Gallery of Australian Boating Maps
About the application that created these maps
These published maps were created by users of the Map Wizard, a flexible map generation system I wrote for Waterways, in Sydney, Australia. The program was based on the Wizard model, which is not typically used for map production. In this case, however, the design specifications called or an easy-to-use application that required no special training, and for this a Wizard-style interface seemed ideal.
In order to create an acceptable interaction between the system and the user, several new techniques were developed for this application. The first was the wizard interface itself. While the idea was hardly new, applying it to a complicated map production application was. The composition and generation of the map was broken down into simple steps, with a dialog box presented for each. After each step, the map was redrawn, incorporating the new information. The user also had the option of returning to previous steps and altering the location or presence of various items.
To define the map extent, the user could either select a preset area, or, after selecting a map scale and page size, be presented with a bounding box that could be dragged across a schematic map of the region to select the exact area to be covered by the map. If the desired region did not fit into the box, the map scale and page size could be altered, or the user could draw a bounding box freehand with an arbitrary mapscale.
After the user selected the proper map extent, he or she could select the data layers to be drawn, and add and place elements such as inset maps, the legend, and additional text.
The interactive nature of the Wizard interface required that map elements be redrawn quickly as they were modified or repositioned. ArcInfo, however, can take minutes to draw a complex map on the screen. While individual elements, such as a north arrow or border redraw quickly, compound elements such as a map legend or inset map can sometimes take up to several minutes to redraw, a time lag that is simply unacceptable in an interactive application.
To avoid the need to redraw complex map elements as they were moved about the screen, the program performed a screen capture of each element after it was initially drawn. As the item was repositioned, the base map in the destination area was captured, and the moved item was redrawn from the bitmap in memory. By using this technique, the user could interactively rearrange map elements and see exactly how the map would look, while the program remained responsive.
Perhaps the most challenging aspect of this program was the drawing of borders. The main map and each inset had a border of two parallel black lines separated by a thin white line. If the insets were positioned too close to the edge of the page, a sort of moiré pattern would be created, with dizzying results. To solve this problem, insets within a certain distance of the edge were "snapped" to the edge of the main map and to each other, and the borders were merged to reduce the numbers of parallel lines. Calculating all the border intersections and joining them together in an attractive manner was exhausting. The trick we finally used consisted of drawing all the black lines first, and then adding an opaque white line between them. (The Upper Georges River map contains a good example of this).
Once the final map was produced, the user could select whether to plot the map in-house, or to create a postscript file to send to a professional printer. The program would also automatically create an AML file which would be able to reproduce the map exactly should the datasets change and the same map require regeneration. This last feature had the unexpected benefit of allowing advanced users to create customized maps by modifying the generated AML code by hand to add additional map layers, symbols, or text. This was far easier than coding a new AML from scratch.
While challenging to program, the Wizard model proved quite successful. The Map Wizard system can be operated with very little training, and is now used to create a variety of published maps, including some that were used in the planning of the 2000 Sydney Olympics.
Entire site © 1996-2004 by Christopher Eykamp