2021-08-06 19:23:07
SurveyingPlane table surveying Principle of plane table is
parallelism The North line of the map is marked on the right hand top corner
It is graphical method of surveying where the field work and plotting are done simultaneously.
The working edge of the alidade is called fudicial edge or bevelled edge
Orientation :- The preparation of keeping the plane table at each station parallel to the position occupied at the previous station is known as orientation.
Orientation by back sighting is more accurate than magnetic needle method
Methods of plane table Radiation :-
~ Detailed plotting generally done by radiation.
~ These method is suitable for survey of small areas which can be done for a single station.
Intersection :-
~ It is employed when inaccessible points to be surveyed
~
Suitable for hilly areas Traversing :-
~ It is used to plot the areas
Resection :-
~ Resection is the process of finding the location of plane table with the help of known locations.
~ Resection is done by following methods
1.
Compass method2.
Back ray method3.
Two point method :-
~ It is more laborious than three point problems
~ Orientation of plane table by solving two point problems is adopted only when given points are accessible
4.
Three point problems~ methods of Three point problems
A.
Trial & error (Lehmann's method) :- It is more accurate and quick
B.
Mechanical method (tracing papar)
C.
Graphical method (Bessel's method)
Sizes of plane table Large :-
750 × 600 mm Medium :-
600 × 500 mm Small :-
500 × 400 mmjoin @Technical_civil
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