Tagger: Code for building online fuzzy / vague GIS (v2.5)

Centre for Computational Geography
University of Leeds

The code below allows developers with no knowledge of java to construct an online fuzzy GIS. This allows you to capture areas with indistinct boundaries and a range of internal intensities. For example, places people think are "high crime". They do this using the "Tagger Tool" - a spraycan, the spray from which they can attach attribute data to.

The code has three different Applets that can be set up as interfaces to the system. Users can add fuzzy areas and attach text attributes to them using the TaggerInput Applet (example). Once data has been added to the system, if the developer believes it appropriate, all the users' combined data can be displayed back to the users using the TaggerQuery Applet (example). Finally, an administrator can uncompress or combine individual's data for further analysis using the TaggerAdmin Applet (example).

Warning: Bug: version 1.0 of this software had an error when working with Netscape 4.x. Version 2.0 has not yet been tested on this platform. When it has, we will remove this notice. The system has been tested on Netscape 7.x and IE6.x

Warning: Setup: the CGI Scripts require that the log directory is owned by the webserver.

To set up the Applets / System for yourself, download this jar file and save it where you want your webpages with the Applets in to reside: tagger2_5.jar. Then look at how the example Applets are set up - you'll need to change the size and PARAM tags to suit your application. The PARAM tags allow for different user interfaces and internationalization. You can find out about the PARAM tags here:

• TaggerInput PARAMs
• TaggerQuery PARAMs
• TaggerAdmin PARAMs

The main thing you'll need in the same directory is a map image in gif format - in the examples this is called mapImage.gif. The gif should have a transparent background.

You'll also need to set up the following server scripts in your cgi-bin: imageScript.pl, arrayScript.pl, and logScript.pl. See the information at the top of the scripts to find out which variables need setting up.

The system saves various files to the server:

• Compressed image files: small images showing individual user sprayings. These can be expanded to the proper size using the TaggerAdmin Applet. The files are named with an ID number used to track the user through the other files. The expanded images also have ".b." or ".big." in their filenames.
• The TaggerAdmin Applet will also combine two or more images into an average image showing all user sprayed areas. This is saved with the filename "c" or "combined" on the server.
• A comments log, containing UserIDs, comments, and any cgi generated "passThrough" text (see TaggerInput PARAMs).
• A small log of just the IDs.
• A binary (non-human-readable) file containing the images in a compressed format.

This code may be freely used by academic and non-profit, non-governmental organisations, as well as private individuals. Other organisations should contact the CCG for information on its use. This tool is offered "as is", with no guarantees, but feel free to drop us a line if you find any problems or want some advice. Feel free, also, to drop us a line if you're using the system for something - we're always glad to hear about it. If you do use the tool, and write up its use in a report or paper, it'd be helpful for us if you'd reference one of the associated documents.

For further information about this software and getting hold of a copy of the source code, contact Dr Andy Evans or Tim Waters (tim@cycletourer.com).

[CCG homepage] [School of Geography homepage]