Analysis of floods using satellite images - case study of the 2007 torrential flood in the Selška valley [Analiza poplav z uporabo satelitskih posnetkov - primer hudourniške poplave v Selški dolini leta 2007]
Lamovec P.,Institute za antropoloske in prostorske studije |
Mikos M.,University of Ljubljana
Geodetski Vestnik | Year: 2011
An application of data mining for the determination of flooded areas was published in the Journal Geodetski vestnik (no. 54/2010-4). This paper analyses the usefulness of these results for further analyses of hydraulic parameters. The velocity and discharges were computed for six locations. The study showed that the flooded areas determined by satellite images can be used for further analyses. Nevertheless, other layers have to be sufficiently precise, especially the digital terrain model (DTM). DTM 12.5 was used. The study showed that DTM 12.5 is not precise enough. The observed area is very rough and the hydraulic parameters (cross sectional area of flow, wetted perimeter, hydraulic radius, river-bottom slope, flow velocity, discharge) cannot be detected with sufficient precision. Consequently, the calculated hydraulic radiuses, velocities and discharges are out of expectations. In the first part of the article, some basic information about remote sensing and its techniques is presented. Some practical examples of their usage (especially satellite images) for the observation of natural disasters are also given.
Debevec L.,Institute za antropoloske in prostorske studije
Dve Domovini | Year: 2010
The article compares traditional and civil wedding celebrations among Muslims in urban Burkina Faso. It analyses the types of food served at the two events and compares their meaning. Traditional African food is served at the traditional wedding celebration, while at the civil ceremony "white man's foods" are served to reflect the modern way of living and thinking. Drawing on these two ceremonial forms and two types of food consumption, the article discusses the ongoing discourse of "traditional" versus "modern" in urban Burkina Faso.
Lenarcic A.S.,Center odlicnosti Vesolje |
Mesner N.,Geodetski Institute Slovenije |
Ostir K.,Institute za antropoloske in prostorske studije
Geodetski Vestnik | Year: 2015
Sentinel satellites and the European Copernicus programme have begun to provide huge amounts of high spatial and temporal resolution images, which need to be processed quickly and preferably automatically. Object based classification is the most commonly used method for the interpretation of high spatial resolution optical images. It is a challenging process of object borders recognition (segmentation) and classification of segments in the user-defined classes (classification). The quality of the segmentation is crucial because it has a direct impact on the quality of final classification results. Several algorithms have been developed for optical remote sensing imagery segmentation with varying (depending on the purpose of the analysis) accuracy. Knowledge of algorithms and adequacy of application are crucial for high quality segmentation results. In this paper, we give an overview of optical remote sensing imagery segmentation algorithms and the possibility of their application. Besides, an overview of object based classification software, with a focus on segmentation process, is given. The intent of this paper is not to provide a recipe for the best algorithm and software selection, but to support users with knowledge they might need to be able to obtain the best possible segmentation results of an analysis in given circumstances. © 2015 Zvava Geodetov Slovenije. All rights reserved.
Popit T.,University of Ljubljana |
Supej B.,Mensuras d.o.o |
Kokalj Z.,Institute za antropoloske in prostorske studije |
Verbovsek T.,University of Ljubljana
Geodetski Vestnik | Year: 2016
A method that gives the clearest individual geomorphometric elements for the requirements of spatial analysis was selected to define the spatial variability of landforms on primary bedrocks and their slope deposits on the northern edge of the Vipava Valley in Slovenia. We tested the most frequently used morphometric indicators of surface roughness, other than the curvature of the surface, and reviewed them based on their performance with lidar data. We analysed in detail five methods that can be used for surface roughness evaluation and that have a potential for the study of the bedrock and slope deposits. Height variability was identified as the most appropriate method. We have also found that maps of properly portrayed height variability can be an indispensable tool for geological and geomorphological mapping. © 2016, Zvava Geodetov Slovenije. All rights reserved.
Marsetic A.,CO Vesolje SI |
Marsetic A.,Institute za antropoloske in prostorske studije |
Kokalj Z.,CO Vesolje SI |
Kokalj Z.,Institute za antropoloske in prostorske studije |
And 2 more authors.
Geodetski Vestnik | Year: 2012
Lossy compression is becoming increasingly used in remote sensing, although its effect on the processing results has yet not been fully investigated. This paper presents the effects of JPEG2000 lossy compression on the classification of very high-resolution WorldView-2 imagery. For the first time, the k-nearest neighbor and support vector machine methods of the object based classification were used. The results explore the impact of compression on the images, segmentation and resulting classification. The study proves that in general lossy compression does not adversely affect the classification of images; moreover, in some cases classification of compressed images yields better results than classification of the original image. Classification accuracy of the support vector machine method indicates that compression ratios of up to 30:1 can be used without any loss of classification accuracy. The best result of the k-nearest neighbor method was obtained with the highest compression ratio (100:1). The support vector machine is recommended for further research. In addition to the classification method, image segmentation also plays an important role in the accuracy of the results.