Pixel-based (PB) and geographic-object-based (GEOBIA) classification approaches allow the extraction of different objects from multispectral images (MS). The primary goal of this research was the ...analysis of UAV imagery applicability and accuracy assessment of MLC and SVM classification algorithms within PB and GEOBIA classification approaches. The secondary goal was to use different accuracy assessment metrics to determine which of the two tested classification algorithms (SVM and MLC) most reliably distinguishes olive tree crowns and which approach is more accurate (PB or GEOBIA). The third goal was to add false polygon samples for Correctness (COR), Completeness (COM) and Overall Quality (OQ) metrics and use them to calculate the Total Accuracy (TA). The methodology can be divided into six steps, from data acquisition to selection of the best classification algorithm after accuracy assessment. High-quality DOP (digital orthophoto) and UAVMS were generated. A new accuracy metric, called Total Accuracy (TA), combined both false and true positive polygon samples, thus providing a more comprehensive insight into the assessed classification accuracy. The SVM (GEOBIA) was the most reliable classification algorithm for extracting olive tree crowns from UAVMS imagery. The assessment carried out indicated that application of GEOBIA-SVM achieved a TACOR of 0.527, TACOM of 0.811, TAOQ of 0.745, Overall Accuracy (OA) of 0.926 or 0.980 and Area Under Curve (AUC) value of 0.904 or 0.929. The calculated accuracy metrics confirmed that the GEOBIA approach (SVM and MLC) achieved more accurate olive tree crown extraction than the PB approach (SVM and MLC) if applied to classifying VHR UAVMS imagery. The SVM classification algorithm extracted olive tree crowns more accurately than MLC in both approaches. However, the accuracy assessment has proven that PB classification algorithms can also achieve satisfactory accuracy.
Terrestrial LiDAR scanning (TLS) has in preceding years emerged as one of the most accurate and reliable geospatial methods for the creation of very-high resolution (VHR) models over gullies and ...other complex geomorphic features. Rough terrain morphology and rapid erosion induced spatio-temporal changes (STCs) can lead to significant challenges in multi-temporal field TLS surveys. In this study, we present a newly developed systematic framework for the optimization of multi-temporal terrestrial LiDAR surveys through the implementation of thorough systematic pre-survey planning and field preparation phases. The developed systematic framework is aimed at increase of accuracy and repeatability of multi-temporal TLS surveys, where optimal TLS positions are determined based on visibility analysis. The whole process of selection of optimal TLS positions was automated with the developed TLS positioning tool (TPT), which allows the user to adjust the parameters of visibility analysis to local terrain characteristics and the specifications of available terrestrial laser scanners. Application and validation of the developed framework were carried out over the gully Santiš (1226.97 m2), located at Pag Island (Croatia). Eight optimal TLS positions were determined by the TPT tool, from which planned coverage included almost 97% of the whole gully area and 99.10% of complex gully headcut morphology. In order to validate the performance of the applied framework, multi-temporal TLS surveys were carried out over the gully Santiš in December 2019 and 2020 using the Faro Focus M70 TLS. Field multi-temporal TLS surveys have confirmed the accuracy and reliability of the developed systematic framework, where very-high coverage (>95%) was achieved. Shadowing effects within the complex overhangs in the gully headcut and deeply incised sub-channels were successfully minimalized, thus allowing accurate detection and quantification of erosion induced STCs. Detection of intensive erosion induced STCs within the observed one-year period was carried out for the chosen part of the gully headcut. Most of the detected STCs were related to the mass collapse and gradual uphill retreat of the headcut, where in total 2.42 m2 of soil has been eroded. The developed optimization framework has significantly facilitated the implementation of multi-temporal TLS surveys, raising both their accuracy and repeatability. Therefore, it has great potential for further application over gullies and other complex geomorphic features where accurate multi-temporal TLS surveys are required for monitoring and detection of different STCs.
Changes in the land use/land cover (LU/LC) model caused by different anthropogenic and natural factors are an important object of numerous scientific research. In this paper, an analysis of the ...spatio-temporal changes (LUCCs) for the area of Significant landscape (SL) of the „Baraćeve špilje“ in the period from 1960 to 2021 was performed. Using aerial photographs and a hybrid classification method, LU/LC models and spatio-temporal changes (STCs) analysis were performed. The research showed that the abandonment of agriculture and the slow disappearance of anthropogenic influence led to the disappearance of low vegetation in the form of lawns, meadows and pastures, while the bushy vegetation and forest gradually prevailed. Finally, in accordance with the degree of protection of the studied area guidelines for stopping negative trends in LU/LC changes were considered.
Changes in the land use/land cover (LU/LC) model caused by different anthropogenic and natural factors are an important object of numerous scientific research. In this paper, an analysis of the ...spatio-temporal changes (LUCCs) for the area of Significant landscape (SL) of the „Baraćeve špilje“ in the period from 1960 to 2021 was performed. Using aerial photographs and a hybrid classification method, LU/LC models and spatio-temporal changes (STCs) analysis were performed. The research showed that the abandonment of agriculture and the slow disappearance of anthropogenic influence led to the disappearance of low vegetation in the form of lawns, meadows and pastures, while the bushy vegetation and forest gradually prevailed. Finally, in accordance with the degree of protection of the studied area guidelines for stopping negative trends in LU/LC changes were considered.
In order to determine the presence and spatial distribution of gully erosion on the Pag Island (Croatia), a gully erosion susceptibility model was developed using GIS-based multicriteria decision ...analysis (GIS-MCDA). To simplify the GIS-MCDA modelling process, we developed automated multicriteria GIS analysis - GAMA method that is applicable to other karstic areas. The analytic hierarchy process (AHP) was used to assign specific weight coefficients to each criterion in regard to its importance for gully erosion occurrence. In total four different gully erosion susceptibility models were created, based on different criteria weight coefficients. The final GIS-MCDA model (3) was chosen based on the quality validation. Validation of GIS-MCDA model quality was done using ROC curves that were made based on two reference gully datasets. Validation confirmed the consistency of created models and proved that existing gullies are within high gully erosion susceptibility areas. The entire Pag Island was divided, through generated gully erosion susceptibility model into areas of: very low susceptibility, low susceptibility, medium susceptibility, high susceptibility and very high susceptibility. High and very high gully erosion susceptibility areas cover around 30% of the total area of Pag Island. Developed GAMA method allows easier and faster application of GIS-MCDA methodology in gully erosion susceptibility modelling, as well as in various other research areas.
•Gully erosion susceptibility model is created through GIS-MCDA based on 10 predisposing and one Boolean criteria.•ROC curve quality validation confirmed the consistency of created gully erosion susceptibility model (AUC = 0,8965).•Final model has shown that high and very high gully erosion susceptibility areas cover around 30% of Pag island.•GAMA method makes GIS-MCDA process more direct, practical and applicable in various susceptibility modelling purposes.
Commercial micrometer silicon (Si) powder was investigated as a potential anode material for lithium ion (Li-ion) batteries. The characterization of this powder showed the mean particle size of ...approx.75.2 nm, BET surface area of 10.6 m
g and average pore size of 0.56 nm. Its band gap was estimated to 1.35 eV as determined using UV-Vis diffuse reflectance spectra. In order to increase the surface area and porosity which is important for Li-ion batteries, the starting Si powder was ball-milled and threatened by metal-assisted chemical etching. The mechanochemical treatment resulted in decrease of the particle size from 75 nm to 29 nm, an increase of the BET surface area and average pore size to 16.7 m
/g and 1.26 nm, respectively, and broadening of the X-ray powder diffraction (XRD) lines. The XRD patterns of silver metal-assisted chemical etching (MACE) sample showed strong and narrow diffraction lines typical for powder silicon and low-intensity diffraction lines typical for silver. The metal-assisted chemical etching of starting Si material resulted in a decrease of surface area to 7.3 m
/g and an increase of the average pore size to 3.44 nm. These three materials were used as the anode material in lithium-ion cells, and their electrochemical properties were investigated by cyclic voltammetry and galvanostatic charge-discharge cycles. The enhanced electrochemical performance of the sample prepared by MACE is attributed to increase in pore size, which are large enough for easy lithiation. These are the positive aspects of the application of MACE in the development of an anode material for Li-ion batteries.
Across Europe marginalization has been highlighted as an object of important political concern. In the area of Central Europe and the Balkans, the problem of marginalization has not been sufficiently ...researched. This particularly applies to the Bosnia and Herzegovina (BiH). Using the GIS multicriteria decision analysis a composite index of geographical marginalization (GMAR) was created. Marginalization is analyzed as a multidimensional concept using the 4 groups with a total of 40 criteria. Spatial patterns were detected from extremely marginalized to extremely non-marginalized regions. The GMAR indicates the existence of regional disparities in BiH. The high degree of marginalization, especially those in the border sector, alerts the implementation of the demarginalization measures.
Tufa sedimentary systems are sensitive fluvial landscapes subject to various external disturbances. Tufa landscape degradation reflected in negative hydrological changes and a decrease in the ...intensity of the tufa formation process have been detected in National Park Krka (Croatia). The main causes were recognized in the uncontrolled spread of invasive vegetation (Ailanthus altissima) and increased anthropogenic influence. Therefore, the Park administration launched the project, Management and Maintenance of Macro-Vegetation at Skradinski Buk (SB)—Development of a Multicriteria Model for Sustainable Management. The methodological framework was divided into three scales of research. The macro-scale research comprised a set of activities aimed at selecting the most suitable test surface within a wider area of the Skradinski Buk (SB) waterfall. The meso-scale research involved mapping the reference and final state of the vegetation and hydrological network after the removal of invasive vegetation and mitigation of negative anthropogenic impact. At the micro-scale, a monitoring system was established to track the quality of the tufa sedimentary system. Special emphasis was placed on the measurement of tufa formation dynamics (TFD) on limestone plates using a new methodological approach based on structure from motion (SfM) photogrammetry. Implementation of the proposed multiscale framework resulted in reactivation of tufa-forming watercourses, prevention of invasive vegetation regeneration and achievement of sustainable conditions for the tufa formation process. In reactivated watercourses, the average tufa growth rate was 4.267 mm a−1 (n = 18). Potential users of this framework include local authorities and administrators of protected areas.
Gully erosion is one of the most prominent natural denudation processes of the Mediterranean. It causes significant soil degradation and sediment yield. Most traditional field methods for measurement ...of erosion-induced spatio-temporal changes are time and labor consuming, while their accuracy and precision are highly influenced by various factors. The main research question of this study was how the measurement approach of traditional field sampling methods can be automated and upgraded, while satisfying the required measurement accuracy. The VERTICAL method was developed as a fully automated raster-based method for detection and quantification of vertical spatio-temporal changes within a large number of gully cross-sections (GCs). The developed method was tested on the example of gully Santiš, located at Pag Island, Croatia. Repeat unmanned aerial vehicle (UAV) photogrammetry was used, as a cost-effective and practical method for the creation of very-high-resolution (VHR) digital surface models (DSMs) of the chosen gully site. A repeat aerophotogrammetric system (RAPS) was successfully assembled and integrated into one functional operating system. RAPS was successfully applied for derivation of interval (the two-year research period) DSMs (1.9 cm/pix) of gully Santiš with the accuracy of ±5 cm. VERTICAL generated and measured 2379 GCs, along the 110 m long thalweg of gully Santiš, within which 749 052 height points were sampled in total. VERTICAL proved to be a fast and reliable method for automated detection and calculation of spatio-temporal changes in a large number of GCs, which solved some significant shortcomings of traditional field methods. The versatility and adaptability of VERTICAL allow its application for other, similar scientific purposes, where multitemporal accurate measurement of spatio-temporal changes in GCs is required (e.g., river material dynamics, ice mass dynamics, tufa sedimentation and erosion).
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