The interactive Graph Visualization System daVinci V1.3
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							Michael Froehlich,
							Mattias Werner, 
							University of Bremen

daVinci is an universal, generic visualization system of high quality for 
directed graphs. Nowadays, the importance of a visualization of graph 
structures is obvious. Directed graphs are very common in modern computer 
applications: module dependencies in a software project, file systems on 
storage devices, dataflows in a program, the structure of a computer network, 
time dependencies in a project management system, the tree of chapters in a 
structured document and so on. The graphical representation of these partly 
huge and complex objects offers the foundation for getting an overview, 
looking down on details, exploring interesting areas and finally obtaining 
the understanding of the structure. Sometimes one can find specific 
visualization tools for a concrete application, but these tools are often 
integrated into the program that handles the graph; they are not designed 
for a general use. Moreover, a viewer has often only a limited influence on 
the way the graph is represented.

daVinci is an interactive visualization system which tries to overcome these 
deficits. The basic philosophy of daVinci is to be independent from an 
application and to offer the definition of the visualization. In daVinci a 
user is able to load a graph in a readable term representation from a file. 
Layout qualities like edge crossing minimization or bend elimination are 
considered for a graph layout. Furthermore an interface for the connection 
with a graph administrating application is available. With this interface, 
an application program is able to send graphs to the visualization system 
as well as define application specific menus and simple user dialogues. A 
connected application is informed about events like user selection of graph 
nodes and edges, selection of application generated menus or the result of 
user dialogues. By using daVinci this way like an abstract user interface, 
an application program can offer the user the opportunity to work on the 
graphical view of a graph. A graph editor, available in the distribution of 
daVinci, demonstrates the advantages of the application interface.

The visualization of a graph is not static in daVinci. The user can 
manipulate the layout interactively to obtain a better view. The most 
important features of the current release daVinci V1.3 are:

	o Application interface for the connection with a graph 
	  administrating program.

	o Acyclic and cyclic graphs are supported as well as multiple edges 
	  and self-refering edges.

	o Automatic graph layout considering aesthetics like edge crossing 
	  minimization, edge bend minimization, etc.

	o Fine-tuning of a graph layout by dragging nodes and edges.

	o High quality scaling down to 1% with preservation of the full 
	  functionality in a scaled visualization.

	o Interactive abstractions like fading out of uninteresting subgraphs 
	  or edges.

	o PostScript(TM) interface.

	o Graph attributes for influencing the visualization of nodes and 
	  edges individually: colors, patterns, shapes, fonts, etc.

	o Global font size can be set interactively from 6pt up to 34pt.

The interactive graph visualization system daVinci was developed at the 
Institute for Formal Methods in Software-Engineering of the University of 
Bremen, Germany. The system has been implemented since the end of 1992 by 
Michael Frohlich and Mattias Werner. daVinci is written in the pure 
functional language ASpecT, developed at the University of Bremen also. 
The OPEN LOOK(TM) conform X-Window(TM) user interface of daVinci is 
implemented in C using the window toolkit XView. 

Until now daVinci was distributed to more than 600 users all over the world 
like MIT, ETH Zurich, the Universities of Alberta, Bordeaux, Delft, San 
Diego, Nancy, Oregon, Purdue, Toronto, Washington as well as Adobe, AT&T, 
BASF, Chevron, DEC, Dupont, Ericsson, Kodak, Motorola, NASA, Nokia, Panasonic, 
Siemens, Sony, Sun Microsystems, Texas Instruments, Toshiba, Xerox and many 
more.

daVinci is available free of charge for non-profit use by anonymous ftp 
from ftp.Uni-Bremen.DE (Internet: 134.102.228.9) in the directory 
/pub/graphics/daVinci. Any commercial exploitation of this software is 
prohibitted without the explicit authorization of the authors. 

daVinci V1.3 is available for Sun SPARCstations with Solaris 1 (known as 
SunOS 4.x) or Solaris 2 and for Intel PC's with Linux. In principle the 
system can be ported to each UNIX platform which is supported by the public
available OPEN LOOK toolkit XView, e.g. Apple Macintosh (A/UX), DECstation 
(Ultrix), HP 9000/7xx (HP-UX), IBM RS6000 (AIX) or SGI (Irix).

If you are using daVinci, please send us your opinion about this software. 
We are very interested in applications of daVinci as well as critics or 
suggestions about new features. You can contact the daVinci project by 
e-mail to daVinci@Informatik.Uni-Bremen.DE. A mailing list is also 
available.
