A map is a scale representation of a geographical environment. The purpose of a map is to provide a meaningful picture of reality. A map, therefore, can be a particularly useful guide in the orientation of terrain, as well as conveying other multi-faceted information through supplementary annotations. The map is the basic feature for numerous applications in the Geosciences: Geology, Tectonics, Geophysics, Seismology, Geothermics, Geomorphology, Geochemistry, Volcanology, Marine Sciences, etc. Cartography is the art and technique of map reproduction. It is in a narrower sense to be characterized as a refining process between the original source material and the reproduction.
Digital Cartography involves the creation and analyses of maps through the use of computers. As such, Geographical Information Systems (GIS) are an integral tool for Cartography. Digital Cartography is sometimes called computer cartography. Digital Cartography is very widespread.
Various Thematic and Ortho-photo Maps (using the Arc/Info and ArcView GIS software packages) were created, following the demands of Cartography (e.g. scale, generalization, map projections) in the Space Applications Research Unit during the last few years.
Cartography is the art of actually drawing the maps. There are several strategies for doing Digital Cartography. One can do it entirely in the raster domain. This is most similar to the mylar techniques. The main problem is cleaning up the USGS base maps, which have a lot of stuff that is extraneous or even wrong. We could start from a scan of our current maps but this does not help in regions were we need to extend the coverage. If we decide to do 100 ft contours instead of the 20s that are on the quads, there is even more stuff to remove.
One can do it in a pure vector mode. One has to spend a lot of time vectorizing the raster data. There are programs which aid in this process by following the curves and producing vectors, e.g. the contours. The problem is that the programs get confused when the contours get close together or have breaks, for example where the height is imbedded in the contour line. It requires a lot of hand touchup. It can follow individual colors so it is not confused by crossing streams and roads. In vector mode one would plot the trails directly from GPS data or draw the trail on a map and digitize it. I have not seen the output of a pure digital map at high resolution so it remains to be seen how good it is. Herbie has a lot of the 1:100000 maps and has produced some incouraging output. It has 20 meter contours and that may be a show stopper for those used to feet.
One can produce contours from DEM data. NYS now has 10 meter DEM almost available. This is accurate enough to show most but not all features. The data can be used by a program such as Surfer or the Spatial Analyist extension of ArcView to produce contour lines at any spacing, e.g. 20 feet instead of the meters that the data format has. This process produces some artifacts which have to be cleaned up by hand.
One can do a mixture of raster and vector data, e.g. a base map of fixed up USGS quads as above with the trails overlaid with a vector representation.