What makes the map different from the other maps the Trail Conference publishes?  As you can see in the snippet of the map above the map uses shaded relief. There are many more wiggles in the hiking trails because the field checking was more precise. But the biggest change, largely invisible, is in how the map was put together.

Since 1975, the Trail Conference has used USGS topographic maps as the base for their hiking maps. Unfortunately, many of the maps are so old that they need numerous corrections. The cartographic process involved working with layers for each color and painstakingly adding and subtracting the information layer by layer. Within the last 4 years, computer programs for drawing and digital technology have improved so that is it possible to produce a high quality map completely on a computer.

Instead of starting with data that needs correcting, the Trail conference can now start from digital elevation maps (DEMs) in which the elevation on a 10 meter grid is measured from aerial photographs. The information is then used in two different programs. One creates shaded relief which interpret the slopes on the map. The other draws contour lines at a selected interval, 50 feet in the case of the Sterling Forest map. USGS also produces digital line graphs (DLG’s) which have all the features such as roads and streams recorded as line segments with lengths, directions and feature codes. The results of these programs are combined to produce a base on which the trails can be laid.

While all the base layers were being integrated together, other volunteers were busy finding out exactly where the trails went. Chris Cesar developed a method using a compass, measuring wheel, altimeter and keen observation to obtain good measurements. He trained others to use his method, took their data and then ran a special computer program that plotted the trail.

A special thanks are due to Herb Chong for his wizardry to make the base and to John Jurasek, Steve Kelman, and Joe Bohmer for the field work. Fancy new maps warranted a new design for the map backs, which Steve Butfilowski volunteered to do.

Over the next few years Trail Conference maps will gradually be switched to the more accurate and easily updated digital maps. The switch will happen at a faster rate, if there is a larger cadre of volunteers available to work on projects. Chris Cesar’s manual method of data collection has been upgraded. In November 1999, thanks to partial funding via a grant from the Greenway Conservancy for the Hudson River Valley, the Trail Conference was able to purchase a commercial grade global positioning system (GPS). The information the GPS collects can be corrected to an accuracy of 2-5 meters, smaller than the width of the trail on the map. The collector still has to be observant, because even that small error can place the trail on the wrong side of a stream.

If you are interested in helping on the next digital mapping project, you will need to learn either the digital cartographic skills or the GPS measuring techniques. Training will be provided. Call the office 201-512-9348 or e-mail info@nynjtc.org. More details about GPS and digital cartography are available at http://www.nynjtc.org/news/sfmap.html.