Introduction
Earth is an oblate Spheroid.
Diameter= 12740 km ( Average) Average Radius = 6370 km
At Equator = 12756.75 km      At Poles= 12713.80 km
 Difference = 42.95 km (0.34 % of Length)
Theory Of Surveying
Geodetic Surveying–Â If earth curvature is considered for Survey work called Geodetic Surveying.
Plane Survey– If earth curvature is not considered suitable for small distance called as Plane Survey.
Fig. Earth Surface
Principal of Surveying
Location of Point is measured w.r.t two reference point.
In this category various surveying comes.
- Chain Survey
- Compass Survey
- Traverse Survey
- Offset Method etc.Â
Working Whole to Part.
Major control points are decided and measured accurately with high degree of precise. Minor details can be collected later to avoid the error to be accumulated.
Linear Measurements
You have to study very deeply the following point refer some standard books. These points are as below.
- Scale – Types of scale
- Â Plane Scale
- Diagonal Scale
- Vernier Scale
- Shrunk Scale  Â
Note- Take Complete Knowledge Tape CorrectionÂ
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Chain Survey
It is also Known as Limitting Length of Offset.
Imp. Point of Chain Survey—–
- Main Stations- Major Control points to devide the area.
- Main Lines- Lines Joining Main Stations.
- Base Line- The longest line in the area that divide the total area almost in two parts.
- Check Line- Check Line are measured to check the accuracy of Survey work done.
- Tie Line- Any Line drawn to collect more information about different Object in area.( for Collecting Details)
Compass Survey
- Meridian – A fixed line w.r.t which bearing of line can be measured.
- Bearing – Angle measured w.r.t a fixed meridian.
- True Meridian – The line joining True North and True South on Earth Surface is called true meridian.
- True Bearing- The Bearing measured w.r.t True meridian is called true bearing.
- Magnetic MeridianÂ
- Magnetic Bearing.
System Of Bearing Measurements-
- WCB Method ( Whole Circle Bearing Method)
- Â QSB System ( Quadrantal System of bearing) also called Reduced Bearing.Â
Reciprocal Leveling
Reciprocal Leveling used to find out any error in the leveling instrument and to eliminate the affect of such error and other errors like due to earth curvature and refraction.
Contours
Contours are the locus of equal elevation point on ground surface.
Plane Table Surveying
There are four methods-
- Radiation
- Intersection
- TraversingÂ
- Resection
Again in this Three Point Problems are there-
- Tracing paper method
- Bessel’s graphical method
- Lehman’s Method
Tachometer Surveying
Using a Tachometer Staff reading can be read to calculate the R.L of point, as well as distance of the staff location the instrument.
Surveying is not only a engineering subject but also a Life Lesson how science works.
Thank you. Have a Nice Day.Â
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