	$Id: trad.hlp,v 2.4 1994/11/05 09:31:49 greg Exp $

This help file is associated with the trad interface to the Radiance
rad(1) program.  Trad consists of trad.wsh and one do_*.tcl file for
each screen.  There are currently seven such screens:  Action, File,
Options, Results, Scene, Views and Zone.

.Trad.Intro

Trad is a graphical user interface (GUI) to the
rad(1) program, which controls the operation of the basic
Radiance scene compiling, rendering and picture filtering programs.
Trad also includes links to a few utilities for displaying and
converting results, but most of what it does can be done by editing a
small text file, called the "rad input file".
Scene creation still requires the use of a text or graphical editor,
or translation from some external CAD format.

Trad interaction is broken into seven screens.
Each screen is accessed by pressing its associated radio
button along the right-hand side of the main window.
If trad is started with no file name, the File screen is displayed,
and you must pick a valid rad input file before any other screen may
be accessed.
If a name is given for a file that doesn't exist, trad goes to the
Scene screen and prompts you to enter the names of one or more
Radiance scene description files.
If a rad input file exists already, trad determines if there are
renderings still to be done or if everything is finished.
If there is still work to be done, trad opens first with the Action
screen.
If all renderings are complete and up-to-date, trad opens right to
Results screen.

For additional guidance on Radiance in general, consult the Radiance
Tutorial, Reference Manual, and man pages.
In particular, it is a good idea to read through the rad(1) man page
before using this interface.

To find out how to get more help, press the "Next" button to the
right.

.Trad.Help

If you have specific questions about trad, search through the
category and topic menus on this help window, or press and release
the left mouse button while holding the control key over the object of
curiosity in the main trad window.
(In general, only active windows are given help file links -- click
on these rather than the text labels.)

For help on the help facility itself, Control-click on the problem
help widget or on the window title in the upper right corner for
more general information.
(To get back to trad-specific help, press the "HELP" button in the
main trad window or Control-click on a trad widget.)

Once the help window has been displayed, it is usually best to
lower or iconify it rather than dismissing it if further help is
needed.
This way, you will not have to wait for the help file to be read in
all over again every time you have a question.

.Trad.Messages

Informative messages, commands executed by rad, and errors
appear in the message window at the bottom of the trad frame.
Growing the trad window means growing this message window, and
not much else.
This is not really necessary, since the window will be grown
automatically if the message requires it.

Serious errors will be accompanied by the sounding of the bell.

.Trad.Quit

To quit the trad application, press the "Quit" button at any time.
If you have made changes to the rad input variables, you will be
asked prior to program exit if you want to save your changes first.

Any batch process running in the background will continue to run,
and the associated error messages will be viewable by
trad later when you open the same rad input file.

.File.Intro

This button selects the trad File screen, which allows rad input
files to be loaded and saved, and new files to be created.

.File.Load

This button loads the selected file into trad.
If the current file has been changed and these changes have not been
saved, you will be given first the opportunity to save your changes.

The actual load operation may take several seconds or even minutes,
depending on the status of the rendering process.
This is because the rad program itself is used to interpret the
input file, and if there is no up-to-date octree associated with the
file, it is necessary to run getbbox on the entire scene
before the variable values can be set.
It is possible to eliminate this delay in future loads by going to
the Action screen and running oconv.

If the opened file has read-only mode set (see chmod(1)), then the
"Read Only" check box will be lit.
Unchecking this box means that it will be possible to save the file
later, though the actual mode on the file will not be changed until
it is saved.
Loading a writable file always clears the "Read Only" check box.

If an error is encountered while trying to load the file, a message
will be printed in the box at the bottom.

.File.Save

The "Save" button in the File screen saves any changes to the
current file.
This information is saved in the original file by default, but may
be saved in another file by entering a new name in the "File" field.
If this new file already exists, a dialogue box will ask if you really
want to overwrite it.
If the file name is different than the original
one loaded, the "Read Only" check box will be ignored.

.File.New

The "New" button clears all rad variables in preparation for
writing a new rad input file.
If the file selected already exists, a warning box will ask if you
really want to ignore the previous file contents.
If you agree, then no warning will be given when the file is later
overwritten.

.File.ReadOnly

The "Read Only" check box permits you to indicate that the opened
file should not be overwritten.
This box will be checked automatically if the permissions on the
edited file do not allow writing by the user.
If the box is subsequently unchecked, trad will attempt to change
permissions and write to the file when a save is requested.
If this fails, an error message will indicate the problem.

.Scene.Intro

This button selects the trad Scene screen.
On this screen, you may enter the octree file and the scene files
that go into it, as well as any mkillum or other files on which the
scene depends.
These files are generally produced by hand in a text editor or by
conversion from an external CAD format, such as DXF.
(See the Radiance Reference Manual and Radiance Tutorial for details on the
information contained in these files.)

To enter a file of a particular type, press the corresponding button
to get a dialogue box that allows you to pick existing files from any
directory.

Use the "Discard" button to remove one or more files from a specific
list.
The actual file is untouched.

.Scene.Octree

The "Octree" entry in the Scene screen names the octree file to be
compiled by oconv from the materials and scene files.
(See the oconv(1) man page for more details.)

If make(1) is being used to build the octree, you should leave all
other windows on this screen empty.
The octree can still be rebuilt from trad by pressing the "oconv"
or "Force" buttons on the Action screen, but normally it is
expected to be current.
In particular, an unsupported octree must exist before loading
a rad input file on which it depends.

The default octree name is the root name from the render input file
plus ".oct".
If mkillum is being used (i.e. one or more illum files is given),
then two additional octrees will be created, named the same except
for an additional "0" or "1" immediately before the file suffix
(normally ".oct").

To delete the named octree, and therefore force the scene to be
recompiled and all the pictures to be rerendered, use the "Delete"
button next to the octree window.

.Scene.OctDelete

The "Delete" button next to the octree window removes the named
octree from the filesystem, forcing the scene to be later recompiled
and all the pictures to be rerendered (if desired).
This is appropriate if you add or remove materials, scene or illum
files from one or more lists, or make some change to a materials file
that requires the octree to be rebuilt (such as adding or removing
individual materials).

Verification is required before the octree will be deleted.

You can achieve the same effect as manually removing the octree by
pressing the "Force" button on the scene compilation section
of the Action screen.
(See the "Force" topic under the "Action" help category for more
information.)

.Scene.Materials

Materials files generally contain Radiance material descriptions
only, not geometry.
The purpose of listing them separately is so that minor changes to
material parameters will not force the octree to be rebuilt,
incurring an additional delay that is unnecessary.

The "Materials" button is used to add materials files to the list.
A dialogue box appears when you press this button and allows you to
select files to be included.
Each new selection is added to the end of the materials list.
The default matching pattern for material files is "*.mat".
This may of course be reassigned within the file selection window.

The list box showing the current materials may be edited in three
ways besides the dialogue for adding files.
First, entries may be removed from the list
using the "Discard" button.
Second, entries may be moved within the box by selecting them with
the left mouse button and clicking the middle mouse button over the
entry you wish to place the selected items above.
If you wish to put the selected items at the very end of the list,
click the middle mouse button below the last entry.
Third, entries may be moved from other windows by
selecting them and pressing the middle button.
This works for the list boxes on this screen as well as selections
in other windows on the display.

The order of materials files is usually unimportant, but sometimes
there are definitions in later files that depend on prerequisites in
earlier files.
An example of this is a window illum source that depends on a sky
description file, which must appear before it.
The order of files shown in the list is the order they will be given
to oconv and therefore to the rendering programs.

.Scene.Illum

Illum files are Radiance scene descriptions that contain surfaces
to be converted into illum sources by mkillum(1).
Please consult the manual page for mkillum and understand the
Radiance Tutorial before using this box, since these files differ slightly
from standard Radiance scene descriptions.

The "Illum" button is used to add illum files to the list.
A dialogue box appears when you press this button and allows you to
select files to be included.
Each new selection is added to the end of the illum list.
The default matching pattern for material files is "*.rad".
This may of course be reassigned within the file selection window.

The list box showing the current illum files may be edited in three
ways besides the dialogue for adding files.
First, entries may be removed from the list
using the "Discard" button.
Second, entries may be moved within the box by selecting them with
the left mouse button and clicking the middle mouse button over the
entry you wish to place the selected items above.
If you wish to put the selected items at the very end of the list,
click the middle mouse button below the last entry.
Third, entries may be moved from other windows by
selecting them and pressing the middle button.
This works for the list boxes on this screen as well as selections
in other windows on the display.

.Scene.Scene

Scene files give the geometry and (perhaps) some of the materials
used in a particular Radiance model.
These files are given to oconv(1) in the order specified.
The ordering of files is usually not important, unless some later
files use materials or other modifiers defined in earlier files.

The "Scene" button is used to add scene files to the list.
A dialogue box appears when you press this button and allows you to
select files to be included.
Each new selection is added to the end of the scene list.
The default matching pattern for material files is "*.rad".
This may of course be reassigned within the file selection window.

The list box showing the current scene files may be edited in three
ways besides the dialogue for adding files.
First, entries may be removed from the list
using the "Discard" button.
Second, entries may be moved within the box by selecting them with
the left mouse button and clicking the middle mouse button over the
entry you wish to place the selected items above.
If you wish to put the selected items at the very end of the list,
click the middle mouse button below the last entry.
Third, entries may be moved from other windows by
selecting them and pressing the middle button.
This works for the list boxes on this screen as well as selections
in other windows on the display.

.Scene.Objects

Object files are files on which the given octree depends, but which
are not included directly on the oconv command line.
If any of these files is modified, then it is assumed that the
octree must be rebuilt.

To automatically determine which files in the working directory
affect the octree, press the "Auto" button just below the "Objects"
button.
Note that this will only add files to the object list.
If you wish to completely replace what is already there, you must
therefore select all the files and use the "Discard" button before
pressing "Auto".

.Scene.Discard

The "Discard" button removes the selected file names from a list.
The actual files are untouched, of course.
(Some care should be taken here, since there is no undo
function associated with this window other than reloading the
original information with the "Revert" button.)

.Scene.Edit

Use the "Edit" button to open a text editor on the selected file(s).
This is a convenient way to look at and change the contents of the
Radiance input files.

.Scene.Copy

The "Copy" button may be used to selectively copy the scene file
information from another rad input file.
Specifically, the variables "OCTREE, materials, illum, scene and
objects" will be read in to replace the current values.

All other variables will be unaffected.

.Scene.Revert

The "Revert" button is a convenient way to revert to the original
values in the rad input file.
Only the variables on the Scene screen will be affected, but any changes
to these variables since the last save will be lost.

.Zone.Intro

This button selects the trad Zone screen.
On this screen, the user should enter the maximum and minimum
coordinates of the zone of interest for this set of renderings.
This zone need not correspond exactly to any interior or exterior
walls, as it is used primarily to set rendering parameters and
standard viewpoints.

An interior zone means that standard viewpoints will be selected
from the inside of this box.
An exterior zone means that standard viewpoints will be selected
from the outside of this box.
The default zone is an exterior one computed from the bounding box
of the entire scene.
(Note that this is not usually desirable.)

In addition to the ZONE variable, this screen offers the ability
to set four other rad variables that are generally associated with a
particular scene and a particular zone.
These are the rad DETAIL, INDIRECT, VARIABILITY and EXPOSURE
variables.
For more information on these topics, use the Topic menu or consult
the rad manual page.

.Zone.Type

There are two types of zones understood by rad, "Interior" and
"Exterior".
An interior zone is indicated when renderings generally take place
inside a specified 3-d box.
A typical example might be a single room or auditorium.
An exterior zone is indicated when renderings generally take place
outside a specified 3-d box, which is the focus of attention.
A typical example might be a building exterior or a single object,
such as a chair.

.Zone.Zone

A zone is specified by six real numbers, corresponding to the world
coordinates of the box's corners.
Zone boxes are always axis-aligned, therefore one need only specify
the minimum and maximum X, Y, and Z coordinates.

The exact values of these coordinates is not terribly important, as
they are only used to guide the setting of certain rendering
parameters and standard view positions.
It does not matter for instance whether the values lie on the inside
or the outside of walls, or if there are non-rectilinear geometries
defining the space perimeter.
In fact, the whole space may not even be aligned with the X, Y, and Z
axes, and a very approximate box may be given.
In this case, the standard views may not be very intelligent or
useful, but the rendering parameters will still be satisfactory so
long as the overall size of the given box is close to the overall
size of the space.

The Zone entry windows may be manipulated in the following ways.
Control-U clears the current window.
Control-V pastes the contents of the current selection at the
insertion point.
Return moves the focus to the next window in the chain.

.Zone.Detail

The "Detail" setting indicates the relative level
of geometric detail in this zone.
If the zone is empty except for a few large pieces of furniture, a
"Low" setting is indicated.
(For an exterior zone, low detail would mean that the object is
relatively simple.)
If the zone contains a usual amount of furniture and clutter, a
"Medium" setting is appropriate.
If the zone contains a great many small objects or protrusions, a
setting of "High" is indicated.

This variable is used by rad to set rendering parameters that are
affected by the sizes of objects relative to the overall size of the
space.

.Zone.Indirect

The "Indirect" setting indicates how important indirect illumination
is in this space.
A setting of "0" means that most light falls directly on visible
surfaces, and this setting can be used in most cases.
A setting of "1" means that most objects are not directly
illuminated by light sources, but receive light only after it has
bounced once off some other surface, such as the ceiling.
Likewise, a setting of "2" means that light must reflect twice off
other surfaces before reaching most objects of interest.

Keep in mind that the rendering calculation increases substantially
with each increment to this variable, so it is a good idea to use
the smallest reasonable value.

.Zone.Variability

The "Variability" setting gives a qualitative indication of how
light varies in magnitude over surfaces in this zone.
In a typical direct or indirect lighting situation, this variable
would be set to "Low", indicating that light is fairly uniform
throughout the space.
If there are some areas that are much better lit than others, such
as desks with powerful tasks lights in a room with dimmer ambient
lighting, a "Medium" setting is appropriate.
If there is direct sunlight entering the room, casting bright
patches on some surfaces and not others, then a setting of "High" is
indicated.

Note that this variable speaks to the magnitude of light variations
more than the patterns of light.
It may well be that the light is casting interesting patterns such
as scallops on the walls or something, but as long as the variations
in brightness are less than an order of magnitude or so, it is a low
variability situation.
The high variability
example given above of direct sun entering a space corresponds to a
a variation in brightness of about three orders of magnitude, or
1,000 to 1!

.Zone.Exposure

The "Exposure" setting gives the multiplier between the initial
radiance values at each pixel (in watts/steradian/meter^2) to the
display pixel values (in the range of 0-1, where 0 is black and 1 is
the maximum monitor output).
This setting also determines the average "ambient level," which is
an important parameter for rendering accuracy.

There are two basic ways to compute the exposure value.
The first is by trial and error, where the value is adjusted up and
down within rview using the "e = value" command.
Though it sounds flaky, this is the most reliable way to set the
exposure (and ambient level) in general lighting situations.

The second method is using a zonal cavity approximation.
For this, you must estimate the total light flux entering the zone
from light sources and windows, and the total illuminated area.
(This applies to interior zones, only.  For exterior zones, use the
value suggested by gensky in its output.)
In addition, you must approximate the area-weighted average
reflectance of the illuminated surfaces.
The formula then for the exposure multiplier using this information
is:  pi*tot_area*(1-avg_refl)/(2*tot_flux*avg_refl)
where pi is 3.1416, tot_area is given in square meters and
tot_flux is given in watts.
(Divide total lumens by 179 lumens/watt to get watts.)

The exposure value may either be given as a positive real value, or
as a real value preceeded by a '+' or '-' indicating a positive or
negative number of f-stops (powers of two) from the original value.

If no exposure is given, pfilt will automatically compute the
average for each image, and a default ambient level of 10 will be
used for exterior zones and 0.01 for interior zones.

.Zone.Copy

The "Copy" button on the Zone screen takes all values for this
screen from another rad input file, replacing the current values.
Specifically, the rad variables "ZONE, DETAIL, INDIRECT,
VARIABILITY and EXPOSURE" will be copied from the named file.

All other variables will be left untouched.

.Zone.Revert

The "Revert" button is a convenient way to revert to the original
values in the rad input file.
Only the variables on the Zone screen will be affected, but any changes
to these variables since the last save will be lost.

.Views.Intro

This button selects the trad Views screen.
This screen provides a means of setting the multi-valued
"view" variable.
Each view setting is listed by name, or by number if no name has
been assigned.
To add a new view, enter a unique name and specify the view
options,
then press the "Add" or "Set Default" button.
If a view with the same name already exists, it is unconditionally
overwritten.
To modify a particular view, simply select it, change its name
and/or parameters, and press the "Change" button.
To remove an unwanted view, select it and press the "Delete" button.
To undo this action, simply press the "Add" button again.

The first view in the list is the default given to rview during
interactive rendering, and is the first view rendered in a batch run.
To change the default view, select the newly desired view and press
the "Set Default" button.
This button also acts like the "Add" button inasmuch as a new view
may be entered and this button will add it and make it the default
at the same time.

The Views screen also allows the standard view up vector to be
changed, as well as the root picture name and the output resolution.

.Views.List

The list box on the far left of the Views screen shows the
currently defined view names.
Clicking on any of these with the left mouse button shows the view
parameters and allows the view to be edited.

To change the name or options, edit the "Name" or "Options"
entry and click on the "Change" button.

Use the "Add" button to add a new view, which may be modified from
an old one by changing the name and options.

Use the "Delete" button to delete the selected view from the list.

Views are listed in the order in which they appear in
the rad input file.

The standard view is "X" is used if no views are specified.

.Views.Name

Each view has a unique name, which may be chosen at the user's
discretion or taken from a list of standard views, described below.
An invented name should be kept as short as possible, since it is
added to the picture file name along with the standard ".pic" suffix.

The standard views are specified by strings of the form
"[Xx]?[Yy]?[Zz]?[vlah]?".
(That is, an optional upper or lower case X followed by an optional
upper or lower case Y followed by an optional upper or lower case Z
followed by an optional lower case V, L, A or H.)
The letters indicate the desired view position, where upper case "X"
means maximum X, lower case "y" means minimum Y and so on.
The final letter is the view type, where 'v' is perspective (the
default), 'l' is parallel, 'a' is angular fisheye, and 'h' is
hemispherical fisheye.
A perspective view from maximum X, minimum Y would be "Xy" or
"Xyv".
A parallel view from maximum Z would be "Zl".
If "ZONE" is an interior zone, the standard views will
be inside the perimeter.
If it is an exterior zone, the standard views will be outside.
Note that the standard views are best used as starting points,
and additional arguments may be given after the
identifier to modify a standard view to suit a particular model.

.Views.Options

The "Options" entry window is where the Radiance view
corresponding to the selected name is given.
If the view is one of the standard names (described in the "Views
Name" section), then the options are truly optional, and will
modify the standard view.
Otherwise, it is usually necessary to specify a set of options to
define a view.

The simplest view specification is of the form "-vf viewfile", where
"viewfile" is a file created with the rview "view" command, or a
Radiance picture.
This method of naming views, although convenient, is not the best
since it is difficult to know exactly where such a view is by
seeing only its file name.
Also, the file may change or be moved or removed, and then the view
may be different than expected or gone altogether.

To add view options selected from another X11 window, select the
text from another window in the normal fashion, use the left mouse
button to click on the insertion point in the options string, then
use Control-V to insert the text at that point.
For convenience, the middle mouse button has been made
equivalent to Control-V in this window, but it is not the normal
interaction mode for trad.

Consult the rpict(1) manual page for a full description of the various
view options, all of which begin with "-v".
Just briefly, the "-vt?" option sets the view type, where "?" is
replaced by one of the letters "v, l, a or h", corresponding to
perspective, parallel, angular and hemispherical fisheye, respectively.
The "-vp x y z" option sets the view position (eyepoint), where "x y z"
is replaced by the position in 3-space.
The "-vd xd yd zd" option sets the view direction, where "xd yd zd"
is a vector pointing in the desired direction.
(To compute this direction from a "look-at" point, simply subtract
the eyepoint from the look-at point.  Vector normalization is
unnecessary.)
The "-vh horiz" and "-vv vert" options set the horizontal and
vertical view sizes, respectively.
For perspective views, these correspond to full camera angles in
degrees.
For parallel views (using the "-vtl" option), they correspond to
image plane size in world coordinates.
The lesser used "-vu xd yd zd", "-vs vs" and "-vl vl" options
will not be discussed here.

The order of the view options is irrelevant, unless the same option
is given twice, in which case the last one is used.
Trad does not check the syntax of the view options strings, so be
careful!
In particular, make sure that each option and each argument has a
space between it and whatever follows.

Hitting return in the "Options" window is equivalent to pressing the
"Add" button followed by the "Clear" button.

.Views.Add

The view "Add" button takes the currently defined view given by the
"Name" and "Options" windows and appends it to the list of views.
If another view by the same name exists, it is removed first.

Since the view is added to the end of the "Views" list, the "Add"
button is a convenient way to move views to a lower-priority
position.
Simply select the view you wish to be last and press "Add".

To add a view as the first (i.e. the default) view instead of the
last, use the "Set Default" button.

.Views.Change

The view "Change" button deletes the currently selected view and
adds the currently defined view in its place, changing the name
and/or view options in the process.

.Views.Delete

The view "Delete" button removes the currently selected view from
the view list.

To undo this action, simply press the "Add" button immediately
afterwards, while the deleted view is still present in the edit
window.

.Views.Clear

The "Clear" button simply clears the "Name" and "Options" windows
for the convenience of entering a new view.
It has no effect on the rad input variables.

Note that Control-U will always clear an entry box whose cursor is
active.

.Views.Default

The "Set Default" button may be used to make the selected view the
default view for rendering.
This simply moves the view to the top of the list in the rad input file.
The default view will be the one normally rendered by rview when rad
is started interactively, and is the first view rendered in a batch
process.

A new view may be added as the default view by pressing the "Set
Default" button rather than the "Add" button.
It is never necessary to press both.

If the selected view is already the default, this button will be
disabled and will read "Is Default" instead of "Set Default".

.Views.Up

The standard view up vector may be set to the positive X axis (+X),
the positive Y axis (+Y), the positive Z axis (+Z), the negative
X axis (-X), the negative Y axis (-Y), or the negative Z axis (-Z).

This setting may always be overriden by the "-vu xd yd zd" option,
and will be altered for a particular view if it happens to be
parallel to the view direction.

.Views.Picture

The root picture file name is given in the "Picture" entry window.
To this will be added an underscore, followed by the name of
the particular view being rendered, followed by the ".pic" suffix.

To render pictures into a different directory than the one
containing the rad input file, simply precede the file name by a
relative or absolute directory.
(Do not use the tilde shorthand for home directories,
as it is not guaranteed to work on all systems.)

The default picture name is the root name of the rad input file.

.Views.Resolution

The final picture resolution is set in the "Resolution" entry
window.
The first entry is the X resolution (in pixels), and the second
(optional) entry is the Y resolution.
If there is only one entry, the maximum X and Y resolution will be
equal.
If a third entry is given, it is taken as the aspect ratio of the
destination pixels.
A number greater than one means that the pixels on the destination
device are taller than they are wide (and therefore there are more
of them horizontally than vertically spanning a like distance), and
a number less than one means the opposite.
An aspect ratio of zero means that the exact given X and Y
dimensions are to be honored, whatever the resulting pixel ratio.
Normally, either the X or the Y resolution is reduced as necessary
to maintain a specific pixel aspect ratio (1 by default).

The default value for this variable is "512".

.Views.Copy

The "Copy" button in the Views screen permits those variables
represented on this screen to be copied from another rad input file.
Specifically, the affected variables are "view, UP, PICTURE, and
RESOLUTION".

The original values will be lost, and all other variables will be
untouched.

.Views.Revert

The "Revert" button is a convenient way to revert to the original
values in the rad input file.
Only the variables on the Views screen will be affected, but any changes
to these variables since the last save will be lost.

.Options.Intro

This button selects the trad Options screen.
This screen allows the setting of various options for
controlling the rendering process.
The most general option is rendering "Quality", which determines the
overall accuracy and beauty of the pictures produced.
A separate "Penumbras" option indicates the importance of soft
shadows in this scene.
The "Ambfile" variable allows you to specify a file for sharing
ambient files between runs, and it is recommended that you set
this variable for high quality renderings.
The "Optfile" variable allows you to specify a separate file for
storing rendering options, which reduces the size of the command
line and makes it easier to run programs such as rtrace(1).
The "Report" variable may be used to specify a time interval (in
minutes) between progress reports.

Other windows allow the user to customize the options to oconv(1),
mkillum(1), rview(1) and rpict(1), and pfilt(1).

.Options.Quality

The "Quality" setting affects the overall accuracy and beauty of the
renderings produced.

A "Low" setting is appropriate for quick checks of scene geometry and
crude lighting studies.
No interreflection calculation will take place, regardless of the
setting of the "INDIRECT" variable, and other options are tuned for
speed over accuracy.
The computed picture size will exactly equal the final picture
size, thus some aliasing may be apparent.

A "Medium" quality setting is most often used for draft renderings, as
it provides a good balance between rendering time and accuracy.
The number of interreflections calculated will be equal to the
setting of the "INDIRECT" variable.
The computed picture size will be twice the final size, for a modest
degree of anti-aliasing.

A "High" quality setting is usually reserved for final renderings.
The number of interreflections computed will equal the value of the
"INDIRECT" variable plus one, to guarantee accuracy.
The computed picture size will be three times the final size, so
aliasing artifacts should be negligible.

When increasing the value of the "Quality" setting, it is usually a
good idea to delete the old "Ambfile", if there is one.
(See the "AmbDelete" topic under the current help category for
details.)

.Options.Penumbras

The "Penumbras" setting determines whether or not Radiance will
make a special effort to generate soft shadows from area light sources.
Since this is a potentially expensive calculation, penumbras should
only be switched "On" when they are really needed.

Leaving this setting "Off" does not mean that area light sources
will be treated as points.
It only means that some accuracy and possibly some smoothness
will be traded for speed in the shadow calculations.

.Options.Ambfile

The "Ambfile" is the file used to store Radiance ambient values for
later reuse in other renderings.
This can greatly reduce the time required to generate multiple
views, as well as improve the quality of a single view whenever
interreflections are computed.

It is strongly recommended that the user set this variable, especially
when the "QUALITY" variable is set to "High".
The usual convention is to use the root name of the rad input file,
followed with the ".amb" suffix.
It is generally not a good idea to share ambient files between
different zones, as the placement and accuracy of these values will
vary according to the location and characteristics of each zone.

.Options.AmbDelete

The "Delete" button next to the "Ambfile" window on the Options
screens allows you to remove the named ambient file.
This is usually done when a change to one or more rad variables
casts doubt on the accuracy of the values stored in this file.
In particular, increases in the variables, "DETAIL, INDIRECT,
VARIABILITY, EXPOSURE or QUALITY" generally invalidate this file.

If the ambient file is not empty, you will be asked to verify this
operation since the values may represent a significant computational
effort.

.Options.Optfile

The "Optfile" setting assigns a file to hold rendering options,
which may be a convenience when these options are reused for
rtrace(1) or rpiece(1), or manual invocations of rview or rpict.
Using an options file also reduces the size of the command line,
making it a little easier on the eye.

To assure that the "Optfile" contents are up-to-date, you should press
the "oconv" or "Script" button on the Action screen.

.Options.Report

The "Report" setting indicates the time interval (in minutes)
between rpict progress reports.
Normally, rpict runs silently, but it is often nice to know how far
a given rendering has progressed.
Normally, progress reports and errors during batch renderings
are sent to the error file given by the root of the rad input
file name followed by the ".err" suffix.
(See the "Errors" topic under the "Action" screen category.)
If you wish these reports and errors to be directed to a different
file, follow the time interval by a space and a file name.

No setting on this variable means do not report rendering progress.
A zero setting means the same thing, and may be used when a
separate error file is desired but progress reports are not.

.Options.Oconv

The "oconv opts" window may be used to specify any additional
options to the oconv(1) command used to compile the scene
description.

In particular, the "-f" option for creating a "frozen" octree may
speed rendering start-up substantially, although it makes it
impossible to change even material properties without
recompiling the scene again.
(The "-f" option is technically incompatible with naming
"materials" files on the Scene screen.)

If oconv generates a "set overflow" error, it may mean that the "-r
res" option is needed to increase the octree resolution.
See the oconv(1) man page for details.

The "-i octree" option should be used with extreme caution, as incremental
building of octrees is not very well supported by rad.
You may do it this way if you specify the input octree as one of the
"Objects" files on the Scene screen, but it is preferable to use the
UNIX make(1) utility to incrementally build the octree instead, and
indicate this by not specifying any illum or scene files.

.Options.Mkillum

The "mkillum opts" window may be used to specify options to the
mkillum(1) command, whose options are actually passed to rtrace(1).
These options apply only if there are one or more "Illum" files
named on the Scene screen.

It is very important to set mkillum options sensibly,
since rad does not have the intelligence to do it for you.

.Options.Render

The "render opts" window is used to specify additional options to
the rview(1) and rpict(1) rendering programs.
Most of the important parameters are computed by rad, so this
window is usually used to override specific parameters or to give
additional information, such as which materials to exclude from the
interreflection calculation.

.Options.Pfilt

The "pfilt opts" window is used to specify additional options to
the pfilt(1) picture filtering program.

Note that the "-e expval", "-x xres" and "-y yres" options are
already dictated by the settings of the "EXPOSURE" and "RESOLUTION"
variables, and should therefore be used with caution.

Also note that the setting of some pfilt options require a
two-pass filtering process, rather than the default single pass.
If no "EXPOSURE" setting is given, this is not a problem, but if a
value for the "EXPOSURE" variable is set as recommended, then it is
necessary to manually specify the "-2" option to pfilt, followed by
an exposure that undoes the "EXPOSURE" setting.
An equivalent workaround is to unset the EXPOSURE variable and
manually set the render option "-av V V V", where "V" is equal to
0.5/old_EXPOSURE.

.Options.Copy

The "Copy" button in the Options screen permits those variables
represented on this screen to be copied from another rad input file.
Specifically, the affected variables are "QUALITY, PENUMBRAS,
AMBFILE, OPTFILE, REPORT, oconv, mkillum, render and pfilt".

The original values will be lost, and all other variables will be
untouched.

.Options.Revert

The "Revert" button is a convenient way to revert to the original values
in the rad input file.
Only the variables on the Options screen will be affected, but any changes
to these variables since the last save will be lost.

.Action.Intro

This button selects the trad Action screen.
This screen is where the actual Radiance programs are
run, usually via rad(1).
The top row of buttons is used to update the octree following a
change to one or more input files.
The "rview" button starts an interactive rendering in the
foreground.
The next set of buttons provides for the control of a batch
rendering process, taking place in the background.
Finally, the bottom set of buttons allows you to preview what would
happen during a batch rendering, or (equivalently) make a script of
UNIX commands for later execution.

When the Action screen is first brought up, the message window
displays the current status of any batch rendering process.
The status must either be "No batch rendering in progress," which
means that as far as trad can tell a batch rendering was never
started, "Batch rendering stopped," meaning that there is no current
process but at least some views have not been rendered or are
out-of-date, or "Batch rendering finished," meaning that everything
is done.

.Action.Oconv

The "oconv" button on the Action screen may be used to manually
compile the scene description and bring the octree up to date.
It is normally not necessary to use this button, since the octree
will be rebuilt if appropriate prior to rendering.
However, if the octree is maintained by make(1) rather than rad, or
the octree was never created and you want trad to start a little
faster next time, or you just need the octree for some reason other
than rendering, this is the button for you.

If you have made changes to the rad variables or the Radiance
material files that invalidate the current octree or renderings but
would not automatically rebuild the octree because the scene files
themselves were not changed, it may be wise to use the "Force"
button.
In contrast, if you have made some insignificant changes to the
scene files that should not make any difference to the octree or the
renderings, you may want to use the "Touch" button.

Pressing the "oconv" button also updates the contents of the
"Optfile" if one is given on the Options screen.
This may be useful for computing rendering parameters for rtrace(1)
or rpiece(1).

.Action.Force

The "Force" button on the Action screen
causes the octree to be unconditionally rebuilt,
by removing it first.
This will also require all pictures to be rerendered, so only use
this button if it is really necessary, i.e. if you have made
some important changes to the rad
variables on the Scene, Zone or Options screens, but have not
changed any scene file on which the octree depends.

If the octree itself should not be affected by these changes, only
the renderings, you may delete the faulty picture files instead from
the Results screen and the ambient file (if it exists) from the
Options screen.

.Action.Touch

The "Touch" button on the Action screen
should be used when some insignificant change has
been made to the Radiance input files, which might otherwise cause
the octree to be rebuilt and the picture files to be rerendered.

Care should be exercised in using this button since you may have
made a change that really does affect the octree in an important
way.
Even something as seemingly trivial as deleting an unused material
will cause an unfrozen octree to become invalid and unusable.

Therefore, if you know the octree should be rebuilt, but you do not
want to cause any of the currently rendered pictures to be redone,
press the "oconv" button to bring the octree up to date, followed
by the "Touch" button.
(This will still cause the ambient file to be removed,
unfortunately.)

.Action.Rview

The "rview" button on the Action screen starts an interactive
rendering for the selected view, indicated by the menu button
just to the right.
Other views may be accessed within rview using the "L name"
command, and new views can be added with the "V name"
command.
(See the rview(1) man page and the "View" topic in the current
help category for more information.)

If the octree is out-of-date, it will be rebuilt before rendering
begins.

.Action.View

The Action screen contains two menus for selecting views.
The top menu, next to the "rview" button, sets the view to start
with in rview, and is selected from the current view list.
The second view menu, next to the "Start" button for batch
rendering, selects the view or views to render in batch mode.
If the special entry "ALL" is selected, then every view in the
current list will be rendered if it hasn't been already.

The batch rendering view menu also selects the view or views
to use in producing a script during a dry run.

.Action.Start

The "Start" button for batch rendering on the Action screen
initiates a rad rendering process in the background using the
selected view or views shown on the menu button to the right.

If any of the rad variables have been changed since the
file was last saved, you will first be asked if you wish to save
your changes before starting a background process.
If you discard these changes, then the batch rendering will be
conducted using the previously saved values.

Once a background process is going, the "Start" button is
disabled, and rendering progress can be monitored by checking
the error file periodically.
(This file is named by the root of the rad input file followed by
".err".)
When a batch process is started or already running, this button
will be disabled.

The background process can be killed during this or later
invocations of trad using the "Kill" button.

.Action.Kill

The batch rendering "Kill" button kills the
background process started earlier with the "Start" button.
The rad process id is taken from the first line of the error file,
and this process and all its children are killed when the
button is pressed.

So long as there is an ambient file specified in the Options
screen, no data is lost by killing and restarting a batch
rendering, though some new startup costs will be incurred.

The "Kill" button is disabled if no running batch process is
detected.

.Action.CheckErr

Pressing the "Check errors" button
displays the contents of the batch rendering error file, named
by the root of the current rad input file followed by the ".err"
suffix.
This file will contain the command lines executed by rad so far,
and may or may not contain additional progress reports from
rpict, depending on the initial setting of the "REPORT" variable.

If no error file exists, this button will be disabled.

.Action.Script

The dry run "Script" button runs rad with the
"-n" option so that you may see the commands that would be
executed during a batch run without actually executing them.
If a file is named in the window next to this button, the output
will simply be written to that file.
If no file is named, a temporary file is created and an editor
window is opened on it.

Producing a dry run also writes the "Optfile" if one is specified
on the Options screen.
This may be useful for computing rendering parameters for rtrace(1)
or rpiece(1).

The view or views are selected by the same menu used for
batch rendering.
(See the "View" topic under the current help category for more
information.)

.Action.Edit

The dry run "Edit" button is used to edit the named script file
created by pressing the "Script" button.
If no file is named, this button is ineffective.

.Action.Delete

The "Delete" button removes the named script file, created by the
"Script" button.
If no file is named, or the named file does not exist, this button has
no effect.

.Results.Intro

This button selects the trad Results screen.
This screen permits rendered pictures to be displayed,
converted to other image formats, and printed.
Only finished pictures may be converted or printed, but
incomplete pictures (i.e. aborted renderings or renderings in
progress) may be displayed interactively.

The left-hand window shows a list of completed views, and the
right-hand window shows views that have been started but not
finished.
Note that other views may not even be started, thus may not
appear in either list.
Also, just because a view appears on the Results screen, it does
not mean that view is up-to-date with respect to the Radiance
input files.
(The best way currently to tell which pictures are out-of-date
is to press the "Script" button on the Action screen and examine
the output.)

.Results.Finished

The "Finished views" list box on the Results screen shows those
renderings which have completed, whether or not they are up-to-date
with respect to the Radiance input files.
Select pictures in this box for display, conversion to other image
formats, and/or printing.
Selected pictures may also be deleted with the "Delete" button.

To select one or more pictures from this box, click the left mouse
button on a view name, and drag it up or down to select multiple
views.
Shift-click also allows views to be added to the selection.

.Results.Unfinished

The "Unfinished views" list box on the Results screen shows those
renderings which have not yet completed.
These partial pictures may or may not be out-of-date
with respect to the Radiance input files.
Select pictures in this box for display or deletion.
It is not possible to convert or print an unfinished picture.

To select one or more pictures from this box, click the left mouse
button on a view name, and drag it up or down to select multiple
views.
Shift-click also allows views to be added to the selection.

.Results.Rescan

The "Rescan" button on the Results screen is used to update the
finished and unfinished view lists, in case one or more pictures
has completed since the Results screen was brought up.

.Results.Delete

The "Delete" button on the Results screen is used to remove the
selected picture files from the filesystem.
Verification is required before any action is taken.

.Results.Display

The "Display" button on the Results screen may be used to display
the selected images using ximage(1) or any other Radiance picture
display program.

The current display command is shown in the adjacent command window,
and may be customized if necessary.
(See the "DispCommand" topic in the current help category for
details.)

.Results.DispCommand

The current display command in the Results screen determines how
finished and unfinished Radiance pictures will be displayed.
This command contains two variable fields.
The first field is a signed integer, indicated by the "%+d" format.
The second field is a string, indicated by the "%s" format.
Both fields must appear in any display command used, and must be in
this order on the command line.
The first field is used to adjust the exposure of an unfinished
picture, and the second field is the file name.
The rest of the command is arbitrary, so long as it is understood by
the system.

The default command is "ximage -e %+d %s >& /dev/null &", which
executes ximage in the background and sends any output (including
error messages) to the null device.
If you don't wish ximage to run in the background, you may remove
the last part of the command (" >& /dev/null &").

.Results.Convert

The "Convert" button on the Results screen converts the selected
pictures to the format indicated on the menu button to the right.
(See the "ConvType" topic under the current help category for
details.)

Each finished picture is converted to the selected format and given
the name indicated by the adjacent window labeled "File".
(See the "ConvFile" topic under the current help category for
details.)

.Results.ConvType

The image type button on the Results screen determines the
destination format for converted Radiance pictures.
You may choose from the list that pops up when you press this
button.
Often, a given format may have more than one subtype.
In general, 8-bit means 8-bit color with a lookup table,
B&W means 8-bit greyscale with no lookup, and 24-bit means 24-bit
true color.

The file suffix is determined by the basic conversion type, but may
be changed along with the rest of the name by editing the file name
window.
(See the "ConvFile" topic under the current help category for
details.)

.Results.ConvFile

The image conversion file name window on the Results screen should contain
a single "%s" format field, which will be replaced by the view name
being converted.

The default name is the same as the value of the rad "PICTURE"
variable, followed by a suffix appropriate to the selected file type.

.Results.Print

The "Print" button on the Results screen executes the given
system command to print one copy each of the selected picture(s).
This button does not work on unfinished pictures.

The actual command used for printing may be edited in the adjacent
window.
(See the "PrintCommand" topic under the current help category for
details.)

.Results.PrintCommand

The print command window on the Results screen contains the system
command to use in printing out finished Radiance pictures.
The "%s" format field, which must appear somewhere in the command,
is replaced by the selected Radiance picture file name(s).

The default command is "ra_ps %s | lpr", which converts the Radiance
picture to a black and white PostScript file and sends it to the lpr
print spooler.
If your printer does not understand PostScript, or your system does
not support lpr, this command must obviously be changed.
