Levelling
Levelling, Important Terminologies In Levelling, Elevation & Altitude, Reduced Level, Mean Sea Level, Bench Marks(B.M)– G.T.S Bench Marks, Permanent Bench Marks, Temporary Bench Marks, Arbitrary Bench Marks. Measurement in Leveling Work- Horizontal Line, Vertical Line, Level Line, Back Sight Reading, Fore Sight Reading, Intermediate Sight Reading. Method to Find Reduced Level- Height of Instrument, Rise and Fall Method. Inverted Staff, Correction Required in Levelling Work- Correction due to Earth Curvature (Cc), Correction due to Refraction (CR), Combined Correction due to Both (C). Distance of Visible Horizon- When height of any one point is considered, When height of both points are considered. Reciprocal Leveling – When the instrument near A, When the instrument near B, Collimation error– When Area is Large, When Area is small, Angular / Inclination Error, Sensitivity of Bubble Tube , The sensitivity of level tube increases with?.
Topics
In fundamentals of surveying (part-2), we details analysis about plan & map, scale, representation of scale- engineer’s scale, representation fraction (rf), graphical scale. Shrinkage factor or shrinkage ratio, error due to shrinkage of map, error due to wrong measuring scale, type of scales- plane scale, diagonal scale, vernier scale (direct vernier, retrograde vernier, extended vernier, double vernier).
In this photogrammetry chapter, we detailed discuss about photogrammetry, aerial photogrammetry, vertical photograph, scale of photograph, datum scale of photograph, average scale of photograph, flying height, ground co-ordinates & length of a line from a vertical photograph, crab, drift, relief displacement, number of photograph required to cover an area, exposure interval, air base, etc.