Stal C.,Ghent University |
Briese C.,Vienna University of Technology |
De Maeyer P.,Ghent University |
Dorninger P.,Vienna University of Technology |
And 4 more authors.
International Journal of Remote Sensing | Year: 2014
This article presents a newly developed procedure for the classification of airborne laser scanning (ALS) point clouds, based on binomial logistic regression analysis. By using a feature space containing a large number of adaptable geometrical parameters, this new procedure can be applied to point clouds covering different types of topography and variable point densities. Besides, the procedure can be adapted to different user requirements. A binomial logistic model is estimated for all a priori defined classes, using a training set of manually classified points. For each point, a value is calculated defining the probability that this point belongs to a certain class. The class with the highest probability will be used for the final point classification. Besides, the use of statistical methods enables a thorough model evaluation by the implementation of well-founded inference criteria. If necessary, the interpretation of these inference analyses also enables the possible definition of more sub-classes. The use of a large number of geometrical parameters is an important advantage of this procedure in comparison with current classification algorithms. It allows more user modifications for the large variety of types of ALS point clouds, while still achieving comparable classification results. It is indeed possible to evaluate parameters as degrees of freedom and remove or add parameters as a function of the type of study area. The performance of this procedure is successfully demonstrated by classifying two different ALS point sets from an urban and a rural area. Moreover, the potential of the proposed classification procedure is explored for terrestrial data. © 2014 Taylor & Francis.
Harzhauser M.,Natural History Museum Vienna |
Djuricic A.,Natural History Museum Vienna |
Djuricic A.,Vienna University of Technology |
Mandic O.,Natural History Museum Vienna |
And 11 more authors.
Palaeogeography, Palaeoclimatology, Palaeoecology | Year: 2015
We present the largest GIS-based data set of a single shell bed, comprising more than 10,280 manually outlined objects. The data are derived from a digital surface model based on high-resolution terrestrial laser scanning (TLS) and orthophotos obtained by photogrammetric survey, with a sampling distance of 1. mm and 0.5. mm, respectively. The shell bed is an event deposit, formed by a tsunami or an exceptional storm in an Early Miocene estuary. Disarticulated shells of the giant oyster Crassostrea gryphoides are the most frequent objects along with venerid, mytilid and solenid bivalves and potamidid gastropods. The contradicting ecological requirements and different grades of preservation of the various taxa mixed in the shell bed, along with a statistical analysis of the correlations of occurrences of the species, reveal an amalgamation of at least two pre- and two post-event phases of settlement under different environmental conditions. Certain areas of the shell bed display seemingly significant but opposing shell orientations. These patterns in coquinas formed by densely spaced elongate shells may result from local alignment of neighboring valves due to occasional events and bioturbation during the years of exposure. Similarly, the patchy occurrence of high ratios of shells in stable convex-up positions may simply be a result of such "maturity" effects. Finally, we document the difficulties in detecting potential tsunami signatures in shallow marine settings even in exceptionally preserved shell beds due to taphonomic bias by post-event processes. © 2015.
Pertry I.,Outreach |
Pertry I.,Ghent University |
Nothegger C.,Vienna University of Technology |
Nothegger C.,4D IT GmbH |
And 17 more authors.
New Biotechnology | Year: 2014
Risk assessment of genetically modified organisms (GMOs) remains a contentious area and a major factor influencing the adoption of agricultural biotech. Methodologically, in many countries, risk assessment is conducted by expert committees with little or no recourse to databases and expert systems that can facilitate the risk assessment process. In this paper we describe DTREEv2, a computer-based decision support system for the identification of hazards related to the introduction of GM-crops into the environment. DTREEv2 structures hazard identification and evaluation by means of an Event-Tree type of analysis. The system produces an output flagging identified hazards and potential risks. It is intended to be used for the preparation and evaluation of biosafety dossiers and, as such, its usefulness extends to researchers, risk assessors and regulators in government and industry. © 2013 Elsevier B.V.
Rasztovits S.,Vienna University of Technology |
Dorninger P.,4D IT GmbH
International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences - ISPRS Archives | Year: 2013
Terrestrial Laser Scanning (TLS) is an established method to reconstruct the geometrical surface of given objects. Current systems allow for fast and efficient determination of 3D models with high accuracy and richness in detail. Alternatively, 3D reconstruction services are using images to reconstruct the surface of an object. While the instrumental expenses for laser scanning systems are high, upcoming free software services as well as open source software packages enable the generation of 3D models using digital consumer cameras. In addition, processing TLS data still requires an experienced user while recent web-services operate completely automatically. An indisputable advantage of image based 3D modeling is its implicit capability for model texturing. However, the achievable accuracy and resolution of the 3D models is lower than those of laser scanning data. Within this contribution, we investigate the results of automated web-services for image based 3D model generation with respect to a TLS reference model. For this, a copper sculpture was acquired using a laser scanner and using image series of different digital cameras. Two different webservices, namely Arc3D and AutoDesk 123D Catch were used to process the image data. The geometric accuracy was compared for the entire model and for some highly structured details. The results are presented and interpreted based on difference models. Finally, an economical comparison of the generation of the models is given considering the interactive and processing time costs.
Szekely B.,Vienna University of Technology |
Szekely B.,Eötvös Loránd University |
Koma Z.,Eötvös Loránd University |
Karatson D.,Eötvös Loránd University |
And 7 more authors.
Earth Surface Processes and Landforms | Year: 2014
Quasi-planar morphological surfaces may become dissected or degraded with time, but still retain original features related to their geologic-geomorphic origin. To decipher the information hidden in the relief, recognition of such features is required, possibly in an automated manner. In our study, using Shuttle Radar Topography Mission (SRTM) digital elevation model (DEM), an existing algorithm has been adapted to recognize quasi-planar features fulfilling specified criteria. The method has been applied to a study area of the Central Andes with Miocene to Quaternary volcanic edifices, tilted ignimbrite surfaces, and basin-filling sediments. The result is a surface segmentation, whereas non-planar features (gullies, tectonic faults, etc.) are sorted out. The main types of geomorphic features that can be distinguished and interpreted are as follows. (1) The west-dipping western margin of the Altiplano is differentiated into segments of the lower sedimentary cover that of increased erosion by tectonic steepening at intermediate levels, and an upper plane with limited erosion. (2) In the central part of the Western Cordillera, the Oxaya ignimbrite block shows a 'striped' bulging pattern that results from a smoothly changing surface dip. This pattern is due to continuous folding/warping of the ignimbrite block possibly related to gravitational movements. (3) To the west, large, uniform planes correspond to flat, smooth, tectonically undisturbed surfaces of young sedimentary cover of the Central Basin. (4) The evolution of Taapaca volcanoes with sector collapse events and cone-building phases is shown by several segments with overlapping clastic aprons. (5) To the east, on the western margin of the Altiplano, young intermontane basins filled by Upper Miocene sediments show progressively increasing dip toward basin margins, reflected by a circular pattern of the segmentation planes. We show that the segmentation models provide meaningful images and additional information for geomorphometric analysis that can be interpreted in terms of geological and surface evolution models. © 2014 John Wiley & Sons, Ltd.