Internet Archaeol. 20. Wright. Scalable Vector Graphics (SVG) and Archaeology

3.2 The development of SVG

Scalable Vector Graphics (SVG) is something entirely new. Far from being an inexpensive substitute for Flash, SVG belongs to the growing family of open-source World Wide Web Consortium (W3C) technologies that are actively shaping the way information is presented on the Web, and it is best understood when viewed within that context (Winter and Neumann 2003). As with any other discipline, the philosophy of 'best practices' dictates that those working in archaeology should use and promote solutions that consider the larger issues in Web development, and SVG falls into this category. To understand SVG and how it fits with other W3C recommendations, it is important to explore how SVG developed.

When Tim Berners-Lee founded the W3C in 1994, his purpose was to help stabilise the implementations of his expanding HyperText Markup Language (HTML) used to create the World Wide Web (Cagle 2002, 8; Berners-Lee 2000, 143). Berners-Lee never expected HTML to become the phenomenon it is today, but the fact that he chose to make it open-source and therefore freely available to anyone, sparked a creative surge that should be instructive for anyone weighing the value of a new technology. By bringing together developers from disparate and often competing vendors, the W3C guides the intentionally unwieldy Web forward with some sense of cohesion. A marked example is the 'browser wars' of the late 1990s, a proprietary struggle which resulted in frustrated designers trying to create multiple sites that would work with different browsers, and frustrated users who never knew if their browser of choice would work at any given website (Zeldman 2003, 26). The W3C tries to be a voice of reason, and that voice has become increasingly authoritative (Castro 2003, 16).

The success or failure of a commercial Web product is now understood to depend more on universality than carving out its own niche. This is good news for designers and users alike. In practice, the workings of the W3C are necessarily contentious, but through the W3C 'official recommendations' system, commercial and non-commercial developers are brought together to give input into a standard, which creates a sense of where a technology is going and how to concentrate their own design efforts (Watt 2002, xxiii; Berners-Lee 2000, 129).

SVG was developed to address the lack of an alternative to the raster images that dominate the Web (Watt 2002, xvii). Raster is the native, and therefore most appropriate format for images such as photographs, but even with file compression, the most common image file formats, .gif and .jpg, create large files that are slow to load, with limited image quality. The practice of 'thumbnailing' an image to give the user a small, quick-loading preview is a common practice. If the user chooses to click on the thumbnail to bring up a larger version of the image, they may regret their choice. Most web users have a common experience of sitting, annoyed and waiting, wishing they had not clicked on a slow-loading image, only to be rewarded by a poor-quality result. Web designers have been working around the conflict between low bandwidth and large raster file sizes for years, and only the advent of inexpensive broadband has started to mitigate the problem.

XML is an entirely text-based language that creates comparatively small file sizes, so calling on its extensible nature, developers looked for a way to develop a graphics format that could be text based as well. For example, SVG is written in XML, so the SVG markup for a circle is simply <circle> </circle> which makes it perfectly understandable to humans. A circle, marked up in SVG, with a radius of 50 pixels and a black outline of three pixels looks like:

<circle r="50" style="stroke-width: 3: black: fill: none;"/ >

Because vector graphics render from text, they can be recalculated using different variables each time they are loaded (Watt 2002, xvi). By changing the radius from r="50" to r="100", the size of the circle will become larger, but it will retain all of its other characteristics. This allows users to pan and zoom around an image at any magnification without loss of image quality, because the vector image just re-calculates each time. This ability is completely basic to the workings of a vector graphic, but impossible for a raster image. Making out details in small raster images can be very difficult. Many Web users share the experience of trying to obtain driving directions from a website using raster-based maps. When zooming into a particular area close enough to read the street names, the image becomes so 'pixilated' (blocky or jagged) that the text is obliterated because the resolution is too low. Vector graphics create images that look good no matter the level of magnification.

The commercial sector was quick to see the potential for defining a graphic specification for XML. Adobe and Microsoft both submitted proposals to the W3C in 1998, the same year XML became an official recommendation. Adobe's submission was called Precision Graphics Markup Language (PGML) and Microsoft's was Vector Markup Language (VML) (Story 2002). Macromedia's Flash specification was also released at this time in a non-XML binary format. Macromedia chose to throw their support behind Microsoft's bid against Adobe, their traditional rival. The SVG working group took both specifications under consideration, and chose to merge the two technologies into what would become SVG. Through the working group, a wide variety of vendors were able to contribute to the process of creating the specification. These included AutoDesk, IBM, Netscape, Apple, Sun Microsystems, Xerox, Corel, Visio, Hewlett-Packard and Quark. Despite SVG's subsequent adoption as an official W3C recommendation, Microsoft, in typical proprietary fashion, has continued to use VML. The result of this is a browser plug-in that is only compatible with Microsoft Internet Explorer 5 for Windows (Cagle 2002, 10).

The development of SVG also set historic precedents for the W3C. As stated by Chris Lilley, chair of both W3C SVG working groups, SVG was

'a demonstration of the process that enables competing companies to come together in a vendor-neutral space and work on commonly agreed, open specifications for the benefit of the Web in general and to grow the market. SVG was the first specification to not only have a test suite, but also publish the results of testing on named implementations. During the Candidate Recommendation phase, implementers and content creators gave a large amount of valuable feedback that helped to improve the clarity and technical accuracy of the specification. As a result, compared to other specifications at an equivalent level of maturity, SVG was extremely well implemented by the time it became a W3C Recommendation on September 4, 2001.' (Watt et al. 2003, xxiv)