Please enter your email address. You will receive a link and will create a new password via email. Sorry, you do not have permission to ask a question, You must log in to ask a question. Join now! Do you need to remove the ads? As we all know, Geodetic surveying and Plane surveying comes under the primary classification of surveying. In geodetic surveying, the curvature of the earth is taken into account while taking surveying.
In this surveying conducted a larger area. Geodetic surveying is mainly conducted to determine the precise positions on the earth surface. It is also called as Trigonometrical surveying. In-plane surveying, the curvature of the earth is ignored because surveying is conducted in small areas.
Coast and Geodetic Survey and the U. Geological Survey ; the Ordnance Survey in the U. The aim may be purely scientific, that is, to determine the size and shape of the earth, or it may be the production of accurate maps of large areas. These points serve as control points for surveys covering smaller areas.
When large areas are involved, the computations must be based on the mean spheroidal shape of the earth. But the assumption that the earth is a perfect sphere is adequate for areas such as a province or a city, simplifying the analysis significantly. In any case, a knowledge of spherical trigonometry and calculus is required. However, it is now becoming common to do geodetic computations in a three-dimensional, earth-centered, Cartesian coordinate system.
Plane surveying ignores the curved shape of the earth , which is considered a plane. This is valid for s urveys of small extent, where the effect of curvature is negligible.
In-plane surveys, the directions of plumb-lines are considered parallel at different points, and all angles are plane angles. The sum of the three angles of a spherical triangle is greater than that of the corresponding plane triangle.
This is called the spherical excess. It is only one second of arc for an area of about sq. This indicates that plane surveying procedures are adequate up to about sq. It is the type of surveying in which the curvature of the earth is taken into account and a very high standard of accuracy is maintained.
It is also evident that it is necessary to carry out the geodetic trigonometrical survey before these dimensions can be determined. Secondly, as the survey extends or is completed, further data becomes available for a check on the value used or, if necessary, to calculate another value to fit more closely the territory being surveyed.
In a geodetic survey, all lines resting on the surface are curved lines and the triangles formed are referred to as Spherical triangles. Measurements are obtained with high precision instruments, and calculations are made applying the spherical trigonometry practice. What is Contour? Save my name, email, and website in this browser for the next time I comment. A triangle formed by joining three points is considered as plane triangle and angles formed are considered as trigonometry is required.
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