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This research conducts a comparative analysis of the vertical accuracies of satellite-derived Digital Elevation Models (DEMs) in the Akure South Local Government Area, Ondo State, Nigeria. The DEMs assessed were obtained from three open-source satellite missions: Sentinel-1A, ALOS PALSAR, and TanDEM-X. The reference Ground Control Points (GCPs) used in the evaluations comprised 133 GCPs of 2nd and 3rd-order accuracy acquired from the Office of the Surveyor General, Ondo State, and through field surveys using the South Galaxy-1 Differential GPS. These obtained GCPs provided extensive coverage of the study area. The evaluation was undertaken based on the land cover, which was established by dividing the study area into open (built-up and bare land) and vegetation-covered (agricultural and forested) areas. The vertical accuracies of the satellite-based DEM collected within the study area were then compared and analyzed. The results revealed that Sentinel-1A and TanDEM-X were the most suitable in both open and vegetation-covered parts of the study area, with Sentinel-1A exhibiting the best performance. The effect of vegetation cover was mostly felt by ALOS PALSAR. Sentinel-1A and TanDEMX displayed commendable vertical accuracies, deemed highly suitable for applications in topographic mapping, as shown by an RMS of less than 2m. This research recommends the open-source satellite DEMs Sentinel-1A and TanDEM-X for planning and engineering applications because they offer the highest accuracy among their counterparts within Akure and its environs. [ABSTRACT FROM AUTHOR]

Highlights: • The research contributes to a better understanding of the forms of settlement in the ancient landscape of Alto de Toche, influenced by Cerro Machin Volcano disaster risk. • A terrain modelling reconstructed a geoarchaeological mountain landscape, composed of massive systems of terraces at Alto de Toche Wax Palm cloud forest. • From digital photogrammetry in fieldwork, three sites were detailed. A DEM of the settlement pattern projected 37 possible new terraces. The resulting map is accessible in an ArcGIS-online web application. Abstract: The enhancement of the archaeological terraces on the Alto de Toche and the Wax Palm forest is unprecedented. The Toche region in Colombia contains an outstanding anthropised ecosystems presence (8000 BP), characterised by complex inherited cultural patterns, according to the evidences on the eastern margin of the Andes Central Cordillera. The research focused on i) the cultural landscape of the Premontane and Montane Cloud Forests of the Alto de Toche, built by the Toches; ii) its high-altitude settlements, interpreted as a strategy of ecological knowledge, deeply linked to their symbolic understanding of the landscape. Fieldwork in three sets of tambos (terraces for habitational settlements) in La Carbonera, Gallego, and Las Cruces sites was analysed using remote sensing, drone digital photogrammetry, and on-site data. Their interpretation projected a settlement pattern; a typological-topological tambos classification inferred its possible functions such as sighting, funerary, and dwelling, from 2600 MASL to biggest sites at 3000 MASL, related to the sun-moon proximity presumed for gatherings. The authors conclude that the patterns respond to a territorial understanding of its resources and the vertical exploitation of the agricultural thermal floors and micro-watersheds, associated with the east-west solar illumination over both sides of the Tochecito River basin; linked with the transit between ridges and steep slopes, through the network of pathways that originated the Quindío Trail. Data were projected crossing field-data photogrammetry with GIS spatial analysis; this resulted in a terrain model that reconstructs a geoarchaeological landscape composed of massive systems of tambos. Thirty-seven new sites were classified, twenty of them above 2800 MASL. The resulting terrain model facilitates a non-invasive previous prospection for fieldwork planning and a more feasible knowledge of accessibility, due to on-site transit difficulties (steep slopes and very unstable soil due to cattle ranching). Finally, the terrain model was uploaded in an easy-to-access ArcGIS-online web application for sharing with community stakeholders and visiting scientists.

ABSTRACTPoint clouds are widely used in Earth surface research but usually exhibit gaps of missing data. Previous point cloud restoration methods used in terrain modelling have not fully considered complex terrain characteristics, which can be summarised as the controlling role of topographic features in shaping terrain surfaces and the inherent similarities observed among these surfaces. This work introduces a novel method that integrates Topographic Features and Patch Matching (TFPM) into point cloud restoration processes for terrain modelling. The method mainly contains three steps. First, identifying gap boundary points. Second, topographic feature points are extracted and subsequently interpolated into the identified gaps. Third, searching other parts of the raw point cloud for patches resembling the gaps, and the identified patches are used as templates to restore the point cloud. The proposed method is benchmarked against three state-of-the-art point cloud restoration methods. The experimental results demonstrate that the TFPM method consistently exhibits superior accuracy in terrain modelling and analysis, as evidenced by low values of the root mean square error, average elevation difference, and average slope difference. This work endeavours to incorporate topographic features into point cloud restoration processes and can benefit future research related to terrain modelling and analysis.

This research presents a comprehensive analysis of the production of terrain passability maps in southeastern Serbia, employing a multi-criteria decision-making (MCDM) analysis. The study integrates various geographical and infrastructural aspects, assigning coefficients to each input parameter, including rivers, roads, rails, CORINE Land Cover (CLC), soil, slope, and the Topographic Ruggedness Index (TRI). The introduction of the TRI marks an innovative advancement in terrain analysis and passability. By comparing wet and dry periods, the study provides critical insights into the dynamic nature of terrain passability, with implications for transportation planning and emergency response. The research's innovative approach and detailed examination set it apart, offering valuable contributions to scholarly comprehension and practical applications. The findings underscore the potential for interdisciplinary collaboration and the broad impact of geographic information systems (GIS) and terrain analysis in addressing real-world challenges. Future research may explore additional factors influencing terrain passability and expand the geographical scope of the study. [ABSTRACT FROM AUTHOR]

This research presents a comprehensive analysis of the production of terrain passability maps in southeastern Serbia, employing a multi-criteria decision-making (MCDM) analysis. The study integrates various geographical and infrastructural aspects, assigning coefficients to each input parameter, including rivers, roads, rails, CORINE Land Cover (CLC), soil, slope, and the Topographic Ruggedness Index (TRI). The introduction of the TRI marks an innovative advancement in terrain analysis and passability. By comparing wet and dry periods, the study provides critical insights into the dynamic nature of terrain passability, with implications for transportation planning and emergency response. The research's innovative approach and detailed examination set it apart, offering valuable contributions to scholarly comprehension and practical applications. The findings underscore the potential for interdisciplinary collaboration and the broad impact of geographic information systems (GIS) and terrain analysis in addressing real-world challenges. Future research may explore additional factors influencing terrain passability and expand the geographical scope of the study.

Geospatial data obtained using Unmanned Aerial Vehicles (UAVs) and Unmanned Surface Vehicles (USVs) are increasingly used to model the terrain in the coastal zone, in particular in shallow waterbodies (with a depth of up to 1 m). In order to generate a terrain relief, it is important to choose a method for modelling that will allow it to be accurately projected. Therefore, the aim of this article is to present a method for accuracy assessment of topo-bathymetric surface models based on geospatial data recorded by UAV and USV vehicles. Bathymetric and photogrammetric measurements were carried out on the waterbody adjacent to the public beach in Gdynia (Poland) in 2022 using a DJI Phantom 4 RTK UAV and an AutoDron USV. The geospatial data integration process was performed in the Surfer software. As a result, Digital Terrain Models (DTMs) in the coastal zone were developed using the following terrain modelling methods: Inverse Distance to a Power (IDP), Inverse Distance Weighted (IDW), kriging, the Modified Shepard’s Method (MSM) and Natural Neighbour Interpolation (NNI). The conducted study does not clearly indicate any of the methods, as the selection of the method is also affected by the visualization of the generated model. However, having compared the accuracy measures of the charts and models obtained, it was concluded that for this type of data, the kriging (linear model) method was the best. Very good results were also obtained for the NNI method. The lowest value of the Root Mean Square Error (RMSE) (0.030 m) and the lowest value of the Mean Absolute Error (MAE) (0.011 m) were noted for the GRID model interpolated with the kriging (linear model) method. Moreover, the NNI and kriging (linear model) methods obtained the highest coefficient of determination value (0.999). The NNI method has the lowest value of the R68 measure (0.009 m), while the lowest value of the R95 measure (0.033 m) was noted for the kriging (linear model) method.

Image collection strategies and ground control points (GCPs) are of particular importance for uncrewed aerial vehicle combined with Structure‐from‐Motion (UAV–SfM) photogrammetry, and the generalization of their effects has proved elusive. This study designed various photogrammetric scenarios to investigate the effects of image collection strategies, ground control quantity, and their interaction on digital elevation model (DEM) errors and their spatial structure in high‐relief terrain. The results of 1.77 × 105 UAV–SfM scenarios provide insights for improving UAV–SfM practices. A high image capture angle (20–40°) enhances camera calibration quality decreasing the magnitude and spatial correlation of errors. High camera inclination reduces the sensitivity of mean and standard deviation of error to flying height but not the spatial correlation of error. Including additional data (e.g. supplemented convergent images; images captured at multiple flying heights) has only a minor effect if imagery is highly inclined. GCPs provide more effective constraints than image collection strategies. The mean error and standard error decline quickly with a small number of GCPs and then become stable in all scenarios, but the spatial correlation of error can be further improved with increasing GCPs. However, the effects of GCP quantity do interact with image collection strategies. High camera inclination reduces requirements for GCPs, whilst strategies combining different flying heights and image orientations have little effect on necessary GCP quantity. The distribution of GCPs still affects the errors, but the effect of GCP distribution becomes less important with an increase in the number of GCPs. Finally, we show that UAV–SfM photogrammetric quality assessment should routinely assess the spatial dependence of error using a statistic like Moran's I. [ABSTRACT FROM AUTHOR]

The coastal zone is an area that includes the sea coast and adjacent parts of the land and sea, where the mutual interaction of these environments is clearly marked. Hence, the modelling of the land and seabed parts of the coastal zone is crucial and necessary in order to determine the dynamic changes taking place in this area. The accurate determination of the terrain in the coastal zone is now possible thanks to the use of Unmanned Aerial Vehicles (UAVs) and Unmanned Surface Vehicles (USVs). The aim of this article is to present land and seabed surface modelling in the coastal zone using UAV/USV-based data integration. Bathymetric and photogrammetric measurements were carried out on the waterbody adjacent to a public beach in Gdynia (Poland) in 2022 using the DJI Phantom 4 Real Time Kinematic (RTK) UAV and the AutoDron USV. As a result of geospatial data integration, topo-bathymetric models in the coastal zone were developed using the following terrain-modelling methods: Inverse Distance to a Power (IDP), kriging, Modified Shepard's Method (MSM) and Natural Neighbour Interpolation (NNI). Then, the accuracies of the selected models obtained using the different interpolation methods, taking into account the division into land and seabed parts, were analysed. Research has shown that the most accurate method for modelling both the land and seabed surfaces of the coastal zone is the kriging (linear model) method. The differences between the interpolated and measurement values of the R95 measurement are 0.032 m for the land part and 0.034 m for the seabed part. It should also be noted that the data interpolated by the kriging (linear model) method showed a very good fit to the measurement data recorded by the UAVs and USVs. [ABSTRACT FROM AUTHOR]

Orienteering is a sport in which the orienteer completes a course of control points in the shortest possible time, aided only by a map and compass, involving the choice of itineraries, through reading and interpreting the map and its relationship with the terrain. The most important factors for selecting areas for orienteering are difficult and challenging terrain that enables good course setting. Finding a suitable area for foot orienteering involves multiple criteria. The main features that provide the athlete greater opportunities for testing navigation skills are, among others, a detailed representation of the terrain, containing rich landforms, and its cover, since foot orienteering is a sport organized in forests or natural areas. Based on these principles, this study aims to assess the suitability of the Central Eastern Region of Continental Portugal for the practice of Foot Orienteering. The suitable areas and their constraints were identified based on integrating a set of criteria using multicriteria spatial analysis tools in a GIS environment. For this purpose, the following descriptors were integrated: land cover, slope, slope variation, Topographic Position Index (TPI), and aspect variation. The criteria were classified into four levels of suitability, calculated by applying the Hierarchical Analytical Process. Based on the results obtained by the proposed methodology, we concluded that 52.5% of the study area presents high suitability for foot orienteering at a competitive level. That is a notable potential resource for the advancement of the sport, and for further refinement of the presented methodology based on additional data and criteria. [ABSTRACT FROM AUTHOR]

Geospatial data obtained using Unmanned Aerial Vehicles (UAVs) and Unmanned Surface Vehicles (USVs) are increasingly used to model the terrain in the coastal zone, in particular in shallow waterbodies (with a depth of up to 1 m). In order to generate a terrain relief, it is important to choose a method for modelling that will allow it to be accurately projected. Therefore, the aim of this article is to present a method for accuracy assessment of topo-bathymetric surface models based on geospatial data recorded by UAV and USV vehicles. Bathymetric and photogrammetric measurements were carried out on the waterbody adjacent to the public beach in Gdynia (Poland) in 2022 using a DJI Phantom 4 RTK UAV and an AutoDron USV. The geospatial data integration process was performed in the Surfer software. As a result, Digital Terrain Models (DTMs) in the coastal zone were developed using the following terrain modelling methods: Inverse Distance to a Power (IDP), Inverse Distance Weighted (IDW), kriging, the Modified Shepard's Method (MSM) and Natural Neighbour Interpolation (NNI). The conducted study does not clearly indicate any of the methods, as the selection of the method is also affected by the visualization of the generated model. However, having compared the accuracy measures of the charts and models obtained, it was concluded that for this type of data, the kriging (linear model) method was the best. Very good results were also obtained for the NNI method. The lowest value of the Root Mean Square Error (RMSE) (0.030 m) and the lowest value of the Mean Absolute Error (MAE) (0.011 m) were noted for the GRID model interpolated with the kriging (linear model) method. Moreover, the NNI and kriging (linear model) methods obtained the highest coefficient of determination value (0.999). The NNI method has the lowest value of the R68 measure (0.009 m), while the lowest value of the R95 measure (0.033 m) was noted for the kriging (linear model) method. [ABSTRACT FROM AUTHOR]

Virtual globes render large-scale real-world earth’s surface in real-time for geographic information visualization. Modern GPUs have introduced hardware tessellation features for high-performance rendering. Patch-based terrain rendering using hardware tessellation introduces cracks and swimming artifacts during navigation. Hardware tessellation-based terrain rendering methods limit the tessellation factors to power-of-two and render patches with discrete-level-of-detail (DLOD). We present a novel method for adaptive terrain rendering using tessellation codes. In the proposed method, we present novel memory-efficient bit-field-based tessellation codes to encode patch Level-of-detail (LOD). The encoding scheme enabled patch rendering with Continuous-level-of-detail (CLOD) on tessellation hardware. The view-dependent simplification algorithm simplifies and encodes the patch’s Level-of-detail (LOD) in tessellation codes. The proposed method, based on tessellation codes, tessellates patches as uniformly spaced vertices grid. A novel relocation algorithm, based on tessellation codes, relocates uniformly spaced vertices to construct an encoded simplified vertices grid to avoid boundary cracks and swimming artifacts. The tessellation codes consumed 28 kilobytes of memory for a patch size of 65. The proposed method rendered 2.5 million triangles with a frame rate of 570 frames-per second for an ultra-HD display. The proposed method achieved a high simplification and rendering rate with low computational and memory usage as compared to state-of-the-art methods.

Terrain models are widely used to depict the shape of the Earth's surface. With the development of photogrammetric methods, point cloud data have become one of the most popular data sources for terrain modelling. However, the obtained point clouds are of high density, which often increases redundancy rather than improving accuracy. Therefore, point cloud simplification should be a core component of terrain modelling. This paper proposes a point cloud simplification method by integrating topographic knowledge into terrain modelling (TKPCS). The method contains two steps: (1) topographic knowledge recognition and construction and (2) point cloud simplification using this topographic knowledge for terrain modelling. The proposed approach is benchmarked against improved versions of existing methods to validate its capability and accuracy in digital elevation model construction and terrain derivative extraction. The results show that the simplified points of the TKPCS method can generate finer resolution terrain models with higher accuracy and greater information entropy. The good performance of the TKPCS method is also stable at different scales. This work endeavours to transform perceptive topographic knowledge into a process of point cloud simplification and can benefit future research related to terrain modelling. [ABSTRACT FROM AUTHOR]

Geospatial data are increasingly used to model the terrain in the coastal zone, in particular in shallow waterbodies (with a depth of up to 1 m). In order to generate a terrain relief, it is important to choose a method for its modelling that will allow it to be accurately projected. Therefore, the aim of this publication is to analyze the terrain modelling methods in the coastal zone. For the purposes of the research, five most popular methods for terrain modelling were described: Inverse Distance Weighted (IDW), Modified Shepard's Method (MSM), Natural Neighbor Interpolation (NNI), kriging and spline. Each of the methods has been described in a uniform way in terms of: the essence of its operation, mathematical expression and application examples. The advantages and disadvantages of each of the methods for terrain modelling are also discussed. It should be stated that the choice of the method for the terrain modelling of a shallow waterbody is not unambiguous, as it depends on the type of data recorded during bathymetric and photogrammetric measurements. [ABSTRACT FROM AUTHOR]

Geospatial data are increasingly used to model the terrain in the coastal zone, in particular in shallow waterbodies (with a depth of up to 1 m). In order to generate a terrain relief, it is important to choose a method for its modelling that will allow it to be accurately projected. Therefore, the aim of this publication is to analyze the terrain modelling methods in the coastal zone. For the purposes of the research, five most popular methods for terrain modelling were described: Inverse Distance Weighted (IDW), Modified Shepard's Method (MSM), Natural Neighbor Interpolation (NNI), kriging and spline. Each of the methods has been described in a uniform way in terms of: the essence of its operation, mathematical expression and application examples. The advantages and disadvantages of each of the methods for terrain modelling are also discussed. It should be stated that the choice of the method for the terrain modelling of a shallow waterbody is not unambiguous, as it depends on the type of data recorded during bathymetric and photogrammetric measurements.

Point clouds are widely used in Earth surface research but usually exhibit gaps of missing data. Previous point cloud restoration methods used in terrain modelling have not fully considered complex terrain characteristics, which can be summarised as the controlling role of topographic features in shaping terrain surfaces and the inherent similarities observed among these surfaces. This work introduces a novel method that integrates Topographic Features and Patch Matching (TFPM) into point cloud restoration processes for terrain modelling. The method mainly contains three steps. First, identifying gap boundary points. Second, topographic feature points are extracted and subsequently interpolated into the identified gaps. Third, searching other parts of the raw point cloud for patches resembling the gaps, and the identified patches are used as templates to restore the point cloud. The proposed method is benchmarked against three state-of-the-art point cloud restoration methods. The experimental results demonstrate that the TFPM method consistently exhibits superior accuracy in terrain modelling and analysis, as evidenced by low values of the root mean square error, average elevation difference, and average slope difference. This work endeavours to incorporate topographic features into point cloud restoration processes and can benefit future research related to terrain modelling and analysis. [ABSTRACT FROM AUTHOR]

In this paper, we describe two related scripting methods of cartographic data processing and visualization that provide 2D and 3D mapping of Japan with different algorithm complexity. The first algorithm utilizes Generic Mapping Toolset (GMT), which is known as an advanced console-based program for spatial data processing. The modules of GMT combine the functionality of scripting with the aspects of geoinformatics, which is especially effective for the rapid analysis of large geospatial datasets, multi-format data processing, and mapping in 2D and 3D modes. The second algorithm presents the use of the R programming language for cartographic visualization and spatial analysis. This R method utilizes the packages 'tmap', 'raster', 'maps', and 'mapdata' to model the morphometric elements of the Japanese archipelago, such as slope, aspect, hillshade and elevation. The general purpose graphical package 'ggplot2' of R was used for mapping the prefectures of Japan. The two scripting approaches demonstrated an established correspondence between the programming languages and cartography determined with the use of scripts for data processing. They outperform several well-known and state-of-the-art GIS methods for mapping due to their high automation of data processing. Cartography has largely reflected recent advances in data science, the rapid development of scripting languages, and transfer in the approaches of data processing. This extends to the shift from the traditional GIS to programming languages. As a response to these new challenges, we demonstrated in this paper the advantages of using scripts in mapping, which consist of repeatability and the flexible applicability of scripts in similar works. [ABSTRACT FROM AUTHOR]

With the increasing population, the problem of people's need for shelter has also emerged. In many settlements, structures were built without the necessary planning. Three-dimensional (3D) models of these lands should be created in order to make land management plans. Technological improvements in remote sensing have made easier the terrain modelling. To make a better land management plan of rural areas, we need high resolution maps. Unmanned aerial vehicle (UAV) is one of the methods in map production, which can obtain spatial data with high accuracy. In this study, we created 3D model of Yaylak village located in Aksaray District using UAV Photogrammetry. We created high resolution Digital Surface Map and orthophoto map of the village using the pictures obtained from e-Bee. Using these maps, the administrator of the region will decide healthy decision. This study shows us UAV can be used in preparing the necessary maps for designing the settlement area. [ABSTRACT FROM AUTHOR]

The coastal zone is an area that includes the sea coast and adjacent parts of the land and sea, where the mutual interaction of these environments is clearly marked. Hence, the modelling of the land and seabed parts of the coastal zone is crucial and necessary in order to determine the dynamic changes taking place in this area. The accurate determination of the terrain in the coastal zone is now possible thanks to the use of Unmanned Aerial Vehicles (UAVs) and Unmanned Surface Vehicles (USVs). The aim of this article is to present land and seabed surface modelling in the coastal zone using UAV/USV-based data integration. Bathymetric and photogrammetric measurements were carried out on the waterbody adjacent to a public beach in Gdynia (Poland) in 2022 using the DJI Phantom 4 Real Time Kinematic (RTK) UAV and the AutoDron USV. As a result of geospatial data integration, topo-bathymetric models in the coastal zone were developed using the following terrain-modelling methods: Inverse Distance to a Power (IDP), kriging, Modified Shepard’s Method (MSM) and Natural Neighbour Interpolation (NNI). Then, the accuracies of the selected models obtained using the different interpolation methods, taking into account the division into land and seabed parts, were analysed. Research has shown that the most accurate method for modelling both the land and seabed surfaces of the coastal zone is the kriging (linear model) method. The differences between the interpolated and measurement values of the R95 measurement are 0.032 m for the land part and 0.034 m for the seabed part. It should also be noted that the data interpolated by the kriging (linear model) method showed a very good fit to the measurement data recorded by the UAVs and USVs.

Virtual globes render large-scale real-world earth's surface in real-time for geographic information visualization. Modern GPUs have introduced hardware tessellation features for high-performance rendering. Patch-based terrain rendering using hardware tessellation introduces cracks and swimming artifacts during navigation. Hardware tessellation-based terrain rendering methods limit the tessellation factors to power-of-two and render patches with discrete-level-of-detail (DLOD). We present a novel method for adaptive terrain rendering using tessellation codes. In the proposed method, we present novel memory-efficient bit-field-based tessellation codes to encode patch Level-of-detail (LOD). The encoding scheme enabled patch rendering with Continuous-level-of-detail (CLOD) on tessellation hardware. The view-dependent simplification algorithm simplifies and encodes the patch's Level-of-detail (LOD) in tessellation codes. The proposed method, based on tessellation codes, tessellates patches as uniformly spaced vertices grid. A novel relocation algorithm, based on tessellation codes, relocates uniformly spaced vertices to construct an encoded simplified vertices grid to avoid boundary cracks and swimming artifacts. The tessellation codes consumed 28 kilobytes of memory for a patch size of 65. The proposed method rendered 2.5 million triangles with a frame rate of 570 frames-per second for an ultra-HD display. The proposed method achieved a high simplification and rendering rate with low computational and memory usage as compared to state-of-the-art methods. [ABSTRACT FROM AUTHOR]

Modelling the terrain with high accuracy is vital to create modern settlement areas, and to find solutions that threaten the people. Traditional land surveying is a time-consuming and expensive method. Unmanned aerial vehicle (UAV) is a powered aerial vehicle without a human operator. UAV related case study publications have been increased since last two decades. Detailed three-dimensional (3D) information on the land surface can be obtained from high spatial resolution point clouds. Modelling the terrain requires up-to date information. UAV can provide high-resolution images with low cost in the order of centimeters. We can reconstruct the terrain in a 3D representation using photogrammetry. In this study, we model a village located in Aksaray city using UAV photogrammetry. We created the orthomosaic and Digital Surface Map (DSM) of the region to characterize the terrain in detail. The obtained model and maps will help us to generate modern living space. [ABSTRACT FROM AUTHOR]

This study presents the effect of image data sources on the topographic modelling of part of the National Trust site located at Weston-Super-Mare, Bristol, United Kingdom, covering an approximate area of 1.82 hectares. The accuracy of the DEM generated from 1m resolution and 2m resolution LiDAR data together with the accuracy of the DEM generated from the UAV images acquired at different altitudes are analysed using the 1 m LiDAR DEM as reference for the accuracy assessment. Using the NSSDA methodology, the horizontal and vertical accuracy of the DEMs generated from each of the four sources were computed while the paired sample t-test was conducted to ascertain the existence of statistically significant difference between the means of the X, Y, and Z coordinates of the check points. The result obtained shows that with a RMSE of -0.0101499 and horizontal accuracy of -0.175674686m, the planimetric coordinates extracted from 2 m LiDAR DEM were more accurate than the planimetric coordinates extracted from the UAV based DEMs while the UAV based DEMs proved to be more accurate than the 2m LiDAR DEM in terms of altimetric coordinates, though the DEM generated from UAV images acquired at 50 m altitude gave the most accurate result when compared with the vertical accuracy obtained from the DEM generated from UAV images acquired at 30 m and 70 m flight heights. These findings are also consistent with the result of the statistical analysis at 95% confidence interval.

In this paper, we describe two related scripting methods of cartographic data processing and visualization that provide 2D and 3D mapping of Japan with different algorithm complexity. The first algorithm utilizes Generic Mapping Toolset (GMT), which is known as an advanced console-based program for spatial data processing. The modules of GMT combine the functionality of scripting with the aspects of geoinformatics, which is especially effective for the rapid analysis of large geospatial datasets, multi-format data processing, and mapping in 2D and 3D modes. The second algorithm presents the use of the R programming language for cartographic visualization and spatial analysis. This R method utilizes the packages ‘tmap’, ‘raster’, ‘maps’, and ‘mapdata’ to model the morphometric elements of the Japanese archipelago, such as slope, aspect, hillshade and elevation. The general purpose graphical package ‘ggplot2’ of R was used for mapping the prefectures of Japan. The two scripting approaches demonstrated an established correspondence between the programming languages and cartography determined with the use of scripts for data processing. They outperform several well-known and state-of-the-art GIS methods for mapping due to their high automation of data processing. Cartography has largely reflected recent advances in data science, the rapid development of scripting languages, and transfer in the approaches of data processing. This extends to the shift from the traditional GIS to programming languages. As a response to these new challenges, we demonstrated in this paper the advantages of using scripts in mapping, which consist of repeatability and the flexible applicability of scripts in similar works.

Terrain is an essential part of any outdoor environment and, consequently, many techniques have appeared that deal with the problem of its automatic generation, such as procedural modeling. One form to create terrains is using noise functions because its low computational cost and its random result. However, the randomness of these functions also makes it difficult to have any control over the result obtained. In order to solve the problem of lack of control, this paper presents a new method noise-based that allows procedural terrains creation with elevation constraints (GPS routes, points of interest and areas of interest). For this, the method establishes the restrictions as fixed values in the heightmap function and creates a system of equations to obtain all points that they depend this restrictions. In this way, the terrain obtained maintains the random noise, but including the desired restrictions. The paper also includes how we apply this method on large terrain models without losing resolution or increasing the computational cost excessively. The results show that our method makes it possible to integrate this kind of constraints with high accuracy and realism while preserving the natural appearance of the procedural generation. [ABSTRACT FROM AUTHOR]

Wireless networks on university campuses has gained importance in recent years. These networks in major areas such as university campuses, are faced with many problems during the planning, design and establishment. These problems are among the first that comes to mind, the physical properties of the campus and is selected according to the characteristics of network equipment. There is no doubt at all points of a wireless network set up in order to provide uninterrupted service and quality of the signal is expected to be good. However, it should be understood literally cannot meet these expectations. Therefore, to solve many problems to campus planning and design can be made to have acceptable signal distribution will have the appropriate use of and satisfaction with increasing effect. In this study, due to the start of construction on the North Campus of Hitit University, wireless signal spread using the current spread has been determined with the help of geographic information systems visibility analysis. An area of 56 hectares, with the total of 9 AP the acceptable signal distribution was obtained.

The use of electric vehicles (EVs) has been viewed as a potential solution to reduce the oil dependence in transportation. Nevertheless, the performance of the EV changes according to the nature and characteristics of the terrain. This work focuses in modelling the instantaneous power consumption (IPC) of an EV as it traverses through different types of terrains, classified using an artificial vision system. The EV is sensorized with voltage and current sensors, accurate real time kinematics device, an artificial vision system and a real time processing unit, to perform field tests. To see the advantages of using terrain information for energy prognosis in EVs, we compared our proposal with the information provided by the manufacturer and previously published approaches. Our system showed to be up to 95% more accurate when tested over clay, gravel, pavement and grass in both short term and long term trials, and it does not need of a complete knowledge of the system's model. [ABSTRACT FROM AUTHOR]

Featured Application: The presented approach can be implemented as an interactive tool for creating mesa and butte terrain features in modelling applications and game engines. Natural terrains created by long-term erosion processes can sometimes have spectacular forms and shapes. The visible form depends often upon internal geological structure and materials. One of the unique terrain artefacts occur in the form of table mountains and can be observed in the Monument Valley (Colorado Plateau, USA). In the following article a procedural method is considered for terrain modelling of structures, geometrically similar to the mesas and buttes hills. This method is not intended to simulate physically inspired erosion processes, but targets directly the generation of eroded forms. The results can be used as assets by artists and designers. The proposed terrain model is based on a height-field representation extended by materials and its hardness information. The starting point of the technique is the Poisson Faulting algorithm that was originally used to obtain fractional Brownian surfaces. In the modification, the step function as the fault line generator was replaced with a circular one. The obtained geometry was used for materials' classification and the hardness part of the modelled terrain. The final model was achieved by the erosive modification of geometry according to the materials and its hardness data. The results are similar to the structures observed in nature and are achieved within an acceptable time for real-time interactions. [ABSTRACT FROM AUTHOR]

In this contribution, we deal with the methodology of visualisation of terrain surface, on which experimental measurements of driving manoeuvres of an agricultural technological vehicle MT8-222 were performed. The introduced methodology uses a defined approach when determining the dynamic stability of agricultural vehicles following the standard STN 47 017. Records of the centre of gravity accelerations were obtained from driving manoeuvres at every instance of time during the drive. From records of accelerations and by using Euler‘s parameters with respect to the inertial system, there were evaluated contact points of the wheel with the terrain. Performed driving manoeuvres consisted of movement in the direction of down grade slope as well as in the direction of tractive movement on the slope. We created a model of terrain surface in the Surfer® program from obtained experimental data. Next, by using supporting commands in Matlab®, we created an algorithm for visualisation of terrain surface. Following this algorithm, there was created another model of terrain surface. Both visualisations of terrain surface are depicted in Figs 4 and 5.

Natural terrains created by long-term erosion processes can sometimes have spectacular forms and shapes. The visible form depends often upon internal geological structure and materials. One of the unique terrain artefacts occur in the form of table mountains and can be observed in the Monument Valley (Colorado Plateau, USA). In the following article a procedural method is considered for terrain modelling of structures, geometrically similar to the mesas and buttes hills. This method is not intended to simulate physically inspired erosion processes, but targets directly the generation of eroded forms. The results can be used as assets by artists and designers. The proposed terrain model is based on a height-field representation extended by materials and its hardness information. The starting point of the technique is the Poisson Faulting algorithm that was originally used to obtain fractional Brownian surfaces. In the modification, the step function as the fault line generator was replaced with a circular one. The obtained geometry was used for materials’ classification and the hardness part of the modelled terrain. The final model was achieved by the erosive modification of geometry according to the materials and its hardness data. The results are similar to the structures observed in nature and are achieved within an acceptable time for real-time interactions.

Wireless networks on university campuses has gained importance in recent years. These networks in major areas such as university campuses, are faced with many problems during the planning, design and establishment. These problems are among the first that comes to mind, the physical properties of the campus and is selected according to the characteristics of network equipment. There is no doubt at all points of a wireless network set up in order to provide uninterrupted service and quality of the signal is expected to be good. However, it should be understood literally cannot meet these expectations. Therefore, to solve many problems to campus planning and design can be made to have acceptable signal distribution will have the appropriate use of and satisfaction with increasing effect. In this study, due to the start of construction on the North Campus of Hitit University, wireless signal spread using the current spread has been determined with the help of geographic information systems visibility analysis. An area of 56 hectares, with the total of 9 AP the acceptable signal distribution was obtained. [ABSTRACT FROM AUTHOR]

Erosion, which is one of the most important exogenous processes forming the landscape, has become a main degradation factor affecting agroecosystems. One of the direct erosion effects is a change in the soil cover structure. Colluvisols, originating in the material accumulated in depressions and foot part of slopes, represent a significant element in such a segmented soil mosaic. In the Chernozem loess area of Žďánický les, a method of areal delimitation of Colluvisols was proposed. Considering the homogeneity of the relative soil properties, the terrain morfometric characteristics (slope, profile curvature, and plan curvature) were applied as the main criteria. The final map reflects specifically the general zones of potential Colluvisol formation, such as lateral valleys and slope bases - floodplain interfaces. In the locality under study (size 3 ha), the microrelief evaluation of the colluvial process was proceeded particularly in a colluvial-alluvial zone. The results showed a significant difference between the soil properties of adjacent Colluvisol and Fluvisol resulting mainly from the distinct character of sedimentation.

In recent decades, terrain modelling and reconstruction techniques have increased research interest in precise short and long distance autonomous navigation, localisation and mapping within field robotics. One of the most challenging applications is in relation to autonomous planetary exploration using mobile robots. Rovers deployed to explore extraterrestrial surfaces are required to perceive and model the environment with little or no intervention from the ground station. Up to date, stereopsis represents the state-of-the art method and can achieve short-distance planetary surface modelling. However, future space missions will require scene reconstruction at greater distance, fidelity and feature complexity, potentially using other sensors like Light Detection And Ranging (LIDAR). LIDAR has been extensively exploited for target detection, identification, and depth estimation in terrestrial robotics, but is still under development to become a viable technology for space robotics. This paper will first review current methods for scene reconstruction and terrain modelling using cameras in planetary robotics and LIDARs in terrestrial robotics; then we will propose camera-LIDAR fusion as a feasible technique to overcome the limitations of either of these individual sensors for planetary exploration. A comprehensive analysis will be presented to demonstrate the advantages of camera-LIDAR fusion in terms of range, fidelity, accuracy and computation. [ABSTRACT FROM AUTHOR]

As part of the national space promotion plan and presidential national agendas South Korea's institutes and agencies under the auspices of the Ministry of Science, Information and Communication Technology and Future Planning (MSIP) are currently developing a lunar mission package expected to reach Moon in 2020. While the officially approved Korean Pathfinder Lunar Orbiter (KPLO) is aimed at demonstrating technologies and monitoring the lunar environment from orbit, a lander - currently in pre-phase A - is being designed to explore the local geology with a particular focus on the detection and characterization of mineral resources. In addition to scientific and potential resource potentials, the selection of the landing-site will be partly constrained by engineering constraints imposed by payload and spacecraft layout. Given today's accumulated volume and quality of available data returned from the Moon's surface and from orbital observations, an identification of landing sites of potential interest and assessment of potential hazards can be more readily accomplished by generating synoptic snapshots through data integration. In order to achieve such a view on potential landing sites, higher level processing and derivation of data are required, which integrates their spatial context, with detailed topographic and geologic characterizations. We are currently assessing the possibility of using fuzzy c-means clustering algorithms as a way to perform (semi-) automated terrain characterizations of interest. This paper provides information and background on the national lunar lander program, reviews existing approaches - including methods and tools - for landing site analysis and hazard assessment, and discusses concepts to detect and investigate elemental abundances from orbit and the surface. This is achieved by making use of manual, semi-automated as well as fully-automated remote-sensing methods to demonstrate the applicability of analyses. By considering given boundary conditions, concrete procedures for determining potential landing sites of the Korean lunar lander could be proposed. [ABSTRACT FROM AUTHOR]

We introduce a compact hierarchical procedural model that combines feature-based primitives to describe complex terrains with varying level of detail. Our model is inspired by skeletal implicit surfaces and defines the terrain elevation function by using a construction tree. Leaves represent terrain features and they are generic parametrized skeletal primitives, such as mountains, ridges, valleys, rivers, lakes or roads. Inner nodes combine the leaves and subtrees by carving, blending or warping operators. The elevation of the terrain at a given point is evaluated by traversing the tree and by combining the contributions of the primitives. The definition of the tree leaves and operators guarantees that the resulting elevation function is Lipschitz, which speeds up the sphere tracing used to render the terrain. Our model is compact and allows for the creation of large terrains with a high level o detail using a reduced set of primitives. We show the creation of different kinds of landscapes and demonstrate that our model allows to efficiently control the shape and distribution of landform features. [ABSTRACT FROM AUTHOR]

Underground terrain poses a highly intricate and challenging environment to the propagation of waves carrying information from sensor to the sink nodes. Due to the complexity and level of detail, it is often difficult to realistically model such an environment for conducting tests. However, using numerical methods, the environment characteristics could be translated to a compatible framework, for testing complex networking models such as Wireless Underground Sensor Network (WUSN). Such transformation should lend the necessary clarity and simplicity required for effective problem analysis. In this paper, we demonstrate this possibility using the typical underground terrain environment for nut tree plantations, basing the field data on a full-fledged commercial pecan farm. The results shown are introductory to ongoing research on the effective use of such numerical methods for maximum power efficiency and bit rate for distributed WUSN, and optimum water usage in irrigation control. This paper forms a sequel to previous related research publications. [ABSTRACT FROM AUTHOR]

In recent decades, terrain modelling and reconstruction techniques have increased research interest in precise short and long distance autonomous navigation, localisation and mapping within field robotics. One of the most challenging applications is in relation to autonomous planetary exploration using mobile robots. Rovers deployed to explore extraterrestrial surfaces are required to perceive and model the environment with little or no intervention from the ground station. Up to date, stereopsis represents the state-of-the art method and can achieve short-distance planetary surface modelling. However, future space missions will require scene reconstruction at greater distance, fidelity and feature complexity, potentially using other sensors like Light Detection And Ranging (LIDAR). LIDAR has been extensively exploited for target detection, identification, and depth estimation in terrestrial robotics, but is still under development to become a viable technology for space robotics. This paper will first review current methods for scene reconstruction and terrain modelling using cameras in planetary robotics and LIDARs in terrestrial robotics; then we will propose camera-LIDAR fusion as a feasible technique to overcome the limitations of either of these individual sensors for planetary exploration. A comprehensive analysis will be presented to demonstrate the advantages of camera-LIDAR fusion in terms of range, fidelity, accuracy and computation.

Purpose: Determination of reservoir volume has been used in the calculation of sedimentation, hydrodynamic modelling, and dam safety assessment, among others, and the method used as well as its associated error play an important role in the quality of these studies. This study assessed the accuracy of reservoir volume calculations based on different standards for the definition of the spacing between bathymetric range lines. A technique for terrain modelling and a method for determining the survey accuracy are also proposed. Materials and methods: The reference reservoir volume was based on highly detailed bathymetry (10 m resolution). Seven different spacings were selected, which generated 99 separate bathymetric data sets. For each data set, the volume was calculated based on a digital terrain model according to the usual model (triangular irregular network (TIN)) and according to the insertion of mesh points (IMP) method. This was then compared with the reference volume, and the accuracy of each survey was determined. Results and discussion: Utilization of a highly detailed and reliable bathymetric survey allowed for the assessment of the associated error in each of the bathymetric data sets, as well as of the spacing standards analyzed. The accuracy of the standards analyzed using TIN modeling ranged from 0.31% to 14.40% (30 and 300 m, respectively). The high errors are attributed to the limitation of the TIN in representing regions near shores, producing incorrect shallow depth readings, resulting in a lower calculated volume than the real volume. IMP modeling exhibited great improvement in performance over the standard TIN (i.e., for 300 m accuracy of 5.51% for IMP and 14.40% for standard TIN), and in none of the cases were the generated volumes greater than the reference volume. Conclusions: The IMP method proved to be consistent, improving quality of the data while reducing effort in field work. The low accuracies found showed that even surveys following the widely accepted standards contain errors of a magnitude that cannot be ignored. Thus, knowing and evaluating the survey accuracy is of fundamental importance. Definition of standard spacing for reservoirs proved to be unfeasible. This must be defined on a case-to-case basis, considering the error acceptable for the purpose of the survey. [ABSTRACT FROM AUTHOR]

At present, computers, lasers, radars, planes and satellite technologies make possible very fast and accurate topographic data acquisition for the production of maps. However, the problem of managing and manipulating this data efficiently remains. One particular type of map is the elevation map. When stored on a computer, it is often referred to as a Digital Elevation Model (DEM). A DEM is usually a square matrix of elevations. It is like an image, except that it contains a single channel of information (that is, elevation) and can be compressed in a lossy or lossless manner by way of existing image compression protocols. Compression has the effect of reducing memory requirements and speed of transmission over digital links, while maintaining the integrity of data as required. In this context, this paper investigates the effects of the PNG (Portable Network Graphics) lossless image compression protocol on floating-point elevation values for 16-bit DEMs of dissimilar terrain characteristics. The PNG is a robust, universally supported, extensible, lossless, general-purpose and patent-free image format. Tests demonstrate that the compression ratios and run decompression times achieved with the PNG lossless compression protocol can be comparable to, or better than, proprietary lossless JPEG variants, other image formats and available lossless compression algorithms. [ABSTRACT FROM AUTHOR]