Geomatics 1
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Transcript of Geomatics 1
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COURSE: DCEB 1 FT
MODULE: GEOMATICS 1
MODULE CODE: BE8101
TOPIC : BASIC PRINCIPLES
In Chapter 1, (this should be read in total) the basic principles of surveying are
discussed.
What is surveying?
Essential Activities associated with
surveying
Working from whole to part,
reconnaissance, observation &
presentation
Plane & Geodetic Surveying Whats the difference?
In plane surveying, the earth is
considered to be flat-a plane surface. In
geodetic surveying, the curvature needs
to be taken into account.
Generally, the extent of a survey will
dictate which method is required.
Branches of surveying There are many types of surveys which
are done for various purposes. It is usual
to classify them as :
Topographic surveys
Engineering surveys
Cadastral surveys
Characteristics of each classification are
given in the text.
Methods of point location Locating positions of points, features, etc
is of fundamental importance. There are 4
basic principles of point location:
Trilateration
Offsets
Traverse survey commonly used
Intersection
Reliability of a survey
All surveys must be reliable. Survey
processes must be designed in such a way
that the specifications are achieved.
The occurrence of errors-mistakes,
systematic errors, random errors must
be taken into account and check
measurements must be incorporated into
the survey process to eliminate or detect
for the presence errors. ( see page 8 )
Scale
The results of a survey are usually plotted
(shown) on plan drawing on a piece
of paper. To represent the measurements
correctly, a scale must be adopted.
Examples of typical scales used:
1: 100, 1:2000 etc.
1:1000 means 1 unit on plan represents
1000 units on ground
A distance of 1000 cm (10 m) on ground
would be represented by 1 cm on plan.
If a distance between 2 points on a line
with a scale of 1:400 was found to be
5.35 cm, what is the ground distance?
SMALL SCALE?
LARGE SCALE?