In this method, a number of radial lines are set out at known angular interval at each station and points are marked at the ground at convenient distance apart on the rays that are set. Spot levels of these points are determined by leveling. The points are plotted to the scale of the map and spot levels are entered. The contours of desired values are then located by interpolation. This method is convenient in hilly terrain with level stations chosen at high points so as to command a large area from each. Horizontal control may be obtained by taping (Figure 17.13).

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