138 research outputs found

    Geomatics bachelor and masters program in Belgium

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    A 4-year curriculum degree of Licence in Geography option Land Surveying was introduced in 1990 at two Belgian academic universities: both at the Universite de Liege in the French speaking part of Belgium and at Ghent University in the Dutch speaking part of Belgium. With the BAMA revolution in 2004, this degree has been converted into a 5-year curriculum finalised into an academic "Master in Geomatics and Surveying" (Ghent University) or a "Master in Geography, option Geomatics and Geometrology" (Universite de Liege) and subsequent "Ph.D. in Geomatics and Surveying" (Ghent University). The academic bachelor degree that gives direct access to the Master curriculum without additional compulsory courses is "Bachelor in Geography and Geomatics, Main subject: Surveying" (Ghent University), that can be obtained after 3 years of study. As suggested by the title, the geomatics/surveying degree is related to geographical sciences and located in the Faculty of Sciences. On the opposite, University Colleges (also called Technical Universities) offer professional Bachelor degrees, while academic universities only offer academic Bachelor or Master degrees. In October 2014, Ghent University will start an enhanced academic Bachelor program in Geomatics that allows direct access to the profession of chartered surveyor. The paper will discuss the education experiences, student number evolution and motivation for the enhancements of the Bachelor program

    The demand for hydrographic surveyors in the Benelux

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    In February 2015, the Hydrographic Society Benelux (HSB) sent an extended questionnaire to 77 of the most important hydrographic companies in the Benelux (Belgium, The Netherlands and Luxemburg). The organization of this questioning was in cooperation with the Department of Geography of Ghent University (Belgium). The purpose was to inquire the demand for hydrographic surveyors during the next 5 years in the Benelux. The Benelux is hosting the four biggest dredging companies in the world, so the demand for hydrographic surveyors is usually fairly high and a good parameter for the general demand in the West of Europe. On the one hand, the aim of the questionnaire was to research the demand for the preferred level of hydrographic surveyor, allowing a concise estimation of the demand for IHO category-A and category-B certified hydrographic surveyors. On the other hand, the required balance between hydrographic surveyors with a Bachelor versus Master degree was questioned. As a similar questionnaire and analysis has been performed in 2009, trends over the past 6 years can be discerned and analyzed. The results are important, not only for the private companies, but also for the higher education institutes. In the Benelux, but also outside the Benelux, one can find hydrographic institutes delivering cat. A and cat. B. IHO certified hydrographic surveyors, combined or not with a Bachelor and/or Master diploma. It is generally assumed that there is a shortage of hydrographic surveyors and/or of hydrographical educated employees in the Benelux. Currently, part of the active hydrographic surveyors in the Benelux are engineers, geologists and other non-specifically hydrographic trained people, who received additional bathymetric trining within private companies. But does this hypothesis withstands a scientific analysis? This will be critically analyzed in this paper

    The use of terrestrial laser scanning for measurements in shallow-water : correction of the 3D coordinates of the point cloud

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    Although acoustic measurements are a wide-spread technique in the field of bathymetry, most systems require a water depth of at least 2 m. Furthermore, mapping shallow-water depths with acoustic techniques is expensive and complicated. Over the last decades, the use of laser scanning for mapping riverbeds has increased. However, the level of accuracy and the point density which can be obtained by Airborne Laser Scanning (ALS), and Airborne Laser Bathymetry (ALB) in particular, are not as high as those of terrain measurements originating from ALS. Moreover, ALS and ALB are not yet suited for mapping shallow-water beds. Therefore, more recent research focuses on the use of Terrestrial Laser Scanning (TLS) from either a fixed or static position (STLS) or from a mobile platform (MTLS). An obvious advantage of using STLS and MTLS is that both the river beds and the river banks can be modelled by means of the same data acquisition system. This ensures a seamless integration of data sets describing both dry and wet surfaces, and thus of topography and bathymetry. However, although STLS and MTLS have the potential to produce high resolution point clouds of shallow-water riverbeds and - banks, the resulting point clouds have to be corrected for the systematic errors in depth and distance that are caused by the refraction of the laser beam at its transition through the boundary of air and water. In this research a procedure was implemented to adjust the coordinates of every point situated beneath the water surface, based on the refractive index. The refractive index depends on the wavelength of the laser beam and the properties of the media the beam travels through. The refractive index for a laser beam with a wavelength of 532 nm varies by less than 1% for a wide range of temperature and salinity conditions. Nevertheless, during the case studies, it became clear that it is important to use an estimate of the refractive index which approaches the actual value as closely as possible in order to obtain accuracies of less than 1 to 2 cm. Therefore, the refractive index was determined for each specific case by using water samples

    Towards cost-efficient prospection and 3D visualization of underwater structures using compact ROVs

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    The deployment of Remotely Operated Vehicles (ROV) for underwater prospection and 3D visualization has grown significantly in civil applications for a few decades. The demand for a wide range of optical and physical parameters of underwater environments is explained by an increasing complexity of the monitoring requirements of these environments. The prospection of engineering constructions (e.g. quay walls or enclosure doors) and underwater heritage (e.g. wrecks or sunken structures) heavily relies on ROV systems. Furthermore, ROVs offer a very flexible platform to measure the chemical content of the water. The biggest bottleneck of currently available ROVs is the cost of the systems. This constrains the availability of ROVs to a limited number of companies and institutes. Fortunately, as with the recent introduction of cost-efficient Unmanned Aerial Vehicles on the consumer market, a parallel development is expected for ROVs. The ability to participate in this new field of expertise by building Do It Yourself (DIY) kits and by adapting and adding on-demand features to the platform will increase the range of this new technology. In this paper, the construction of a DIY OpenROV kit and its implementation in bathymetric research projects are elaborated. The original platform contains a modified webcam for visual underwater prospection and a Micro ElectroMechanical System (MEMS) based depth sensor, allowing relative positioning. However, the performance of the standard camera is limited and an absolute positioning system is absent. It is expected that 3D visualizations with conventional photogrammetric qualities are limited with the current system. Therefore, modifications to improve the standard platform are foreseen, allowing the development of a cost-efficient underwater platform. Preliminary results and expectations on these challenges are reported in this paper

    Airborne photogrammetry and LIDAR for DSM extraction and 3D change detection over an urban area : a comparative study

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    A digital surface model (DSM) extracted from stereoscopic aerial images, acquired in March 2000, is compared with a DSM derived from airborne light detection and ranging (lidar) data collected in July 2009. Three densely built-up study areas in the city centre of Ghent, Belgium, are selected, each covering approximately 0.4 km(2). The surface models, generated from the two different 3D acquisition methods, are compared qualitatively and quantitatively as to what extent they are suitable in modelling an urban environment, in particular for the 3D reconstruction of buildings. Then the data sets, which are acquired at two different epochs t(1) and t(2), are investigated as to what extent 3D (building) changes can be detected and modelled over the time interval. A difference model, generated by pixel-wise subtracting of both DSMs, indicates changes in elevation. Filters are proposed to differentiate 'real' building changes from false alarms provoked by model noise, outliers, vegetation, etc. A final 3D building change model maps all destructed and newly constructed buildings within the time interval t(2) - t(1). Based on the change model, the surface and volume of the building changes can be quantified

    Applied surveying education : documenting cultural heritage in 3D in the city of Ghent (Belgium) using laser scanning and photo modelling

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    For several years the city of Ghent (Belgium) and the Ghent University, Department of Geography have been working together to document and measure important cultural heritage sites in 3D. The partnership enables master students in Geomatics and Surveying at the Ghent University to take part in a project driven measuring campaign. During the project, students use and compare several 3D data acquisition methods. This allows the students to implement their theoretical knowledge in the field. The used methods are analysed and critically compared by the students. Through this hands-on-training, students are encouraged to think “outside the box”. When problems occur, they are stimulated to think how these problems could have happened and most importantly how they can solve them. The documentation of these historic monuments in Ghent will be used during future renovation works and archaeological research. This paper will discuss the measurements in the Ghent City Museum (Stadsmuseum or STAM). The following methods are applied during the extensive field work: engineering surveying using total station and GNSS, photo modelling and laser scanning. The deliverables are created in a CAD or GIS environment. After successful completion of the course, students have gained a significant expertise concerning the processing of topographic data, 3D point clouds and imagery in an integrated way. This knowledge can be used after their studies to assess which equipment is most suitable for any given survey project. The final products of the photo modelling and the laser scanning process is a 3D model. Furthermore, digital elevation models and orthorectified images of the historic monument can be created. The orthorectified images are visualised and processed into high resolution orthophoto plans, in a CAD or GIS environment

    The use of high resolution digital surface models for change detection and viewshed analysis in the area around the pyramids of Giza, Egypt

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    One of the biggest threats to cultural heritage is related to their rapidly changing and developing surroundings. The Giza pyramid plateau is a prime example of this phenomenon, as it is threatened by the enormous urban expansion of Cairo over the last decades. Documenting, monitoring and modelling such a pressure requires accurate and detailed geographic data, which can be derived from recent up-to-date, high resolution satellite images. Remote sensing techniques have proven to be very useful to visualize and analyze urban sprawl and land use changes in two dimensions. The impact assessment of urban sprawl near specific heritage sites, however; needs to be complemented with accurate 2.5D-information. In an attempt to do so, digital surface models (DSMs) from Ikonos-2 (2005) and GeoEye-1 stereoscopic images (2009 and 2011) have been computed in order to analyze recent urban changes. Change detection methods are mainly developed for large scale high resolution aerial images; however this paper focuses on the one hand DSM creation and its challenges resulting in an improvement of 2.5D change detection method for small scale satellite imagery in mainly informal areas. On the other hand a view shed evolution is presented. The combination of the enhanced digital terrain extraction (eATE) module of Erdas Imagine® and ground control points collected in the field provides accurate and high resolution DSMs. The impact of shadow and different urban morphologies however influence the pixel-wise comparison of the two DSMs, which results in different approaches for different city districts. The resulting 2.5D change model clarifies not only the urban sprawl, but also the increase in building levels, directly related to pressure on the famous pyramids. This pressure is furthermore analyzed by creating different view sheds through time from the plateau towards the city and vice versa. An integration of population statistics complements the model, hence allowing it to become a useful policy instrument
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