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                               Volren

               A Hardware Accelerated Volume Renderer

                            (version 6.0)

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What Is It?
-----------

	Volren is a hardware accelerated volume renderer based upon
the texture mapping capabilities available in Silicon Graphics'
Indigo2 Impact, Onyx Reality Engine, and Onyx Infinite Reality
architectures.  The renderer provides the ability to control the
mapping from scalar data value to color and opacity as well as the
ability to render voxel and geometric data together.  The renderer
loads data as a collection of 2D image files in one of many formats.


What's New?
-----------

	Volren has changed significantly since version 5.0.  Most
notably it now supports all three Silicon Graphics platforms that have
hardware accelerated texture mapping.  Additionally, many buggy or
semi-coded features of version 5.0 have been removed.


	Version 6.0 features:

	First Class Open GL support
	---------------------------
	Volren now first supports OpenGL.  The IrisGL code remains in
volren, but it has not been extensively tested.  Future versions of
volren will probably only support OpenGL.  OpenGL should compile and
run cleanly on any Irix 6.2 platform (even those without texture
mapping hardware, though it will be slow).  Additionally volren should
work properly on Indigo2 Impacts running Irix 5.3 as well as Onyx
Reality Engines with the latest OpenGL patch installed (patch 918).

	Extended Lookup Table support
	-----------------------------
	Volren nows supports a more sophisticated and powerful color
and opacity lookup mechanism.  It can read the tablemap files
supported by version 5.0 as well as color only (colormap) and opacity
only (alphamap) files.  The colormap and alphamap are possibly altered
by the currently selected transfer function.  The result is the lookup
table used to map the volume when it is rendered.  Many transfer
functions are now supported, including "window/level", "triangle",
"inverse triangle", "double triangle", and "medical".  Additionally
the code easily supports the addition of extra transfer functions.

	Reorganized Interface
	---------------------
	The interface has been reorganized and restructured to provide
a flatter and less intimidating look.  Additionally, functions are now
grouped into menus logically for easier access.  Menu entries also
show hot keys to facilitate quick learning of key short cuts.


	Version 5.0 features:

	Multiple Volume support
	-----------------------
	Volren now supports loading multiple volumes concurrently.
The volumes can intersect each other arbitrarily and will be correctly
merged and rendered.  Each volume can be translated and rotated
individually.  Additionally, each volume can use its own texture
lookup table allowing an enormous range of flexibility in merged
rendering.

	Time Variant Volume support
	---------------------------
	Volren can now load four dimensional volumes that change over
time.  The animation rate is controllable from the command line and
the user interface.  These time variant volumes can be loaded with
normal volumes or other time variant volumes or both.

	Geometry Code improved
	----------------------
	The geometric matrix code is entirely rewritten and much
cleaner.  The source is much more readable and a description of the
different important coordinate spaces exists in src/README.CODERS.

	Stereo Viewing support
	----------------------
	Volren version 5.0 supports stereo.  The stereo code is
reworked and looks better than ever.

	Numerous Other fixes
	--------------------
	Option to disable generation of four-bit bricks.  Slice plane
extents now computed correctly.  Picking works right in perspective
and orthogonal modes. Pixel replication mode works correctly again.
Brick seaming code reworked; minor bugs fixed.  Supports two
resampling filters (box and triangle).  Updated man page and data
sets!


How Do I Get It?
----------------

	A compressed tar file can be fetched from sgigate.sgi.com in
the ~ftp/pub/demos directory.  Login as "ftp" and provide your email
address as the password (e.g. "foo@bar.com").  The file of interest is
called "volren-6.tar.Z".  Uncompress the tar file using zcat or
uncompress.  Untarring the file should produce a directory called
"volren-6".

Structure
---------

	Below is the basic structure of this distribution of volren.

	README		This file
	README.html	Top level HTML documentation
	bin/		Open GL volume renderers
	data/		Data files
	demo/		Shell scripts
	doc/		Documentation
	doc/how-to/	How to build a volume renderer article
	doc/man/	Nroff and packed man pages
	doc/manual/	HTML volren manual
	etc/		Support binaries
	html/		Support HTML files
	lib/		Support libraries
	rundemos*	Shell script to launch the demo scripts
	slides/		Volume rendering showcase slides
	src/		Source code

Authors
-------

	Volren was written by Brian Cabral and Todd Kulick with help
and suggestions from far too many to name.  Thanks to all of you!


Administrivia
-------------

	SGI reserves the right to maintain this software as much or as
little as it sees fit.  Bugs fixes, explanations and installation help
are not guaranteed.  For more information see src/Copyright.  If you
have questions, comments, or remarks about volren feel free to
contact:

	Todd Kulick	kulick@sgi.com

Thanks and have fun!
