scholarly journals Model-based combination of spatial information for stream networks

2007 ◽  
Vol 14 (3) ◽  
pp. 267-284 ◽  
Author(s):  
Mark S. Handcock
Sensors ◽  
2021 ◽  
Vol 21 (13) ◽  
pp. 4295
Author(s):  
Dongsheng Liu ◽  
Ling Han

Ship detection with polarimetric synthetic aperture radar (PolSAR) has gained extensive attention due to its widespread application in maritime surveillance. Nevertheless, designing identifiable features to realize accurate ship detection is still challenging. For this purpose, a fine eight-component model-based decomposition scheme is first presented by incorporating four advanced physical scattering models, thus accurately describing the dominant and local structure scattering of ships. Through analyzing the exclusive scattering mechanisms of ships, a discriminative ship detection feature is then constructed from the derived contributions of eight kinds of scattering components. Combined with a spatial information-based guard filter, the efficacy of the feature is further amplified and thus a ship detector is proposed which fulfills the final ship detection. Several qualitative and quantitative experiments are conducted on real PolSAR data and the results demonstrate that the proposed method reaches the highest figure-of-merit (FoM) factor of 0.96, which outperforms the comparative methods in ship detection.


2020 ◽  
Vol 14 (2) ◽  
pp. 139-150
Author(s):  
M. Simon ◽  
C.A. Popescu ◽  
Loredana Copăcean ◽  
Luminiţa Cojocariu

Data from the specialized literature show that in the last decade there has been a rapid development in the use of unmanned aerial vehicles (UAV) for obtaining spatial information from the pastoral environment. The idea of investigating grassland surfaces with the help of drones was based on the following practical considerations: the size and complexity of pastoral space and the need for data acquisition in hard-to-reach areas and in a short time. In this context, the purpose of the research is to integrate UAV technology and GIS applications into pratological research, the results obtained having both practical and methodological character. For the efficient research of the pastoral space with UAV equipment, a working model was developed, complex from a technical point of view, consisting of several stages: identifying the areas of interest, planning and setting the flight parameters, "photographing" the area, downloading and image processing, and then processing the results in the GIS environment. From each stage, geospatial products can be extracted, and the final products can be used in various ways, both in the pastoral space and in other segments of the geographical environment. Following the application of the working algorithm results the orthophotoplan and the point clouds, from which can be extracted topo-cadastral information (related to the "physical" surface of grasslands), pratological information (related to vegetation and mode of use) or useful information in territorial planning (risk phenomena, relief aspects), with high precision and spatial location. Compared with the classical research methods, the use of the working model based on geomatic technologies, has the effect of reducing the working time and the number of operators, the possibility of tracking time and space of the investigated territory, but also the formation of graphic and descriptive databases that they can be used in other subsequent projects.


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