 run, usually via rad(1).
1006 The top row of buttons is used to update the octree following a
1007 change to one or more input files.
1008 The "rview" button starts an interactive rendering in the
1009 foreground.
1010 The next set of buttons provides for the control of a batch
1011 rendering process, taking place in the background.
1012 Finally, the bottom set of buttons allows you to preview what would
1013 happen during a batch rendering, or (equivalently) make a script of
1014 UNIX commands for later execution.
1015
1016 When the Action screen is first brought up, the message window
1017 displays the current status of any batch rendering process.
1018 The status must either be "No batch rendering in progress," which
1019 means that as far as trad can tell a batch rendering was never
1020 started, "Batch rendering stopped," meaning that there is no current
1021 process but at least some views have not been rendered or are
1022 out-of-date, or "Batch rendering finished," meaning that everything
1023 is done.
1024
1025 .Action.Oconv
1026
1027 The "oconv" button on the Action screen may be used to manually
1028 compile the scene description and bring the octree up to date.
1029 It is normally not necessary to use this button, since the octree
1030 will be rebuilt if appropriate prior to rendering.
1031 However, if the octree is maintained by make(1) rather than rad, or
1032 the octree was never created and you want trad to start a little
1033 faster next time, or you just need the octree for some reason other
1034 than rendering, this is the button for you.
1035
1036 If you have made changes to the rad variables or the Radiance
1037 material files that invalidate the current octree or renderings but
1038 would not automatically rebuild the octree because the scene files
1039 themselves were not changed, it may be wise to use the "Force"
1040 button.
1041 In contrast, if you have made some insignificant changes to the
1042 scene files that should not make any difference to the octree or the
1043 renderings, you may want to use the "Touch" button.
1044
1045 Pressing the "oconv" button also updates the contents of the
1046 "Optfile" if one is given on the Options screen.
1047 This may be useful for computing rendering parameters for rtrace(1)
1048 or rpiece(1).
1049
1050 .Action.Force
1051
1052 The "Force" button on the Action screen
1053 causes the octree to be unconditionally rebuilt,
1054 by removing it first.
1055 This will also require all pictures to be rerendered, so only use
1056 this button if it is really necessary, i.e. if you have made
1057 some important changes to the rad
1058 variables on the Scene, Zone or Options screens, but have not
1059 changed any scene file on which the octree depends.
1060
1061 If the octree itself should not be affected by these changes, only
1062 the renderings, you may delete the faulty picture files instead from
1063 the Results screen and the ambient file (if it exists) from the
1064 Options screen.
1065
1066 .Action.Touch
1067
1068 The "Touch" button on the Action screen
1069 should be used when some insignificant change has
1070 been made to the Radiance input files, which might otherwise cause
1071 the octree to be rebuilt and the picture files to be rerendered.
1072
1073 Care should be exercised in using this button since you may have
1074 made a change that really does affect the octree in an important
1075 way.
1076 Even something as seemingly trivial as deleting an unused material
1077 will cause an unfrozen octree to become invalid and unusable.
1078
1079 Therefore, if you know the octree should be rebuilt, but you do not
1080 want to cause any of the currently rendered pictures to be redone,
1081 press the "oconv" button to bring the octree up to date, followed
1082 by the "Touch" button.
1083 (This will still cause the ambient file to be removed,
1084 unfortunately.)
1085
1086 .Action.Rview
1087
1088 The "rview" button on the Action screen starts an interactive
1089 rendering for the selected view, indicated by the menu button
1090 just to the right.
1091 Other views may be accessed within rview using the "L name"
1092 command, and new views can be added with the "V name"
1093 command.
1094
1095 When using the "V" command to change an existing view, do not
1096 give it an existing name because the previous view will not be overridden.
1097 Instead, give it a new name (or no name, which will show up as
1098 a number later), then use the Views screen to override the previous
1099 view definition with the new one.
1100 (See the "View" topic in the current
1101 help category, the "Change" topic under "Views" and the rview(1)
1102 manual page for more information.)
1103
1104 If the octree is out-of-date, it will be rebuilt before rendering
1105 begins.
1106
1107 .Action.View
1108
1109 The Action screen contains two menus for selecting views.
1110 The top menu, next to the "rview" button, sets the view to start
1111 with in rview, and is selected from the current view list.
1112 The second view menu, next to the "Start" button for batch
1113 rendering, selects the view or views to render in batch mode.
1114 If the special entry "ALL" is selected, then every view in the
1115 current list will be rendered if it hasn't been already.
1116
1117 The view menu next to the "rview" button will be disabled if there
1118 is only one view to choose from.
1119 The view menu next to the "Start" button will be disabled if there
1120 is a batch job in progress, and thus the view cannot be changed.
1121
1122 The batch rendering view menu also selects the view or views
1123 to use in producing a script during a dry run.
1124
1125 .Action.Start
1126
1127 The "Start" button for batch rendering on the Action screen
1128 initiates a rad rendering process in the background using the
1129 selected view or views shown on the menu button to the right.
1130
1131 If any of the rad variables have been changed since the
1132 file was last saved, you will first be asked if you wish to save
1133 your changes before starting a background process.
1134 If you discard these changes, then the batch rendering will be
1135 conducted using the previously saved values.
1136
1137 Once a background process is going, the "Start" button is
1138 disabled, and rendering progress can be monitored by checking
1139 the error file periodically.
1140 (This file is named by the root of the rad input file followed by
1141 ".err".)
1142 When a batch process is started or already running, or when a
1143 process is on another host and its status is unknown,
1144 this button will be disabled.
1145
1146 The background process can be killed during this or later
1147 invocations of trad using the "Kill" button.
1148 If the process was started on another machine and the status is unknown,
1149 it will be necessary to run trad from the other host or remove the error
1150 file manually before starting a background process on this machine.
1151 This is to protect you from the great confusion that results when two
1152 machines are working from the same project file.
1153
1154 .Action.Kill
1155
1156 The batch rendering "Kill" button kills the
1157 background process started earlier with the "Start" button.
1158 The rad process id is taken from the first line of the error file,
1159 and this process and all its children are killed when the
1160 button is pressed.
1161
1162 So long as there is an ambient file specified in the Options
1163 screen, no data is lost by killing and restarting a batch
1164 rendering, though some new startup costs will be incurred.
1165
1166 The "Kill" button is disabled if no running batch process is
1167 detected on the current host machine.
1168
1169 .Action.CheckErr
1170
1171 Pressing the "Check errors" button
1172 displays the contents of the batch rendering error file, named
1173 by the root of the current rad input file followed by the ".err"
1174 suffix.
1175 This file will contain the command lines executed by rad so far,
1176 and may or may not contain additional progress reports from
1177 rpict, depending on the initial setting of the "REPORT" variable.
1178
1179 If no error file exists, this button will be disabled.
1180
1181 .Action.Script
1182
1183 The dry run "Script" button runs rad with the
1184 "-n" option so that you may see the commands that would be
1185 executed during a batch run without actually executing them.
1186 If a file is named in the window next to this button, the output
1187 will simply be written to that file.
1188 If no file is named, a temporary file is created and an editor
1189 window is opened on it.
1190
1191 Producing a dry run also writes the "Optfile" if one is specified
1192 on the Options screen.
1193 This may be useful for computing rendering parameters for rtrace(1)
1194 or rpiece(1).
1195
1196 The view or views are selected by the same menu used for
1197 batch rendering.
1198 (See the "View" topic under the current help category for more
1199 information.)
1200
1201 .Action.Edit
1202
1203 The dry run "Edit" button is used to edit the named script file
1204 created by pressing the "Script" button.
1205 If no file is named, this button is ineffective.
1206
1207 .Action.Delete
1208
1209 The "Delete" button removes the named script file, created by the
1210 "Script" button.
1211 If no file is named, or the named file does not exist, this button has
1212 no effect.
1213
1214 .Results.Intro
1215
1216 This button selects the trad Results screen.
1217 This screen permits rendered pictures to be displayed,
1218 converted to other image formats, and printed.
1219 Only finished pictures may be converted or printed, but
1220 incomplete pictures (i.e. aborted renderings or renderings in
1221 progress) may be displayed interactively.
1222
1223 The left-hand window shows a list of completed views, and the
1224 right-hand window shows views that have been started but not
1225 finished.
1226 Note that other views may not even be started, thus may not
1227 appear in either list.
1228 Also, just because a view appears on the Results screen, it does
1229 not mean that view is up-to-date with respect to the Radiance
1230 input files.
1231 (The best way currently to tell which pictures are out-of-date
1232 is to press the "Script" button on the Action screen and examine
1233 the output.)
1234
1235 .Results.Finished
1236
1237 The "Finished views" list box on the Results screen shows those
1238 renderings which have completed, whether or not they are up-to-date
1239 with respect to the Radiance input files.
1240 Select pictures in this box for display, conversion to other image
1241 formats, and/or printing.
1242 Selected pictures may also be deleted with the "Delete" button.
1243
1244 To select one or more pictures from this box, click the left mouse
1245 button on a view name, and drag it up or down to select multiple
1246 views.
1247 Shift-click also allows views to be added to the selection.
1248
1249 .Results.Unfinished
1250
1251 The "Unfinished views" list box on the Results screen shows those
1252 renderings which have not yet completed.
1253 These partial pictures may or may not be out-of-date
1254 with respect to the Radiance input files.
1255 Select pictures in this box for display or deletion.
1256 It is not possible to convert or print an unfinished picture.
1257
1258 To select one or more pictures from this box, click the left mouse
1259 button on a view name, and drag it up or down to select multiple
1260 views.
1261 Shift-click also allows views to be added to the selection.
1262
1263 .Results.Rescan
1264
1265 The "Rescan" button on the Results screen is used to update the
1266 finished and unfinished view lists, in case one or more pictures
1267 has completed since the Results screen was brought up.
1268
1269 .Results.Delete
1270
1271 The "Delete" button on the Results screen is used to remove the
1272 selected picture files from the filesystem.
1273 Associated raw picture and z-buffer files
1274 will also be deleted if they exist.
1275 Verification is required before any action is taken.
1276
1277 .Results.Display
1278
1279 The "Display" button on the Results screen may be used to display
1280 the selected images using ximage(1) or any other Radiance picture
1281 display program.
1282
1283 The current display command is shown in the adjacent command window,
1284 and may be customized if necessary.
1285 (See the "DispCommand" topic in the current help category for
1286 details.)
1287
1288 .Results.DispCommand
1289
1290 The current display command in the Results screen determines how
1291 finished and unfinished Radiance pictures will be displayed.
1292 This command contains two variable fields.
1293 The first field is a signed integer, indicated by the "%+d" format.
1294 The second field is a string, indicated by the "%s" format.
1295 Both fields must appear in any display command used, and must be in
1296 this order on the command line.
1297 The first field is used to adjust the exposure of an unfinished
1298 picture, and the second field is the file name.
1299 The rest of the command is arbitrary, so long as it is understood by
1300 the system.
1301
1302 The default command is "ximage -e %+d %s >& /dev/null &", which
1303 executes ximage in the background and sends any output (including
1304 error messages) to the null device.
1305 If you don't wish ximage to run in the background, you may remove
1306 the last part of the command (" >& /dev/null &").
1307
1308 .Results.Convert
1309
1310 The "Convert" button on the Results screen converts the selected
1311 pictures to the format indicated on the menu button to the right.
1312 (See the "ConvType" topic under the current help category for
1313 details.)
1314
1315 Each finished picture is converted to the selected format and given
1316 the name indicated by the adjacent window labeled "File".
1317 (See the "ConvFile" topic under the current help category for
1318 details.)
1319
1320 .Results.ConvType
1321
1322 The image type button on the Results screen determines the
1323 destination format for converted Radiance pictures.
1324 You may choose from the list that pops up when you press this
1325 button.
1326 Often, a given format may have more than one subtype.
1327 In general, 8-bit means 8-bit color with a lookup table,
1328 B&W means 8-bit greyscale with no lookup, and 24-bit means 24-bit
1329 true color.
1330
1331 The file suffix is determined by the basic conversion type, but may
1332 be changed along with the rest of the name by editing the file name
1333 window.
1334 (See the "ConvFile" topic under the current help category for
1335 details.)
1336
1337 .Results.ConvFile
1338
1339 The image conversion file name window on the Results screen should contain
1340 a single "%s" format field, which will be replaced by the view name
1341 being converted.
1342
1343 The default name is the same as the value of the rad "PICTURE"
1344 variable, followed by a suffix appropriate to the selected file type.
1345
1346 .Results.Print
1347
1348 The "Print" button on the Results screen executes the given
1349 system command to print one copy each of the selected picture(s).
1350 This button does not work on unfinished pictures.
1351
1352 The actual command used for printing may be edited in the adjacent
1353 window.
1354 (See the "PrintCommand" topic under the current help category for
1355 details.)
1356
1357 .Results.PrintCommand
1358
1359 The print command window on the Results screen contains the system
1360 command to use in printing out finished Radiance pictures.
1361 The "%s" format field, which must appear somewhere in the command,
1362 is replaced by the selected Radiance picture file name.
1363 This command is executed multiple times if multiple files are
1364 selected.
1365
1366 The default command is "ra_ps %s | lpr", which converts the Radiance
1367 picture to a black and white PostScript file and sends it to the lpr
1368 print spooler.
1369 Add a "-c" option to "ra_ps" if the printer supports color.
1370 If your printer does not understand PostScript, or your system does
1371 not support lpr, this command must obviously be changed.