No matter what the purpose, making a map requires similar steps. Here is a summary of some of the major steps involved in producing a map.
Step 1: Collect the Data
The first step in creating a map is to collect accurate data. Research may involve the collection and evaluation of mappable information firsthand through field work, or secondhand from existing maps, aerial photographs, statistical reports, computerized data files, or other data sources. Research also may involve the development of new cartographic methods and symbols, as well as the evaluation of their accuracy and effectiveness in representing the original data and communicating these to the map user.
Step 2: Compile a Base Map
Existing maps, such as U. S. Geological Survey topographic quadrangles, may serve as a base upon which geologic, land use and other information can be added. A photomap also may be assembled, and special features highlighted to form a base map. Sometimes very precise instruments are used to compile the information from aerial photography. If suitable base map data are not available in digital form, then geographic data need to be digitized and edited as the first step of base map compilation. This can be a time-consuming process that is often done by outside contractors who specialize in such services. The trend is toward more direct field data coding, especially with the use of Global Positioning System (GPS) satellite data.
Data collection can be very expensive, but with good design the same database can be used by many organizations for a wide range of purposes. Once the digital records have been created they can be entered into a digital database that can be used repeatedly. For example, in the 1980's the U.S. Geological Survey was able to create digital versions of its maps that were then used by the U.S. Bureau of the Census for the 1990 and 2000 Census of Housing and Population. These same digital maps are now widely used for land use planning, automated routing and map production.
In many parts of the U.S. and Europe, local governments have established consortia to generate large scale digital photographs with resolutions as small as one meter. With sophisticated computer processing and highly accurate ground control points these digital photographs provide excellent bases for generating base maps of roads, buildings, water bodies, and land use. They also provide the base for generating digital elevation files.
When complex color maps are being prepared, an assortment of prepress color proofing systems allows careful color control before printing. A growing number of maps are produced specifically for users of the Internet. These are usually printed at the user’s workstation or displayed on a screen.
GIS databases are critical for making decisions about a range of activities including zoning, permits, location of facilities, road construction, school planning and routing of buses and emergency vehicles. Because the data are so important to community operations, it is important that they be developed according to rigorous standards and carefully edited and maintained.
Step 3: Design the Map
Map and chart design involves the planning of every detail and step of a specific cartographic project. Cartographers must select the appropriate geographic data. During the data collection stage, they must ensure that the appropriate data are available. They then must make decisions regarding map projection, scale, symbols, fonts, and placement of text, as well as the methods of production and printing.
The cartographer must balance the requirements of effective design against those of time and cost. At this stage he or she often prepares rough or detailed prototypes. Traditionally, changes in maps have been expensive and complicated. Design with computer assistance or GIS technology provides a much wider range of choices than traditional methods, allowing mapmakers to consider many alternatives.
Step 4: Prepare the Artwork
The combination of increased processing power and reduction in cost have made digital map production economically feasible without sacrificing quality. The advancements in speed and resolution of new printing technology have made production of color maps dramatically faster and less expensive. The aesthetic quality of graphics produced by computer-driven printers and plotters has surpassed that achieved by painstaking hand drawing, particularly in shading and relief.
Step 5: Print or Distribute the Map
Maps to be reproduced in large quantities are usually printed by offset lithography, but with digital methods, maps can be created on demand and customized to meet the customer’s requirements. While the cartographer may not be directly responsible for printing the map, close cooperation with the printer will be necessary in the checking of proofs, making final adjustments in color selection and registration of the plates.
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