Methods Of Plane Tabling
Radiation
Intersection
Traversing
Resection
-Special Methods of Resection
Two-point problem
Three-point problem
RADIATION METHOD:
In this method the objects are located by radiating lines from the point, and measuring the distance with chain or tape with suitable scale. It is chiefly used for locating the details from the station, which have been established previously by other methods triangulation, or traversing.
INTERSECTION METHOD:
In this method the point is fixed on the plane by the intersection of the rays drawn from the two instrument stations. The line joining the stations is called Base line. The method requires only the linear measurements of this line.
TRAVERSING METHOD:
This is similar to that of Compass Survey or Transit Traversing. It is used for running survey lines between stations, which have been previously fixed by other methods of survey, to locate the topographic details. It is also suitable for the survey of roads, rivers, etc.
This method is used for establishing the instrument stations only. After fixing the stations, details are located either by radiation or intersection.
ERRORS IN PLANE TABLING
Following precautionary measures should be taken while performing field work:
The table must be accurately oriented once the table is shifted.
The alidade should be correctly centred on the station point on paper.
The expansion and contraction of paper should be taken care off.
The table should accurately centred.
The rays should be accurately drawn through the station points.
Table should be sufficiently clamped.
The board should be horizontal.
The objects should be accurately sighted.
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