Some Presentation Slides Dr. Maher A. El-Hallaq Lecturer of - - PowerPoint PPT Presentation

Some Presentation Slides

• Dr. Maher A. El-Hallaq

Lecturer of Surveying The Islamic University of Gaza

The determination of relative spatial location of points on or near the earth surface.

It includes: Mapping tasks Setting out tasks

Surveying

Natural surface. Geoid surface. Ellipsoid surface.

Earth Surfaces

According to the According to the size size of survey

• f survey
• Plane surveying. ﺔﻳﻮﺘﺴ ﺔﺣﺎﺴﻣ

area of survey < 50 km2

• Geodetic surveying. ﺔﻴﺴﻳد ﻴﺟ ﺔﺣﺎﺴﻣ

area of survey > 50 km2

Survey Types

According to the According to the purpose purpose of survey

• f survey
• Cadastral or Land surveying. ﺔﻴﻠﻴﺼ ﺗ ﺔﺣﺎﺴﻣ
• Topographic surveying. ﺔﻴﻓاﺮ ﻮﺒﻃ ﺔﺣﺎﺴﻣ
• Route surveying. قﺮﻄﻟا ﺔﺣﺎﺴﻣ
• Hydrographic surveying. ﺔﻴﺋﺎﻣ ﺔﺣﺎﺴﻣ
• Construction surveying. ﺔﻴﺋﺎﺸ إ ﺔﺣﺎﺴﻣ
• Mine surveying. ﻢﺟﺎﻨﻣ ﺔﺣﺎﺴﻣ

Survey Types

According to the According to the method method of survey

• f survey
• Ground or Field surveying. ﺔﻴﺿرأ ﺔﺣﺎﺴﻣ

Ex: Leveling, total station surveys

• Remote surveying. ﺔﻳﺮﻳﻮ ﺗ ﺔﺣﺎﺴﻣ

Arial photographs and satellite images

Survey Types

• Distances.
• Angles and directions.
• Elevations.

Coordinates (x, y, z)

Survey Measurements

• Distances.

{tapes, EDM, theodolite, total station, etc}

• Angles and directions.

{theodolite, compass, total station, etc}

• Elevations.

{level, theodolite, total station, GPS, etc}

Survey Equipment

Survey Equipment

Survey Equipment

0.5 m

Total Station

Survey Equipment

Survey Scale

• Planning and design of the survey.
• Care, handling and adjustment of the instrument.
• Fixing horizontal locations of objects.
• Determining the elevations of objects.
• Recording field measurements.
• Field computations for purpose of verifying the

data.

• Office computations.

Field and office work

• Establishing specifications for accuracies.
• Locations and analysis of all existing maps,

photographs, etc.

• Preliminary examination of the site.
• Selection of equipment and surveying

procedures appropriate for the task.

• Selection of computational procedures and

methods for presenting the data.

Planning and Design of the Survey

• Maps. (planimetric and topographic)
• geographic maps: large areas.
• hydrographic maps: shorelines, bottom conditions, depths.
• thematic maps: concentration of a specified subject.
• photogrammetric maps and orthophotos
• Profiles.
• Cross sections.
• Geographic calculations.
• others.

Methods of presenting data

• Ground – field techniques.
• Aerial – photogrammetric techniques.
• Combination.

Mapping Survey Techniques

Planimetric maps

• Tape surveying methods.
• Plane table methods.
• Theodolite methods.
• Total station methods.

Topographic maps

• Level methods.
• Total station methods.

Ground Techniques

• 11. Sources of Errors

5

Measure a distance several times and compare the obtained measurements????

They are not equal and the reason:

The imperfections of the instruments The fallibility of the human operator The uncontrollable nature of the environment

Errors always exist in measurements, where:

The error ( The error (e ei

i) =

= the measured value (x the measured value (xi) ) – the true value (x) the true value (x)

But since the true value can never be determined, we can use instead the most probable value (xm). Thus:

ei = x = xi

i – xm

Where,

Types of Errors ءﺎطﺧﻷا فﯾﻧﺻﺗ

Blunders (Mistakes)ﺔﻣﯾﺳﺟ ءﺎطﺧأ Random Errorsءﺎطﺧأ ﺔﯾﺋاوﺷﻋ Systematic Errorsءﺎطﺧأ ﺔﻣظﺗﻧﻣ

Blunder Errors (Mistakes) ﺔﻣﯾﺳﺟ ءﺎطﺧأ

caused by human carelessness, fatigue and haste can be positive or negative, large or small and their

• ccurrence is unpredictable

recording 43.18 instead of 34.18 and sighting a wrong target when measuring an observation Blunders are disastrous if left in the surveying measurements must be eliminated by careful work and by using field procedures that provide checks for blunders

Random Errors ﺔﯾﺋاوﺷﻋ ءﺎطﺧأ

caused by imperfections of the measuring instruments, the surveyor to make an exact measurement, and the variations in the environment can be minimized by using better instruments and properly designed field procedures and by making repeated measurements have small magnitudes Positive and negative errors of the same magnitude

• ccur with the same frequency. Cancel each other

Consider the mean value

Systematic Errors ءﺎطﺧأ ﺔﯾﻣﺎظﻧ

behave according to a particular system or physical law

• f nature, which may or may not be known

When the law of occurrence is known, systematic errors can be calculated and eliminated always occurs with the same sign and magnitude and is therefore often referred to as a constant error Examples: assuming occupy point coordinates, earth curvature and temperature or pressure corrections Correction doesn’t require field re-measurements

Example:

Given 12 measurements of a certain distance, as follows:

٥٨.٧٨ ، ٥٨.٨٣ ، ٥٨.٨٠ ، ٥٨.٨٥ ، ٥٨.١٨ ، ٥٨.٧٧ ، ٥٨.٧٩ ، ٥٨.٨٠ ٥٨.٨١ & ٥٨.٨٢ ، ٥٨.٧٩ ، ٥٨.٨٢

First iteration (n = 12) = 58.75 m = ± 0.18 m

Second iteration (n = 11):

xm = 58.81 m σx = ± 0.02 m max. error= ± 0.06 m

Precision and Accuracy

In general, to obtain high precision and high accuracy in surveying, the following strategies must be followed: Follow techniques that will help detect and eliminate all the blunders. Eliminate

• r

correct all systematic errors by frequent calibration and adjustment

• f

the instruments Minimize the random errors by using good instruments and field procedures.

Point Elevation Point Elevation

vertical distance above a certain datum (MSL). +ve if above datum (e.g. Jerusalem) –ve if below datum (e.g. Jericho)

Leveling Leveling

determination of elevation or difference in elevation

Definitions

Leveling can be done in several ways:

• Tape leveling.
• Barometric leveling.
• Trigonometric leveling.
• GPS leveling.
• Photogrammetric leveling.
• Differential leveling.

Methods of leveling

Differential leveling equipment

The line of sight must be in a horizontal plane

Basic Principle in Diff. Leveling

Rise Fall

Basic Theory in Diff. Leveling

BM: BM: relatively permanent point of known elevation. HI: HI: elevation of the line of sight of the level.

= elevation of BM + staff reading at BM

BS BS: the first staff reading after setting up the level. FS FS: the last staff reading before moving the level. IS IS:

reading(s) between BS and FS.

TP: TP: point that has FS and BS readings.

• Diff. Leveling Definitions

General Procedure

Height of Instrument method Height of Instrument method

Booking and Calculations

Rise and Fall method Rise and Fall method

Booking and Calculations

• Longitudinal sections (profiles).
• Cross sections.
• Contour maps.
• Setting out elevations.
• Others.

Leveling Applications

Common Mistakes

Suggestion for good leveling

Thank You !!!