VOLREN(1) SGI (1996 Apr. 23) VOLREN(1)
NAME
volren - Interactive Volume Renderer
SYNOPSIS
volren [intfopts] -- [volopts] -- object [-- object [...]]
DESCRIPTION
Volume visulization is a powerful technique for displaying
and understanding three (and four) dimensional scalar data
sets. Such data sets are common in medicine, physics,
engineering, biology, and chemistry. Volume rendering when
performed using traditional CPU based algorithms can take
minutes to hours to compute. However, the real power of
volume visualization is only realized if it can be done at
interactive rates (at least 10 frames per second). Volren
is a tool which does this. It uses a combination of three
dimensional texture mapping and high speed textured polygon
rendering found in Silicon Graphics' Indigo2 Impact, Onyx
Reality Engine, and Onyx Infinite Reality architectures.
JUSTIFICATION
Nearly every technical discipline deals with three
dimensional volumetric data. By three dimensional
volumetric data we mean data that is defined for every point
(or at least a dense set of points) in some chunk of 3
space. Mechnical engineering has volumetric data when
dealing with strain on a three dimensional part. Chemists
and molecular biologists image and synthesize three
dimensional density functions. Radiologists look at three
dimensional CAT (CT) scan data. Physists look at everything
from whole galaxies to minute particles all of which are
defined volumetrically. The auto industry and aerospace
industry study three dimensional wind flows which can be
viewed volumetrically. And lastly, weird ephemeral, cloud
like renderings are useful for special effects.
INTERFACE
Volren starts by reading in the slices and displaying them
as it does so. Once all slices of all volumes are read in,
Volren reformats the data into bricks so that it can be
loaded into texture memory. This formatting takes some
time. Once this has been completed the program displays the
data in the rendering window.
The Rendering Window
There are twelve supported commands in the Rendering Window.
Each one is associated with a mouse button either with or
without either the shift or ctrl key pressed. The functions
are summarized in the table below. More detailed
descriptions follow the table. In the table, Btn1 is the
left mouse button. Btn2 and Btn3 are the middle and right
mouse buttons respectively.
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Btn1 Rotate World
Btn2 Select Clip Plane / Translate Point
Btn3 Rotate Selected Clip Plane
Shft Btn1 Zoom World
Shft Btn2 Place Point
Shft Btn3 Translate Selected Clip Plane
Ctrl Btn1 Rotate Selected Volume
Ctrl Btn2 XY Translate Selected Volume
Ctrl Btn3 Z Translate Selected Volume
Ctrl Shft Btn1 Scale Selected Volume
The left mouse button is used to move the world (all
volumes, geometry, and clip planes). Pressing and dragging
this button rotates the world. If you release the button
while you are dragging the world will continue to spin in
the direction it was last rotating. The spin velocity is
dictated by the speed at which the mouse was moving when the
button was released.
Pressing the middle mouse button selects the nearest plane
at the current mouse position. This allows a quick, simple
way to select a plane. This plane will then be affected by
all subsequent plane commands (right mouse). The current
plane may also be selected via the "Clip Plane" menu item
under the "Select" menu. The plane selection command only
works when the clip planes are enabled. If the middle mouse
button is pressed while the mouse is on or near a point,
vertical motion of the mouse will be used to translate that
point rather than selecting a plane.
The right mouse button is used to rotate the currently
selected clip plane. The clip plane is moved just as the
world is when the left mouse button is used, via a virtual
trackball model. This command only works if clip planes are
enabled.
By pressing shift and the left mouse button, the world can
be zoomed. Dragging the mouse up and down while holding the
left button down will zoom in and out.
Points may be placed in three-space by clicking with middle
mouse button while holding shift. Points may only be placed
when the clip planes are shown. If clip planes are
disabled, pressing the middle mouse button with shift will
cause generate a warning message. If clip planes are
enabled, points may be placed simply by clicking in the
Rendering Window on a clip plane. A point will be placed in
three-space on the nearest clip plane. Dragging the mouse
will cause the point to move, following the mouse. The
nearest plane (the one that the point will be placed on)
will become the selected plane and it will highlight. If
the mouse is moved to a place outside all volumes or where
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no plane exists the point will disappear. If the mouse is
released at this point then no point will be created. To
edit points, simply shift middle click on a point already on
the screen. This allows grabbing a point rather then
creating a new one. This feature may make it difficult to
place numerous points near each other. To force the
creation of a new point, shift middle click outside the
volumes and drag the new point to the position desired.
This method will always create a new point.
The currently selected clip plane can also be moved in a
constrained fashion. This constrained move, a translation
along the plane's normal, is affected by holding shift while
pressing the right mouse button. The clip plane is moved
only up and down along the direction of its normal. Moving
the mouse up and down while holding the right button down
moves the plane. Like clip plane rotation, this works if
clip planes are enabled.
Holding control and dragging the left mouse button rotates
just the selected volume. A warning message will be
generated if no volume is selected. This is the way to
rotate one volume with respect to others or the world.
Dragging the mouse after pressing the middle button with the
control key pressed translates the selected volume. If no
volume is selected the program present a warning message.
Dragging the mouse rotates the volume in the XY plane.
Holding control while pressing the right mouse button allows
translation of the current volume along the Z axis. This
will fail if no volume is selected.
The left mouse button with both the control and shift keys
depressed will allow scaling of the selected volume. As
with all other volume controls, this is will beep and
display a warning message if no volume is selected.
The Menus
The "File" menu provides the basic control options. The
"Reset State" menu item can be used to reset Volren to its
initial state. A snapshot of the current volume rendering
can be written to the disk with the "Snap Image" option.
This option causes Volren to generate an image file of size
specified by the '-f' interface option. The image is
written to the file specified by the '-F' interface option.
The "Close" item closes the window, causing the application
to exit only if the colosing window is the last one. As one
might expect, the "Exit" menu item ends the program, closing
all windows.
The "Option" menu provides access to rendering options,
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volume options, surface options, and miscellaneous options.
The "Rendering" option menu allows toggling of resolution,
stereo (if a stereo window has been allocated), perspective,
and blending type. High resolution can be deactivated to
provide faster rendering. Activating stereo mode enables
the "Stereo Separation" slider and allows stereo viewing
with stereo in a window. The "Field of View" slider will be
enabled whenever perspective rendering is active. Volren
supports two blending modes, "Over" (back-to-front weighted
opacity accumulation) and "MIP" (maximum intensity
projection).
The "Volume" option menu allows modification of per volume
parameters for the selected volume. The "Colored" menu item
can be used to toggle between color and black and white
volume rendering. Trilinear interpolation will be used when
the "Interpolated" menu item is active. Otherwise, simpler
nearest neighbor calculations will be done. Colormap and
alphamap modulation are explained in more detail in the
GENERATING LOOKUP TABLES section.
The selected surface's parameters can be modified from the
"Surface" option menu. To generate a surface from a
collection of points choose the "Generate" item. The
surface can be rendered with or without lighting and as a
mesh or polygonal surface. These options are controlled by
the "Lighted" and "Meshed" toggle items. The "Textured"
toggle item allows for surfaces textured with three
dimensional volume data.
Miscellaneous options are accessible from the "Misc." option
submenu. The "Clip Plane Looping" menu item controls loop
mode. Activating this mode, causes the clip planes to be
displayed. Additionally, the planes will loop back and
forth through the volume. The volume will not be shown,
even if volumes are enabled. The portions of the surface
and the points that are clipped by the clip planes will only
be displayed in volume mode if the "Clip Geometry" menu item
is not selected. If geometry clipping is enabled and
volumes are enabled, then points and surfaces will be
clipped by the clip planes.
The "Enable" menu item on the menu pane allows enabling and
disabling of classes of objects and individual objects.
Selecting an item in the "Enable Objects" submenu will
toggle the display of all objects of that type. Individual
objects can be enabled and disabled using the "Enable
Volumes", "Enable Surfaces", and "Enable Clip Planes"
submenus.
Volumes, surfaces, and clip planes are selected using the
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submenus under the "Select" item on the menu pane.
The "Transfer" menu provides a list of all the available
transfer functions. It is only enabled when a volume is
selected. It is used to select a transfer function to apply
to a volume. The use of this transfer function is described
further in GENERATING LOOKUP TABLES.
The "Colormap" and "Alphamap" menus are used to choose the
selected volume's colormap and alphamap. They are therefore
only active when a volume is selected. GENERATING LOOKUP
TABLES describes the use of these tables.
Lookup Table Window, Buttons, and Sliders
The lookup table window, buttons, and sliders are only
enabled if a volume is selected as they always pertain to a
specific volume. The lookup table buttons determine the
state of the lookup table window and sliders. The lookup
table window always displays the selected volume's data
histogram in grey.
When the "Transfer" button is depressed the lookup table
window displays the current single-valued transfer function
in white. The sliders will display the names and values of
the selected transfer function's parameters.
The lookup table window will display the selected colormap
and alphamap when the "Color/Alpha" lookup table button is
depressed. The colormap will be shown as one red, one
green, and one blue line (or possibly one white line if the
red, green, and blue lines overlap and blend together). The
alphamap will be shown as a white line. The sliders will
display the colormap and alphamap scale and rotate names.
Moving the sliders will manipulate these scale and rotate
parameters not the current transfer function's parameters.
Lastly if the "Lookup" button is depressed then the lookup
table window will display the current lookup table. Colors
will be drawn with red, green, and blue lines and alpha will
be drawn with a white line. The sliders will show the names
and values of the selected transfer function's parameters.
The lookup table sliders are described further in the
GENERATING LOOKUP TABLES section.
Status Window
The status window at the bottom of the screen provides
feedback during the running of Volren. It provides warning
messages and other feedback.
GENERATING LOOKUP TABLES
Perhaps the single most important function of a volume
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renderer is its ability to provide an interactive mechanism
for classification of complex data. In Volren data is
classified by a lookup table. This lookup table is
generated by a transfer function and possibly a colormap and
an alphamap. Each volume can use a separate transfer
function, colormap and alphamap.
All transfer functions are controlled by one to four
parameters which have a different meaning for each transfer
function. These sliders will be accessible whenever either
of the "Transfer" or the "Lookup" buttons are depressed in
the transfer function panel at the right side of the screen.
If the "Color/Alpha" button is selected instead then the
sliders will control the colormap and alphamap parameters
instead. These parameters allow scaling and rotation of the
colormap and alphamap.
Transfer functions
Volren supports five transfer functions. Each function is
one of two types. Most of the transfer functions are
single-valued and simply modulate the user-chosen colormap
and alphamap. These are "single-valued" transfer functions.
However some transfer functions ignore the colormap and
alphamap entirely and specify the volume lookup table
directly. These are "programmatic" transfer functions.
Below the process used to generate a lookup table from
single-valued and programmatic transfer functions is
considered.
When a single-valued transfer function is selected for a
volume that volume's lookup table is generated by combining
the function with the volume's selected colormap and
alphamap. If the volume has the "Modulate Colormap" item
active in the "Volume" option menu, then the lookup table's
colors are specified by multiplying the colormap and the
transfer function. If the "Modulate Colormap" item is not
enabled then the lookup table's color is simply taken from
the colormap selected for this volume. The lookup table's
alpha values are generated in a similar way from the
transfer function, the selected alphamap, and the "Modulate
Alphamap" menu item.
While using a programmatic transfer function, the "Colormap"
and "Alphamap" menu items will be disabled. Additionally
the "Transfer" and "Color/Alpha" lookup table buttons will
be disabled as well. Programmatic transfer functions
directly specify the color and alpha values to be placed in
the lookup table. These values are generated from the
transfer functions parameters.
The five transfer functions currently available are
described below.
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Window/Level This single-valued transfer function
computes a classical window level
function. Its parameters control its
window, level, and its center point
height.
Triangle Another single-valued transfer function,
the triangle computes a triangle function
centered at the location specified by the
center parameter. The width parameter
controls the triangle's width and the
height controls its height.
Inverse Triangle Three parameters generate an inverted
triangle that defines this single-valued
transfer function.
Double Triangle This single-valued transfer function
generates two triangles centered about the
location specified by the center
parameter. The width and height control
the size of the triangles and the final
parameter controls the distance between
them.
Medical This is the only programmatic transfer
function currently written. This transfer
function allows direct control of the
opacity of air, fat, tissue, and bone in a
volume. This transfer function is
specially tuned for CT data sets and is
based upon Bob Drebin's work (see 1988
Siggraph proceedings page 68).
You can create your own colormap, alphamap, and tablemap
files as described below (see READING MAP FILES). Each will
appear as a selectable item under one or both of the
"Colormap" or "Alphamap" menus.
OPTIONS
Volren is highly configurable from the command line.
Specifying the '-O' flag will cause it to immediately print
out the compilation options it was created with including
the version number and graphics architecture then exit.
In standard usage the command line is broken into
collections of options. These configure the interface,
other volume options, and the individual objects to be
loaded. Each of these collections of options is terminated
on the command line by the special option '--'.
Interface Options
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The first set of options changes the standard defaults for
Volren's user interface. These options are:
-C colormap Load file colormap for use as a colormap.
This flag may be specified multiple times
(see READING MAP FILES below).
-A alphamap Load file alphamap for use as an alphamap.
This flag may be specified multiple times
(see READING MAP FILES below).
-T tablemap Load file tablemap for use as a colormap and
an alphamap. This flag may be specified
multiple times (see READING MAP FILES
below).
-P file Load file file and read polygonal geometry
data from it. See the section READING
POLYGON FILES below.
-S count The initial number of slices to draw when
rendering the volume (defaults to 175).
-r width height Specify the default width and height of the
Rendering Window. This can be necessary
when using a version of Volren that doesn't
have auxilary buffer support, but utilizes
graphics hardware to accelerate start-up
processing. In these cases, the window must
be forced to at least the largest X and Y
sizes of the all the volumes to be loaded.
-p count The maximum number of hardware clip planes
to use (defaults to 6).
-e Since stereo mode windows require more
resources they will not be allocated by
default, resulting in the inability to
utilize stereo mode. Use this flag to force
allocation of stereo windows (if possible).
-a Do not modulate the alphamap by the transfer
function when generating the alpha table
(see GENERATING LOOKUP TABLES). The default
is to modulate the alphamap.
-m Do not modulate the colormap by the transfer
function when generating the color table
(see GENERATING LOOKUP TABLES). The default
is to modulate the colormap.
-c obj color Specify the color of an object obj. Color
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should be a valid X11 color string (for
example, "#f00", "#ff0000", or "red").
Valid objects are:
back The background color
frame Each volumes' frame color
cframe The current volume's frame color
plane Each clip planes' color
cplane The current clip plane's color
point Each points' color
cpoint The current point's color
xvec The X axis vector's color
yvec The Y axis vector's color
zvec The Z axis vector's color
upvec The up vector's color
northvec The north vector's color
frontpoly The front of polygons' color
backpoly The back of polygons' color
frontelev The front of elevations' color
backelev The back of elevations' color
xysurf The XY surfaces' geometry
zsurf The Z surfaces' geometry
surf# The #th surfaces' geometry
-F file Used to specify the file to which to write
snapshot images.
-f width height Specifies the width and height of any
snapshot images generated.
-O Force Volren to print out the compilation
options defined when this version of Volren
was compiled. The program then immediately
exits.
-V Verbose progress, mostly for debugging
purposes.
-D level Start up in debug mode level. This is
useful as some useful information can be
gleaned about the data during the reading
process if certain debug modes are enabled.
For example, to redisplay the loaded data
after it is all read in, use debug mode #2
for brick by brick updates with pauses and
mode #3 for slice by slice updates without
pauses.
Volume Options
The next set of options effect the volumetric data in the
renderer. These options are:
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-m count Break each volume into bricks count slices
deep in the Z dimension. This will
deactivate bricking in X and Y. In
addition, count must be at least 4.
-r resample Volren now resamples data by default to
remove seams. This option allows the
disabling of this capability. Specifying
this option with any valid argument resample
turns off volume resampling. Valid
arguments are { false, f, no, n, off }.
-f filter Specifies a sampling filter to be used
during resample (if resampling will occur).
The provided filters are:
box A 2D separable box filter
triangle A 2D separable triangle filter
-4 Force the creation of four-bit brick data as
well as the default eight-bit brick data.
Not creating four-bit bricks is now the
default to help conserve texture memory in
normal cases where both sets of bricks are
not needed.
-U dir Specify which axis points up. Valid choices
are { X, Y, Z }.
-N angle Specify the north vector as an angle around
the up vector.
-V Verbose progress (optional).
-D level Start up in debug mode level. This is
useful as some useful information can be
gleaned about the data during the reading
process if certain debug modes are enabled.
For example, to redisplay the loaded data
after it is all read in, use debug mode #2
for brick by brick updates with pauses and
mode #3 for slice by slice updates without
pauses.
Per Object Information
Each object given on the command line has the following
form:
objtype [objopts] objinfo
Two object types are currently supported, volumes (objtype =
volume) and elevations (objtype = elevation). If no object
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type is specified, volume is assumed. Each object type has
different options (objopts) and required information
(objinfo). These requirements are described below.
Per Volume Options
Each volume specification consists of two parts. The first
part is the volume options. A list of all per volume
options is given here:
-h Toggle the handedness of the volume. The
default is to the left, causing sucessive
images to be stacked downwards as they are
read in. This option will cause right
handedness to be used.
-X scale Specifies the relative voxel spacing in the
X dimension for this volume.
-Y scale Specifies the relative voxel spacing in the
Y dimension for this volume.
-Z scale Specifies the relative voxel spacing in the
Z dimension for this volume.
-T number Specifies the number of time steps over
which the volume is defined. By default,
volumes are not time variant (number = 1)
and will not be animated.
-S millisecs Specifies the default time interval before
moving to the next time step in a time
variant volume. In other words, it
specifies the animation speed of the
volume's time component (in milliseconds per
frame). The default value is 3000, or 3
seconds between time step changes.
-e extension The file extension for this volume's data
files. The default extension is ".tiff".
-o zoff The number of the first slice in Z. This
option can be used to load only specific
spatial (Z) ranges of non-time variant data
volumes or only specific time (T) ranges of
time variant data volumes (see READING
VOLUMES below).
-O xoff yoff The offset of the lower left corner of each
slice. This option can be used to load
subregions of a volume offset from the data
images' origins (see READING VOLUMES below).
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The second part of each volume's specification is mandatory.
This volume information specifies the volume's resolution
and the location of the data files containing the volume
data. The format of this information is:
ex ey ez data
The above format shows that the minimum specification for a
volume includes the volume's resolution (ex ey ez) and file
path to the data (data). For more information on the exact
use of these parameters see READING VOLUMES below.
Per Elevation Options
Each elevation specification consists of two parts. The
first part is the elevation options. A list of all per
elevation options is given here:
-X scale Specifies the relative pixel spacing in the
X dimension for this elevation.
-Y scale Specifies the relative pixel spacing in the
Y dimension for this elevation.
-L Cause the elevation not to be lighted. The
default behavior is to light elevations.
-R angle Rotate the elevation counter-clockwise by
angle degrees in the XY plane.
-T tx ty tz Translate the elevation in space by tx, ty,
and tz.
The second part of each elevation's specification is
mandatory. The format of this information is:
[colorimg] elevimg
This elevation information specifies a greyscale image
(elevimg) used to define the height field that is the
elevation and optionally a color image (colorimg) that will
be draped onto this height field.
READING VOLUMES
Volren takes as input a series of two dimensional images
which represent slices of a three (or four) dimensional
volume. With non-time variant volumes (no '-T' option is
specified), files will be accessed for all slices in the
range [0, ez-1], where ez is the value specified as the size
of the volume in the Z dimension (as described in the per
volume options above). That is, ez files must be opened to
define the volume; one for each slice in the Z dimension.
Time variant (four dimensional) volumes are discussed below.
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Finding Data Slices
Volume slices (individual files) should be named following
this scheme:
concat(data, slice, extension)
Data is the basename of all the data files as specified for
the given volume in its per volume options. Each file will
have a number, slice, appended after the basename. In
addition, an extension, extension, will be added at the end
of each filename constructed. Volren uses the ImageVision
library to read these files, so they may be of any format
supported (try TIFF or SGI) by the installed IL environment
(see IL(1)). The files should be single channel (greyscale
or luminance) and contain eight-bit data. Additionally,
each file should be large enough to facilitate the
extraction of an ex by ey image offset by xoff and yoff
pixels in the X and Y directions respectively. Volren will
print a warning if these conditions are not met by any file.
Volren will try numerous different filenames when trying to
find a specific slice of data. This is done to accommodate
both variable and constant width slice fields in data
filenames (test017.tif and test17.tif). Consider a
situation where data is specified as "data/chemical/oxy" and
the extension is ".bw". Note that the "." is included in
the extension specification. Also, assume that the offset
parameter (per volume option '-o') was not set on the
command line. It will then default to zero. When searching
for the third slice (slice 2, since the first slice was 0)
for example, Volren will try to locate the data in each of
the following files, in order:
data/chemical/oxy2.bw
data/chemical/oxy02.bw
data/chemical/oxy002.bw
data/chemical/oxy0002.bw
data/chemical/oxy00002.bw
data/chemical/oxy000002.bw
data/chemical/oxy0000002.bw
data/chemical/oxy00000002.bw
data/chemical/oxy000000002.bw
Time Variant Volumes
If the volume is time variant then files will be accessed
for slices in the range [0, ez*et-1] where et is the size of
the time dimension for this volume (the argument to the per
volume '-T' option).
For example, imagine a 128 (ex) by 128 (ey) by 64 (ez)
volume that is defined over 16 (et) time steps. The 64
slices of the volume cooresponding to the third time step
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(time equals 2, since the first time step is time equal 0)
could be found in the files cooresponding to the slice range
[128, 191]. This makes it easy to skip the first N time
steps by simply setting the slice offset (per volume '-o'
option) to N times the Z size of the volume (ez).
READING MAP FILES
Volren uses a lookup table to map the scalar data quanity in
each volume into color and opacity to be composited together
during rendering. These lookup tables are generated from
transfer functions and map files read from disk. Volren can
read and store up to 20 different map files. There are
three different types of map files: colormaps, alphamaps,
and tablemaps. Each type of map file has 257 lines. The
first line contains overall map weights specified as
floating point numbers. Every entry in the map will be
scaled by these values. The remaining 256 lines specify the
map, each line containing integers in the range [0, 255].
Colormap files have three entries on each line, one for red,
one for green, and one for blue. Alphamap files have one
entry on each line, the alpha value. Tablemap files specify
both color and alpha values and correspondingly have four
entries per line: red, green, blue, then alpha. Tablemaps
are equivalent to previous versions of Volren's lookup
tables.
READING POLYGON FILES
Polygon geometry files are a way of importing arbitrary
three dimensional geometry into Volren. The polygon
geometry file format is pretty arbitrarily defined, but it
is also very simple. The format supports two kinds of
objects, disjoint triangles and quadrilateral strips.
Any line beginning with '#' is assumed to be a comment and
ignored. Each piece of data (object count, object type,
object part count, or point) belongs on its own line and
should not be combined with other lines or broken up onto
multiple lines.
The file begins with the number of objects to follow in the
file (object count). Following this count are the objects
themselves. Each one begins with a string defining its
type. This object type precedes the object part count.
Following the part count are the parts. Each part is made
up of some number of 3D points. Each point is three
floating point numbers (on the same line!) The number of
points per part is a function of the object type. Disjoint
triangles require three points per part. Quadrilateral
strips require only two.
The format of the file resembles:
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| # A demonstration polygon geometry file
|
| # First is the number of objects in the file
| 3
|
| # Begin first object
| # First is the object's type
| disjtris
| # Next is the number of parts in the object
| 2
| # Now the first part (triangle). Since this object
| # is disjoint triangles, we know that each part
| # will contain three 3D points (nine floats).
| 0.5 0.3 0.2
| 0.3 0.6 0.7
| 0.4 0.8 0.1
| # Now the second part (triangle).
| 0.4 0.9 0.7
| 0.6 0.3 0.8
| 0.9 0.2 0.9
| # End first object
|
| # Begin second object
| quadstrip
| 3
| # Quadrilateral strips have only two 3D points
! # per part.
| 0.4 0.2 0.7
| 0.6 0.4 0.3
| 0.3 0.8 0.2
| 0.4 0.5 0.7
| 0.9 0.4 0.7
| 0.1 0.1 0.9
| # End second object
|
| # Begin third object
| disjtris
| 1
| 0.8 0.9 0.4
| 0.3 0.6 0.3
| 0.7 0.4 0.8
| # End third object
USING STEREO
Stereo mode is available with either projection technique,
but perspective is better. The stereo separation may be
adjusted using the "Stereo Separation" slider. The stereo
separation should be increased as you move further away from
the screen. Note that some monitors can not reach the 120hz
used in the "setmon" call that the volume renderer uses to
turn on stereo mode. A monitor which cannot achieve the
120hz rate will appear scrambled. The work around for this
Page 15 (printed 4/23/96)
VOLREN(1) SGI (1996 Apr. 23) VOLREN(1)
is to manually specify the resolution that Volren will use
to setup stereo mode. This resolution should be specified
in the VOLREN_STEREO_MONITOR environment variable. The
default value is "815x611_120s". Likewise setting the
VOLREN_MONO_MONITOR variable specifies the resolution the
renderer returns to when stereo is deactivated. Its default
value is "1280x1024_60". Each of these variables is simply
passed as an argument to the setmon(1G) program. See its
man page for more information about other resolution options
supported by your hardware.
DEBUG MODES
The '-D' switch sets the debug level at startup time. The
debug level can be changed interactively by placing the
mouse in the Rendering Window and hitting the '+' or '-'
keys. Additionally, to see Volren render you can deactivate
double buffering using the "Misc." option submenu item
"Double Buffering".
EXAMPLES
Example shell scripts are provided that run Volren on a
collection of data sets. They provide a relatively thorough
example of how Volren works.
FILES
$distribution/demo/*
Volren example scripts.
$distribution/bin/volren-6*.ogl
The volren executable.
$distribution/data/*
Example data sets.
$distribution/data/luts/*
Example lookup tables.
BUGS
Volren should let you change the colors during a run, not
just on the command line. It should probably support saving
all the parameters associated with a data set in a file that
it can read and write.
Volren should read inventor file format or something else
more portable than the geometry format it supports now.
This man page probably needs help. If you want to know more
about this code, it's applications, or just want to post
bugs (er...features), contact the maintainer or authors.
CURRENT MAINTAINER / DEVELOPER
Todd Kulick, Silicon Graphics
kulick@sgi.com
AUTHORS
Page 16 (printed 4/23/96)
VOLREN(1) SGI (1996 Apr. 23) VOLREN(1)
Brian Cabral, Silicon Graphics
cabral@sgi.com
Todd Kulick, Silicon Graphics
kulick@sgi.com
CAVEAT
Copyright 1994 Silicon Graphics, Inc. -- All Rights Reserved
If the Software is acquired by or on behalf of an entity of
government of the United States of America, the following
provision applies: U. S. GOVERNMENT RESTRICTED RIGHTS
LEGEND: Use, duplication or disclosure of Software by
the Government is subject to restrictions as set forth in
FAR 52.227-19(c)(2) or subparagraph (c)(1)(ii) of the
Rights in Technical Data and Computer Software clause
at DFARS 252.227-7013 and/or in similar or successor clauses
in the FAR, or the DOD or NASA FAR Supplement. Unpub-
lished- rights reserved under the Copyright Laws of the
United States. Contractor/manufacturer is SILICON
GRAPHICS, INC., 2011 N. Shoreline Blvd., Mountain View,
CA 94039- 7311.
Silicon Graphics, Inc. hereby grants to you a non-
exclusive, non- transferable, personal, paid-up license to
use, modify and distribute the Software solely with SGI
computer products. You must include, in all copies of
the Software and any associated documentation, the
copyright notice and restricted rights legend set forth
above.
THE SOFTWARE IS PROVIDED TO YOU "AS-IS" AND WITHOUT
ANY SUPPORT OBLIGATION OR WARRANTY OF ANY KIND,
EXPRESS, IMPLIED OR OTHERWISE, INCLUDING WITHOUT
LIMITATION, ANY WARRANTY OF MERCHANTABILITY OR FITNESS
FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL SGI BE LIABLE
FOR SPECIAL, INCIDENTAL, INDIRECT OR CONSEQUENTIAL DAMAGES,
OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA
OR PROFITS, WHETHER OR NOT ADVISED OF THE POSSIBILITY OF
DAMAGE, AND ON ANY THEORY OF LIABILITY, ARISING OUT OF
OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
SOFTWARE.
You agree that you will not export or re-export the
Software, directly or indirectly, unless (a) the Export
Administration of the U. S. Department of Commerce
explicitly permits the export or re-export of the
Software or (b) the Office of Export Licensing of the
U. S. Department of Commerce has granted au-thorization to
you in writing for the export or re- export the Software.
If you fail to fulfill any of the foregoing obligations,
Page 17 (printed 4/23/96)
VOLREN(1) SGI (1996 Apr. 23) VOLREN(1)
SGI may pursue all available legal remedies to
enforce these terms and conditions, and SGI may, at any
time after your default hereof, terminate the license
and rights granted to you hereunder. You further agree
that, if SGI terminates this license for your default, you
will, within ten (10) days after any such termination,
deliver to SGI or render unusable all Software
originally provided to you hereunder and any copies
thereof embodied in any medium.
Page 18 (printed 4/23/96)
Documentation
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