Ground-based Objects Research Articles

Utilizing Aerial Photography to Trace the Development of Urbanization in the Chennai District

Chennai, India is growing more urbanized by the day, hence studying its development is essential. We may see the world from a bird's-eye viewpoint thanks to aerial photography, a method for taking pictures of the Earth's surface from an elevated position—typically from an aircraft or drone. Scientific research, land surveying, urban planning, environmental monitoring, and mapping are just a few of the applications for these photos. Using remote sensing techniques, we are able to examine and record changes in Chennai's physical terrain over time, allowing us to trace the city's evolution through these aerial photos. ArcGIS, ERDAS, ENVI, Pix4D, Global Mapper, and QGIS were among the programs we used to process and examine the aerial photo data. Through the help of these software programs, users can extract insightful data and useful information from photos taken by satellites, drones, or airplanes. When compared to satellite images, aerial photography frequently produces imagery with a better spatial resolution, enabling more accurate and thorough study of ground-based objects. Through a comparative analysis of maps produced using aerial photography data throughout time, we have discovered that Chennai is losing open land, green spaces, and water bodies because of its growing urbanization. By closely analysing this trend and taking into account various factors, we can forecast the continued growth of Chennai.

The Method of Multi-Angle Remote Sensing Observation Based on Unmanned Aerial Vehicles and the Validation of BRDF

The measurement of bidirectional reflectivity for ground-based objects is a highly intricate task, with significant limitations in the capabilities of both ground-based and satellite-based observations from multiple viewpoints. In recent years, unmanned aerial vehicles (UAVs) have emerged as a novel remote sensing method, offering convenience and cost-effectiveness while enabling multi-view observations. This study devised a polygonal flight path along the hemisphere to achieve bidirectional reflectance distribution function (BRDF) measurements for large zenith angles and all azimuth angles. By employing photogrammetry’s principle of aerial triangulation, accurate observation angles were restored, and the geometric structure of “sun-object-view” was constructed. Furthermore, three BRDF models (M_Walthall, RPV, RTLSR) were compared and evaluated at the UAV scale in terms of fitting quality, shape structure, and reflectance errors to assess their inversion performance. The results demonstrated that the RPV model exhibited superior inversion performance followed, by M_Walthall; however, RTLST performed comparatively poorly. Notably, the M_Walthall model excelled in capturing smooth terrain object characteristics while RPV proved applicable to various types of rough terrain objects with multi-scale applicability for both UAVs and satellites. These methods and findings are crucial for an extensive exploration into the bidirectional reflectivity properties of ground-based objects, and provide an essential technical procedure for studying various ground-based objects’ in-plane reflection properties.

Evaluation of the thermal contrast of low-temperature ground-based objects

Subject of study. The thermal contrast of low-temperature passive terrain objects is the difference in radiant temperatures of an object and background in operating spectral regions of air- and ground-based thermal imaging devices for surveillance. Aim of study. The study attempted to provide the designers of thermal imaging devices with initial data for signature features of ground-based objects. Method. The study employed a theoretical analysis on the physical dependences of the formation of thermal contrast in ground-based objects using the previously published model of thermal radiation of the atmosphere, which, in addition to temperature contrast owing to the different thermal inertias of the object and background upon alterations in meteorological conditions, considers the optical properties of the object, solar and environmental (of the Earth’s surface and atmosphere) radiation reflected from the object, and viewing direction of three-dimensional objects. Main results. A methodological approach and corresponding mathematical model were proposed for the quick engineering evaluation of the main signature feature of low-temperature ground-based objects, particularly vehicles surveilled using thermal imaging devices from the upper hemisphere against the background of the Earth’s surface at different cloud coverage, i.e., their thermal contrast in the spectral regions of 3–5 and 8–12 µm corresponding to the atmospheric windows. Accordingly, we presented the analytical expressions for this evaluation considering environmental thermal radiation, direct and scattered solar radiation reflected by the diffuse spherical surface imitating the surveilled object, and its viewing direction. The possibility of thermal contrast variation in the rather wide range and its inversion was demonstrated even for a fixed temperature contrast. An example of a practical application of the proposed model was considered. Practical significance. The developed engineering method for calculating the thermal contrast of ground-based objects can be applied to quickly estimate effectiveness, including the operating range of air- and ground-based thermal imaging devices, and validate the requirements on the main technical parameters of prospective devices of this type.

Threshold sensitivity of staring thermal imaging devices operating in slant atmospheric paths

Subject of study. A method for predicting threshold sensitivity, i.e., the resulting noise equivalent temperature difference of modern air- or ground-based staring thermal imaging devices, was considered. Aim of study. The study aimed to estimate the effectiveness of thermal imaging devices surveying aerial and ground-based objects. Method. The method implied a theoretical computational analysis based on a previously developed model for emission of the atmosphere in arbitrarily oriented paths considering the following: the nominal noise equivalent temperature difference that characterizes the quantum or thermal array photodetectors used in thermal imaging devices; the temperature profile of the atmosphere whose emission, together with background emission of, e.g., the ground surface, significantly affects the external photon noise in thermal imaging devices; elevation of the line of sight of the object; presence and type of clouds; and season. Results. A method was developed for refined calculation of the threshold sensitivity of staring thermal imaging devices determined by photon noise resulting from the radiation of the elements of the thermal imaging device itself, particularly its objective, dark-current noise, readout noise, and spatial (geometric) noise resulting from the residual dispersion of sensitivity of photodetector elements after correction. This threshold sensitivity determines the effectiveness of thermal imaging devices in object detection and recognition against a quasi-uniform background of ground or sky under different conditions, including long slant ground-to-air and air-to-ground atmospheric paths. The investigation results are presented in a form convenient for practical applications, i.e., reduced to equations and illustrated with a calculation example. Practical significance. The engineering method for calculating the resulting noise equivalent temperature difference proposed in this study, which considers the thermal stratification of the atmosphere and corresponds to real operating conditions of thermal imaging devices, is advantageous for adequate assessment of their effectiveness in surveilling ground-based and aerial objects, including low-contrast objects.

Extraction of Water Body Information from Remote Sensing Imagery While Considering Greenness and Wetness Based on Tasseled Cap Transformation

Water, as an important part of ecosystems, is also an important topic in the field of remote sensing. Shadows and dense vegetation negatively affect most traditional methods used to extract water body information from remotely sensed images. As a result, extracting water body information with high precision from a wide range of remote sensing images which contain complex ground-based objects has proved difficult. In the present study, a method used for extracting water body information from remote sensing imagery considers the greenness and wetness of ground-based objects. Ground objects with varied water content and vegetation coverage have different characteristics in their greenness and wetness components obtained by the Tasseled Cap transformation (TCT). Multispectral information can be output as brightness, greenness, and wetness by Tasseled Cap transformation, which is widely used in satellite remote sensing images. Hence, a model used to extract water body information was constructed to weaken the influence of shadows and dense vegetation. Jiangsu and Anhui provinces are located along the Yangtze River, China, and were selected as the research area. The experiment used the wide-field-of-view (WFV) sensor onboard the Gaofen-1 satellite to acquire remotely sensed photos. The results showed that the contours and spatial extent of the water bodies extracted by the proposed method are highly consistent, and the influence of shadow and buildings is minimized; the method has a high Kappa coefficient (0.89), overall accuracy (92.72%), and user accuracy (88.04%). Thus, the method is useful in updating a geographical database of water bodies and in water resource management.

Selection of an algorithm for automatic classification of satellite images for the study of agricultural crops on the territory of Vietnam

The paper is devoted to the choice of an algorithm for automatic controlled classification of multi-zone satellite images of Landsat 8 OLI for the purposes of agricultural crop research based on the analysis of various mathematical classification algorithms and comparison of the practical results of these algorithms when using the ENVI 5.4 software package. In the period from June to August 2020, a field survey was conducted by coordinating and ground-based object recognition for the purpose of compiling decryption standards based on images. The paper analyzes four frequently used popular algorithms for automatic controlled classification – maximum likelihood, minimum distance, Mahalanobis distance, parallelepiped. As a result, it is concluded that when classifying objects with very close brightness values, the maximum likelihood algorithm gives optimal and objective results. This conclusion was confirmed by the cameral method by evaluating the reliability of the classification results. The result of the study can be used for mapping agricultural crops and solving other problems of agricultural activity in Vietnam. The methodology presented in the paper can be applied when choosing controlled classification algorithms for other groups of plant complexes and objects based on remote sensing data from space.

Detection of Abnormal Vibration Dampers on Transmission Lines in UAV Remote Sensing Images with PMA-YOLO

The accurate detection and timely replacement of abnormal vibration dampers on transmission lines are critical for the safe and stable operation of power systems. Recently, unmanned aerial vehicles (UAVs) have become widely used to inspect transmission lines. In this paper, we constructed a data set of abnormal vibration dampers (DAVDs) on transmission lines in images obtained by UAVs. There are four types of vibration dampers in this data set, and each vibration damper may be rusty, defective, or normal. The challenges in the detection of abnormal vibration dampers on transmission lines in the images captured by UAVs were as following: the images had a high resolution as well as the objects of vibration dampers were relatively small and sparsely distributed, and the backgrounds of cross stage partial networks of the images were complex due to the fact that the transmission lines were erected in a variety of outdoor environments. Existing methods of ground-based object detection significantly reduced the accuracy when dealing with complex backgrounds and small objects of abnormal vibration dampers detection. To address these issues, we proposed an end-to-end parallel mixed attention You Only Look Once (PMA-YOLO) network to improve the detection performance for abnormal vibration dampers. The parallel mixed attention (PMA) module was introduced and integrated into the YOLOv4 network. This module combines a channel attention block and a spatial attention block, and the convolution results of the input feature maps in parallel, allowing the network to pay more attention to critical regions of abnormal vibration dampers in complex background images. Meanwhile, in view of the problem that abnormal vibration dampers are prone to missing detections, we analyzed the scale and ratio of the ground truth boxes and used the K-means algorithm to re-cluster new anchors for abnormal vibration dampers in images. In addition, we introduced a multi-stage transfer learning strategy to improve the efficiency of the original training method and prevent overfitting by the network. The experimental results showed that the mAP@0.5 for PMA-YOLO in the detection of abnormal vibration dampers reached 93.8% on the test set of DAVD, 3.5% higher than that of YOLOv4. When the multi-stage transfer learning strategy was used, the mAP@0.5 was improved by a further 0.2%.

Determining a technique for transmitting measuring data on the spatial positioning of the piercing head in small-size installations during controlled soil piercing

For laying of underground utility systems in urban conditions by the method of horizontally directed soil piercing, small-sized units are designed. Such units should have measurement systems for determining the spatial position of the piercing head. In known systems, the surface layer of the soil is used as a data transmission line for transmitting measurement information. This method of transmitting information signals in urban conditions is not very acceptable. Ground-based objects reflect electromagnetic radiation of the head transmitter which leads to distortion of the directional diagram of the emitter and complicates the reliable reception of measurement information. It was proposed to use an autonomous measuring system with an operating frequency of 5 GHz based on Wi-Fi technologies and an unconventional method of transmitting measurement information using hollow steel bars in the piercing unit itself. This transmission line has periodic discontinuities because of the bar design. These discontinuities accumulate as the piercing head advances. For the basic vibration type Н 11 , more accurate analytical expressions were obtained for calculating the power transfer coefficient of the measurement signal in such non-uniform lines. It was shown that inhomogeneity of the transmission line in comparison with its surface resistance does not significantly affect the transmission coefficient. For example, damping in the line increased by 1.2 dB with the maximum length of inhomogeneity of 5 mm and the total length of jointed bars of 50 m. It has been theoretically proven that the range of soil piercing with reliable signal reception can be up to 50 meters. The proposed method for transmitting information signals makes it possible to reduce the transmitter power, ensure noise immunity of the measuring system, and reliable reception of the measuring information throughout the entire piercing path

Магнитные системы бесконтактных регулируемых синхронных генераторов с основным магнитоэлектрическим возбуждением

The article is devoted to the search and research of ways to optimize magnetic systems of contactless synchronous generators with a capacity of 30–50 kVA used in Autonomous power supply systems for ground-based mobile objects. The main atten-tion is paid to electric generators with a combined excitation system, the air gap magnetic flux of which is created by the combined action of permanent magnets of the main inductor and an electromagnetic adjustment link necessary to maintain the constancy of the output voltage when the rotor speed and generator load change. Ac-cording to the authors, with an increase in the power of the source over 30–35 kVA, DC machines will be replaced by generators of this type. The article also describes a machine with a fundamentally new magnetic system, which contains elements of the design of electric machines with radial and axial flux. The proposed magnetic system, according to the authors, allows us to fully utilize the potential inherent in machines of both forms, improve the specific characteristics and, most importantly, maintain the highest technical reliability inherent in contactless Electrical Machines.

Application of convolutional neural networks in the intelligence security system subsystem

The article proposes the structure of an integrated security system for areal facilities. The main subsystems included in its composition are considered. The tasks of the intelligence subsystem for detecting and recognizing ground-based objects of observation in a complex phono-target environment are defined.The task of detecting an object of observation was solved on the basis of a previously proposed algorithm. The disadvantage of this algorithm was the presence of false positives from a flickering complex phono-target environment. To eliminate this drawback, it is proposed to apply a classifier based on the convolutional neural network, which distributes the selected objects to specific classes.The analysis and experimental studies to evaluate the accuracy of recognition of ground objects by convolutional architectures such as VGG-16, VGG-19, Inception v3, ResNet-50, MobileNet. Training and verification of the recognition quality of architecture data was carried out on an experimentally created data set with a human image on a contrasting background and at different ranges. The results obtained indicate the possibility of using a convolutional neural network in the security system and its ability to work in real time.

A technique for target run-in direction justification based on theory of risk when striking ground-based objects by aircraft complexes

A technique for target run-in direction justification based on theory of risk when striking ground-based objects by aircraft complexes

Reducing the probability of detecting systems by passively active millimeter-wave detection small-sized ground objects

Options for reducing the probability of detecting small-sized ground objects by passive-active millimeter-range detection systems are considered.Urgency of the problem. At present, passive-active millimeter-wave systems are widely used to detect small-sized ground objects. These systems are used in many areas - to detect radiation sources in the range of tens and hundreds of GHz, to conduct environmental radio monitoring of the area, for all-weather navigation of vehicles, to search for objects closed by camouflage.One of to reduce the range and probability of detecting small ground-based objects by passive radiometric systems are the use of active “backlighting” of objects with a broadband noise or deterministic signal and the use of a wide-range masking coating.

Calculating the real object paths in terms of signals received by internal and external information sources

Hypothesis, internal, and output paths of the airborne, seaborne, and ground-based objects in a complex informational environment (low probability of detection, uncertainty and incompleteness of coordinates, maneuvering and group objects) onboard an aircraft are discussed. All measurements of internal and external sources operating in survey, passive detection, and tracking modes are used for calculation. For external sources the composition of transmitted data is determined. In the partial measurement of the coordinates, a complex aircraft control system is formed, which increases the accuracy of the paths of such objects and puts the aircraft in the conditions of a rocket launch with the maximum range.

Quality metric in matched Laplacian of Gaussian response domain for blind adaptive optics image deconvolution

Adaptive optics (AO) in conjunction with subsequent postprocessing techniques have obviously improved the resolution of turbulence-degraded images in ground-based astronomical observations or artificial space objects detection and identification. However, important tasks involved in AO image postprocessing, such as frame selection, stopping iterative deconvolution, and algorithm comparison, commonly need manual intervention and cannot be performed automatically due to a lack of widely agreed on image quality metrics. In this work, based on the Laplacian of Gaussian (LoG) local contrast feature detection operator, we propose a LoG domain matching operation to perceive effective and universal image quality statistics. Further, we extract two no-reference quality assessment indices in the matched LoG domain that can be used for a variety of postprocessing tasks. Three typical space object images with distinct structural features are tested to verify the consistency of the proposed metric with perceptual image quality through subjective evaluation.

THE ANALYSIS OF GASEOUS POLLUTANTS DISPERSION IN HILLY TERRAIN

The emission of a dangerous substance overlaps in vicinity of wide-range ground-based objects. Consequently, part of the process of dispersion pollution is determined by the flowing conditions and is shaped by their presence and distribution. However, under real conditions, complexes systems of terrain obstacles exist. A subject of interest among many authors is the flow and dispersion of pollutants surrounding single elements such as a hill or a building. This type of research enables a better understanding of the flow and propagation of pollutants on terrain with complex topography. The aim of the present work is the investigation of the influence of the complex character of a velocity field, particularly its periodic composition (non-stationary blowing) as well as rotating structures generated by obstacles such as hills on the propagation of various types of gaseous pollutants. The base of analysis represents the evolution of the carbon dioxide concentration in profiles surrounding hills or different locations in relation as well to the height of the source emission. By propagating a gaseous tracer in a oscillating flow from a source located in a flush zone, a source's location relative to circulation zones of increased level turbulent fluctuations of flow velocity can be determined.

Classification of the forest cover of Tver oblast using hyperspectral airborne imagery

Recent research efforts have been focused on building a system of hyperspectral aerial sounding of forest vegetation on regional scales. The components of this system are developed using data obtained in the course of measurement campaigns in Tver forestry test sites. Hyperspectral airborne surveys are conducted using a Russian video spectrometer produced by the NPO Lepton company. The technique for recognizing ground-based objects is based on Bayesian classification principles with the feature space optimization. The choice of the most informative spectral channels is based on the step-up method. We propose an approach allowing the choice of channels to be more stable. We compare the classification of timber stands on the basis of hyperspectral imagery with ground-based data to demonstrate the consistency of the system developed.

Corona discharges and their effect on lightning attachment revisited: Upward leader initiation and downward leader interception

Previous studies have suggested the possibility of using glow corona discharges to control the frequency of lightning flashes to grounded objects. In order to revisit the theoretical basis of this proposal, the self-consistent leader inception and propagation model – SLIM – is used together with a two-dimensional glow corona drift model. The analysis is performed to quantify the effect of glow corona generated at the tip of ground-based objects on the initiation and propagation of upward positive connecting leaders under the influence of downward lightning leaders. It is found that the presence of glow corona does not influence the performance of Franklin lightning rods shorter than 15m, while it slightly reduces the lateral distance of rods up to 60m tall by a maximum of 10%. Furthermore, the results indicate that it is not possible to suppress the initiation of upward connecting leaders by means of glow corona. It is found instead that unconventional lightning protection systems based on the generation of glow corona attract downward lightning flashes in a similar way as a standard lightning rod with the same height.

A Study of Parameters of the Counterpropagating Leader and its Influence on the Lightning Protection of Objects Using Large-Scale Laboratory Modeling

UDC 537.86 In this work, the results of experiments on initiating the upward and descending leaders during the development of a long spark when studying lightning protection of objects with the help of large-scale models are shown. The influence of the counterpropagating leaders on the process of the lightning strike of ground-based and insulated objects is discussed. In the first case, the upward negative leader is initiated by the positive downward leader, which propagates from the high-voltage electrode of the “rod–rod”-type Marx generator (the rod is located on the plane and is 3-m high) in the gap with a length of 9–12 m. The positive-voltage pulse with a duration of 7500 µs had an amplitude of up to 3 MV. In the second case, initiation of the positive upward leader was performed in the electric field created by a cloud of negatively charged aerosol, which simulates the charged thunderstorm cell. In this case, all the phases characteristic of the ascending lightnings initiated by the tall ground-based objects and the triggered lightnings during the experiments with an actual thunderstorm cloud were observed in the forming spark discharge with a length of 1.5– 2.0 m. The main parameters of the counterpropagating leader, which is initiated by the objects during the large-scale model experiments with a long spark, are shown.

On a criterion of the appearance of an upward leader from ground-based objects

Results of an experimental study of processes forming an upward leader discharge from a grounded rod electrode in the electric field of an artificial cloud of charged water aerosol are presented. The transition of the streamer corona flash to an upward leader discharge was found to be of a probabilistic character and to be determined, first of all, not by the current amplitude, and not only by the flash charge passing through the stem of the pulse corona, but by a set of parameters: duration of the current passage at a rather high level and optimum value of the corona charge passed through the stem base. The range of radii of curvature of the rod-shaped lightning arrester tip (from 20 to 25 mm) at which the highest probability of the appearance of an upward leader is observed has been revealed.

Modified Board System for Ecological Monitoring of Ground-Based Objects State

In order to improve characteristics and to increase reliability of board systems used at researches of the ground objects, estimation of natural resources and control of ecological state of environment, determination and estimation of accidents and explosions of industrial fields, etc. the structural and methodological solutions are offered. At that increase of system response speed and reliability of received results are provided.