THE GRAPHIC REPRODUCTION OF A COORDINATE NETWORK ON A CATHODE-RAY TUBE USING A COMPUTER,
FOREIGN TECHNOLOGY DIV WRIGHT-PATTERSON AFB OHIO
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Two methods are described for plotting a geographic network on the screen of a cathode-ray tube, using a computer. The first method involves the calculation of Cartesian coordinates of latitudes and longitudes based on formulas for a stereographic projection. The second method is based on the consideration of equations of isolines latitude and longitude described in Cartesian coordinates. The methods described can easily be extended to other types of projections. In principle, the method of plotting charts on a cathode-ray tube is similar to plotting charts with mechanical printers. However, due to the high resolution of the CRT, isolines appear as a continuous line. Formulas are derived for describing latitude and longitude in both methods, and two computer programs for the process are given. It is stated that the time required to plot a network using the first method is 1 min 30 sec when the pole falls outside the screen limit. With the pole on the screen, the time is about 3 min. For the second method, the times are 30 and 42 sec, respectively. A geographic network produced on a CRT can be used as a datum to which weather data can be related in order to obtain weather charts or isoline charts.
- Cartography and Aerial Photography
- Computer Hardware