SURVEYING Chapter 1 Introduction

Transcription

1 PHILADELPHIA UNIVERSITY Faculty of Engineering. Department of Civil Engineering. SURVEYING Chapter 1 Introduction

2 Surveying : the art or science of measuring and representing natural and artificial features on the ground. Surveying involves the measurements of. elevations,distances,angles and Position determination and plotting these measurements to some suitable scale to produce map, plan or section.

3 Purposes of surveying: 1- Determine the position of the point of earth's surface 2- Used in producing Topographic map 3-Setout and layout the proposed engineering and agricultural project.

4 History of Surveying the units for measuring lengths : (Cubit)= 52.4cm (Palm) = 7.48 cm (Finger)= 1.87 cm (Cubit)= 7 palm = 28 fingure (Khet) =100 cubit= 52.4 m.

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7 TYPE OF SURVEYING : 1-Plane Surveying - Cadastral Surveying -Topography Surveying 3-Engineering Surveying - Construction Surveying 5- Mine Surveying 7- Geological Surveying 2-Geodetic Surveying 4- Aerial Surveying - Photogrammetry 6- Hydrographic Surveying

8 Figure of the Earth

9 the earth s surface is round, however highly irregular and not suitable as a computational surface because of the mountains, valleys, rivers and the surface of the sea, so the more suitable surfaces were assumed for computational purposes, namely the Geoid and an Ellipsoid.

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11 The geoids is defined as the more smoothed representation of the earth and is described as the surface that would be assumed by the undisturbed surface of the sea, continued underneath the continents. ellipsoid is a smooth mathematical surface that best fits the shape of the geoids and is the next level of approximation of the actual shape of the earth.

12 There are two general classes of land surveying: plane and geodetic. - the plane Survey is the survey in which curvature of earth is not taken into account and where the survey is extend over small areas assumed as flat area or horizontal plane - Geodetic surveying takes into account the true shape of the earth(which take in the consideration the curvature of the earth. These surveys are usually of a very large scale and most often performed by government agencies.

13 PLANE SURVEYING GEODETIC SURVEYING

14 1-Plane Surveying: When surveying area <10 mile radius, (1 mile = 1609 km) and there are two types : - Cadastral Surveying -Topography Surveying Cadastral Surveys The name Cadastre is a Latin base term which refers to a registry of lands. Cadastral Surveying is surveying of land so as to determine and define land ownership and boundaries.

15 Topographic or Detail Surveys The purpose of topographic survey is to gather survey data about the natural and manmade features of the land as well as its elevations. Maps are then prepared from this information. Topographic maps median scale and they contain the following elements : 1- Natural Features Such as mountains, valleys and rivers. 2- Man made Features and artificial features Such as roads, cities, canals and drains and engineering constructions.

16 And where are mapping a large-scale drawing showing allows details of the artificial features sufficiently precise, such as: 1- agricultural maps include the names of the governorates and centers and villages and agricultural land boundaries 2- Cities Maps: and include survey district names, unique identifying numbers for positions of existing structures, section or lot numbers and their respective areas, adjoining and adjacent street names.

17 Engineering Surveys This type of survey is associated with the engineering design (topographic, layout and as built) often requiring geodetic computations beyond normal civil engineering practice. It is required in planning and execution of nearly every form of construction. The equipment commonly used for this are theodolites,(gps) and leveling instruments.

18 Aerial Surveys Aerial survey is a method of collecting information conducted from an airborne platform. This is collected by using aerial photography, laser scanning. It is often recognized similarly as aerophotogrammetry. This involves estimating the three dimensional coordinates of points on an object. These are determined by measurements made in two or more photographic images taken from different positions. Common points are identified on each image. A line of sight (or ray) can be constructed from the camera location to the point on the object. It is the intersection of these rays (triangulation) that determines the three dimensional location of the point.

19 Aerial surveys are used for: -Land surveys -- Agriculture - Mining - Reconnaissance - Fishery surveys - Monitoring vegetation and ground cover - Large scale planning for land development

20 Mining Surveys Mining survey is a specialist area of surveying involving the measurement, representation and management of data associated with mining operations which could be the underground and open cut mine workings. These measurements enable new mine works to avoid older and possibly flooded ones.

21 Hydrographic Surveys Hydrographic survey is the science of measurement and description of the physical features of the navigable portion of the earth s surface (seas) and adjoining coastal areas,with special reference to their use for the purpose of navigation

22 GIS Gathering information about natural resources. Here we use GIS GIS geographic Information System. Remote sensing

23 GPS: Global positioning system -In this type we use satellites to know the coordinates of a point in X Y (GPS) Global positioning system by using 3 or 4 satellites to track a signal came from an antenna(arial) from the position globe