Lecture

Geodetic Concepts: Reference Systems and Projections

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In course

ENV-140: Fundamentals of geomatics

Bases de la géomatique pour les ingénieur·e·s civil et en environnement. Présentation des méthodes d'acquisition, de gestion et de représentation des géodonnées. Apprentissage pratique avec des méthodes topométriques et d'imagerie du territoire. ...

Description

This lecture introduces geodetic concepts such as geodesy, geoid, ellipsoid, and reference systems. The instructor explains the importance of defining a global coordinate system, the challenges of defining a system at a large scale, and the types of coordinates used for spherical or ellipsoidal systems. The lecture also covers the difference between geoid and ellipsoid heights, the convergence of meridians, and the need to correct distances between the map and the terrain. The instructor emphasizes the significance of understanding different reference systems for accurate measurements and projections in engineering and environmental projects.

Instructors (2)

Pierre-Yves Gilliéron

He graduated in Surveying Engineering at the Swiss Federal Institute of Technology Lausanne in 1988. He started his professional career in photogrammetry and digital mapping. He joined the Geodetic Eng. Laboratory in 1997 where he worked as research scientist on various navigation and satellite positioning projects. Since 2018 he is deputy head of the section in environmental sciences and engineering at EPFL. -- He was member of the board of the swiss institute of navigation (ION-CH), member of the swiss geodetic committee (SGK) and expert in different committees of the swiss road association (VSS).

Devis Tuia

I come from Ticino and studied in Lausanne, between UNIL and EPFL. After my PhD at UNIL in remote sensing, I was postdoc in Valencia (Spain), Boulder (CO) and EPFL, working on model adaptation and prior knowledge integration in machine learning. In 2014 I became Research Assistant Professor at University of Zurich, where I started the 'multimodal remote sensing' group. In 2017, I joined Wageningen University (NL), where I was professor of the GeoInformation Science and Remote Sensing Laboratory. Since 2020, I joined EPFL Valais, to start the ECEO lab, working at the interface between Earth observation, machine learning and environmental sciences.

Official source

Ontological neighbourhood

Earth science

Geology: Geodesy

Related concepts (32)

Earth ellipsoid

An Earth ellipsoid or Earth spheroid is a mathematical figure approximating the Earth's form, used as a reference frame for computations in geodesy, astronomy, and the geosciences. Various different ellipsoids have been used as approximations. It is a spheroid (an ellipsoid of revolution) whose minor axis (shorter diameter), which connects the geographical North Pole and South Pole, is approximately aligned with the Earth's axis of rotation.

Geodesics on an ellipsoid

The study of geodesics on an ellipsoid arose in connection with geodesy specifically with the solution of triangulation networks. The figure of the Earth is well approximated by an oblate ellipsoid, a slightly flattened sphere. A geodesic is the shortest path between two points on a curved surface, analogous to a straight line on a plane surface. The solution of a triangulation network on an ellipsoid is therefore a set of exercises in spheroidal trigonometry .

Physical geodesy

Physical geodesy is the study of the physical properties of Earth's gravity and its potential field (the geopotential), with a view to their application in geodesy. Traditional geodetic instruments such as theodolites rely on the gravity field for orienting their vertical axis along the local plumb line or local vertical direction with the aid of a spirit level. After that, vertical angles (zenith angles or, alternatively, elevation angles) are obtained with respect to this local vertical, and horizontal angles in the plane of the local horizon, perpendicular to the vertical.

Hayford ellipsoid

The Hayford ellipsoid is a geodetic reference ellipsoid, named after the US geodesist John Fillmore Hayford (1868–1925), which was introduced in 1910. The Hayford ellipsoid was also referred to as the International ellipsoid 1924 after it had been adopted by the International Union of Geodesy and Geophysics IUGG in 1924, and was recommended for use all over the world. Many countries retained their previous ellipsoids. The Hayford ellipsoid is defined by its semi-major axis a = 6378388.000m and its flattening f = 1:297.

Systems engineering

Systems engineering is an interdisciplinary field of engineering and engineering management that focuses on how to design, integrate, and manage complex systems over their life cycles. At its core, systems engineering utilizes systems thinking principles to organize this body of knowledge. The individual outcome of such efforts, an engineered system, can be defined as a combination of components that work in synergy to collectively perform a useful function.

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