Distance measurement
Distance is one of the fundamental measurements in surveying. Although frequently measured as a spatial distance (sloping distance) in three-dimensional space, usually it is the horizontal component which is required.…
EQUIPMENT
The equipment used in the levelling process comprises optical levels and graduated staffs. Basically, the optical level consists of a telescope fitted with a spirit bubble or automatic compensator to…
Bench mark (BM)
In order to make OD accessible to all users throughout the country, a series of permanent marks were established, called bench marks. The height of these marks relative to OD…
Vertical control
INTRODUCTION This chapter describes the various heighting procedures used to obtain the elevation of points of interest above or below a reference datum. The most commonly used reference datum is…
Basic concept of errors
The basic concept of errors in the data captured by the surveyor may be likened to target shooting. In the first instance, let us assume that a skilled marksman used…
Errors In Measurement
It should now be apparent that position fixing simply involves the measurement of angles and distance. However, all measurements, no matter how carefully executed, will contain error, and so the…
Units Of Measurement
The system most commonly used for the definition of units of measurement, for example of distance and angle, is the ‘Système Internationale’, abbreviated to SI. The basic units of prime…
Error and uncertainty
In surveying nothing is ever absolutely certain. The product of surveying may be thought of as being in two parts, that is, the derivation of the desired quantities such as…
Plotting Detail
In the past, detail would have been plotted on paper or a more stable medium such as plastic film. However, today all practical ‘plotting ‘is computer based and there is…
Locating Position
Establishing control networks and their subsequent computation leads to an implied rectangular coordinate system over the area surveyed. The minor control points in particular can now be used to position…
