$Id: trad.hlp,v 2.18 1998/10/20 11:52:15 gwlarson 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: File, Scene, Zone, Views, Options, Action and Results. .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.) Additional search capabilities are available over all topics using the "Grep" button. 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.) .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-V pastes the contents of the current selection at the insertion point. Return moves the focus to the next window in the chain. The "Auto" button may be used to set these values based on the bounding box of one or more Radiance scene files. .Zone.Auto Use this button to automatically determine the bounding box for this zone, based on the output of the "getbbox" command run on one or more Radiance scene files. The appropriate scene files are entered via a file selection dialogue box, which comes up after the button is pressed. The reason for selecting specific files rather than running getbbox on the entire scene is that a zone usually does not include large external objects, which may be present in the complete scene description. .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 preceded 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]?[vlahc]?". (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, H or C.) 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, 'h' is hemispherical fisheye and 'c' is for cylindrical panorama. 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, h or c", corresponding to perspective, parallel, angular fisheye, hemispherical fisheye and cylindrical panorama, 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. .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 overridden 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.Eyesep The eye separation is used for generating stereo views of the scene. It is the measured distance between a viewer's pupils in world coordinate units. It is not used directly by rad, but should be set for other programs that need it, such as rholo and glrad. .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.Rawfile The "Rawfile" entry window determines if and where the raw output picture from rpict will be saved. If the entry is empty, the file will be removed after rendering and filtering. This is the normal action, since the raw file takes up disk space and is not generally useful. However, if you wish to perform some special filtering function, this file can be renamed instead of removed by giving a root file name in this entry window. The final name in this case will be the given root plus and underscore plus the view name followed by a ".pic" suffix. In the special case when the raw file name and picture file name are the same, the raw file is saved and no filtering takes place. .Views.Zfile The "Zfile" entry window gives the root name of the file in which to store the raw (binary floating point) distances to pixels in the original generated image. If this entry is empty, then no z-file will be saved. The final z-file name will be the given root plus an underscore plus the view name plus a ".zbf" suffix. To convert this image to human-readable form, the program "od" will work on some systems, or the Radiance "pvalue" program may be used to first convert it to a greyscale Radiance picture using the options "-r -h -b -df `getinfo -d < pictname`" where "pictname" is replaced by the raw picture file name. (Getinfo simply gets the original image dimensions, which are not stored in the z-file.) .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 "CheckErr" 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. When using the "V" command to change an existing view, do not give it an existing name because the previous view will not be overridden. Instead, give it a new name (or no name, which will show up as a number later), then use the Views screen to override the previous view definition with the new one. (See the "View" topic in the current help category, the "Change" topic under "Views" and the rview(1) manual page 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 view menu next to the "rview" button will be disabled if there is only one view to choose from. The view menu next to the "Start" button will be disabled if there is a batch job in progress, and thus the view cannot be changed. 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, or when a process is on another host and its status is unknown, this button will be disabled. The background process can be killed during this or later invocations of trad using the "Kill" button. If the process was started on another machine and the status is unknown, it will be necessary to run trad from the other host or remove the error file manually before starting a background process on this machine. This is to protect you from the great confusion that results when two machines are working from the same project file. .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 on the current host machine. .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. Associated raw picture and z-buffer files will also be deleted if they exist. 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. This command is executed multiple times if multiple files are selected. 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. Add a "-c" option to "ra_ps" if the printer supports color. If your printer does not understand PostScript, or your system does not support lpr, this command must obviously be changed.