DACS General Meeting
January 2009
Program Review:
Digital Cartography

by Rob Limbaugh

Our Digital Cartography presentation kicked off with an icebreaker activity that Ed Hicks shared with us. Groups of 12 were given map sections and told that they needed to locate the persons with adjacent map pieces and find out some details about the individual. Afterwards, the maps were assembled.

Ed took us through the history of map making and the concepts behind it. Markers and maps going back many thousands of years have been found. The earliest maps were certainly not portable, as they were often large stone engravings. As tools and skills progressed, so did cartography. Paper, of course, made maps portable. One of the more recent ingenious designs was a wrist band that held multiple scrolls.

There are many different types of maps. Different maps are made with different technologies. For example, infrared imagery can enhance features, such as foliage, to bring out better detail. Other maps, such as those used for the sport of ‘orienteering’ may be made from scratch using a starting point and manual mapping techniques, or may be overlaid on an existing map to enhance the details with things such as stone walls, fences, sheds, and other items not commonly found on road maps or even Google Earth.

Orienteering is a sport in which participants use a highly detailed map and compass to find various positions and points of interest on or in the landscape. There is usually a ‘start’, control sites, and a ‘finish’. Orienteers use a punch card to mark the places they have been.

When merging existing map data with another map or new data, it is important to know what type of coordinate system, or datums, each map uses. Coordinates that may appear to be similar might have many feet of discrepancy when compared to each other due to differences in the datums. If merging multiple maps, the coordinates must be converted into a common format. WGS 84 (World Geodetic System Revision 84) is the most common datum and is used in GPS equipment.

OCAD is an application used to create new and composite maps. It uses vector drawings so a map can be printed in various scales—even several feet across—without losing detail or pixelizing. Ed showed us how an existing map could be accented with features such as a trail, a building, or other details that may not be present on the source map. OCAD is capable of making maps for use with outside terrain or even those found on mall directories showing stores, exits, and bathrooms.

For more information about Digital Cartography, check out Ed Hick’s website at http://www.orienteeringunlimited.com.