Summary BS Geodetic Engineering General Surveying Midterm Reviewer
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Course
BS Geodetic Engineering
Institution
BS Geodetic Engineering
A brief and descriptive midterm reviewer material of General Surveying subject of BS in Geodetic Engineering in Western Mindanao State University, Philippines. Topics includes Surveys and its types, Errors and its types, Sources of Errors, Surveying Instruments, Field Surveying Party, Mapping, Mea...
Surveying
The art and science of determining angular and linear measurements to establish the form, extent, and
relative position of points, lines, and areas on or near the surface of the earth or on the other
extraterrestrial bodies through applied mathematics and the use of specialized equipment and
techniques.
The process of delineating a portion of the earth’s surface or substance or of establishing the position
or boundaries of some object upon it. Surveying activities during the earlier part of the decade have
only been limited to surveys on or near the surface of the earth. Times, however, have changed and
modern surveying techniques are now applied to space exploration and in the mapping of
extraterrestrial bodies such as the moon, mars, and in the near future the other planets, stars, and
other heavenly bodies in the universe.
Surveys are divided into two general classifications:
1) Plane surveying – is that type of surveying in which the earth is considered to be a flat surface,
and where distances and areas involved are of limited extent that the exact shape of the earth is
disregarded. Regarding horizontal distances and directions, a level line is considered
mathematically straight, and the direction of the plumb line is assumed to be the same at all
positions within the limits of the survey, and all angles are considered to be plane angles.
Unless extreme accuracy is required, plane surveying is applicable to areas of some thousands
of square kilometers in extent.
2) Geodetic surveying – are surveys of wide extent which take into account the spheroidal shape
of the earth. These surveys employ the principles of geodesy, are of high precision, and the
related calculations involve the solving of equations derived from advanced mathematics. This
type of survey is used as a basis to produce accurate base and topographic maps.
Types of surveys
The following types of commonly executed surveys:
1) Cadastral Surveys – closed surveys in urban and rural locations to determine and define
property lines and boundaries, corners, and areas.
2) Control Surveys – establish a network of horizontal and vertical monuments that serve as a
reference framework for initiating other surveys. Many control surveys performed today are
done using techniques with GNSS instruments.
3) City Surveys – surveys in the city for planning expansions, locating property lines, fixing
reference monuments, determining physical features of land, and preparing maps.
4) Construction Surveys – surveys done at a construction site to provide data regarding grades,
reference lines dimensions, ground configuration, and location and elevation of structures which
are of concern to engineers and architects, and builders.
5) Forestry Surveys – surveys in connection with forest management and mensuration, and the
production and conservation of forest lands.
6) Hydrographic Surveys – surveys made to map shorelines, chart the shape of areas underlying
water surfaces, and measure the flow of streams.
7) Industrial Surveys – known as optical tooling and are surveys used for ship building,
construction and assembly of aircraft, layout and installation of heavy and complex machinery,
and for industries requiring very accurate dimensional layouts.
, 11) Topographic Surveys – surveys to determine the shape of the ground, the location and
elevation of natural and artificial features upon it.
Surveying instruments
Surveying instruments are used to assist in measuring land, including vertical distance, horizontal
distance, and volume of excavated material. A land surveyor uses surveying instruments to make
precise measurements of the earth’s surface. Surveying instruments were developed gradually. It is
believed that an extensive use of surveying instruments came about during the early days of the
Roman empire.
The oldest historical records in existence today that bear directly on surveying state that this science
began in Egypt. Herodotus recorded that Sesostris (about 1400 B.C.) divided the land of Egypt into
plots for the purpose of taxation. Annual floods of the Nile River swept away portions of these plots,
and surveyors were appointed to replace the boundaries. These early surveyors were called
ropestretchers, since their measurements were made with ropes having markers at unit distances.
The following instruments were the early forerunners of our present-day surveying instruments:
➢ Astrolabe – invented by Hipparchus in 140 BC and further improved by Ptolemy and used to
determine the altitude of stars.
➢ Telescope – invented by Lippershey (1607) Galileo constructed a refracting telescope for
astronomical observations in 1609. Only used in surveying after the cross hairs for fixing the line
of sight were introduced.
➢ Transit – invented by Young and Draper (1830) and known as the universal surveying
instrument.
➢ Dioptra – invented by Heron of Alexandria and used in leveling and measuring horizontal and
vertical angles.
➢ Roman groma – for aligning or sighting points, consists of cross arms with suspended plumb
lines fixed at right angles and pivoted upon a vertical staff.
➢ Libella – used by Assyrians and Egyptians and had an A-frame with a plumb line suspended
from its apex used to determine the horizontal distance.
➢ Chorobates – for leveling work, consists of a horizontal straight-edge about 6 m long, a groove
2.5 cm deep and 1.5 m long on top and water is poured into the groove for leveling.
Surveying instruments in the present day:
▪ Auto Level/Dumpy Level
A dumpy level, builder’s auto level, leveling instrument, or automatic level is an optical instrument
used to establish or verify points in the same horizontal plane. It is used in surveying and building
with a vertical staff to measure height differences and to transfer, measure and set heights.
▪ Theodolite
Basic surveying instrument of unknown origin but going back to the 16th-century English
mathematician Leonard Digges; it is used to measure horizontal and vertical angles. In its modern
form it consists of a telescope mounted to swivel both horizontally and vertically. A modern theodolite
consists of a movable telescope mounted within two perpendicular axes the horizontal or trunnion axis,
and the vertical axis. When the telescope is pointed at a target object, the angle of each of these axes
can be measured with great precision.
▪ GPS (Global Positioning System)
A space-based satellite navigation system that provides location and time information in all
weather conditions, anywhere on or near the Earth where there is an unobstructed line of sight to
four or more GPS satellites. The system provides critical capabilities to military, civil and commercial
users around the world. It is maintained by the United States government and is freely accessible to
anyone with a GPS receiver.
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