Some Presentation Slides Dr. Maher A. El-Hallaq Lecturer of Surveying The Islamic University of Gaza
Surveying The determination of relative spatial location of points on or near the earth surface. It includes: � Mapping tasks � Setting out tasks
Earth Surfaces � Natural surface. � Geoid surface. � Ellipsoid surface.
Survey Types According to the According to the size size of survey of survey • Plane surveying. ﺔﻳﻮﺘﺴ ﺔﺣﺎﺴﻣ area of survey < 50 km 2 • Geodetic surveying. ﺔﻴﺴﻳد ﻴﺟ ﺔﺣﺎﺴﻣ area of survey > 50 km 2
Survey Types According to the According to the purpose purpose of survey of 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 of survey • Ground or Field surveying. ﺔﻴﺿرأ ﺔﺣﺎﺴﻣ Ex: Leveling, total station surveys • Remote surveying. ﺔﻳﺮﻳ ﻮ ﺗ ﺔﺣﺎ ﺴ ﻣ Arial photographs and satellite images
Survey Measurements • Distances. • Angles and directions. • Elevations. Coordinates (x, y, z)
Survey Equipment • 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 0.5 m
Survey Equipment Total Station
Survey Scale
Field and office work • 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 .
Planning and Design of the Survey • 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.
Methods of presenting data • 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.
Mapping Survey Techniques • Ground – field techniques. • Aerial – photogrammetric techniques. • Combination.
Ground Techniques Planimetric maps • Tape surveying methods. • Plane table methods. • Theodolite methods. • Total station methods. Topographic maps • Level methods. • Total station methods.
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 true value (x) The error ( The error (e e i i ) = = the measured value (x the measured value (x i ) the true value (x) But since the true value can never be determined, we can use instead the most probable value (x m ). Thus: i – x m e i = x = x i Where,
ءﺎطﺧﻷا فﯾﻧﺻﺗ Types of Errors Blunders (Mistakes) ﺔﻣﯾﺳﺟ ءﺎطﺧأ Random Errors ءﺎطﺧأ ﺔﯾﺋاوﺷﻋ Systematic Errors ءﺎطﺧأ ﺔﻣظﺗﻧﻣ
ﺔﻣﯾﺳﺟ ءﺎطﺧأ Blunder Errors (Mistakes) caused by human carelessness, fatigue and haste can be positive or negative, large or small and their occurrence 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
ﺔﯾﺋاوﺷﻋ ءﺎطﺧأ Random Errors 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 occur with the same frequency. Cancel each other Consider the mean value
ءﺎطﺧأ ﺔﯾﻣﺎظﻧ Systematic Errors behave according to a particular system or physical law of 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 . ٨٠ ، ٥٨ . ٧٩ ، ٥٨ . ٧٧ ، ٥٨ . ١٨ ، ٥٨ . ٨٥ ، ٥٨ . ٨٠ ، ٥٨ . ٨٣ ، ٥٨ . ٧٨ ٥٨ . ٨٢ ، ٥٨ . ٧٩ ، ٥٨ . ٨٢ ٥٨ . ٨١ & First iteration (n = 12) = 58.75 m = ± 0.18 m
Second iteration (n = 11): x m = 58.81 m σ x = ± 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 or correct all systematic errors by frequent calibration and adjustment of the instruments Minimize the random errors by using good instruments and field procedures.
Definitions 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
Methods of leveling Leveling can be done in several ways: • Tape leveling. • Barometric leveling. • Trigonometric leveling. • GPS leveling. • Photogrammetric leveling. • Differential leveling.
Differential leveling equipment
Basic Principle in Diff. Leveling The line of sight must be in a horizontal plane
Basic Theory in Diff. Leveling Rise Fall
Diff. Leveling Definitions BM: relatively permanent point of known elevation. BM: HI: elevation of the line of sight of the level. HI: = 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 : reading(s) between BS and FS. IS TP: point that has FS and BS readings. TP:
General Procedure
Booking and Calculations Height of Instrument method Height of Instrument method
Booking and Calculations Rise and Fall method Rise and Fall method
Leveling Applications • Longitudinal sections (profiles). • Cross sections. • Contour maps. • Setting out elevations. • Others.
Common Mistakes
Suggestion for good leveling
Thank You !!!
Recommend
More recommend
