Surveying | EPFL Graph Search

Surveying or land surveying is the technique, profession, art, and science of determining the terrestrial two-dimensional or three-dimensional positions of points and the distances and angles between them. A land surveying professional is called a land surveyor. These points are usually on the surface of the Earth, and they are often used to establish maps and boundaries for ownership, locations, such as the designed positions of structural components for construction or the surface location of subsurface features, or other purposes required by government or civil law, such as property sales. Surveyors work with elements of geodesy, geometry, trigonometry, regression analysis, physics, engineering, metrology, programming languages, and the law. They use equipment, such as total stations, robotic total stations, theodolites, GNSS receivers, retroreflectors, 3D scanners, LiDAR sensors, radios, inclinometer, handheld tablets, optical and digital levels, subsurface locators, drones, GI

WebAL Comes of Age: A Review of the First 21 Years of Artificial Life on the Web

Joshua Evan Auerbach, Sebastian Risi, Jason Yosinski

We present a survey of the first 21 years of web-based artificial life (WebAL) research and applications, broadly construed to include the many different ways in which artificial life and web technologies might intersect. Our survey covers the period from 1994—when the first WebAL work appeared—up to the present day, together with a brief discussion of relevant precursors. We examine recent projects, from 2010–2015, in greater detail in order to highlight the current state of the art. We follow the survey with a discussion of common themes and methodologies that can be observed in recent work and identify a number of likely directions for future work in this exciting area.

Mit Press2016

Analyse et exploitation des données de LIDAR aéroportés pour la caractérisation des milieux boisés de la Suisse

Gilles Gachet

Forest ecosystems show diverse and evolving structures. Accurate descriptions and a good knowledge of these environments are therefore a real challenge. Existing forest cover investigation methods are mostly laborious, hard to replicate and usually based on the skills of a small number of experts. Moreover, these methods are bound to standard two-dimensional information originated from aerial images or land surveys. The use of LiDAR elevation models leads to the development of new methodologies likely to propose innovative solutions to improve and ease the description and study of forests. In practice, managers often carry out maintenance forestry tasks as well as experimental ones. These tasks are successfully completed by means of tree observation and census. It is precisely with census that LiDAR technology can provide innovative solutions, allowing collection of accurate and reliable information from objects standing out of ground surface. Spatial analysis tools are then used to establish suitable indicators or cartographic documents to identify and define forest management objectives, to plan measures to achieve these goals, or even to monitor the results. The main objective of this PhD thesis is to propose new methods based on LiDAR technology applied to forestry. At first the study focuses on basic characteristics of a forest cover. Specific investigation of the potential of LiDAR elevation models to estimate the location, the height of individual trees and stands is carried out. In a second stage issues closer to management tasks are addressed, in particular analysis of horizontal and vertical structure of the forest, quantification of stock and identification of significant changes between two successive planting situations on the same site. Concerns of this study are to divert synthetic and normalized indicators in order to facilitate the actions and decision making process of the forester. It wants to extract innovative information in order to improve the knowledge and the description of wooden environments. A more or less significant participation of the skilled practitioner is required to configure the operations and to interpret the indicators, purpose of which is to save time by allowing more targeted and more complete ground investigation, subjective factor being in the benefit of the results. Although discussed issues as well as presented developments are based on common forest problems and of universal nature, they are presented in a context strongly influenced by Swiss forestry. The new contributions as well as the boundaries of the LiDAR technology are central to the reflection.

EPFL2009

Seismic vulnerability of cultural heritage buildings in Switzerland

Mylène Devaux Baudraz

Seismic risk for cultural heritage buildings has been underestimated for years in Switzerland. A strong earthquake can occur at any time in this region, as it has been shown during the last centuries. As reminder the 1356 seismic event that destroyed the city of Basel can be quoted; this event, whose intensity is assessed as having been I=IX on the European Macroseismic Scale (EMS-98), is recorded as the most violent earthquake that struck central and northern Europe. Since 2003 or even 1989, the seismic safety of common buildings is well defined through modern building codes (Swisscodes (SIA)). However, this is not the case of cultural heritage buildings whose seismic vulnerability has been only partly addressed. This PhD thesis was initiated in order to fill in this void of knowledge by creating a methodology for assessing the seismic vulnerability of historical edifices. Surveys carried out on cultural heritage buildings after seismic event showed that such kind of structures are particularly vulnerable under seismic actions. This vulnerability is essentially due to their particular structure that is characterized by slender components (pillars), wide open spaces, quite big masses located at high levels (vaults and their filling, lantern towers, etc.) on one hand; on the other hand, they generally have few components that can resist the lateral actions perpendicular to the nave and their masonry fabric is non-ductile. Moreover the non-existence of a stiff horizontal component (or a deformable one in case of wooden ceilings) and heavy masses concentrated in walls rather at floors make it impossible to apply models that have been developed for common buildings. The methodology that is presented in this report is composed of four steps. It gives the possibility to first sort out the sacred edifices that are seismically vulnerable from the ones that are not vulnerable. The second step allows engineers to determine the seismic vulnerability of a given edifice by the use of simplified models that give valuable results. In case more accurate results are required, more sophisticated models can be applied, as the Finite Element Method. In the last step, the seismic vulnerability of the edifice is put in parallel with the expected peak ground acceleration of the region. This last phase permits to set if the given edifice can be damaged by earthquakes, which damage is expected and which retrofitting is required.

EPFL2008