SUBCOURSE EDITION - Modern Prepper

4-13. Plotting Positions of Control Stationsa. Rectangular Grid Coordinates. The station description cards or trig lists furnished for controldata, normally give the grid coordinates of the control station. The positions of the station can beplotted on the compilation base using the same methods described in paragraph 4-11c or 4-12 for theplotting of projection intersections. After the point is plotted, it should be carefully identified andlabeled.b. Geographic Coordinates. Control points may also be located and plotted using thegeographic coordinates of the projection. The nearest projection ticks should be connected andsubdivided into 1-minute quadrangles. Each 1-minute quadrangle, which equals 60 seconds, can bedivided into 60 divisions using a metric scale. On the scale, choose a value easily divisible by 60, such as60 millimeters, 120 millimeters, 180 millimeters, or 240 millimeters and capable of covering the distancebetween the minute lines. Each value of 1 second is then equal to 1, 2, 3, or 4 millimeters, respectively.The number of seconds multiplied by these factors equals the number of divisions to be plotted.4-14. Accuracy RequirementsThe final accuracy of any map depends upon the accuracy of the grid, projection, and control plotting onthe compilation. To maintain the required accuracy, the grid must be plotted to 0.13 millimeters (0.005inch), the projection must not be in error by more than 0.13 millimeters when referred to the grid, andthe control must be within 0.13 millimeters when referred to the projection.143