19-06-2012, 04:22 PM
Plane Table Survey
Plane Table Survey.ppt (Size: 567.5 KB / Downloads: 52)
Plane Table Mapping
Note: While carrying plane table survey, you have applied the principle of triangulation, which is the basis of all map-making and cartography
Plane Table Traversing
This method of plane table surveying is used to plot a traverse in cases stations have not been previously plotted by some other methods. In this method, traverse stations are first selected. The stations are plotted by method of radiation by taking back sight on the preceding station and a fore sight to the following station. Here distances are generally measured by tachometric method and surveying work has to be performed with great care.
Radiation Method
In the radiation method of plane table surveying, the direction of the objects or points to be located are obtained by drawing radial lines along fiducial edge of alidade after getting the objects or points bisected along the line of sight of the alidade. The horizontal distances are then measured and scaled off on the corresponding radial lines to mark their positions on the drawing.
Resection
This method of plane table surveying is employed to locate and plot the position of the plane table during surveying. This also results in the orientation of the plane table. The basic principle of resection is opposite to that of the method of intersection. In this method, the position of the plane table is determined by drawing resectors from already plotted points. There are different methods for locating plane table by method of resection and are primarily based on the type of orientation which precedes resection. Of these, resection after orientation by three points is widely prevalent and has been considered in the next section.