RAD(1)

NAME
rad - render a RADIANCE scene

SYNOPSIS
rad [ -s ][ -n | -N npr ][ -t ][ -e ][ -V ][ -w ][ -v view ][ -o device ] rfile [ VAR=value .. ]

DESCRIPTION
Rad is an executive program that reads the given rfile and makes appropriate calls to oconv(1), mkillum(1), rpict(1), pfilt(1), and/or rvu(1) to render a specific scene. Variables in rfile give input files and qualitative information about the rendering(s) desired that together enable rad to intelligently set parameter values and control the simulation.

Normally, commands are echoed to the standard output as they are executed. The -s option tells rad to do its work silently. The -n option tells rad not to take any action (ie. not to actually execute any commands). The -N option instructs rad to run as many as npr rendering processes in parallel. The -t option tells rad to bring rendering files up to date relative to the input (scene description) files, without performing any actual calculations. If no octree exists, it is still necessary to run oconv(1) to create one, since the -t option will not create invalid (i.e. empty) files, and a valid octree is necessary for the correct operation of rad. The -e option tells rad to explicate all variables used for the simulation, including default values not specified in the input file, and print them on the standard output.

Normally, rad will produce one picture for each view given in rfile. The -v option may be used to specify a single desired view. The view argument may either be a complete view specification (enclosed in quotes and beginning with an optional identifier) or a number or single-word identifier to match a view defined in rfile. If the argument is one of the standard view identifiers, it may or may not be further elaborated in rfile. (See "view" variable description, below.) If the argument does not match any views in rfile and is not one of the standard views, no rendering will take place. This may be convenient when the only action desired of rad is the rebuilding of the octree. In particular, the argument "0" will never match a view.

If the -V option is given, each view will be printed on the standard output before being applied, in a form suitable for use in a view file or rpict rendering sequence. This is helpful as feedback or for accessing the rad view assignments without necessarily starting a rendering.

By default, rad will run rpict and pfilt to produce a picture for each view. The -o option specifies an output device for rvu (usually "x11") and runs this interactive program instead, using the first view in rfile or the view given with the -v option as the starting point.

Additional variable settings may be added or overridden on the command line following rfile. Upper case variables specified more than once will result in a warning message (unless the -w option is present), and the last value given will be the one used.

The -w option turns off warnings about multiply and misassigned variables.

Rendering variable assignments appear one per line in rfile. The name of the variable is followed by an equals sign ('=') and its value(s). The end of line may be escaped with a backslash ('\'), though it is not usually necessary since additional variable values may be given in multiple assignments. Variables that should have only one value are given in upper case. Variables that may have multiple values are given in lower case. Variables may be abbreviated by their first three letters. Comments in rfile start with a pound sign ('#') and proceed to the end of line.

The rendering variables, their interpretations and default values are given below.

OCTREE
    The name of the octree file. The default name is the same as rfile but with any suffix replaced by ".oct". (The octree must be a file -- rad cannot work with commands that produce octrees.)

ZONE
    This variable specifies the volume of interest for this simulation. The first word is either "Interior" or "Exterior", depending on whether the zone is to be observed from the inside or the outside, respectively. (A single letter may be given, and case does not matter.) The following six numbers are the minimum and maximum X coordinates, minimum and maximum Y, and minimum and maximum Z for the zone perimeter. It is important to give the zone as it is used to determine many of the rendering parameters. The default exterior zone is the bounding cube for the scene as computed by oconv.

EXPOSURE
    This variable tells rad how to adjust the exposure for display. It is important to set this variable properly as it is used to determine the ambient value. An appropriate setting may be discovered by running rvu and noting the exposure given by the "exposure =" command. As in rvu and pfilt, the exposure setting may be given either as a multiplier or as a number of f-stop adjustments (eg. +2 or -1.5). There is no default value for this variable. If it is not given, an average level will be computed by pfilt and the ambient value will be set to 10 for exterior zones and 0.01 for interior zones.

EYESEP
    The interocular spacing for stereo viewing. I.e., the world distance between the pupils of the left and right eyes. The default value is the sum of the three "ZONE" dimensions divided by 100.

scene
    This variable is used to specify one or more scene input files. These files will be given together with the materials file(s) and any options specified by the "oconv" variable to oconv to produce the octree given by the "OCTREE" variable. In-line commands may be specified in quotes instead of a file, beginning with an exclamation mark ('!'). If the "scene" variable is not present, then the octree must already exist in order for rad to work. Even if this variable is given, oconv will not be run unless the octree is out of date with respect to the input files. Note that the order of files in this variable is important for oconv to work properly, and files given in later variable assignments will appear after previous ones on the oconv command line.

materials
    This variable is used to specify files that, although they must appear on the oconv command line, do not affect the actual octree itself. Keeping the materials in separate files allows them to be modified without requiring the octree to be rebuilt (a sometimes costly procedure). These files should not contain any geometry, and the -f option must not be given in the "oconv" variable for this to work.

illum
    This variable is used to specify files with surfaces to be converted into illum sources by mkillum(1). When this variable is given, additional octree files will be created to contain the scene before and after illum source conversion. These files will be named according to the (default) value of the OCTREEE variable, with either a '0' or a '1' appearing just before the file type suffix (usually ".oct").

objects
    This variable is used for files that, although they do not appear on the oconv command line, contain geometric information that is referenced indirectly by the scene files. If any of these files is changed, the octree will be rebuilt. (The raddepend(1) command may be used to find these dependencies automatically.)

view
    This variable is used to specify a desired view for this zone. Any number of "view" lines may be given, and each will result in a rendered picture (unless the -v or -o option is specified). The value for this variable is an optional identifier followed by any number of view options (see rpict(1) for a complete listing). The identifier is used in file naming and associating a desired view with the -v command line option. Also, there are several standard view identifiers defined by rad. These standard views are specified by strings of the form "[Xx]?[Yy]?[Zz]?[vlcahs]?". (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, C, A or H.) The letters indicate the desired view position, where upper case X means maximum X, lower case means minimum and so on. The final letter is the view type, where 'v' is perspective (the default), 'l' is parallel, 'c' is a cylindrical panorama, is a planisphere (stereographic) 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. The default view is "X" if no views are specified. A single specified view of "0" means no views will be automatically generated.

UP  The vertical axis for this scene. A negative axis may be specified with a minus sign (eg. "-Y"). There is no default value for this variable, although the standard views assume Z is up if no other axis is specified.

RESOLUTION
    This variable specifies the desired final picture resolution. If only a single number is given, this value will be used for both the horizontal and vertical picture dimensions. If two numbers are given, the first is the horizontal resolution and the second is the vertical resolution. If three numbers are given, the third is taken as the pixel aspect ratio for the final picture (a real value). If the pixel aspect ratio is zero, the exact dimensions given will be those produced. Otherwise, they will be used as a frame in which the final image must fit. The default value for this variable is 512.

QUALITY
    This variable sets the overall rendering quality desired. It can have one of three values, "LOW", "MEDIUM" or "HIGH". These may be abbreviated by their first letter, and may be in upper or lower case. Most of the rendering options will be affected by this setting. The default value is "L".

PENUMBRAS
    This is a boolean variable indicating whether or not penumbras are desired. A value of "TRUE" will result in penumbras (soft shadows), and a value of "FALSE" will result in no penumbras (sharp shadows). True and false may be written in upper or lower case, and may be abbreviated by a single letter. Renderings generally proceed much faster without penumbras. The default value is "F".

INDIRECT
    This variable indicates how many diffuse reflections are important in the general lighting of this zone. A direct lighting system (eg. fluorescent troffers recessed in the ceiling) corresponds to an indirect level of 0. An indirect lighting system (eg. hanging fluorescents directed at a reflective ceiling) corresponds to an indirect level of 1. A diffuse light shelf reflecting sunlight onto the ceiling would correspond to an indirect level of 2. The setting of this variable partially determines how many interreflections will be calculated. The default value is 0.

PICTURE
    This is the root name of the output picture file(s). This name will have appended the view identifier (or a number if no id was used) and a ".hdr" suffix. If a picture corresponding to a specific view exists and is not out of date with respect to the given octree, it will not be re-rendered. The default value for this variable is the root portion of rfile.

RAWFILE
    This is the root name of the finished, raw rpict output file. If specified, rad will rename the original rpict output file once it is finished and filtered rather than removing it, which is the default action. The given root name will be expanded in the same way as the "PICTURE" variable, and if the "RAWFILE" and "PICTURE" variables are identical, then no filtering will take place.

ZFILE
    This is the root name of the raw distance file produced by the -z option of rpict. To this root name, an underscore plus the view name plus a ".zbf" suffix will be added. If no "ZFILE" is specified, none will be produced.

AMBFILE
    This is the name of the file where "ambient" or diffuse interreflection values will be stored by rpict or rvu. Although it is not required, an ambient file should be given whenever an interreflection calculation is expected. This will optimize successive runs and minimize artifacts. An interreflection calculation will take place when the "QUALITY" variable is set to HIGH, or when the "QUALITY" variable is set to MEDIUM and "INDIRECT" is positive. There is no default value for this variable.

DETAIL
    This variable specifies the level of visual detail in this zone, and is used to determine image sampling rate, among other things. If there are few surfaces and simple shading, then this should be set to LOW. For a zone with some furniture it might be set to MEDIUM. If the space is very cluttered or contains a lot of geometric detail and textures, then it should be set to HIGH. The default value is "M".

VARIABILITY
    This variable tells rad how much light varies over the surfaces of this zone, and is used to determine what level of sampling is necessary in the indirect calculation. For an electric lighting system with uniform coverage, the value should be set to LOW. For a space with spot lighting or a window with sky illumination only, it might be set to MEDIUM. For a space with penetrating sunlight casting bright patches in a few places, it should be set to HIGH. The default value is "L".

PGMAP
    This variable designates a global photon map to be generated by mkpmap(1) and used to accelerate rendering. The file name must be followed by the number of photons to be stored in the map, and this number may be followed by a bandwidth for rendering. There is no default value, meaning that a global photon map will not normally be created.

PCMAP
    This variable designates a caustic photon map to be generated by mkpmap(1) and used during renderings to model light transmission by reflecting and refracting surfaces. The file name must be followed by the number of photons to be stored in the map, and this number may be followed by a bandwidth for rendering. There is no default value, meaning that a caustic photon map will not normally be created.

OPTFILE
    This is the name of a file in which rad will place the appropriate rendering options. This file can later be accessed by rpict or rvu in subsequent manual runs using the at-sign ('@') file insert option. (Using an "OPTFILE" also reduces the length of the rendering command, which improves appearance and may even be necessary on some systems.) There is no default value for this variable.

REPORT
    This variable may be used to specify a reporting interval for batch rendering. Given in minutes, this value is multiplied by 60 and passed to rpict with the -t option. If a filename is given after the interval, it will be used as the error file for reports and error messages instead of the standard error. (See the -e option of rpict(1). There is no default value for this variable.

oconv
    This variable may be used to specify special options to oconv. If the first word of the first instance of this variable is not an option, it will be used in place of the default command path, "oconv". See the oconv(1) manual page for a list of valid options.

mkillum
    This variable may be used to specify additional options to mkillum. If the first word of the first instance of this variable is not an option, it will be used in place of the default command path, "mkillum". See the rtrace(1) manual page for a list of valid options.

mkpmap
    This variable may be used to specify additional options to mkpmap. If the first word of the first instance of this variable is not an option, it will be used in place of the default command path, "mkpmap". See the mkpmap(1) manual page for a list of valid options.

render
    This variable may be used to specify additional options to rpict or rvu. These options will appear after the options set automatically by rad, and thus will override the default values.

rpict
    This variable may be used to specify overriding options specific to rpict. If the first word of the first instance of this variable is not an option, it will be used in place of the default command path, "rpict". See the rpict(1) man page for a list of valid options.

rvu This variable may be used to specify overriding options specific to rvu. If the first word of the first instance of this variable is not an option, it will be used in place of the default command path, "rvu". See the rvu(1) man page for a list of valid options.

pfilt
    This variable may be used to specify additional options to pfilt. If the first word of the first instance of this variable is not an option, it will be used in place of the default command path, "pfilt". See the pfilt(1) manual page for details.

EXAMPLES
A minimal input file for rad might look like this:

    ::::::::::
    sample.rif
    ::::::::::
    # The octree we want to use:
    OCTREE= tutor.oct		# w/o this line, name would be "sample.oct"
    # Our scene input files:
    scene= sky.rad outside.rad room.rad srcwindow.rad
    # The interior zone cavity:
    ZONE= I  0 3  0 2  0 1.75		# default would be scene bounding cube
    # The z-axis is up:
    UP= Z				# no default - would use view spec.
    # Our exposure needs one f-stop boost:
    EXPOSURE= +1			# default is computed ex post facto

Note that we have not specified any views in the file above. The standard default view "X" would be used if we were to run rad on this file. If we only want to see what default values rad would use without actually executing anything, we can invoke it thus:

    rad -n -e sample.rif

This will print the variables we have given as well as default values rad has assigned for us. Also, we will see the list of commands that rad would have executed had the -n option not been present. (Note if the octree, "tutor.oct", is not present, an error will result as it is needed to determine some of the opiton settings.)

Different option combinations have specific uses, ie:

    rad -v 0 sample.rif OPT=samp.opt    # build octree, put options in "sample.opt"
    rad -n -e -s sample.rif > full.rif    # make a complete rad file
    rad -n sample.rif > script.sh    # make a script of commands
    rad -V -v Zl -n -s sample.rif > plan.vf    # make a plan view file
    rad -t sample.rif    # update files after minor change to input
    rad -s sample.rif &    # execute silently in the background
    rad -N 2 sample.rif    # render views using two parallel rpict calls
    rad -N 4 -v 1 sample.rif    # render first view with four rpiece calls

If we decide that the default values rad has chosen for our variables are not all appropriate, we can add some more assignments to the file:

    QUAL= MED		# default was low
    DET= low		# default was medium - our space is almost empty
    PEN= True		# we want to see soft shadows from our window
    VAR= hi		# daylight can result in fairly harsh lighting
    view= XYa -vv 120	# let's try a fisheye view
    PICT= tutor		# our picture name will be "tutor_XYa.hdr"

Note the use of abbreviations, and the modification of a standard view. Now we can invoke rad to take a look at our scene interactively with rvu:

    rad -o x11 sample.rif

Rad will run oconv first to create the octree (assuming it doesn't already exist), then rvu with a long list of options. Let's say that from within rvu, we wrote out the view files "view1.vp" and "view2.vp". We could add these to "sample.rif" like so:

    view= vw1 -vf view1.vp		# Our first view
    view= vw2 -vf view2.vp		# Our second view
    RESOLUTION= 1024		# Let's go for a higher resolution result

To start rvu again using vw2 instead of the default, we use:

    rad -o x11 -v vw2 sample.rif

Once we are happy with the variable settings in our file, we can run rad in the background to produce one image for each view:

    rad sample.rif REP=5 >& errfile &

This will report progress every five minutes to "errfile".

FILES
$(PICTURE)_$(view).unf    Unfinished output of
rpict

AUTHOR
Greg Ward

BUGS
You cannot run more than one rad process at a time on the same input file, as the second process will attempt to recover the output files of the first process, damaging the results. The exceptions to this are running interactively via the -o option, or rendering different views using the -v option.

Incremental building of octrees is not supported as it would add considerable complexity to rad. Complicated scene builds should still be left to make(1), which has a robust mechanism for handling hierarchical dependencies. If make is used in this fashion, then only the "OCTREE" variable of rad is needed.

The use of some pfilt options is awkward, since the "EXPOSURE" variable results in a single pass invocation (the -1 option of pfilt and two passes are necessary for certain effects, such as star patterns. The way around this problem is to specify a "RAWFILE" that is the same as the "PICTURE" variable so that no filtering takes place, then call pfilt manually. This is preferable to leaving out the "EXPOSURE" variable, since the exposure level is needed to accurately determine the ambient value for rpict.

The use of upper and lower case naming for the standard views may be problematic on systems that don't distinguish case in filenames.

SEE ALSO
glrad(1), make(1), mkillum(1), mkpmap(1), objview(1), oconv(1), pfilt(1), raddepend(1), ranimate(1), rholo(1), rpict(1), rpiece(1), rtrace(1), rvu(1), touch(1), vgaimage(1), ximage(1)