1. 4.1 Introduction
• The elevation of a point: vertical distance
between point and a reference level surface
called datum.
• Datum: If a whole series of heights is given
relative to a plane, this plane is called a datum. In
topographical work the used datum is the mean
sea level (MSL)
• +ve if above MSL such as Jerusalem
• -ve if below MSL such as Jericho.
4.1 Introduction
Leveling: is the operation required in the
comparison of heights of points on the surface of
the earth. Its purpose to provide spot heights or
contour lines on a map, to provide data for
making longitudinal and cross-sections.
4.1 Introduction
Leveling can be done in several ways:
• Chain surveying
• Barometric leveling: using barometer to measure the atm.
Pressure to determine elevation
• Trigonometric leveling: using Theodolite
• Photogrammetric leveling: using Camera
• GPS leveling
• Differential leveling: using level and staff