These are general design guidelines and are not technical in nature. The intent is to be a resource for those involved in creating new interactive mapping sites. It includes suggestions on how to make sites more useful, tips on where to go for technical help, and examples of good and bad design. The guidelines are directed primarily toward designers of GIS-based sites, they are, however, intentionally broad to accommodate the variety of interactive mapping applications. It should be emphasized that creating an interactive mapping site is not a simple task and should not be undertaken lightly. Successful sites require a large investment in time and money. Updates are in brackets. These guidelines are copyright Karl Musser, 1997.


Designers should keep in mind the purpose of their site and their potential audience. Whom are you designing the site for? Is it for the general public or other GIS users? Are they likely to have a high speed connection or are they accessing your site via a modem? Questions like these will help you determine how much you have to worry about bandwidth and what level of instructions you should offer the user.


There are a few things all sites should have. The first is a title. Titles are particularly important in Web documents because it is used by Web searches and when a site is bookmarked. The title should clearly identify the contents of your site. For example, "Virginia County Interactive Mapper" is a much more informative title than "Java SDV."

Be sure to sign and date your Web pages. Solicit comments from your users. Feedback from users is the best means of finding out problems with your site and is a good source of suggestions. Dates are also important due to the rapidly changing nature of the Web. They allow a user to quickly tell if a site is being maintained and whether the data you present is up to date. Dating your pages is more effective than saying your data are "current" or "new." On a related note, maintain your site. You should periodically check your links to make sure they are still active and check any mapping tools (like query) that you offer to make sure they are working properly.

If you have a GIS-based site, be sure to include metadata if you want your data to be useful. Sol Katz (1997) maintains a list of metadata related resources, including standards. The GRASSlinks site demonstrates a nice way to unobtrusively include metadata on your site. Even if you do not expect others to use your data directly, you should still list your sources. It is also wise to explain the limitations of your data to help prevent any misuse. The TIGER site includes this sort of information in a FAQ list. If you want to be helpful to other interactive mapping Web site designers, you should also include some documentation on how you created your site. Some sites, such as GRASSlinks and Andy Wick's Cool Java Map Page, even include the source code on their pages. Currently there is quite a bit of documentation on how to use CGI to link a GIS to the Web. Documentation on Java and VRML is more difficult to come by.

Site Design

Web design guides offer quite a bit of advice regarding your overall site design. To briefly summarize you should make it easy to navigate your site and maintain a consistent look to your pages. Do not bury your content. Users should be able to access your data with three or fewer clicks (Lynch and Horton, 1997). If you have a large site, you should include a table of contents. The use of headers or footers is a good way to repeat an abbreviated table of contents on each page.

The biggest issue for interactive mapping sites is what type of GIS-WWW interface you want to use. The basic choice is between a form-based page using CGI and using Java. [There are other methods, such as using Active X, but I found very little information on them]. According to the responses I received both have their pros and cons. Java is more interactive and versatile, while forms are faster and more reliable. Java is also not yet supported by all Web browsers and generally requires more programming experience to implement well. Despite its problems, Java has more potential for truly interactive mapping. Most commercial browsers and GIS-WWW interfaces will probably support Java in the future. Bandwidth problems will also hopefully be overcome. The Mapquest site uses Castanet software to speed up their Java performance (Strand, 1997). The best solution is to offer more than one version of your site, then your users can choose whichever interface they prefer. Unfortunately, many sites do not have the time or resources to do this. You should base which interface you choose on the purpose of your site and your users. Some applications may be impossible without using Java. If you want to accommodate users with slow connections and old browsers you should stick with forms and basic HTML.

Page Design

Page design is what most Web design guides focus on. I will repeat some of the more important points here. Each page should be an independent document. Others may link to pages in the middle of your site and users may want to print out pages, so a page should be able to stand on its own. Web guides recommend a balance between text and images, to keep your page visually interesting. If you do not have any training in graphic design, you may want to take a look at the "Yale Style Guide" (Lynch and Horton, 1997). You should also keep you pages short, most guides recommend only one or two screens worth of information in a page. Longer pages, however, are easier to maintain and easier for users to print out. If you use a long page, it is a good idea to include internal links to different sections of the page. Most of the lists of Web sites used in this report use this approach.

"Creating Killer Web Sites" (Siegal, 1996) offers many tips on formatting pages in HTML. One useful trick is using blank GIF files to control the layout of your page. Tables can also be used effectively to control your layout. Recently it has become popular to use frames to display more than one window of information at a time. Frames limit how much space you can devote to your map and will slow down a Web site considerably. Since most interactive mapping sites need all the speed they can get I do not recommend using them.

Graphics and Map Design

Obviously graphics are the focus of most mapping sites. You should know the difference between GIF and JPEG files. GIF is better for drawings and vector type graphics. JPEG is designed for photographs and other images that require more than 256 colors. Most maps will probably look better in a GIF format. Large graphics do slow down a site, so I recommend avoiding using many images other than your maps. Background graphics especially slow down a site and make it difficult to read. Something like a small logo graphic is OK.

Be careful of the size of your maps. Several sites I reviewed had maps that did not fit on a 15" screen and could not be resized. You can use the HTML height and width tags to define the size of an image. Users with 14 or 15" screens will usually have a default resolution of 640 x 480 pixels. To be sure your map appears correctly you should restrict its size to 535 x 320 pixels (Lynch and Horton, 1997). [If your maps are better viewed at a different resolution, be sure to state this in your opening page].

Maps should follow some basic map design guidelines. Like Web pages, maps should have an informative title and be as independent as possible. It should be clear where in the world the map is located. This is especially important for large scale (small area) maps. Not everyone knows where the Murray Basin or Clinch River are located. Small scale maps can show location and orientation by including latitude and longitude coordinates and grid lines. Large scale maps should also include a locator map, making it easier for the user to orient themselves. Some indication of scale should also be included on all maps. Scale can also be shown using coordinates and grid lines on small scale maps. For larger scale maps I recommend using the traditional bar scale, or simply including the scale as a fraction (e.g., 1:25000). [Bar scales have an advantage of being independent of screen resolution and remaining accurate if the map is reduced or enlarged]. The TIGER Map Service and the Berkeley GIS Viewer are examples of maps with scales that change as the user zooms in and out. Finally, all maps need a legend. The query ability can substitute for a legend to some degree, but I still recommend one for any map that shows more than one feature. The Xerox Parc Map Viewer is an example of a site that can get away without having a legend, anything more complex should have one. Once you have a legend, make sure it is understandable. Having a legend with a bunch of codes on it is not much good if you do not explain the codes. Generally labels on your map are also a good idea, although they can clutter up your map. Many sites have labels as a layer which can be turned on and off, which is a good solution. Robinson (1995) provides a good guide to label placement.

Other aspects of map design are the same as more general graphic design. Monmonier's, How to Lie With Maps (1996) is a nice guide for basic map creation. Make sure that type on your map is readable. Features should be distinguishable, variations in the visual hierarchy should be used to make important features stand out. Try to avoid making the map too cluttered. The Cool Java Map Page is an example of a map that is difficult to read because of clutter and a lack of hierarchy. Use appropriate symbols and colors. Colors in particular are often used carelessly. Maps showing gradations in data from low to high values (e.g., many thematic maps) should use light to dark color scales or different sized objects. Primary colors, like those used on the Demographic Data Viewer site make thematic maps very difficult to interpret. [This note applied to version 1, Version 2 of the Demographic Data Viewer makes excellent use of color]. If your map is an imagemap, the hotspots should be obvious.

The best solution to map design is to put as much of it into the hands of the users as possible. Many sites give users control over colors and which layers are turned on. Other possibilities include control over line types, the order in which features are drawn, and what symbols are used for point features.


Some sites have made impressive displays using animation and VRML. Many Web guides recommend avoiding animation because of bandwidth concerns. Multimedia, however, is one of the things that attracts people to the Web. I encourage the use of animation and VRML, simply warn your users by listing the file size. This lets them know they are in for a wait. Do not use frivolous animations that do not contain any content (such as animated logos), they will simply slow down your site. There is a lot more experimentation that could be done with both animation and VRML. One possibility would be to use animation to show a time series of maps. VRML sites could try giving users more control over the maps, such as changing the base layer.

Unfortunately I do not have many tips for Java. Most Web guides do not have a section on Java. Try to keep Java applets as small as possible to minimize loading time. Otherwise, take advantage of what Java has to offer. You can embed menus into your map to make it easier to use. Beware of overwhelming users with options. Try to make it clear how your site works.

As I mentioned before almost no sites allow users to do spatial analysis. GIS vendors should incorporate abilities similar to those in GRASSlinks into their Internet mapping software. It should also be possible to make custom programs for spatial analysis in Java. The IRIS site is notable in that it allows users to manipulate the database directly, the site includes documentation. While there may be security concerns in giving users access to the database, this is another way to let them do their own analysis.

I did not have the time or resources to compare the different commercial GIS-WWW interface tools. The responses I received recommended avoiding making sites that require specific plug-ins. Requiring plug-ins restricts access to your site, and I did not see any plug-ins that did anything that could not also be done in Java.

Accommodating Differences

Most E-mail I received cited increasing access to spatial data as one of the goals in creating an interactive mapping site. With this in mind you should try and accommodate the wide variety of Web users. Do not design a site with a specific browser, such as Netscape, in mind. There are hundreds of different Web browsers and catering to one will exclude people that are using other browsers. Using Java contradicts this suggestion, but I suspect Java will be supported by more browsers in the future due to its popularity. You can do this by having multiple versions of your site, such as a Java and a non-Java or a frames and non-frames version. You can also accommodate text-only browsers by including alternate text for your images. Obviously those with text-only browsers will not be able to make full use of your maps, but they should be able to tell what is on your site so they know if it is worth going back to with a different browser. Your site will look different based on the user's browser and operating system. Test your site with several different browsers to see if it looks right. Siegal (1996) offers tips on how to control colors and layout over different browsers. If you switch to a different interface to take advantage of a new technology, like Java, it is a good idea to leave your old site up so that people with old browsers can still access it.

Make sure you have instructions on how to use your site and explanations of your data. If you are catering primarily to other GIS users, you may not need much explanation. Experienced users may even be annoyed by too much text, as they want to get to the data as quickly as possible. You may want to consider offering direct FTP access to your database so that they can skip the maps entirely. Unfortunately there is no standard file format that has gained common usage among GIS users, so you may want to offer several options if you decide to use FTP. One possibility to watch is the Spatial Data Transfer Standard from the Federal Geographic Data Committee (1997). Novices on the other hand, may not even know what a GIS is. For them you may want to not only explain your data and how to use the site, but general GIS concepts as well. The ICE site offers an example of how to accommodate both groups by offering extensive instructions and explanations as separate help files, which the experienced user can simply skip.

Think globally when creating your site. It is called the World Wide Web for a reason. This is one of the reasons I recommend using locator maps. Write out the date on your pages since the U.S. and Europe use different conventions when abbreviating dates. Avoid slang or jargon that may be difficult to translate. See Lynch and Horton (1997) for other tips on how to accommodate other languages.

Last updated 8-10-97

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