R.T.U / G.I.T JAIPUR SUBJECT – Surveying (3CE4-05) CIVIL ENGG./ III SEM UNIT – 4 TACHEOMETRY AND PHOTOGRAMMETRY SURVEYING 1 PRATEEK SHARMA R.T.U / G.I.T JAIPUR SUBJECT – Surveying (3CE4-05) CIVIL ENGG./ III SEM Blown up Detail 1.1 Introduction 1.2 Instrument used 1.3 Classification of Tacheometry 1.3.1 Stadia Tacheometry 1.3.2 Tangential Tacheometry 1.4 Introduction of Photogrammetry Surveying 1.5 Application of Photogrammetry 1.6 Advantage & Disadvantage 1.7 Principle of Photogrammetry 1.8 Types of Photogrammetry 1.9 Aerial Photographs 1.10 Relief Displacements 1.11 Tilt Displacements 1.12 Flight Planning 2 PRATEEK SHARMA R.T.U / G.I.T JAIPUR Surveying (3CE4-05) CIVIL ENGG./ III SEM 1.1 Introduction • Tacheometry is the branch of survey in which the horizontal and vertical distances of points are obtained by instrumental observations such as staff intercepts and angles. – The process of measuring horizontal distance is eliminated – Less accurate, but more rapid – Best useful in case of rough & difficult terrain – Primary objective is preparation of contour maps or plans – Used in Hydrographic surveys, location surveys etc. 3 PRATEEK SHARMA R.T.U / G.I.T JAIPUR Surveying (3CE4-05) CIVIL ENGG./ III SEM 1.2 Instruments used in Tacheometry are: Tacheometer – A transit Theodolite fitted with a stadia diaphragm Diaphragm is the frame upon which is mounted the crosshairs to give a definite line of sight. Stadia hairs / Stadia Lines are a pair of horizontal hairs provided in addition to the regular crosshairs. Each on of this is equidistant from the central horizontal hair. Commonly used Stadia diaphragms are shown here. 4 PRATEEK SHARMA R.T.U / G.I.T JAIPUR Surveying (3CE4-05) CIVIL ENGG./ III SEM Levelling Staff / Stadia Rod – a scale, shown below, graduated in metres and centimeters. They may be single solid, folding or telescopic. 5 PRATEEK SHARMA R.T.U / G.I.T JAIPUR Surveying (3CE4-05) CIVIL ENGG./ III SEM Important Terminology •Stadia Interval (i)– the actual physical distance between the top & bottom stadia hairs •Staff intercept (S) – the difference between the leveling staff readings corresponding to the top & bottom stadia hairs 6 PRATEEK SHARMA R.T.U / G.I.T JAIPUR Surveying (3CE4-05) CIVIL ENGG./ III SEM 1.3 CLASSIFICATION OF TACHEOMETRY – based on the underlying principle 1) Stadia Tacheometry – make use of stadia hairs. Involves observation of either staff intercepts or stadia intervals. a.Fixed Hair method – • Stadia hairs are stationary => Stadia interval (i) is constant • Staff intercept depends upon the horizontal distance between the tacheometer and stadia rod => Staff intercept (S) is variable • Most commonly used b. Movable Hair method – • Here, the stadia rod or leveling staff is provided with two fixed targets. The stadia hairs can be moved to coincide the targets accurately, using micrometer screws => Stadia interval (i) is variable • Since the same staff with fixed targets is used everywhere => Staff intercept (S) is constant • Rarely used 2) Tangential Tacheometry – does not use stadia hairs, hence stadia diaphragm is not required. Here, a transit Theodolite is used to measure vertical angles to the two fixed targets on a staff held at a station point. 7 PRATEEK SHARMA R.T.U / G.I.T JAIPUR Surveying (3CE4-05) CIVIL ENGG./ III SEM 1.3.1 Stadia Tacheometry 8 PRATEEK SHARMA R.T.U / G.I.T JAIPUR Surveying (3CE4-05) CIVIL ENGG./ III SEM 1.3.1 Stadia Tacheometry 9 PRATEEK SHARMA R.T.U / G.I.T JAIPUR Surveying (3CE4-05) CIVIL ENGG./ III SEM 10 PRATEEK SHARMA R.T.U / G.I.T JAIPUR Surveying (3CE4-05) CIVIL ENGG./ III SEM 11 PRATEEK SHARMA R.T.U / G.I.T JAIPUR Surveying (3CE4-05) CIVIL ENGG./ III SEM 12 PRATEEK SHARMA R.T.U / G.I.T JAIPUR Surveying (3CE4-05) CIVIL ENGG./ III SEM 13 PRATEEK SHARMA R.T.U / G.I.T JAIPUR Surveying (3CE4-05) CIVIL ENGG./ III SEM 14 PRATEEK SHARMA R.T.U / G.I.T JAIPUR Surveying (3CE4-05) CIVIL ENGG./ III SEM 1.3.2 Tangential Tacheometry 15 PRATEEK SHARMA R.T.U / G.I.T JAIPUR Surveying (3CE4-05) CIVIL ENGG./ III SEM 16 PRATEEK SHARMA R.T.U / G.I.T JAIPUR Surveying (3CE4-05) CIVIL ENGG./ III SEM 17 PRATEEK SHARMA R.T.U / G.I.T JAIPUR Surveying (3CE4-05) CIVIL ENGG./ III SEM PHOTOGRAMMETRY SURVEYING 18 PRATEEK SHARMA 1.4 Introduction of Photogrammetry Surveying O It is the science of making measurements fromphotographs. O Output of photogrammetry is typically a map,diagram measurement, or a 3D model of some real-world object or scene. O Photogrammetric surveying or photogrammetry is the branch of surveying in which maps are prepared from photo-graphs taken from ground or air stations. O With anadvancement of the photogrammetric techniques, photographs are also being used for the interpretation of geology, classification of soils and crops,etc. O Is the science of making measurements from photographs, especially for recovering the exact positions of surface points. O Used to recover the motion pathways of designated reference points located on any moving object, on its components and in the immediately adjacent environment. O Photogrammetry may employ high-speed imaging and remote sensing in order to detect, measure and record complex 2-D and 3-D motion fields. Now a days devices– drone camera, aircraft,phototheodolite, digital camera etc. R.T.U / G.I.T JAIPUR Surveying (3CE4-05) CIVIL ENGG./ III SEM • Photogrammetry is traditionally used to create topographic maps from aerial and spatial imagery. Close range photogrammetry is also used at the School of Surveying to obtain accurate measurements of animals in wildlife research or to create virtual models of historical buildings. • The fundamental principle used by photogrammetry is triangulation. By taking photographs from at least two different locations, so-called “lines of sight” can be developed from each camera to points on the object. • Photogrammetry is used in fields such as topographic mapping, architecture, engineering, manufacturing, quality control, police investigation, cultural heritage, and geology. 20 PRATEEK SHARMA R.T.U / G.I.T JAIPUR Surveying (3CE4-05) CIVIL ENGG./ III SEM • At 1 part in 30,000 on a 3m object, point positions would be accurate to 0.1mm at 68% probability (one sigma). This is relative accuracy. To find the absolute accuracy the project must be scaled and or have control points defined. Then the accuracy of these scales and control points affect the absolute accuracy. • In 1849, Aimé Laussedat (April 19, 1819 - March 18, 1907) was the first person to use terrestrial photographs for topographic map compilation. He is referred to as the "Father of Photogrammetry". 21 PRATEEK SHARMA R.T.U / G.I.T JAIPUR Surveying (3CE4-05) CIVIL ENGG./ III SEM • Photogrammetry is the science and technology of obtaining reliable information about physical objects and the environment through the process of recording, measuring and interpreting photographic images and patterns of electromagnetic radiant imagery and other phenomena. • Photogrammetry appeared in the middle of the 19th century, almost simultaneously with the appearance of photography itself. The use of photographs to create topographic maps was first proposed by the French surveyor Dominique F. Arago in about 1840. • The term photogrammetry was coined by the Prussian architect Albrecht Meydenbauer, which appeared his 1867 article "Die Photometrographie." • There are many variants of photogrammetry. One example is the extraction of three-dimensional measurements from two-dimensional data (i.e. images); for example, the distance between two points that lie on a plane parallel to the photographic image plane can be determined by measuring their distance on the image, if the scale of the image is known. Another is the extraction of accurate color ranges and values representing such quantities as albedo, specular reflection, metallicity, or ambient occlusion from photographs of materials for the purposes of physically based rendering. 22 PRATEEK SHARMA R.T.U / G.I.T JAIPUR Surveying (3CE4-05) CIVIL ENGG./ III SEM • Broadly Photogrammetry Requires: • Planning & taking the photographs • Processing the photographs • Measuring the photographs & Reducing • the measurement to produce end results. • Field Application of Photogrammetry : • Used to conduct topographical survey or engineering surveys. • Suitable for mountainous and hilly terrain with little vegetation. • Used for geological mapping which includes identification of land forms, rock type & rock structures. • Used for projects demanding higher accuracy, since it provides • accurate measurements. • Used in urban and regional planning applications. • Used mostly in Planning/designing in transport planning, bridge, • pipeline, hydropower, urban planning, security and strategic • planning, disaster management, natural resources management, city • models, conservation of archaeological sites etc. 23 PRATEEK SHARMA R.T.U / G.I.T JAIPUR Surveying (3CE4-05) CIVIL ENGG./ III SEM 1.5 Application of Photogrammetry • Importance/application of photogrammetry • Its applications include satellite tracking of the relative positioning alterations in all Earth environments. • The quantitative results of photogrammetry are used to guide and match the results of computational models of the natural systems, thus helping to invalidate or confirm new theories, to design novel vehicles or new methods for predicting or/and controlling the consequences of earthquakes, tsunamis, any weather types. • Photogrammetry also helps for the solving of triangulation, trilateration and multidimensional scaling. • In the simplest example, the distance between two points that lie on a plane parallel to the photographic image plane can be determined by measuring their distance on the image, if the scale (s) of the image is known. 24 PRATEEK SHARMA R.T.U / G.I.T JAIPUR Surveying (3CE4-05) CIVIL ENGG./ III SEM 1.6 Advantage & Disadvantage • Used in different fields, such as topographic mapping, architecture, engineering, manufacturing, quality control, police investigation, and geology, as well as by archaeologists to quickly produce plans of large or complex sites and by meteorologists.