It is a art of measuring horizontal and vertical distances between objects, of measuring angles between lines of determining the direction of lines and of establishing points by pre determined angular and linear measurement, distances, angles, direction, locating elevation, areas and volume are determined from data of surveyor and much of surveyor information is pot rate, graphically by the construction of maps, cross sections and diagram.
Objects of Survey
To determine the relative position of distinctive features near the surface of the earth and to represent these information avoiding to some suitable scale, if the scale is large the scheme is called plan, on the other hand if the scale is small the scheme is called the map, horizontal distances are shown on the plan or map.
Uses of Survey
To establish boundaries of ground.
To provide information for selecting a site for engineering projects like highways, railways, water supply, sewerag etc.
The preside location of definite reference points through out the country
Types of Survey
There are two major types of surveying
In plane surveying the curvature of the earth is neglected and the mean surface of the earth is considered as plane. This surveying extended over areas upto three hundred square kilometers, this area may be considered as straight line and the angles as plane angles, so only the knowledge of geometry and plane trigonometry is required in this survey, the required degree of accuracy comparatively low most of the engineering surveys for the location and construction of highways, railways, canals are plane survey.
Curvature correction is applied at regular intervals and this curvature correction is 0.5m for 91 km and 0.1m for 18.2 km also the difference between the sum of angles of spherical triangles on the earth surface and that angles is only 1 second for every 195.5 sq.km area.
In geodetic survey the curvature of the earth is taken into amount
surface of the is considered as curve and are of great circle. Such surveys extend over large areas and are of high precision. Since shape of the earth is spherical, so line connecting any two points is considered as curve. Very refined instruments as well as presided methods of observation are adjustments are used; such surveys are conducted through the agencies of the government.