Most of the vector graphics used in archaeology are created with some form of proprietary software that was either not designed with the Web in mind, or has features that cannot be handled by particular browsers. In general, files must be saved in special formats and a separate viewer or browser plug-in may be required to interpret these files on the Web. Often these viewers have only limited functionality compared to the original software, and only work with particular browsers or operating systems. While the software needed to create a vector image may be expensive, the viewers and plug-ins are usually available for download without cost to the end user.
For files created in Illustrator, there is no particular viewer needed. The Web format for Illustrator files is GIF, and it is a standard that works in virtually any graphical Web browser. Although Illustrator has the ability to divide drawings into layers, the GIF format merely rasterises the vector document, so there is no way to access its functionality. Illustrator files also generate text in PostScript format that could be searchable but, again, this is not part of the limited GIF format. Adobe has made provision for this with their product Acrobat, which uses the Portable Document Format (PDF) to create vector files that retain their formatting, and allow text to be searched. Acrobat's primary purpose, however, is to create vector files that will reproduce a document exactly when printed, not to create vector images. A way to access the functionality of Illustrator image files over the Web is still lacking.
Figure 3: Example of a CAD drawing displayed in AutoDesk's proprietary Web viewer
Volo View Express. Excavations in advance of an oil tank (Sector 2, Intervention 26) plan view
of horizons one and six from the Tarbat Discovery Programme (Carver 1998, The Settlements at Tarbat, Figure 4).
For files created in AutoCAD, the main viewer currently available is AutoDesk DWF Viewer, which includes (like its predecessors, Volo View Express and Express Viewer) the functions of pan and zoom and the ability to control layers. AutoDesk DWF Viewer is a new product, which now allows the viewing of 3-D DWF files, as well as object properties. AutoDesk DWF Viewer is proprietary, and users are therefore limited to the compatibility choices made by AutoDesk. While AutoDesk DWF Viewer is freely available, it is only compatible with Microsoft Windows XP or 2000, and Microsoft Internet Explorer 6 (Anon. 2006a). Much like AutoCAD itself, which is only available for the Microsoft Windows operating system, this seems unacceptably exclusive, not only for those who choose to use the Apple, Linux or any other operating system, but also for those who prefer to use Netscape, Opera, Firefox or any other Web browser. There are third-party options available for purchase that allow AutoCAD files to be shared over the Web, but most are expensive and also only available for the Windows operating system. It is unrealistic to expect a significant number of users to make a software purchase solely to view archaeological AutoCAD drawings on the Web, and once again the solution remains elusive.
Unlike programs like AutoDesk DWF Viewer, which are designed primarily for creating shared work environments, Macromedia's Flash (now owned by Adobe) has long been established as the primary tool for creating vector graphics for the Web. Flash files are viewed with Macromedia's corresponding browser plug-in called Flash Player. This plug-in is available for all major Web browsers and operating systems, and is already installed in virtually all Web-capable computers (Laaker 2002, 14). Flash is a mature technology with many features that appeal to archaeologists wishing to present vector graphics on the Web. Most people already use Flash, it creates small vector files and the Flash Player plug-in loads images quickly and efficiently. Flash creates vector images that include typographic tools, animations and dynamically generated content (Watt 2002, 504). More specifically, Flash allows Adobe Illustrator files and AutoCAD files in .dxf format to be imported and manipulated. Flash would seem to be an ideal solution for presenting vector graphics on the Web, and yet this technology is not widely used by archaeologists.
Looking more deeply at how Flash actually works, it is easy to see why it is not an ideal solution. Flash only supports the importation of AutoCAD files in .dxf format (Release 10) and so is bound to .dxf's limitations. This includes lack of support for standard system fonts, and the inability to use fills. Flash only supports two-dimensional .dxf files, so any three-dimensional AutoCAD files cannot be imported. In addition, Flash doesn't support scaling of .dxf files, which should be fundamental to any vector image (Anon. 2006b).
CAD isn't the only vector format archaeologists use, but even as a robust vector design tool, Flash is marketed toward aesthetic rather than content-rich Web design. Use of Flash does not necessarily result in a content-poor site, and much archaeological information on the Web could certainly be presented more effectively if aesthetics were given greater priority, but this 'style over substance' approach means a program like Flash is not ideal for most archaeological projects.
With choices that are either limited in function or substance, there appears to be a need for a better solution for archaeologists and many other disciplines working with vector graphics on the Web. This gap has been recognised by the World Wide Web Consortium (W3C) and they have attempted to address it with a new application called Scalable Vector Graphics (SVG). While always coupled with Macromedia's Flash for comparison, and even (erroneously) labelled the 'Flash Killer' (Laaker 2002, 14), SVG is only comparable to Flash in its ability to create dynamic, interactive vector images. In reality, SVG is a fundamentally different technology with a whole host of possibilities that may be of great interest to archaeologists. As a former Technical Editor for the Macromedia User Journal has stated 'the principal thing that the Web really needs is not a superb way of building flashy presentations...instead, SVG will succeed because it satisfies the need for an easy-to-use, inexpensive, dynamic, non-proprietary way to build graphical interfaces' (Cagle 2002, 12).
© Internet Archaeology
URL: http://intarch.ac.uk/journal/issue20/1/2.2.html
Last updated: Tue Jul 18 2006