The GIS profession has always maintained a community-focused perspective that pervades both the development and use of geospatial technology. That perspective undoubtedly grows out of the fact that working with map data leads to the realization that the world is fundamentally finite and has few insurmountable barriers. As the GIS community has evolved over the last decades, pioneering companies like ESRI have encouraged the development of a GIS professional archetype; one who, while recognizing the value of a paycheck, also keeps in mind the simple interconnectedness that is obvious on a map and the resulting implication that local actions may have far-reaching effects.

Geospatial technologists currently find themselves in the whirlwind of Web 2.0 technology, which has popularized Web-based GIS in a manner that threatens to wrest the concept of the GIS developer away from the GIS community. The GIS establishment has the responsibility to bring its heightened level of community awareness to these new technologies and applications of GIS. An easy place to start would be to address an area that has been underrepresented in GIS technology but which addresses fundamental characteristics of GIS data openness and sharing: making Web-based GIS tools more accessible to visually impaired and blind users.

Many writers have described the Internet as a leveling technology that improves access to information for everyone. The reality is that the Internet offers a variety of technologies for information sharing, some of which are accessible to anyone who can read text and some which are not as accessible.Companies are rapidly adopting Web development techniques such as Adobe Flash, graphic design and JavaScript to enhance the user's experience.Unfortunately, poorly designed Flash animations, images with no descriptive, alternative ('ALT') text, and JavaScript-masked hyperlinks (anchors in a Web page that use JavaScript to redirect the page instead of simpler HTML) will impede the ability of blind users to access Internet-based information.Also, poor color choices and fixed text sizes may render websites useless for colorblind or moderately visually impaired users.

The population of Web users with some sort of visual impairment may be larger than you realize.It's safe to say that at least 5.5% of the Web-surfing population is colorblind (based on a calculation of the proportion of the general public that is colorblind - male-to-female Internet usage ratios actually suggest that the number may be closer to 7% or 8% in the US). According to the American Foundation for the Blind, approximately 1.5 million American computer users are blind or visually impaired. Furthermore, consider anecdotal evidence such as this: during a casual conversation, a friend of mine mentioned that the CEOs of her two former companies both needed to adjust Web browser fonts to the maximum size to read Web pages. Some of the current Web technology trends include so-called AJAX user interface tools that heavily employ JavaScript, complex style sheets that use fixed font sizes, and even mapping applications with built-in Flash and other less accessible technologies. Because of these trends, a gap has developed that threatens to make Web-based GIS and non-GIS applications less accessible to the blind and visually impaired.

Aside from the need to be good corporate citizens, there are compelling legal reasons for GIS developers to build Web-based mapping applications that provide access to the range of visually impaired and blind Web surfers. Numerous localities including the U.K., the U.S. and many individual states have legislation that has been interpreted by their respective courts to require that websites used by government employees or served by the government to the general public must be accessible to Internet users with visual disabilities. (The SAP Design Guild offers an interesting discussion of international Internet accessibility efforts.) Most of the Web-based and stand-alone GIS applications that I have built fall within one or the other of those categories. Not surprisingly, none of those projects included the requirement that accessible techniques be applied to those applications to accommodate visually impaired users. Although it is my understanding that there have been relatively few lawsuits to date, the implications of an aging workforce which has greater Internet acumen, increasing levels of visual impairments, and greater lobbying power may expose the GIS community to more pressure to increase the accessibility of mapping technology.

Once the need for creating accessible GIS websites is recognized, the next step will be to figure out how to evaluate a website for accessibility. For legally blind Web surfers, a website needs to be "readable," in that an assistive technology application is used to speak aloud all of the readable text on a page with some context information to support navigation. A combination of straightforward HTML element use and nuanced page layout combine to facilitate website readability for such users. Additional techniques improve readability for colorblind and visually impaired users.

Fortunately, many tools exist that will help evaluate a website for compliance with Web accessibility standards, such as those being developed by the W3C's Web Accessibility Initiative. The Ohio State University Web Accessibility Center offers a compilation of Web-based tools to help developers analyze accessibility compliance for websites, including tools that will show a developer how a page actually looks or behaves for a visually impaired user. IBM, Adobe and other software vendors offer guidelines for building applications and websites that improve accessibility.

Figure 1. Wickline's Colorblind Web Filter offers the developer the ability to see a website as a colorblind user might see it (filtered version on the right). Clicking on the map in this particular website leads to a Flash mapping tool that is completely inaccessible to the blind user. (Click for larger image)

Although many projects may not budget the time for accessibility development and the expense of acquiring text-to-speech software for Web browsing, the Lynx text-based Web browser can show the sighted user a rough idea of the website text that will be read to a blind user. While not used heavily by the blind or visually impaired community, the Lynx browser is free and offers sighted users some insight as to how informative and navigable the text information in a Web page may be. Lynx won't process AJAX, JavaScript-based hyperlinks or Flash, so it also gives the developer a feel for what functionality simply won't work in JavaScript-disabled Web page reading software. Be aware that some page reading software will process JavaScript and Flash, so Lynx is not a complete representation of how a website reads to a blind surfer.

Figure 2. The Lynx Web browser reveals that one well-known, but unnamed, company has a website that may appear to be attractive to the sighted user but is complete gibberish to any Web surfer who only has access to text information. This also happens to be a poor design for search engine optimization, as there is no text information to index for content-based search. (Click for larger image)

Once the GIS developer has digested all the tools to assess website accessibility, the realization strikes home that ultimately GIS has one simple problem. The most popular representation for GIS data on the Internet is an image. Is it even possible to make an image more accessible to blind or visually impaired users? In fact, there are many techniques available to GIS developers to make map applications compliant with accessibility laws and standards.

The simplest approach, tackled in an article by Seth Duffy while making his mapping website more available to search engines, is to provide text-based tabular information for critical map coordinates matched to descriptive text that any Internet user may access. Given that many developers are already going through hoops to parse their GIS data for inclusion in JavaScript-based tools such as Google Maps, it should be trivial to provide a link to an alternate page that simply prints out a table of coordinates with descriptive text.

Other techniques that could assist the visually impaired user would be the ability to switch to higher-contrast map coloring, access to toggles to increase symbol and label sizes, and the ability to resize and redraw a map to spread out the map information over a larger page area. Even though these techniques may be obvious, the difficulty in finding mapping websites that employ them suggests that the issue of accessibility is generally missing from the development criteria that drive the online mapping world.

New technologies, such as the recently introduced Google KML search, may also open up the interaction between the Web and the real world for the blind mapping enthusiast.Future Web mapping applications and GPS sharing sites might keep in mind the use of technologies such as voice- and GPS-enabled PDAs and touch tablet technology that open up geospatial data collection and analysis to the blind. The AFB website offers reviews of geospatially enabled technologies. The Royal National College for the Blind's T3 Talking Tactile Technology also offers templates for teaching geography. The GIS industry has long recognized the leveling ability of mapping data and technology. The industry must ensure that its traditional community-based ethics perpetuate, even as inevitable changes in technologies and applications take GIS in new directions. Ensuring and enhancing accessibility to Web mapping applications for blind and visually impaired Web users seem like the obvious place to start.