Digital Terrain Map Research Articles

Frequency dependence of reflections on radar landmarks

Purpose. Reducing the dispersion of radar reflections from local objects, with multi-frequency sensing, to solve the problem of orientation by radar reflections from objects. Methodology. Reflections from local objects in the entire frequency range of the radar station (RS) at the same radio engineering position were measured by three independent radars of the same type on different days and at different antenna elevations. The deviation of the radar stations in the position did not exceed 500 meters. Coordinates (azimuth, range) of reflections of several separate local objects were allocated for each radar. The average values of reflections from local objects and their dispersion in the frequency range were calculated. Using various algorithms, individual frequencies were sampled and the reflected signals were averaged at these frequencies. The decrease in the dispersion of the reflected signal from the number of frequencies at which reflections were measured and from the algorithm for selecting these frequencies was investigated. Findings. Averaging the values of reflections from local objects for several frequencies leads to a decrease in dispersion and, as a result, to a more accurate correspondence of the reflected signal level to the geometric size of the local object. The variance decreases most rapidly for a small number of frequencies selected for averaging when selecting frequencies located in an interval of at least 1% relative to each other. Originality. To solve the problem of orientation based on radar reflections from local objects, it is necessary to identify the landmarks selected on a digital terrain model. Due to the fact that local objects (hills) are a collection of many reflectors falling into the allowed volume of the radar, with different levels of reflections and random phases, there may not be radar reflection from a local object at a certain frequency, or it may be very small. In order to unambiguously identify all landmarks, measurements must be carried out at several frequencies. The work has established how many frequencies measurements should be performed at and on what principle these frequencies should be selected. Practical value. The advent of digital terrain models made it possible to solve the problem of terrain orientation by comparing radar reflections from local objects with reflection models based on digital terrain maps. Radar reflection models use mathematical expectations of reflection values, unlike real reflections, which have random deviations in signal levels depending on the operating frequency. Reducing the variance of these deviations increases the accuracy of identifying characteristic local objects (landmarks) used to orient the radar in the absence of data from satellite navigation systems.

МЕТОДИКА ПОДДЕРЖКИ ПРИНЯТИЯ РЕШЕНИЙ ПО ВЫБОРУ МЕСТОПОЛОЖЕНИЯ ЭЛЕМЕНТОВ ГРУППИРОВКИ СИЛ И СРЕДСТВ ПРИ ЛИКВИДАЦИИ ЧРЕЗВЫЧАЙНЫХ СИТУАЦИЙ

For this period of time, the EMERCOM of Russia system has developed and uses mainly «manual» and partially automated calculation methods when planning the location of elements of the emergency response grouping. The main disadvantages of the known methods are the high labor and time costs, the need for highly qualified performers, as well as the significant importance of the subjectivity factor in the results obtained. When implementing the planning process, these factors negatively affect the quality of calculations. Automation of calculations using a model for estimating the properties of terrain on a digital map in the proposed formats is considered. The approbation of the methodology proposed in the article for solving the problems of choosing the location of elements of the grouping of forces and means in the aftermath of an emergency situation shows that the use of a digital terrain map really allows you to improve the quality of decisions.

The technique for approximation of three-dimensional surfaces in order to synthesize algorithms for preventing aircraft collisions with obstacles

The work marks the beginning of the practical application of algorithms for making the aircraft recovery maneuver from three-dimensional constraint surfaces, which are a combination of terrain and artificial obstacles. An analysis of events leading to aviation accidents was carried out, and a comparison of on-board systems for preliminary notification of aircraft crews about collisions with natural or artificial obstacles was made. It is shown that such systems are insufficient due to their passive-recommendatory nature of issuing warnings. A question has been raised about the need to implement an active automatic collision avoidance system with spatial obstacles. In order to apply existing algorithms for the aircraft recovery maneuver from spatial constraint surfaces, a technique has been developed for approximating three-dimensional surfaces (obstacles) specified on a digital terrain map in the form of discrete height readings with a certain step on a coordinate grid. A paraboloid of revolution was chosen as a continuous 2nd order surface approximating the obstacle, and its characteristic parameters were determined. To determine the characteristic parameters of the paraboloid, an algorithm for determining the intersection of a three-dimensional surface and a plane, based on the principle of determining the intersection of triangles in space, as well as a method for selecting the inflection point of the terrain, based on determining the value of the terrain height gradient, are proposed for use. The construction of an approximating paraboloid using the example of a natural obstacle in the form of a mountain range is given. When synthesizing algorithms for preventing collisions of aircraft with obstacles, the need to take into account not only the parameters of the constraint surfaces and dynamic characteristics of aircraft, but also the accuracy characteristics of data sources about their position is noted. Promising application areas of the developed methodology are shown.

Analysis of faults and pit chains in Noctis Labyrinthus: Implications for early extension and possible magmatic plumbing

Noctis Labyrinthus has been a region of disputed origin due to its complexity and poor understanding of how various processes and mechanisms may have combined to form it. The surface is an integrated record of intensive tectonic activity expressed by a multiple extended sets of dip-slip faults oriented in different directions, and thought to have acted on this region over its history. These faults are always coalescent to pits and pit chains displaying a complicated geological history in the region. To understand this geological history, we mapped the surface features in Noctis Labyrinthus using the High-Resolution Stereo Camera (HRSC) onboard Mars Express ND2 nadir channel basemaps, and we adapted the Digital Terrain Map (DTM) from the Mission Experiment Gridded Data Record (MEGDR) of Mars Orbiter Laser Altimeter (MOLA) onboard Mars Global Surveyor (MGS) for the topography. We have investigated the spatial distribution and trend of fault systems, the pit chains' morphology, and the correlation between these two types of features. Our results show three fault systems: i) NS and NNE-SSW, ii) EW and ENE-WSW, and iii) NNW-SSE and NW. The analysis of the faults trending, cross-cutting correlation and the superimposition led to identify multiple intersections between these faults that have been alongside with the reactivations of some inherited faults. We interpreted the first system of fault to be related to coeval lateral extension, generated by regional stress tensor, which is probably related to the slight bending of Valles Marineris within two phases of bidirectional extension. The second system of faults has been generated by the radial oblate stress tensor related to the formation of the small shield volcanoes in Syria Planum. However, the third system is likely related to the external driving process, probably in the Tharsis province. We classified pits in four evolutionary stages based on their morphometric attributes. We believe that the formation of the pit chains in Noctis Labyrinthus is related to a surface collapse after a pressure drop related to the magma chamber deflation associated with Syria Planum volcanic province. We propose a deformational model based on early extension and magmatic plumbing as driving processes for the formation of Noctis Labyrinthus.

АЛГОРИТМЫ ПРЕОБРАЗОВАНИЯ ЦИФРОВОЙ КАРТОГРАФИЧЕСКОЙ ИНФОРМАЦИИ ДЛЯ РЕШЕНИЯ ЗАДАЧ ВЫБОРА МЕСТОПОЛОЖЕНИЯ ЭЛЕМЕНТОВ ГРУППИРОВКИ СИЛ И СРЕДСТВ МЧС РОССИИ

Mathematical and information support of modern and promising control automation complexes in EMERCOM of Russia currently include mathematical models, methods and algorithms for processing a digital terrain map, as well as formats for using a digital map. 
 Presents the developed algorithms for converting digital cartographic information to solve the problems of choosing the location of elements of the grouping of forces and means of EMERCOM of Russia, which are based on the joint use of possibilities for processing digital maps of the area and methods of evolutionary modeling.

Surveying and mapping of large-scale 3D digital topographic map based on oblique photography technology

In the fields of geographic information systems and cartography, accurate topographic maps are crucial. Although traditional topographic mapping methods have certain accuracy, they have limitations in capturing features and building details. Therefore, this article proposes a large-scale 3D digital terrain mapping method based on oblique photography technology. Firstly, the UAV route is planned and image control points are arranged, to collect large-scale geographical object data by using UAV oblique photography technology. Then Smart 3D software is used to complete the 3D modeling of real large-scale topographic map through data preprocessing, air-to-air survey, control point import, 3D modeling, texture mapping and other steps based on the obtained geographical object data. The 2D and 3D linkage integrated mapping mode is adopted to obtain geomorphic information and elevation information, complete the data collection of indoor features, confirm the features that cannot be read on both sides of the indoor industry, complete the field supplementary mapping and adjustment, and realize the mapping of large-scale 3D digital topographic map. The experimental results show that this method can use oblique photography technology to collect data and establish a three-dimensional model of large-scale 3D digital terrain maps. The mean square error of accuracy detection is 0.202m, the mean square error of elevation is 0.257m, the mean square error of plane is 0.201m, and the mean square error of elevation is 0.197m. It has high drawing accuracy and excellent aerial triangulation performance.

Planning the Optimal Reference Flight Path of an Aircraft Using a Terrain Map

In connection with the development of aviation technology, the expansion of the functionality of modern aircraft and the complication of the tasks being solved, additional stringent requirements are imposed on the accuracy of air navigation. Along with high accuracy, navigation autonomy is also required. The autonomy of aircraft navigation implies the navigation of an aircraft without the use of active radar facilities. In this article, to calculate the optimal reference flight path of an aircraft in a horizontal plane, the Bellman dynamic programming method is proposed using a digital terrain map. A technique, algorithms have been developed, and a numerical experiment has been carried out using fragments of a digital terrain map. High accuracy and autonomy of navigation are necessary, among other things, to ensure stealth (invisibility) of aircraft by ground-based radar facilities of a potential enemy in low-altitude flight mode. The best stealth of an aircraft flight in a low-altitude flight mode is achieved not only by flying around, but also by avoiding obstacles, due to the shielding properties of the earth’s surface. Autonomy of navigation provides periodic correction of the reference flight path during long-term flight, and high accuracy prevents aircraft collisions with the earth’s surface in low-altitude flight mode. The purpose of this work is to select the optimal reference trajectory (route) of an aircraft flight in the low-altitude flight mode. This article discusses a method developed based on the principle of dynamic programming for calculating the reference flight path in the horizontal plane depending on the DEM and the implementation of the algorithm based on the proposed method with a specific numerical example. The method makes it possible to calculate the optimal flight route, which provides the greatest secrecy of the aircraft in the low-altitude flight mode using the screening properties of the earth’s surface irregularities.

Retracted: SLAM 3D Digital Terrain Mapping with SqueezeNet Driven by Road Traffic Data

Retracted: SLAM 3D Digital Terrain Mapping with SqueezeNet Driven by Road Traffic Data

Deep learning-based automated terrain classification using high-resolution DEM data

Landforms are a fundamental component of the natural environment, and digital terrain mapping on a large spatial scale is important when studying landforms. In this study, we adopted a semantic segmentation model in computer vision to classify elementary landform types using AW3D30 digital elevation model (DEM) data. We built a semantic segmentation model with an FCN-ResNet architecture that extracts features using a residual network (ResNet) and obtains pixel-level segmentation of the DEM using a fully convolutional network (FCN). A lightweight decoder based on skip connections was adopted to maintain detailed information at different scales. We used the 1:1,000,000 Chinese landform map as the label and tested different combinations of terrain factors. The experiments indicate that increasing the terrain factors has no significant influence on the model, and the semantic information can be learned using only DEM data. The model has strong feature extraction capability and is tolerant to noise and error. The results of landform category prediction confirm that deep learning methods have strong potential for landform classification and will have great application prospects in the field of geomorphological research.

Martian wind and surface conditions during the night-time descent and landing of Pathfinder

Pathfinder parachuted through the Martian nocturnal boundary layer during the northern hemisphere summer. Encased in airbags the lander bounced across the surface in darkness coming to a stop surrounded by a rugged terrain. Studying the motion of Pathfinder during its descent and landing offers a unique opportunity to study the Martian winds at night in the stable boundary layer. We simulate the atmospheric descent of Pathfinder using a trajectory model together with winds imported from a global climate model. The bouncing trajectory of the airbags was investigated using atmospheric pressure observations made during the landing and a Digital Terrain Map (DTM).Reconstruction of the parachute and airbag trajectories together with accelerometer data indicates that there was possibly strong wind shear in the nocturnal boundary layer prior to the firing of the braking rockets. This is unexpected from atmospheric models. Atmospheric pressure data and the DTM indicate the first airbag impact was on the side of a low hill north of the deployed lander. From this point our airbag model indicates the airbags would have bounced downhill towards the south by about one hundred metres and descended several metres in elevation before arriving on level ground where they would have slowed to a stop.We use modern observations and analytical tools to reconstruct the descent and landing of Pathfinder and provide information on the atmospheric and surface conditions during the night-time landing. In addition we provide clues to the behaviour of the nocturnal boundary layer on Mars.

A new comprehensive performance optimization approach for Earth-contact mechanism based on terrain-adaptability task

AbstractEarth-contact mechanism (ECM), a type of mechanism to keep the system in contact with the earth and to move with the terrain changes. This paper uses the virtual equivalent parallel mechanism (VEPM) to convert the terrain data into the kinematical variables of the moving platform in the VEPM, and further analyzes the performance of the VEPM at each terrain point. Then, the comprehensive performance of the VEPM is chosen as the optimization goal, and a task-oriented dimensional optimization approach combined with the particle swarm algorithm and the neural network algorithm is proposed. This paper conducted a comparative experiment to verify the superiority of the new approach in optimizing the ECM’s comprehensive performance, whose performance analysis also can be applied into the layout design of the ECM. This paper proposed an analysis method to construct the ECM’s performance map based on the digital terrain map, which helps the control system and operator to make the optimal control decision.

SLAM 3D Digital Terrain Mapping with SqueezeNet Driven by Road Traffic Data

In order to improve the efficiency of dynamic visualization of large-scale road traffic data in a web environment, this paper proposes a SLAM 3D digital terrain map visualization method using SqueezeNet in a web environment. We propose a hierarchical organization method of the road network, taking into account road attributes and drawing roads at different view heights; a multiroad merging method based on the line segment indexing feature of WebGL (web graphics library) technology, and optimizing the scene by combining view rejection and multithreading technology. The prototype system was developed and case studies were carried out using the national road network data as an example. The experimental results show that the frame rate of large-scale road traffic data visualization in the network environment is above 40 frames/second, which is 20–30 frames/second higher than that of Baidu’s ECharts GL visualization method.

Experimental and numerical study on the mechanical properties of the rock-concrete contact surface for consideration of ground–liner interaction in rock tunnelling

The mechanical properties of the rock-concrete contact surface are vital in the study of the ground-liner interaction for the tunnels embedded in rock mass. This paper mainly investigates the shear mechanical behaviour and failure mechanisms of the ground-tunnel interface with experimental and numerical approaches. Firstly, a Brazilian test was conducted to make a rough surface that represents the rock-concrete contact surface in the rock tunnelling. The split rough surface was then scanned with a 3 D scanning technique with which the digital terrain map (DTM) model of the split surface was acquired. In conjunction of the DTM model with a 3 D printing technique, synthetical samples that represent the rock-concrete contact surface were produced. These samples were put in shear test in which the shear behaviour and failure mechanism were investigated, and the shear strength criterion of the rock-concrete contact surface was presented. Ultimately, based on the discrete element method (DEM) code 3DEC, the numerical shear tests of the contact surface were performed. A sophisticated, nonlinear, continuously yielding (C-Y) model was adopted to describe the complex shear behaviour of the contact surface during the numerical shear test. The reasonable match of laboratory data with the numerical test results demonstrated the applicability of the DEM approach in reflecting the shear mechanical behaviour of the rock-concrete contact surface of liner.

INFORMATION TECHNOLOGIES OF COMPLEX ENVIRONMENTAL MONITORING BASED ON AEROSPACE AND GROUND RESEARCH DATA

The article considers the possibilities of using geoinformation systems and remote land sensing systems in detecting the development of degradation processes of the soil cover. The use of satellite technologies for the detection of soil degradation and timely response to these processes requires timely information and the availability of a database. The environmental safety system is aimed at forecasting and preventing emergency situations of technogenic and ecological nature. It includes the development of forecasting models and algorithms, as well as the allocation of resources to take immediate action in the event of such situations, as well as information about potential hazards, risks and possible consequences. With the use of geodetic surveying and computer processing of the surveying results, the coordinates of land plot plans were obtained. Satellite images were used to obtain data on changes in soil cover over a large area and on a large scale. Aerial photographs reveal small changes in soil structure, indicating signs of erosion or other degradation processes. Digital electronic terrain maps provide geographic information about an area, including geological and geomorphological features. They are used to combine other data, such as satellite images or aerial photographs, and create a comprehensive picture of the state of the soil. In the course of research, the system of ecological monitoring of soil cover using the method of infrared spectrophotometry was improved. The method of physico-chemical analysis of soil samples is substantiated and the dependence between the state of soil contamination by individual chemical elements and their genesis is established. The creation of a computer database and the use of space images in combination with other geo-information technologies really allows for effective monitoring and analysis of soil degradation and other agricultural objects.

Digital multi-agent system for simulating natural fire fighting processes

A system for modeling and supporting decision-making on the use of forces and means to eliminate wildfires, based on a digital model, implemented in the software “Taiga-Analyst”, is proposed. The system works on the basis of agent-based simulation and allows you to select forces and means to fight a fire, simulate its propagation and elimination with reference to a digital terrain map using a geographic information system. The possibilities and scope of the “Taiga-Analyst” system are described. A decision-making scheme for fighting natural fires is shown, and the use of the system in the process of training fire safety specialists is described.

A new model and method of terrain-aided positioning confidence interval estimation

There are typically unknown deviation tides and stochastic measurement errors in digital elevation map and real-time measurement terrain map, which result in the failure of the matching algorithm. To address the problem of the robust terrain-aided position under the condition of unknown tidal and measurement errors, a new terrain-aided position (TAP) model and a tide level estimation method based on a single-point observation model are proposed in this study. Accordingly, a jump model of the TAP points that considers the nonlinear mapping relationship between the position point and local terrain is proposed. Finally, the effectiveness of the TAP and confidence interval estimation algorithms are verified based on shipborne measurement data with a difference in terrain variability. Future research will focus on revealing the relation between terrain characteristics and directionality of the TAP confidence interval.

An Experimental Investigation of the Influence of Loading Rate on Rock Tensile Strength and Split Fracture Surface Morphology

To investigate the effect of the loading rate on the tensile strength of rock material and the morphology of the resulting split fracture surfaces, three types of rock specimens, namely, granite, basalt and limestone, were collected and tested with Brazilian testing under different loading rates. The tensile strength was measured, and the effect of the loading rate on the tensile strength of the rock material was studied. Digital terrain map models of the split fracture surface were obtained with an optical 3D scanning technique, and the effects of the loading rate on the geometry and morphology of the fracture surface were studied. The influence of the loading rate and tensile strength on the roughness was studied quantitatively by calculating the roughness indices of a fracture surface for all three kinds of rock. The research results show that the rock tensile strength increases with the loading rate. A linear relationship was established in double-logarithmic coordinates to describe the relationship between the tensile strength and the loading rate. Four different roughness indices were used to describe the morphology of the split fracture surface. The analysis results show that the magnitudes of all the roughness indices increase with the loading rate. Additionally, the roughness indices for all three types of rock linearly increase with the tensile strength. This linear trend indicates that it is possible to utilize fracture surface roughness indices to estimate rock tensile strength. The current study may motivate further research on the relationship between the morphology indices of rock fractures and mechanical parameters of the rock.

Digital elevation model and terrain mapping using LiDAR

In this paper, we advise Digital Elevation Model (DEM) and Terrain Mapping from the 3-D map that's received from the dataset received from the surface surroundings the usage of LiDAR. Human existence is surrounded through a range of sensors. Through the aggregate of diverse sensors, a fashion dressmaker can carry out environmental trying out then update the human notion system. This software offers with the interfacing of LiDAR with Robot running Software (ROS). The cause cloud is calibrated from XML layout to YAML layout. The homes of the specified surroundings are often.

Algorithmic support of low-altitude aircraft flight based on the hazard analysis of the flight situation

Low-altitude flight of an aircraft is an effective, but at the same time, a very complex tactical technique, during which the crew does not always have the opportunity to timely recognize the occurrence of an abnormal case, determine the way out of it and counteract an aviation accident development. Despite many advantages of the automatic mode of low-altitude flight performing, its practical implementation is associated with a number of features and disadvantages, which determined the preference for the manual mode of low-altitude flight control. These are the presence of telltale factors, limited ability of performing flights at night and in difficult weather conditions, insufficient reliability etc. The considered features determined the relevance of the of low-altitude flight safety ensuring problem in relation to the manual control mode. As a result of an experimental study of the low-altitude flight performing process in a manual control mode, it was found that when performing manually-controlled low-altitude flight, a hazard assessment of the flight situation becomes pivotal. However the crew being under such conditions is not always able to correctly assess the flight situation hazard due to a combination of objective reasons. The current state of the adaptive and on-board flight safety systems theory makes it possible to increase the safety of the manuallycontrolled low-altitude flight by using adaptive control algorithms based on the flight situation hazard assessment. To solve this problem an adaptive control algorithm is proposed that ensures the formation of a security corridor in the longitudinal control channel, where the upper limit is determined by the critical value of the aircraft detection hazard, and the lower limit is determined by the critical value of the error in maintaining a given flight altitude. For a continuous assessment of the flight situation hazard and the timely formation of control signals the complex information about the current true flight altitude and the foreground is needed. Taking into account the peculiarities of low-altitude flight a digital terrain map containing data on natural and artificial obstacles along the flight route is a more rational source of information, that will make it possible to predict the development of the flight situation hazard. The above reasoning makes it possible to form an aircraft low-altitude flight adaptive control algorithm. A distinctive feature of the proposed algorithm is the implementation of a combined control variety where the pilot is provided with ample manual control opportunities within the security corridor, and the automatic flight control system is assigned the role of a safety subsystem that ensures control and timely return of the flight situation to normal flight conditions. The presented algorithm will allow to increase the crew logical-analytical activity information support during continuous analysis of the existing flight situation due to the formation of protective control actions based on the current flight situation hazard analysis.

Assessment of Terrain and Land Use/Land Cover Changes of Mine Sites using Geospatial Techniques in Plateau State, Nigeria

In this paper, we report a geospatial assessment of the selected mine sites in the Plateau State, Nigeria. The aim of this work is to determine the impact of mining on the terrain as well as the Land Use/Land Cover (LULC) of the host communities. The Shuttle Radar Topographic Mission (SRTM) is used for the terrain mapping. The derived impact of mining on LULC between 1975 and 2014 is determined by classifying the relevant Landsat imageries. The digital terrain map reveal that the mining activity is not well-coordinated. Hence, the parts of the mine sites that are rich in the desired minerals are punctuated with low depth, while the other parts have high terrain as a result of the haphazard mining activity. The analysis of the LULC change show that the degraded land (DL), built-up area (BU), water bodies (WB), and exposed rock outcrop (RO) increase by 15.68%, 4.68%, 0.06%, and 14.5%, respectively, whereas the arable farmland (FL) and forest reserve (FR) decrease by 28.29% and 6.63%, respectively. Mining has adversely affected the natural ecology of the studied area. Therefore, the mine sites should be monitored, and their environmental damages should be pre-determined and mitigated. There should be regular inspections to keep these activities under control. The existing laws and regulations to conserve the natural ecosystems of the host communities should be enforced to curtail the excesses of the operators of the mining industries. Restoration of the minefields to reduce the existing hazards prevent further environmental degradation, and facilitating the socio-economic development of the area is also suggested.