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Lecture 1

This document provides an introduction to geodesy, including defining geodesy as the science of measuring and understanding the shape and gravity of Earth. It discusses the sub-disciplines of geodesy and introduces key concepts like the geoid, which models Earth's gravity field, and the reference ellipsoid, which is a mathematically defined surface that approximates the actual irregular shape of Earth.

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37 views2 pages

Lecture 1

This document provides an introduction to geodesy, including defining geodesy as the science of measuring and understanding the shape and gravity of Earth. It discusses the sub-disciplines of geodesy and introduces key concepts like the geoid, which models Earth's gravity field, and the reference ellipsoid, which is a mathematically defined surface that approximates the actual irregular shape of Earth.

Uploaded by

Ridham
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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Download as PDF, TXT or read online on Scribd
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CH

HAPTER 1: INTRO
ODUCTIO
ON TO GE
EODESY
1.1 Defin
nition and Fundamenta
F als of Geodeesy

 Geodeesy is a sciennce based on earth and maathematics ussed to make gglobal positiooning possiblle and
measu uring, understtanding & mo onitoring the geometric shhape, size, oriientation and its gravity fieeld by
repressenting it in a three dimen nsional spacee. Temporal vvariation in tthe position oof the earth is also
studieed. The term Geodesy
G is deerived from th
he Greek worrd “geodesic”” meaning “diividing the eaarth”.

 The su
ub-disciplines of Geodesy y are:
 Geometrical
G geeodesy
 Ph hysical geodeesy
 Mathematical
M geodesy
 Dynamical
D geoodesy
 Satellite geodeesy
 Marine
M geodessy
 Geophysical
G geodesy, etc.

Geoid

It is a model having saame gravitatio


onal potentiall of the earth’’s gravity fielld. It acts as cclose mathem
matical
and physiical representation includin
ng geometric shape, size oof earth. This is the surfacee that most cllosely
approximates sea leveel, assuming that
t it is freee of winds, oocean currentts and other ddistributing fforces.
(Figure 1..1)

Figu
ure 1.1: Geoid
(Very closse to the topog
graphy of the earth but nott to the actuall shape of the earth)
Figure 1.2: Showing Ellipsoid, Sphere, Geoid andd actual topograaphy of the earrth

Reference Ellipsoid

As shown n in figure 1.2,


1 the earth h is not in a spherical shhape. The E Earth’s shape may be takken as
resemblinng an ellipsoidd but it is nott a perfect elliipsoid. The ppolar radius of earth is appprox 21 km sm
maller
than equaatorial radius. So it is a matthematically defined
d surfacce of the earthh.

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