in this method, three well defined points, having locations already being plotted on the drawing are involved. These are used to find and subsequently plot the location of the plane table station.

The method is based on the fact that, in a correctly oriented plane table, resectors through well defined points get intersected at a point which represents the location of the plane table station on the drawing. For example, as shown in Figure 35.1, if X, Y and Z are well defined objects present in the field whose plotted positions are x, y and z. Now, if the plane table is oriented correctly, the three resectors X_x, Y_y and Z_z get intersected at p which represents the location of the plane table station, P on the drawing sheet. Thus, through solution of three-point problem, both orientation and resection of plane table gets accomplished simultaneously.

There are several methods for solution of the three point problem: (i) trial and Error method, (ii) mechanical method, (iii) graphical method, (iv)Analytical method and (v) geometrical construction method. Of these, the trial and error method is easy, quick and accurate. It is commonly used in practice and hence, has been discussed in detail.

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