Geospatial Analysis Laboratory (GAL) - UIP-2017-05-2694

In recent decades, precision agriculture and geospatial technologies have made it possible to ensure sustainability in an olive-growing sector. The main goal of this study is the extraction of olive tree canopies by comparing two approaches, the first of which is related to geographic object-based analysis (GEOBIA), while the second one is based on the use of vegetation indices (VIs). The research area is a micro-location within the Lun olives garden, on the island of Pag. The unmanned aerial vehicle (UAV) with a multispectral (MS) sensor was used for generating a very high-resolution (VHR) UAVMS model, while another mission was performed to create a VHR digital orthophoto (DOP). When implementing the GEOBIA approach in the extraction of the olive canopy, user-defined parameters and classification algorithms support vector machine (SVM), maximum likelihood classifier (MLC), and random trees classifier (RTC) were evaluated. The RTC algorithm achieved the highest overall accuracy (OA) of 0.7565 and kappa coefficient (KC) of 0.4615. The second approach included five different VIs models (NDVI, NDRE, GNDVI, MCARI2, and RDVI2) which are optimized using the proposed VITO (VI Threshold Optimizer) tool. The NDRE index model was selected as the most accurate one, according to the ROC accuracy measure with a result of 0.888 for the area under curve (AUC).

Since the beginning of the 21st Century, Europe has been affected by destructive floods. European Union Member States have an obligation to develop flood hazard and flood risk maps as support to the Flood Risk Management Plan (FRMP). The main objective of this study is to propose a methodological framework for hazard and risk assessment of pluvial flash floods in Croatia at the catchment level, which can be integrated into the FRMP. Therefore, a methodology based on the source–pathway–consequence approach for flood risk assessment is presented, which complies with the EU Floods Directive. This integrated and comprehensive methodology is based on high-resolution open data available for EU Member States. Three scenarios are defined for a low, medium, and high probability, defined by design storms of different durations. The proposed methodology consists of flood hazard analysis, vulnerability assessment, and risk analysis. Pluvial flash flood hazards are analyzed using a 2D hydrologic–hydraulic model. The flood vulnerability assessment consists of a GIS analysis to identify receptors potentially at risk of flooding and an assessment of susceptibility to potential flood damage using depth–damage curves. Flood risk is assessed both qualitatively in terms of risk levels and quantitatively in terms of direct damages expressed in monetary terms. The developed methodology was applied and tested in a case study in the Gospić catchment in Croatia, which surrounds a small rural town frequently affected by pluvial flash floods.

The geographic information system (GIS) is, at the global level, recognized as one of the best ICTs for implementation in the subject of geography. The application of GIS in the Republic of Croatia (RH) lags behind developed countries. The main objective of this research was to examine the attitudes of secondary school students and geography teachers regarding the introduction of GIS in the educational system process. In the period from 3 October 2021 to 27 January 2022, a survey questionnaire was conducted in 30 secondary schools in the RH on a sample of 611 students and 96 teachers. The results have showed that both teachers and students have a positive attitude toward the introduction of GIS for the purpose of teaching geography. More than 80% of teachers believe that GIS is not sufficiently represented in the high school and geography curricula which is recognized as one of the most important factors which limit GIS implementation. A majority (77%) of teachers are not using GIS on any teaching level, which is not surprising since both surveyed teachers and students have poor knowledge of GIS, although teachers rated their knowledge a little higher. Teachers perceive students’ interest in GIS exactly as students express it; predominantly indifferent. The most important factors limiting the implementation of GIS are recognized as: a lack of necessary GIS software and licenses; not knowing how to use GIS; and an insufficient number of teaching units dedicated to GIS in the geography curricula. An equal percentage of both teachers and students believe that there are prerequisites for GIS implementation in their schools. One of the basic prerequisites for GIS implementation is that education authorities need to “see” GIS as an important part of geography and include it more in school curricula. In almost all countries where GIS has been implemented in schools, difficulties in its implementation have been documented.

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.

In recent decades geospatial technologies (GST) have been affected by a process of rapid development. One of their applications involves the documentation of the protected areas reference state and the development of high-quality models for their preservation and management. The research area of this paper is Lake Zmajevo oko (Lake Dragon eye), near Rogoznica (Croatia). The research goals were to create a multisensor model of the lake and present the application of these technologies for promotional purposes. The secondary objective was to obtain morphometric data about the lake. The research methodology included performing the process of UAV photogrammetry and bathymetry. In UAV photogrammetry, a Phantom 4 Pro was used. In the bathymetric survey, an integrated system composed of WASSP S3 multibeam depth sounder (MBES) and the Hemisphere V320 GNSS smart antenna was used. The data collected by both methods were combined and an multisensor high-quality model of the lake was created. Ten underwater tunnels on the steep sides of the lake were detected. From the derived models, the volume and surface area of the lake, as well as the length of the lake shoreline were calculated. Furthermore, a virtual walk around the lake was made to promote this area. A physical model of the lake, which can serve as a souvenir, was printed with the 3D printer Prusa i3 MK3. The collected high-quality data can serve as the basis for future research, while derived models and a virtual walk can be used for its promotion.

In this paper precision assessment of the 3D handheld scanner, Artec Space Spider was evaluated and critically observed. Namely, a new application of handheld 3D scanners has been found in quantifying tufa formation dynamic (TFD). Such measurements should be characterized by a high level of data quality because tufa usually grows only a few millimeters annually. Therefore, a small limestone plate (PL) used as a substrate on which TFD will be studied was scanned five times by two independent observers. Interval scans of PL were processed using Artec Studio 15 Professional. Data processing consisted of five steps. The precision assessment was determined by statistical analysis of derived sections and a colored distance map (CDM). Results showed that Artec Space Spider generates reliable results considering the characteristics of the scanned object and it certainly can be used for TFD analysis. Also, results suggested that the application of Artec Space Spider in the quantification of TFD can be regarded as a better approach in the context of measurement reliability compared to other direct and indirect methods. The subject of future research will be the precision and accuracy assessment of various 3D handheld scanners in scanning tufa formed in different temporal resolutions with various surface complexity.

Advances in geospatial technologies (GST) have revolutionized the ability to quantify spatio-temporal changes in various geomorphological forms at different scales. One of the most complex geomorphological forms is tufa and travertine cascades whose evolution is the subject of numerous research in various scientific fields. In this paper, we are presenting a new methodological framework for analyzing tufa formation dynamic (TFD) at three levels of research (macro-meso-micro) using the close-range photogrammetry (CRP) method, handheld 3D scanner, and terrestrial laser scanner (TLS). The results, 3D models and digital elevation models (DEMs), of the first (reference) measurement at three levels of research, are presented in this paper. Reference models were generated using Agisoft Metashape, Artec Studio Professional 15, and SCENE software. Measurements were done in an artificial tufa tunnel, located within the Jaruga, the second oldest hydroelectric power plant in the world constructed within National Park Krka, Croatia. This tunnel is a specific tufa-forming environment. The subject of the next paper will be the comparison of interval tufa 3D tufa models at three levels of research and the calculation of volumetric (mm 3 a-1) and linear (mm a −1) tufa growth rates after two years of exposure to the Krka River. The presented methodological framework will expand the knowledge about TFD within this specific depositional sub-environment and can be applied in the dynamic formation analysis of other hydroprecipitates.

The karst landscapes of the Mediterranean are regarded as some of the most vulnerable, fragile, and complex systems in the world. They hold a particularly interesting group of small islands with a distinctive, recognizable landscape. The Republic of Croatia (HR), which has one of the most indented coasts in the world, is particularly known for them. In this paper, we analyzed the spatio-temporal changes (STCs) in the landscape of Ošljak Island, the smallest inhabited island in HR. Landuse/landcover change (LUCC) analysis has been conducted from 1944 to 2021. The methodology included the acquisition of multi-temporal data, data harmonization, production of landuse/landcover (LU/LC) maps, selection of optimal environmental indicators (EIs), and simulation modeling. In total, eleven comparable LU/LC models have been produced, with moderate accuracy. STCs have been quantified using the nine EIs. The dominant processes that influenced the changes in the Ošljak landscape have been identified. The results have shown that, in recent decades, Ošljak has undergone a landscape transformation which was manifested through (a) pronounced expansion of Aleppo pine; (b) deagrarianization, which led to secondary succession; and (c) urban sprawl, which led to the transformation of the functional landscape. The most significant of the detected changes is the afforestation of the Aleppo pine. Namely, in a 77-year span, the Aleppo pine has expanded intensively to an area of 11.736 ha, created a simulation model for 2025, and pointed to the possibility of the continued expansion of Aleppo pine. Specific guidelines for the management of this newly transformed landscape have been proposed. This research provides a user-friendly methodological framework that can efficiently monitor LUCCs of a smaller area in the case when geospatial data are scarce and satellite imagery of coarser-resolution cannot be used. Moreover, it gives an insight into the availability and quality of multi-temporal data for HR.

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.

U radu se prikazuju mogućnosti implementacije GIS-a u preventivnoj fazi vatrogasnog djelovanja za područje Šibensko-kninske županije. Primijenjena je višekriterijska GIS analiza (GIS-MCDA) u izvođenju indeksa rizika izbijanja otvorenih požara. Korištene su četiri grupe kriterija: vegetacija, geomorfometrija, antropogeni utjecaj i klimatski elementi. Izvedeni su modeli na temelju metode donosioca odluka kroz (1) iskustvo zapovjednika iz lokalne sredine i (2) primjerom dobre prakse. Nadalje, analizirana je pokrivenost te prohodnost putova Nacionalnog parka (NP) Krka unutar standardnog vremena intervencije iz nadležnih vatrogasnih postrojbi. Izdvojene su najbliže vatrogasne postrojbe i najbrže rute do najugroženijih zona unutar NP Krka. Rezultati ukazuju kako područje Šibensko-kninske županije spada u zonu umjereno/umjereno-visokog rizika izbijanja požara te da pokrivenost putova NP Krka unutar standardnog vremena intervencije nije zadovoljavajuća.

The accurate extraction of a coastline is necessary for various studies of coastal processes, as well as for the management and protection of coastal areas. Very high-resolution satellite imagery has great potential for coastline extraction; however, noises in spectral data can cause significant errors. Here, we present a newly developed Coastal Extraction Tool (CET) that overcomes such errors and allows accurate and time-efficient automated coastline extraction based on a combination of WorldView-2 (WV-2) multispectral imagery and stereo-pair-derived digital surface model (DSM). Coastline extraction is performed and tested on the Iž-Rava island group, situated within the Northern Dalmatian archipelago (Croatia). Extracted coastlines were compared to (a) coastlines extracted from state topographic map (1:25,000), and (b) coastline extracted by another available tool. The accuracy of the extracted coastline was validated with centimeter accuracy reference data acquired using a UAV system (Matrice 600 Pro + MicaSense RedEdge-MX). Within the study area, two small islets were detected that have not been mapped during the earlier coastline mapping efforts. CET proved to be a highly accurate coastline mapping technique that successfully overcomes spectral-induced errors. In future research, we are planning to integrate data obtained by UAVs infrared thermography (IRT) and in situ sensors, measuring sea and land surface temperatures (SST and LST), into the CET, given that this has shown promising results. Considering its accuracy and ease of use, we suggest that CET can be applied for automated coastline extraction in other large and indented coastal areas. Additionally, we suggest that CET could be applied in longitudinal geomorphological coastal erosion studies for the automated detection of spatio-temporal coastline displacement.

Gully erosion is one of the most prominent natural denudation processes of the Mediter-ranean. 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).

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 has 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.

Quantification and monitoring of complex geomorphic spatio-temporal changes requires multiple field surveys and creation of very-high resolution (VHR) digital elevation models (DEMs). Due to pronounced terrain roughness and complex surface topography modelling of gully erosion induced spatio-temporal changes can be very challenging. Although advanced geospatial technologies, such as terrestrial laser scanning (TLS), provide good basis for modeling of complex morphological features, certain limitations still exist that can lead to the overall devaluation in model quality. Most of these limitations are related to the non-systematic TLS survey approach, that lacks thorough survey planning and preparation phases. Main aim of our research was to provide guidelines for optimization of TLS surveys over gully erosion affected areas, through development of new systematic survey methodology. Established systematic TLS survey methodology allows multiple detection, quantification and monitoring of spatio-temporal changes, where survey characteristics are adjusted to the local terrain characteristics and specifications of available terrestrial laser scanner. Developed survey methodology was applied for TLS survey over chosen gully site at Pag Island, Croatia.

The emergence of handheld 3D surface scanners can play an important role in improving the understanding of tufa formation dynamics. For the first time, volumetric tufa growth was calculated using the Artec Eva handheld 3D scanner. Volumetric tufa growth was measured on two limestone plates (PLs) which were installed near the Roški waterfall (National park Krka, Croatia). Tufa volumetric growth was calculated from 3D models in Artec Studio 14 Professional. The applicability of Artec Eva in the measurement of small objects (25 cm²) was tested by comparing the volume of PL with a reference "true" value measured with Artec Space Spider. The mean volumetric tufa growth for the Roški waterfall site was 1490,02 mmᶟ in six months period. Although initially Artec Eva is not intended for measurement of small objects, it can be used if the dimensions of the PLs on which the volumetric growth is slightly bigger. Artec Eva overestimated the PL volume by only 904.66 mmᶟ or 6.38%. This new approach uses handheld 3D surface scanners and high-quality 3D models providing the alternative and user-friendly method for studying tufa formation dynamics.

Worldview-3 stereo-extracted DSMs represent state-of-the-art products in the domain of satellite-based digital surface modelling. Main goal of our research was to evaluate the vertical accuracy of WV-3 derived DSMs over olive groves. Creation of high-accuracy WV-3 derived DSMs would allow efficient large scale management and protection of this valuable agricultural resource. Vertical accuracy of WV-3 derived DSM was evaluated at two test sites within Olive Gardens of Lun (Pag Island, Croatia), through the comparison with reference UAV photogrammetry derived VHR DSM. Two test sites were selected by object-based approach, established on spectral (NDVI, VARI) and height information (digital olive models (DOMs)). While first test site covers one single, individual oldest olive tree (45 m²), second test site covers larger area (2500 m²) with dense, unattended olive trees. Although vertical accuracy of individual olive trees still significantly deviates from reference model (RMSE = 3.604 m; MAE = 3.203 m), accuracy within larger test was much better (RMSE = 1.462 m; MAE = 1.127 m). This demonstrated that WV-3 stereo imagery has great potential for application in creation of DSMs over large scale forested areas, that would be hard to cover with field geospatial techniques (e.g. LiDAR or UAV photogrammetry).

The production of high-quality digital surface models (DSMs) is an increasing interest throughout the various geomorphometry studies. Consequently, a wide range of advanced geospatial methods has been used at different scales. Despite the fact that Structure-from-Motion (SfM) photogrammetry is one of the most popular methods until now it has not been systematically applied in the studies of tufa formation dynamics (TFD). In this paper, we propose a framework for using SfM photogrammetry and GIS tools in the measurement of tufa growth rates (TGRs). TGRs were measured on two limestone plates (PLs) within the area of Roški waterfall in Croatia. Four submillimetre resolution DSMs of tufa have been created. TGR was 0.407 mm for a six-month period. Checkpoints were used to calculate errors. The results confirm the efficiency of the SfM at this scale. Research shows that photogrammetric measurement system design can produce extremely dense point clouds with high horizontal and vertical accuracy. The application of SfM and GIS in the measurement of TFD can be the great methodological improvement for specific geomorphometric applications at smaller scales.

The production of high-quality digital surface models (DSMs) is an increasing interest throughout the various geomorphometry studies. Consequently, a wide range of advanced geospatial methods has been used at different scales. Despite the fact that Structure-from-Motion (SfM) photogrammetry is one of the most popular methods until now it has not been systematically applied in the studies of tufa formation dynamics (TFD). In this paper, we propose a framework for using SfM photogrammetry and GIS tools in the measurement of tufa growth rates (TGRs). TGRs were measured on two limestone plates (PLs) within the area of Roški waterfall in Croatia. Four submillimetre resolution DSMs of tufa have been created. TGR was 0.407 mm for a six-month period. Checkpoints were used to calculate errors. The results confirm the efficiency of the SfM at this scale. Research shows that photogrammetric measurement system design can produce extremely dense point clouds with high horizontal and vertical accuracy. The application of SfM and GIS in the measurement of TFD can be the great methodological improvement for specific geomorphometric applications at smaller scales.

Accurate determination of the tufa growth rate (TGR) is required to answer the fundamental geomorphological question of tufa evolution. The TGR has been measured by various direct and indirect methods. One of the most popular direct methods uses modified micro‐erosion meter (MEM), which has several drawbacks. Here, we present for the first time a coordinate measuring macro‐photogrammetry device (CMD) for monitoring the TGR in a contactless manner. The CMD was applied on 28 limestone plates at 14 locations within the Skradinski buk area, Croatia, and measurements were performed in the laboratory. The TGR was derived from digital tufa high‐resolution models (DTHRMs). The accuracy of the device was evaluated using state‐of‐the‐art 3D scanners and error calculation at checkpoints. Moreover, the precision was evaluated with the split test (n=5). A total of 74 DTHRMs with a spatial resolution of 0.0236 mm were created. The TGR ranged from 0.327 to 19.302 mm a⁻¹, with an average of 5.771 mm a⁻¹. A higher TGR was observed on the limestone plates near mosses, located in fast and turbulent water rather than in stagnant water. We found that specific micro‐environmental factors (e.g., proximity to moss) positively affected tufa growth. Erosion events were observed, as well as the presence of aquatic insect larvae (Simuliidae and Chironomidae), which positively affected tufa growth. The CMD is a precise and accurate device that does not suffer from the drawbacks of the MEM method and has many other advantages. It has a high capability of tufa erosion detection, enables the identification of macroinvertebrates, and multispectral or hyperspectral cameras can be mounted on the device for spectral reflectance analysis of the tufa surface. The CMD can be applied in any study requiring a sub‐millimetre data quality and involving the comparison of consecutive 3D models and derivation of various parameters of smaller objects.

Razvoj geoprostornih tehnologija (GST) ubrzao je proces 3D dokumentacije te olakšao promociju kulturne baštine. U radu je izvršena 3D dokumentacija te promocija utvrde Fortica (otok Pag, Republika Hrvatska). Korištene su metode blizupredmetne fotogrametrije (CRP), 3D ispisa te moderne vizualizacijske tehnike (virtual reality). Podaci su prikupljeni koristeći UAV Phantom 4 Pro, DSLR Nikon D5300 te GNSS RTK Stonex X10. Visokorezolucijski 3D modeli utvrde izvedeni su u softveru Agisoft Metashape 1.5.1. Generiran je gusti oblak točaka utvrde Fortica s 33 mil. točaka, digitalni model površine (DSM) prostorne rezolucije 1,3 cm te digitalni ortofoto (DOF) od 0,6 cm. Ukupna RMSE kontrolnih točaka iznosila je 4,04 cm u referentnom koordinatnom sustavu i 0,24 pixela u koordinatnom sustavu slike. Izvedeni 3D model je primijenjen za stvaranje virtualne šetnje, dok je 3D printerom Prusa i3 mk3 za potrebe promocije kao suvenir kreiran fizički model utvrde. Virtualna šetnja utvrdom prikazana je u modelu Samsung GearVR. Predložen metodološki okvir stručnjacima za kulturnu baštinu omogućava jednostavan i ekonomičan način generiranja točnih 3D modela te njihovu primjenu u promotivnim i edukacijskim svrhama. Ključne riječi: geoprostorne tehnologije (GST), 3D modeli, virtualna šetnja, 3D ispis.

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.

Developed GIS automated multicriteria analysis (GAMA) method presented in this article allows automation and simplification of multicriteria GIS analysis (GIS-MCDA) susceptibility modelling. Traditional GIS-MCDA susceptibility modelling still represents time and labor demanding process, whose success is highly influenced by the user's experience and knowledge. In order to make overall GIS-MCDA susceptibility modelling process more straightforward and practical, GAMA method is designed as easy to use three step process, which allows automation of following GIS-MCDA steps: (1) standardization of criteria, (2) criteria grouping and weight assignment and (3) susceptibility model aggregation. GAMA method is developed within ArcGIS 10.4 ModelBuilder application, as a toolset that can be easily shared and incorporated within default ESRI’s ArcGIS toolbox. GAMA was successfully applied for gully erosion susceptibility modelling on example of Pag island, Croatia, whose results are published in separate article. Since GAMA method is applicable to various GIS-MCDA susceptibility modelling purposes we are encouraging its future use and therefore open-source GAMA method toolset can be acquired for research purposes (htps://gal.unizd.hr).

The mapping of gully erosion is important for better understanding of erosion spatial distribution and characteristics, as well as various factors associated with its occurrence. Detailed and accurate gully erosion mapping is especially challenging in remote areas, where high spatial resolution data is not available. Aim of this study was evaluation of potential of different morphometric parameters derived from available medium resolution digital elevation model (DEM) for gully erosion mapping. Mapping was based on object-based image analysis (OBIA) approach and application of multi-resolution segmentation algorithm on seven chosen morphometric parameters (slope, mass balance index, topographic position index, vertical distance to channel network, topographic wetness index, stream power index and planar curvature). This approach was tested on Pag island (284 km²), which is known for its bare karstic landscape and numerous active gullies. Classification was performed on segmented objects based on user-defined thresholds for each used morphometric parameter. As a result, 120 active gully erosion zones were detected and mapped within Pag island. Result validation was performed on 12 randomly chosen locations (10 % of all mapped zones). Extracted gully erosion zones were overlapped with reference data, derived by manual vectorisation from high-resolution orthophoto image. Overlap performance was further quantified through following accuracy indicators: Correctnes (COR), Completeness (COM), Overall Quality (OQ) and LOC measure (LOC). Validation has shown that proposed medium resolution morphometric parameters and object-based approach can be successfully applied for mapping of gully erosion in karstic areas with limited spatial resolution data available. Mapped gully erosion areas were used for determination of general characteristics and spatial distribution of affected areas and correlated with existing gully erosion susceptibility model of Pag island.

Exact determination of coastline length and characteristics is necessary for studies of coastal processes and consequently for management and protection of coastal areas. Very-high resolution (VHR) satellite imagery has great potential for coastline extraction, however noises in spectral data (e.g. shadows or sea reflections) can cause significant extraction errors. To overcome this problem, we present newly developed Coastal Extraction Tool (CET) that allows accurate and time-efficient automated coastline extraction based on combination of VHR multispectral satellite imagery and stereo-pair derived digital surface model (DSM). Automated coastline extraction is performed and tested with CET on Iž-Rava island group, situated within Northern Dalmatian archipelago (Croatia). CET extracted coastline accuracy was validated at chosen locations through comparison with the coastline extracted manually from centimetre accuracy reference data collected by in-situ terrestrial LiDAR scanning and UAV photogrammetry. Accuracy of CET extracted coastline was further analysed and quantified through 25 ground control points (GCP) collected along true coastline with high-accuracy RTK-GPS. Validation has shown that CET is highly accurate and that it successfully overcomes spectral induced errors. As a result of analysis two small islets are detected within study area that haven`t been mapped earlier within official state data. Considering its accuracy and ease of use we suggest that CET can be applied for automated coastline extraction in other large and indented coastal areas. Additionally, we suggest that it could be potentially applied in longitudinal geomorphological coastal erosion studies for detection of spatio-temporal coastline displacement.

In the era of diversification of cargo freight facilities, application of advanced geo-modelling and geo-design tools is an imperative. Particularly, in the case of the new construction or redevelopments of large port terminals, its infrastructure and facilities. The main objective of this paper is to demonstrate the importance of bathymetric survey as one of the contemporary tools utilised in the pre-construction phase of port terminals. Contemporary bathymetry provides complex digital modelling and determines the depth, morphology and sedimentology of the river, lake, dam or sea beds. When planning, designing and constructing port terminals, bathymetric surveys are the primary prerequisite, before any physical intervention or material excavation. In order to generate a precise digital model of the sea-bed morphology in its initial and final stage, and calculate the quantity of the excavated material (in m³), our research team used geo-statistic and deterministic interpolation models. Particular emphasis was placed on the Newton-Cotes model affecting the output result (excavated material volume).

The main objective of this paper was to discuss applications of GIS based multi-criteria decision analysis (GIS MCDA) and Analytical Hierarchy Process (AHP). These two techniques were applied in order to assist preparation of the Tourism Management Plan, depicting the most suitable zones for ecotourism development in Dikgathlong Dam Lease Area (DDLA) as one of the largest resources of potable water in Botswana. The MCDA was based on geo-morphometric, hydrologic, landscape and community indicators and criteria which emanated from expert's opinions, intensive field survey and literature review. In addition the AHP has helped to calculate individual criteria weights and to point the degree of suitabil-ity zones classified as highly suitable, moderately suitable, marginally suitable and not suitable for eco-tourism. After performing both processes and establishing broad management zones it has been found that the Sustainable Development Scenario is the most appropriate option as the future ecotourism development proposal. This research provides new methodology that can be incorporated into future tourism policies and management strategies.

Krka National Park is a sensitive hydrologic system, subject to different sorts of external disorder. The problem of direction exchange of tufa-forming watercourses was noticed during the uncontrolled spreading of invasive vegetation, which led to the end of tufa-forming process. In 2017 scientific project Managing and sustaining macro-vegetation in Skradinski buk – developing multicriterial model of sustained management was initiated. The main goal is achievement of sustainable conditions of tufa-formation and reactivation of extinguished watercourses. New methodological approach of tracking the dynamics of tufa-formation on the test limestone tiles with its effective surface of 16 cm² was suggested. The goal of this paper is to create high-resolution models of three samples of limestone tiles and to measure changes in the tufa precipitation. Tiles were placed within locations of extinguished watercourses. Selective removal of vegetation caused their reactivation. High-resolution models were generated for the initial condition and three-six month period. Recording of tiles was performed with a device based on method of very close-range photogrammetry. Main components were non-metric DSLR camera (Nikon D5300) and macro lens (Venus LAOWA 60mm f/2.8 2:1). Calibration was performed on a 2D chess test field. Each tile was represented with 187 high-quality photographs with resolution of 24 MP. Results showed that reactivation of tufa-formation process occurred in all of three test tiles. DSM of tufa with submillimetre resolution (<0.024 mm) and DOP of high-quality texture (<0.012 mm) were generated. The largest growth of tufa measured in sixth-month period amounted to (> 5.5 mm), while the largest volume amounted to (> 9.1 cm³). New methodological approach enables interval tracking of the dynamics of tufa-formation and performing models of submillimetre resolution and high-quality texture. Keywords: tufa, digital surface model (DSM), macro lens, Krka National Park

The paper presents the contemporary findings of remote sensing regarding the control of common ragweed on agricultural land. The two-year research was performed in cooperation with the company Ciklonzacija Ltd., Serbia. The remote sensing process starts with the collection of images captured by several types of cameras equipped with special filters. Images are obtained by modified cameras mounted on helicopters, drones, and airplanes. Next, a special software is used to produce maps based on the obtained images that show the level of weed spread on agricultural land, illegal waste dumping areas, and other uncultivated areas, i.e. the areas that are potential sources of ragweed spread. The maps have a considerable economic benefit when mapping agricultural, wood, and other areas. Moreover, they reduce the use of human resources, and increase the capacity of data acquisition as well as the accuracy of the model of weed spread and its control.

There is still just a small number of geographers in Croatia who choose to focus on the study of the level of satisfaction in regard to the availability of public facilities and services in urban areas. The complexity of the problematics linked to field-specific elements means that multidisciplinary knowledge is required, ranging from sociology to the planning applications. The main aim of the research is to evaluate the level of satisfaction in regard to the availability of public facilities and services, based on 14 selected variables that form its indicator in case study Zadar. On the basis of recent studies, it has been concluded that the two-level approach, that is the subjective and objective measures, is the most adequate approach to analyse the availability of public facilities and services as comprehensively as possible. The 2011 census was chosen as the source of data for objective indicators, with descriptive statistics used to process the data. On the other hand, an opinion poll was conducted to provide the results to be used as subjective indicators. The outcome of the research confirms the author’s assumption that the level of satisfaction in regard to the availability of public facilities and services is very good, with the exception of statistical areas on the outskirts of the city, where it is found to be lower. The most satisfactory availability of public facilities and services has been reported by the residents who are closer to the city centre (Višnjik, Poluotok, Jazine). On the one hand, it is due to the location. On the other hand, it is due to the planned development of the area and satisfactory infrastructure. The most inadequate availability of public facilities and services has been recorded in the statistical area of Novi Bokanjac, which is at the same time the most prosperous part of the city according to demographic factors. However, located on the outskirts of the city, it occupies the corresponding area of its budget. The proposed methodology of calculating the indicators of satisfaction in regard to the availability of public facilities and services on the basis of 14 variables was tested using one selected variable: the distance of educational institutions. The analysis shows that there is a very good spatial distribution of educational facilities in Zadar, with the exception of the statistical areas of Novi Bokanjac and Ploče. This confirms the accuracy of the proposed methodology, that is the fact that the formed indicator of satisfaction in regard to the availability of public facilities and services is scientifically valid, and as such applicable to other areas.

Accessibility of urban green spaces (UGS) is an integral element of satisfying quality of life. Due to rapid urbanization, the studies about UGS are becoming one of the key elements of urban planning. Functional network transport system and optimal spatial distribution of UGS are preconditions for maintaining the environmental balance of the urban landscape. Accessibility analysis of UGS in the settlement of Zadar was conducted as a part of the Urban Green Belts Project (UGB). Development of spatial database was the first step in generating UGS accessibility indicator. Data were collected using the supervised classification method of multispectral LANDSAT images and manual vectorization of high-resolution digital orthophoto (DOP). An analysis of UGS accessibility according to Accessible Natural Greenspace Standard (ANGst) was conducted. Accessibility indicator was generated based on seven objective measures which include the UGS per capita and accessibility of six UGS functional levels. The UGS accessibility indicator was compared with subjective measures that have been obtained by field survey of 718 respondents within 41 statistical units. The collected data reflected an individual assessment and subjective evaluation of UGS accessibility. This study illustrated the importance of using objective and subjective measures in the process of understanding UGS accessibility. It may be concluded that while evaluating accessibility, the residents emphasize the immediate residential environment, neglecting the UGS of higher functional levels. Furthermore, that large amounts of UGS within a city (114 m² per capita) do not necessarily generate a similar satisfaction with their accessibility. The output results may serve as guidelines for the further development of the functional UGS city network. KEY WORDS: urban green spaces (UGS), accessibility indicator, subjective and objective measures, GIS.

In recent years,there has been an increasing demand for the documentation of cultural and historical heritage. Documenting cultural-historical artifacts and buildings is a multidimensional process which depends on the purpose of the record and the features of the object recorded.Nowadays,the application of modern data collection methods (close range photogrammetry, laser scanning) allows a wide range of objects (from tiny pieces of pottery to large archaeological site) to be protected, preserved and valorized. The development of information technology and digital photogrammetry has enabled the production of high-resolution 3D models and virtual spaces (virtual museums).This has contributed to the popularization of cultural heritage and the rapid flow of information to interested users. In this paper, Fortica Fortress on the Island of Pag is documented using close-range photogrammetry(CRP). In the process of data collection, an unmanned aircraft Phantom 4,DSLR camera Nikon 5300 and GNSS receiver Stonex S10 were used. A high-resolution digital surface model (DSM), digital orthophoto (DOP) and 3D model of Fortica Fortress were produced. Finally, a virtual video walk through Fortica Fortress was created for promotional and tourist purposes, using visualization techniques in Lumion software trial.

Jedan od najvažnijih zadataka geomorfometrije je izrada i analiza digitalnog modela reljefa (DMR). Upravo o digitalnom modelu reljefa, koji ima više specifičnih primjena, kao što su predviđanja, procjene rizika, donošenje odluka u upravljanju okolišem itd., ovise izlazni rezultati. U ovoj knjizi istražuje se utjecaj korisničko-definiranih parametara na točnost digitalnog modela reljefa. Prikazan je cjelokupan proces digitalnog modeliranja reljefa s posebnim naglaskom na važnost metoda interpolacije i prostorne rezolucije. U prvome dijelu teksta priložena je iscrpna teorijska osnova. Pri tome se ponajprije podrazumijeva tumačenje različitih faza digitalnog modeliranja reljefa, a kao najistaknutije navode se prikupljanje podataka, prostorna interpolacija i određivanje prikladne veličine piksela. Nakon tumačenja procesa izrade DMR-a, velik dio teksta odnosi se i na digitalne analize reljefa (DAR) na temelju DMR-a. U teorijskom dijelu posebna je pozornost pridana i tumačenju točnosti, odnosno kvaliteti i preciznosti DMR-a. U tekstu su prvi put predstavljeni rezultati anketnog ispitivanja korisnika o njihovim praksama u procesu digitalnog modeliranja reljefa. Rasvijetljeno je, primjerice, kako korisnici ocjenjuju točnost DMR-a, koje metode primjenjuju za prikupljanje podataka ili kakva im je općenito svijest o važnosti korisničko-defi niranih parametara u procesu izrade DMR-a. Teorijsku osnovu prati snažna praktična primjena. Za izradu modela i usporedbu metoda interpolacije korištena su četiri skupa visinskih podataka dobivenih različitim metodama, tehnikama i procedurama prikupljanja podataka: batimetrijskom izmjerom, aerofotogrametrijskom izmjerom i stereorestitucijskom obradom, zračnim laserskim snimanjem i vektorizacijom izohipsi s HOK-a. Lidarski generiran DMR poslužio je kao referentno stanje za ocjenu točnosti ostalih modela. Usporedbom devet determinističkih i osam geostatističkih metoda interpolacije, odabrani su najprikladniji interpolatori za potrebe različitih istraživanja. Za odabir najboljih metoda interpolacije korišteno je osam statističkih parametara, grafički prikazi (dvodimenzionalni i trodimenzionalni), izračun i usporedba profila i mjere strukture za odabrani geomorfometrijski parametar (nagib). Poseban naglasak stavljen je na veličinu piksela, koja je računana za svaki model posebno iz nekoliko formula. Usto, razvijen je koncept hibridnog DMR-a, koji se temelji na prestrukturiranju i progušćivanju ulaznih podataka geostatističkim modifikacijama. Ocjena točnosti DMR-ova, uz uobičajene pokazatelje, izvedena je i s obzirom na uspješnost izvođenja hidroloških parametara: 1. površinskog otjecanja – primjenom razvijenog “DNK” koncepta utvrđivanja horizontalnog odmaka i 2. drenažnog bazena – izračunom kubature i trodimenzionalne površine. Velik dio teksta odnosi se i na batimetrijsko istraživanje Vranskog jezera. Izrađena je prva batimetrijska karta Vranskog jezera u Republici Hrvatskoj na temelju batimetrijske izmjere pomoću RTK-GPS-a i jednosnopnog dubinomjera. Prikazani su novi znanstveno-metodološki utemeljeni podatci o batimetrijskim značajkama, površini i volumenu Vranskog jezera. Tematika ove knjige iznimno je popularna u inozemstvu, no dosadašnja izdanja ovakve prirode na hrvatskom jeziku su oskudna. Dostupna su tek izdanja koja se s nekoga drugog aspekta ili usputno odnose na ovo područje geoinformatike poput Analiza krajolika pomoću GIS-a (Lang i Blaschke, 2010) ili Uvod u geografsko informacijske sutave (Pahernik, 2006). Tekst ove knjige sinteza je doktorskoga rada DMR u analizi geomorfometrijskih parametara: primjer PP Vransko jezero docenta dr. sc. Ante Šiljega, koji je izrađen je na Geografskom odsjeku Prirodoslovno-matematičkog fakulteta Sveučilišta u Zagrebu u sklopu Poslijediplomskoga doktorskog studija Geografske osnove prostornog planiranja i uređenja te diplomskog rada Utjecaj korisničko-defi niranih parametara na točnost DMR-a Mirka Barade, mag. geogr., obranjenog na Odjelu za geografiju Sveučilišta u Zadru, uz nadopunu novim sadržajima gdje god je to bilo potrebno. Tekst sadrži desetak poglavlja. Zbog kompleksnosti problematike sadržaj je strukturno razgranat. Sadržajem je tekst primarno namijenjen studentima, znanstvenicima i nastavnicima iz sfere visokog školstva, osobito u geografiji, geodeziji i geoinformatici. Također, sadržaj je koristan i primjenjiv u mnogim drugim područjima poput građevine, poljoprivrede, šumarstva, ekologije, geologije, hidrologije i u svim ostalim područjima gdje reljef ima veliku važnost te ga je potrebno kvantificirati i vrednovati.

User-defined parameters (point density, interpolation, and pixel size) have a great influence on the accuracy of digital terrain model (DTM). Therefore, the optimal interpolation method (IM) and appropriate pixel size should be used to create a continuous surface. Pixel size or spatial resolution tends to be a compromise between the number of samples and the size of the study area, whereby input dataset is often devaluated. In this paper, the authors propose a new methodological approach to DTM production (hybrid DTM—HDTM) from an aero-photogrammetry dataset. Two different approaches to DTM production are presented: the usual (UDTM) and the hybrid (HDTM). HDTM is based on restructuring and refining the input dataset by generating contour lines, determining the optimal interpolation method and selecting the appropriate spatial resolution. The goal is to develop a qualitative DTM while minimalizing the devaluation of input data and error propagation. The accuracy of different IMs for UDTM was examined in a comparative analysis of six statistical parameters by applying cross-validation, with the focus on the root mean square error (RMSE) parameter. Four different methods of selecting optimal spatial resolution were tested for the same model. The UDTM and HDTM generated were compared by interior, exterior, and visual accuracy assessment and by the performance success of specific hydrological parameters: (1) flow accumulation—by applying a developed DNA concept and (2) watershed—by calculating volume and 3D surface. The reference value for exterior accuracy assessment was high-resolution airborne LiDAR DTM (LDTM). It was found that ordinary kriging (OK) was the best IM (RMSE, 1.9893 m). The spatial resolution of UDTM was calculated by combining two variants of the point pattern analysis method and was found to be 19 m. On the other hand, the complexity of terrain method was used to define the spatial resolution of HDTM (3 m). HDTM achieved better results than UDTM in all aspects of accuracy assessment. The exterior accuracy of HDTM was better by 1.483 m (RMSE). Finally, the results of the applied DNA concept showed that a stream generated from HDTM had a 2.587 m lower horizontal root mean square error (HRMSE) than the stream generated from UDTM.