Prof' Dr' Muhammed SAHIN

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Geodesy, GPS and GIS
Prof. Dr. Muhammed SAHIN
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SURVEYING It is the art of measuring horizontal
and vertical distances between objects, of
measuring angles between lines, of determining
the direction of lines, and of establishing
points by predetermined angular and linear
measurements. The actual measurements are the
mathematical calculations. Distances, angles,
directions, locations, elevations, areas, and
volumes are thus determined from the data of the
survey. Survey data is portrayed (displayed)
graphically by the construction of maps,
profiles, cross sections, and diagrams.
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TYPES OF SURVEYS Geodetic Surveying The type of
surveying that takes into account the true shape
of the earth. These surveys are of high precision
and extend over large areas. Plane Surveying The
type of surveying in which the mean surface of
the earth is considered as a plane, or in which
its spheroidal shape is neglected, with regard to
horizontal distances and directions.
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• Operations in Surveying
• Control Survey Made to establish the horizontal
  and vertical positions of arbitrary points.
• Boundary Survey Made to determine the length and
  direction of land lines and to establish the
  position of these lines on the ground.
• Topographic Survey Made to gather data to
  produce a topographic map showing the
  configuration of the terrain and the location of
  natural and man-made objects.

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• Operations in Surveying (contd)
• Mining Survey Made to control, locate and map
  underground and surface works related to mining
  operations.
• Construction Survey Made to lay out, locate and
  monitor public and private engineering works.
• Route Survey Refers to those control,
  topographic, and construction surveys necessary
  for the location and construction of highways,
  railroads, canals, transmission lines, and
  pipelines.

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• Operations in Surveying (contd)
• Hydrographic Survey The survey of bodies of
  water made for the purpose of navigation, water
  supply, or submarine construction.
• Aerial Survey Made to utilize the principles of
  aerial photogrammetry, in which measurements made
  on photographs are used to determine the
  positions of photographed objects.
• Final (as-built) Survey Ties in features that
  have just been constructed to provide a final
  record of the construction and to check that
  construction has proceeded according to design.

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Survey Reference

• Geographic Reference
• In the broadest sense, the earths reference
  system is composed of surface divisions denoted
  by lines of latitude and longitude. Latitude
  lines run east and west and are parallel to the
  equator. The latitude lines are formed by
  projecting the latitude angle out from the center
  to the surface of the earth. The latitude angle
  itself(90 maximum) is measured at the earths
  center, north or south from the earths
  equatorial plane.

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Survey Reference

• Geographic Reference
• All longitude lines run north and south and
  converge at the poles. Lines of longitude(also
  called meridians) are formed by projecting the
  longitude angles out from the center to the
  surfaceof the earth at the equator. The longitude
  angle itself(180 maximum) is measured at the
  earths center, east or west from the plane 0
  longitude, which has been arbitrarily placed
  through Greenwich, England.

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Survey Reference

• Ellipsoid Reference
• The shape of the earth has been modeled as an
  ellipsoid a solid generated by rotating an
  ellipse on its minor axis . Geodetic Reference
  System of 1980(GRS 80) ellipsoid has been
  selected as reference ellipsoid through satellite
  observations and radio astronomy.

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Survey Reference

• Vertical Reference
• The previous sections showed how the X and
  Y(east and north) horizontal dimensions of any
  feature could be referenced for surveying
  purposes. Although vertical dimensions can be
  referenced to any datum, the most common
  reference datum is that of mean sea level(MSL).
  Mean sea level is assigned an elevation of 0.000
  meters(or feet), and all other points on earth
  can be described as being elevations above or
  below zero.

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Accuracy and Precision Accuracy is the
relationship between the value of a measurement
and the true value of the dimension being
measured. Precision describes the refinement of
the measuring process and the ability to repeat
the same measurement with consistently small
variations in the measurements.
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Mistakes Mistakes are blunders made by survey
personnel. Examples of mistakes include
transposing figures (recording a tape value 68 as
86), miscounting the number of full tape lengths
in a long measurement, measuring to or from the
wrong point, and the like. Mistakes must be
discovered and eliminated prefarably by the
people who made them. All survey measurements are
suspect until they have been verified. As a
rule, every measurement is immediately checked or
repeated. This immediate repetition enables the
surveyor to eliminate most mistakes and, at the
same time. Improve the precision of the
measurement.
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Accuracy Ratio The accuracy ratio of a
measurement or series of measurements is the
ratio of error of closure to the distance
measured. The error of closure is the difference
between the measured location and the
theoretically correct location. The theoretically
correct location can be determined from repeated
measurements or mathematical analysis.
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Application Areas of Surveying in Civil
Engineering

• Streets and highways
• Drainage ditches
• Intersections and interchanges
• Sidewalks
• Buildings high- and low-rise
• Bridges and culverts
• Dams and weirs
• River channelization
• Sanitary landfill
• Mining tunnels, shafts
• Gravel pits, querries

• Storm and sanitary sewers
• Water and fuel pipelines
• Piers and docks
• Canals
• Railroads
• Airports
• Reservoirs
• Site grading, landscaping
• Parks, formal walkways
• Heavy equipment location
• Electricity transmission lines

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What is Civil Engineering Surveying?

• The civil engineering industry involves the
  design and construction of the facilities that
  shape the world we live in. From roads, railways
  and bridges to water supply pipes and power
  stations, this is all civil engineering.
• Civil Engineering Surveyors are involved in
  every stage of the project from initial concept
  through design and construction, to monitoring
  the condition and performance of the completed
  structure.

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• Geospatial Engineering Surveying
• Geospatial Engineers work within construction on
  the measurement and monitoring of projects, as
  well as producing maps, plans and charts of
  different features. The main profession within
  civil engineering is engineering surveying
  (sometimes known as land surveying).

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• Geospatial Engineering Surveying
• Engineering surveyors are generally responsible
  for
• Investigating land, using computer-based
  measuring instruments and geographical knowledge,
  to work out the best position to construct
  bridges, tunnels and roads
• Producing up-to-date plans which form the basis
  for the design of a project
• Setting out a site, so that a structure is built
  in the correct spot and to the correct size
• Monitoring the construction process to make sure
  that the structure remains in the right position,
  and recording the final as-built position
• Providing control points by which the future
  movement of structures such as dams or bridges
  can be monitored.