Journal articles on the topic 'Topographic positioning'
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Mikita, Tomáš, and Martin Klimánek. "Topographic Exposure and its Practical Applications." Journal of Landscape Ecology 3, no. 1 (January 1, 2010): 42–51. http://dx.doi.org/10.2478/v10285-012-0022-3.
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Topographic Exposure and its Practical ApplicationsTopographic exposure is a topographic characteristic representing a degree of protection by a surrounding topography of a certain site. Detailed knowledge of topographic exposure has broad use in a number of applications ranging from studying forest wind damage through research on snow storage dynamics to optimisation in positioning wind power stations. This paper describes a method for creation of topographic exposure on the basis of a digital elevation model (DEM) using GIS. In combination with other climatic data on wind direction and speed, this factor is used to define the degree of terrain ventilation. Low terrain ventilation has, among other things, a significant influence on the creation of valley inversions and related vegetation zoning inversions. By combining the degree of terrain ventilation with DEM and forest vegetation zones in the area of the Training Forest Enterprise Křtiny, a clear relationship between the influence of topographic exposure, or terrain ventilation, and the creation of the vegetation zoning inversion was determined.
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Wang, Lihui, Le Yu, and Yanhua Zhu. "Construction Method of the Topographical Features Model for Underwater Terrain Navigation." Polish Maritime Research 22, s1 (September 1, 2015): 121–25. http://dx.doi.org/10.1515/pomr-2015-0043.
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Abstract Terrain database is the reference basic for autonomous underwater vehicle (AUV) to implement underwater terrain navigation (UTN) functions, and is the important part of building topographical features model for UTN. To investigate the feasibility and correlation of a variety of terrain parameters as terrain navigation information metrics, this paper described and analyzed the underwater terrain features and topography parameters calculation method. Proposing a comprehensive evaluation method for terrain navigation information, and constructing an underwater navigation information analysis model, which is associated with topographic features. Simulation results show that the underwater terrain features, are associated with UTN information directly or indirectly, also affect the terrain matching capture probability and the positioning accuracy directly.
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Han, Jen-Yu, Yu Wu, and Rou-Yu Liu. "Determining the optimal site location of GNSS base stations." Boletim de Ciências Geodésicas 18, no. 1 (March 2012): 154–69. http://dx.doi.org/10.1590/s1982-21702012000100009.
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The relative positioning technique plays an essential role in Global Navigation Satellite System (GNSS) surveys. Simultaneous observation at base and rover stations eliminates the majority of error sources thus the quality of a positioning solution can be substantially improved. However, topographic obstruction is still a key issue affecting positioning quality. In this study, an integrated approach for analyzing the impact of topographic obstruction on GNSS relative positioning has been developed. By considering varied satellite geometry according to actual terrain variation, this approach can be used to realistically determine satellite visibility condition for a specific base station with respect to any rover station. Furthermore, a base station quality index (BSQI) is proposed as an explicit indication of the sufficiency in a relative positioning. By incorporating the proposed approach, one can immediately identify an optimal site location for a GNSS base station with subsequent GNSS field survey thus achieved in a more reliable and cost-efficient manner.
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Rodrigues, Thiago G., Waldir R. Paradella, and Cleber G. Oliveira. "Evaluation of the altimetry from SRTM-3 and planimetry from high-resolution PALSAR FBD data for semi-detailed topographic mapping in the Amazon Region." Anais da Academia Brasileira de Ciências 83, no. 3 (September 2011): 953–66. http://dx.doi.org/10.1590/s0001-37652011000300014.
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The Brazilian Amazon has a deficit of 35% of coverage regarding topographic mapping at semi-detailed (1:100,000) scale. This paper presents an alternative to overcome this scenario using a combination of planialtimetric information from two orbital SAR (Synthetic Aperture Radar) missions. The altimetry was acquired from Shuttle Radar Topography Mission (SRTM), while the planimetry was provided from Fine Beam Dual (FBD) images of the Phased Array L-band Synthetic Aperture Radar (PALSAR) sensor. The research was carried out in the mountainous area of the Serra dos Carajás (Pará State), located on the Amazon region. The quality of the orbital topographic information was evaluated regarding precise planialtimetric measurements acquired from Global Positioning System (GPS) field campaigns. The evaluations were performed following two approaches: (1) the use of Root Mean Square Error (RMSE) and (2) tendency and precision hypothesis tests. The investigation has shown that the planialtimetric quality of the orbital products fulfilled the Brazilian Map Accuracy Standards requirements for 1:100,000 A Class map. Thus, the use of combination of information provided by PALSAR and SRTM-3 data can be considered a promising alternative for production and update of semi-detailed topographic mapping in similar environments of the Amazon region, where topographic information is lacking or presents low quality.
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Carreno-Luengo, Hugo, Guido Luzi, and Michele Crosetto. "First Evaluation of Topography on GNSS-R: An Empirical Study Based on a Digital Elevation Model." Remote Sensing 11, no. 21 (October 31, 2019): 2556. http://dx.doi.org/10.3390/rs11212556.
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Understanding the effects of Earth’s surface topography on Global Navigation Satellite Systems Reflectometry (GNSS-R) space-borne data is important to calibrate experimental measurements, so as to provide accurate soil moisture content (SMC) retrievals. In this study, several scientific observables obtained from delay-Doppler maps (DDMs) ⟨ | Y r , t o p o ( τ , f ) | 2 ⟩ generated on board the Cyclone Global Navigation Satellite System (CyGNSS) mission were evaluated as a function of several topographic parameters derived from a digital elevation model (DEM). This assessment was performed as a function of Soil Moisture Active Passive (SMAP)-derived SMC at grazing angles θ e ~ [20,30] ° and in a nadir-looking configuration θ e ~ [80,90] °. Global scale results showed that the width of the trailing edge (TE) was small T E ~ [100, 250] m and the reflectivity was high Γ ~ [–10, –3] dB over flat areas with low topographic heterogeneity, because of an increasing coherence of Earth-reflected Global Positioning System (GPS) signals. However, the strong impact of several topographic features over areas with rough topography provided motivation to perform a parametric analysis. A specific target area with little vegetation, low small-scale surface roughness, and a wide variety of terrains in South Asia was selected. A significant influence of several topographic parameters i.e., surface slopes and curvatures was observed. This triggered our study of the sensitivity of T E and Γ to SMC and topographic wetness index ( T W I ). Regional scale results showed that T E and Γ are strongly correlated with the T W I , while the sensitivity to SMC was almost negligible. The Pearson correlation coefficients of T E and Γ with T W I are r Γ ~ 0.59 and r T E ~−0.63 at θ e ~ [20, 30] ° and r Γ ~ 0.48 and r T E ~ −0.50 at θ e ~ [80, 90] °, respectively.
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Wilson, John P., Damian J. Spangrud, Gerald A. Nielsen, Jeffrey S. Jacobsen, and David A. Tyler. "Global Positioning System Sampling Intensity and Pattern Effects on Computed Topographic Attributes." Soil Science Society of America Journal 62, no. 5 (September 1998): 1410–17. http://dx.doi.org/10.2136/sssaj1998.03615995006200050038x.
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Sevruk, B., and K. Mieglitz. "The effect of topography, season and weather situation on daily precipitation gradients in 60 Swiss valleys." Water Science and Technology 45, no. 2 (January 1, 2002): 41–48. http://dx.doi.org/10.2166/wst.2002.0025.
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Daily precipitation in the Swiss valleys decreases frequently with altitude, particularly in southern Switzerland. Only one-third of precipitation days show positive precipitation gradients with a fairly strong correlation of precipitation with altitude (R2≥0.5). Generally, precipitation gradients are larger in the north than in the south but there are large differences among valleys situated near to each other. The effects of precipitation amount, weather situation, region and season, wind speed and topography were not very significant at all. It seems that the positioning of the upper and lower precipitation gauges under specific topographic and climate conditions can affect the precipitation gradients in a particular valley.
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Scambos, Ted A., Nadine A. Nereson, and Mark A. Fahnestock. "Detailed topography of Roosevelt Island and Siple Dome, West Antarctica." Annals of Glaciology 27 (1998): 61–67. http://dx.doi.org/10.3189/1998aog27-1-61-67.
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Detailed surface topography is presented for two dome features of the West Antarctic ice sheet, Siple Dome and Roosevelt Island. Both these domes show linear topographic features, or “scars”, on [heir flanks. Topography is determined from a combination of existing digital elevation models (DEMs; based on satellite radar altimctry), photoclinomctry (using advanced very high-resolution radiometer images to quantitatively infer topographic details) and, in the case of Siple Dome, surface global positioning system topographic profiles. The enhanced DEMs provide heights and shapes for a variety of surface features in the vicinity of the domes, such as scars, surface undulations, ice rises and the domes themselves. The DEMs indicate that the scar features on both domes are high relative to adjacent rapid-ice-llow areas. Scars and other related morphologic features on the flanks of both domes can be interpreted as former active ice streams and stream margins. For Siple Dome, this interpretation is confirmed by radar profiling. The evolution of the topographic height of the scars is a combination of two processes: initial elevation rise due to a positive mass balance at the shear margin in the immediate aftermath of shut-down of the ice stream; and later downslope flow as the scars become part of the dome and the dome surface velocity field. Superimposed on these events is accumulation, which buries the original shear margin but elevates the scar surface expression. Depending upon the timing of shut-flown, and the relative magnitude of these processes, the height of the scars above the current rapidly flowing surfaces may be indicative of ice-sheet thinning since shut-down, or dome expansion across former ice-stream trunks in a more or less steady-state ice sheet.
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Barliba, Livia Luminita, Costel Barliba, and Adrian Smuleac. "Topographical survey work and stake out of an agroindustrial building from Periam village, Timis county." Bulletin of University of Agricultural Sciences and Veterinary Medicine Cluj-Napoca. Horticulture 73, no. 2 (November 30, 2016): 299. http://dx.doi.org/10.15835/buasvmcn-hort:12274.
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The main objective of the project was to achieve a topographic survey works and mapping of an agro-purpose storage for vegetables and fruits produced by the existing farms from the village.The work theme includes achieving of cadastral plans base on a 1/5000 scale, using measurements for all studied locations and land cadastre units. GPS technology used in thickening RGNS, namely the determination of network support, lead to the lifting of all topographical stake out of the contour points. (Bârliba Luminiţa Livia, et. all.,2004),After that, the points were used as starting points for execution the tracing of the surface construction with the support of a total station.For topographical survey was used a V82 South GNSS receiver with two frequencies and 7 channels which allows RTK positioning in real time and then it was used permanent topographic station nearby Timisoara (TIM1.2.3). After overlapping the situation plan and plan developed by an architect, it was made the stake out of industrial building’s foundation with Leica Total Station 1205+, through the dedicated "Stakeout" software.Topographical works generally pursue two base objectives: the topographical survey completed by a digital representation of a small land area and staking out the construction building respectively implementing the projects on the ground (Bârliba Luminiţa Livia, et. all.,2005). This paper demonstrated that it is possible to achieve the optimal time of all field and office operations with precision and accuracy parameters required by the topographical laws and rules.
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Herbei, Mihai Valentin, Roxana Claudia Herbei, and Larisa Ofelia Filip. "Spatial Representation of Useful Minerals Deposits." Mining Revue 27, no. 2 (June 1, 2021): 84–92. http://dx.doi.org/10.2478/minrv-2021-0019.
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Abstract Starting from the fact that in the mining industry and in general in the field of underground constructions, the topographic activity, regardless of which of its manifestations, conditions and substantiates the achievement of economic and technological objectives, implicitly resulting in the dependence between topographic precision and qualitative and quantitative performance of mining. The level at which the professional responsibility of the topographic activity, as a whole is engaged in the achievement of some proposed objectives, depends on the framework resulting from the technological complexity of the mining activity in the conditions of its restructuring and efficiency. Spatial representations of useful mineral deposits in the earth's crust, which meet the quality conditions necessary for the design of underground mining works, can be used to choose the most efficient methods of opening, preparation and exploitation of useful mineral deposits. These analyzes are the basis for the realization of underground topographic networks that have a precise connection with the topographic base at the surface. The use of stereographic projection and stereographic networks can be achieved by faithfully representing the tectonics and positioning of deposits of useful mineral matter inside the earth's crust.
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Nawaz, Asif, Huang Zhiqiu, Wang Senzhang, Yasir Hussain, Amara Naseer, Muhammad Izhar, and Zaheer Khan. "Mode Inference using enhanced Segmentation and Pre-processing on raw Global Positioning System data." Measurement and Control 53, no. 7-8 (May 27, 2020): 1144–58. http://dx.doi.org/10.1177/0020294020918324.
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Many applications use the Global Positioning System data that provide rich context information for multiple purposes. Easier availability and access of Global Positioning System data can facilitate various mobile applications, and one of such applications is to infer the mobility of a user. Most existing works for inferring users’ transportation modes need the combination of Global Positioning System data and other types of data such as accelerometer and Global System for Mobile Communications. However, the dependency of the applications to use data sources other than the Global Positioning System makes the use of application difficult if peer data source is not available. In this paper, we introduce a new generic framework for the inference of transportation mode by only using the Global Positioning System data. Our contribution is threefold. First, we propose a new method for Global Positioning System trajectory data preprocessing using grid probability distribution function. Second, we introduce an algorithm for the change point–based trajectory segmentation, to more effectively identify the single-mode segments from Global Positioning System trajectories. Third, we introduce new statistical-based topographic features that are more discriminative for transportation mode detection. Through extensive evaluation on the large trajectory data GeoLife, our approach shows significant performance improvement in terms of accuracy over state-of-the-art baseline models.
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Ribeiro, Roberto de Figueiredo. "Measuring distance through topographic models." Abstracts of the ICA 1 (July 15, 2019): 1. http://dx.doi.org/10.5194/ica-abs-1-313-2019.
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<p><strong>Abstract.</strong> Accurate measurement of distances is of paramount importance to transportation infrastructure planning. Be it for estimating travel time, locating accidents and hazards through road markers, planning maintenance services, or setting prices for building contracts, distance is the primary metric upon which all aspects of the job are based, given that transportation infrastructure deals mostly with linear features. Yet, countries with older infrastructure often don’t know for how long their networks run &ndash; especially so in case of developing countries. Brazil currently has over 2640000&thinsp;km of roads, with construction documentation lacking for most of the network. The most used method for generating distance measurements, the car odometer from driving between two points, while apt for doing macro-regional planning, is unfit for large-scale engineering work, as this study shows below.</p><p>The industry standard for measuring distances uses a precision odometer connected to specialized tires, used either on their own or as a “fifth wheel” on a vehicle. Such method, however, is laborious and slow, and only generates a scalar between two points, with any new distance necessitating a new measurement, even if the two sets share a common space, or if one distance is a subset of the other. This paper proposes the usage of systematic mapping techniques to generate topographic linear features with measuring information, from which any distance can be calculated. To generate these features, first a linear path is constructed in GIS software over a route. The height information of each node in the path is then extracted from a source, and then the topographic distance is calculated from the vertical profile. Finally, an M coordinate is generated for each node.</p><p>For comparison between sources, a base path was used as ground truth. This path was constructed from a GNSS survey along the road, collected on cinematic mode at 10Hz (1.1&thinsp;m gap between points), and post-processed with fixed-phase relative positioning tied to a base station. The mean positional quality achieved was 2.5 cm of planimetric, and 4.3&thinsp;cm of altimetric precision. Two other sources of height information were used for comparison, one a flight DTM with 33&thinsp;cm LE90 and 1 m of cell size, and the NASA 1 Arc-second SRTM with a nominal 9&thinsp;m LE90 and 30&thinsp;m cell size. Furthermore, a planimetric distance using a navigational GPS device (C/A code only) was also calculated. Two highways were selected for testing, and divided into 341 segments of 200 meters each, to account for the influence of slope in the calculations.</p><p>As expected, the flight DTM came the closest to the base model, deviating from it at an average of 31.95&thinsp;ppm, with 2.8&thinsp;ppm of standard error. It is, however, the most expensive and time-consuming method. The SRTM deviated an average of 5131.53&thinsp;ppm and showed very high variation, with 8481.96&thinsp;ppm of standard error. The navigation GPS deviated at an average of 685.18 ppm, with 633.11&thinsp;ppm of standard error. Both the SRTM and GPS appear to deviate further from the base model as slope increases, but given that few segments with over 2.5&deg; of slope were present in the sample, a correlation could not yet be established. For comparison, the average of the car odometer method was 16654.51 ppm, with a standard error of 22661.69&thinsp;ppm.</p><p> Given its high deviation, the SRTM is unfit for precision work, but is a big improvement over using the car odometer for general indications. Further studies with mid-range DTMs should be done to provide a remote sensing alternative. The handheld GPS had better results than expected, given its nominal precision of 15&thinsp;m. Despite a probable larger absolute positioning error, its relative error distribution remained steady enough to allow a good distance measurement.</p>
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Projovic, Damir. "Application of relative positioning in topographic survey preparations on a full basis in artillery." Vojnotehnicki glasnik 65, no. 1 (2017): 125–39. http://dx.doi.org/10.5937/vojtehg65-8061.
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Yao, Jin, Yi Chao-lu, and Fu Ping. "Evaluation of the Accuracy of SRTM3 and ASTER GDEM in the Tibetan Plateau Mountain Ranges." E3S Web of Conferences 206 (2020): 01027. http://dx.doi.org/10.1051/e3sconf/202020601027.
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Topographic data on The Tibetan Plateau (TP) terrain are fundamental for geoscientific research, but are difficult to obtain. The Shuttle Radar Topographic Mission (SRTM) Digital Elevation Model (DEM) and the Advanced Spaceborne Thermal Emission and Reflection Radiometer Global Digital Elevation Model (ASTER GDEM) are two commonly used GDEM data. Verifying the accuracy of the two dataset for the TP mountain areas provides a reference point for the application of both DEMs. For evaluating the elevation accuracy and topographic information, we used 8242 field measurements from Differential Global Positioning System (DGPS) points and DEM data generated from 1:100,000 topographic maps to examine the accuracy of ASTER GDEM V2 and SRTM3 V4.1 elevation results. The average RMSE for elevation differences between DGPS and ASTER GDEM across the study areas was 18.56m while the average RMSE between DGPS and SRTM3 was 10.39m. The average RMSEs of ASTER GDEM and SRTM3 in glaciated areas were 8.55m and 5.87m, respectively. The vertical accuracy of SRTM3 is better than that of ASTER GDEM. The vertical accuracy of both DEMs do not vary with altitude, but is related to aspect and slope.
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Fadda, S., M. Fiori, and C. Matzuzzi. "Use of Global Positioning System in mine landscaping and visual impact assessment: A case study." Journal of Nepal Geological Society 34 (October 9, 2006): 129–34. http://dx.doi.org/10.3126/jngs.v34i0.31887.
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The satellite-based Global Positioning System (GPS) needs a clear view of sky for determining a geodetic position and hence it is particularly suitable in overall projects of open-pit recovery and landscape restoration. The purpose of such measurements is to make highly accurate topographic maps thus forming the backbone of a project. In the work presented here geodetic measurements are combined with advanced visualisation techniques and GIS applications in a possible recovery plan of the abandoned excavations of Bonucoro in the mining district of Orani, central Sardinia, Italy. Considering the naturalistic and geographic settings of the mining area and its surroundings, a few proposals concerning the re-utilisation of these excavations are presented. The preparatory work consisted of the area characterisation by carrying out a topographic survey followed by a geodetic control network establishment by the GPS to describe the morphological features of the landscape and for the subsequent three-dimensional analysis and geoprocessing. The final step involved the use of VueInfinite, a computer program capable to integrate graphical data with geological and morphological attributes. It was also able to create a virtual 3D scene of a present, past, or future landscape required for visual impact assessment.
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Li, Ye, Rupeng Wang, Pengyun Chen, Peng Shen, and Yanqing Jiang. "Terrain Matching Positioning Method Based on Node Multi-information Fusion." Journal of Navigation 70, no. 1 (July 8, 2016): 82–100. http://dx.doi.org/10.1017/s0373463316000369.
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Measurement bias and lack of terrain features often cause false peaks during underwater terrain matching positioning, that is, there is more than one peak near the real position. Previous methods to address this problem have increased the number of measurement beams, but this also increases the data processing time and energy consumption. At the same time, the ratio of measured information that is used does not increase. In other words, we should increase the ratio of measured information that is used, not simply increase the amount of information that is measured. Conventional matching algorithms only use the height of nodes without considering surface information, which is composed of height and the position of multiple nodes in three-dimensional space. Multi-beam sonar can obtain the three-dimensional distribution of terrain nodes. This node information is not just a height sequence, as it is used in previous methods. If we consider the nodes as a three-dimensional distribution of points with height and position information, this increases the matching position information and more of the terrain features can be extracted from the same measured data. Hence, in this paper, a terrain positioning method called the Node Multi-information Fusion (NMIF) is presented. This method focuses on improving the stability and accuracy degraded by bias in the Digital Elevation Map (DEM), terrain repeatability, and other factors. First, the concept of a Single Node Data Packet (SNDP) is introduced. The SNDP includes elevation and surface information surrounding the node, such as roughness, gradient, and slope. This additional topographic feature information improves the robustness and accuracy of the system. A computer simulation using actual ocean bottom topography verifies the advantages of the proposed NMIF algorithm.
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Arias-Hernández, Néstor Alonso, Martha Lucía Molina Prado, and Jaime Enrique Meneses Fonseca. "A reconstruction of objets by interferometric profilometry with positioning system of labeled target periodic." DYNA 82, no. 190 (May 11, 2015): 153–59. http://dx.doi.org/10.15446/dyna.v82n190.42616.
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A method to extract 3D information using a white light interferometer without using PZT is presented. Instead a positioning system that uses the phase sensitivity of a target periodic is employed. The image treatment realized on the periodic target permits to calculate the relative distance between Mirau objective and object surface. Topographic reconstructions of objects with dimensions of some tenths of millimeters were calculated with an accuracy of approximately 28 nanometers. Theoretical analysis and experimental results are shown.
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Treitz, P., L. Elliot, and P. Howarth. "Differential Global Positioning System: Potential for Geographical Information System Database Management." Environment and Planning A: Economy and Space 25, no. 6 (June 1993): 883–98. http://dx.doi.org/10.1068/a250883.
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The primary problem for managers of digital topographic data is maintaining an accurate and up-to-date database. Traditional spatial-data-collection techniques and mapping procedures are expensive and, as a result, occur infrequently. However, the NAVSTAR Global Positioning System (GPS) now provides for the collection of timely, cost-effective spatial information. In this study, differential GPS data were collected for an area of rapid rural-to-urban land-use change by using low-cost GPS receivers in static and kinematic modes. These data were then processed for input to a geographic information system and assessed for their positional accuracy. It was found that GPS data collected in static mode and differentially corrected possessed a circular map accuracy standard (CMAS) of 3.62 m. These accuracies meet the requirements of many large-scale and medium-scale mapping programs.
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Xie, Hui, Haoran Wang, Yayi Yang, Yongcan Chen, Jun Yang, Shuang Wang, and Zhaowei Liu. "Analysis of Underwater Topographic Survey of Stilling Basin Based on Unmanned Survey System." Advances in Materials Science and Engineering 2021 (April 1, 2021): 1–15. http://dx.doi.org/10.1155/2021/5514165.
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The combination of Global Positioning System-Real Time Kinematic (GPS-RTK) and depth sounder is an important technical method of modern underwater topographic survey. In this paper, the combined technology was integrated with unmanned surface vehicle (USV) technology to construct an unmanned survey system suitable for underwater topographic survey in stilling basin, and it was applied to survey the underwater topography of the stilling basin of Tingzikou hydrojunction project. Based on the surveying and mapping data and 3D model, the trend of elevation change of the stilling basin including apron, end sill, antiscour section, and river convergence section was analyzed. The results show that, for the surface outlet stilling basin of Tingzikou, after flood, the structure is complete, the boundaries are clear, the water quality is good, and there is little sediment on the surface of apron from overflow dam section to end sill. Furthermore, no obvious sediment or structural abnormality has been found in the still basin. Affected by the bedrock and cofferdam cobble gravel sediment, the elevation of the antiscour section and the downstream convergence section of the surface outlet stilling basin increased significantly. For the bottom outlet stilling basin of Tingzikou, there is large sediment within a range of 20 m∼40 m from the bottom sill and the maximum height of it reaches 2.04 m, while there is no obvious sediment or structural abnormality in the remaining region of basin. The critical sedimentation height can effectively judge the safety grade of the sedimentation height in stilling basin and provide a reliable support for assessing the overall safety of stilling basin. The application of unmanned survey technology improves the accuracy and timeliness of underwater topography and sedimentation distribution of stilling basin, which has significant application research value and promotion significance.
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Shanurov, G. A., and A. D. Manilova. "Mobile scanning complex positioning accuracy depending on the coordinate systems used." Geodesy and Cartography 919, no. 1 (February 20, 2017): 13–17. http://dx.doi.org/10.22389/0016-7126-2017-919-1-13-17.
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Inertial coordinate system and geodetic (terrestrial) coordinate system are used in processing of results of topographic survey, carried out with a mobile scanning complex. Mobile scanning complex geodetic coordinates, in turn, are presented in geodetic three-dimensional rectangular coordinate system form, in geodetic ellipsoidal coordinate system form and in the form of coordinates on a geodetic projection plane. The results of research, carried out earlier [4–7], suggest that the coordinate transformation on large areas distorts geodetic points coordinates. The article presents the results of similar investigations, but applied to a local area, limited by a mobile scanning complex surveying area. The accuracy of the mobile scanning complex coordinates is characterized by the mobile scanning complex coordinates errors cofactor matrix. It turned out that the local site sequential coordinate transformation procedure from one coordinate system to another coordinate system does not introduce any distortion into the mobile scanning complex coordinates.
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Oliveira, Cleber G. de, and Waldir R. Paradella. "Evaluating the quality of the Digital Elevation Models produced from ASTER stereoscopy for topographic mapping in the Brazilian Amazon Region." Anais da Academia Brasileira de Ciências 81, no. 2 (June 2009): 217–25. http://dx.doi.org/10.1590/s0001-37652009000200008.
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Brazilian Amazon is a vast territory rich in natural renewable and non-renewable resources. Due to the adverse environmental condition (rain, cloud, dense vegetation) and difficult access, topographic information is still poor, and when available needs to be up-dated or remapped. In this paper, the feasibility of using elevation generated from orbital ASTER- stereo-pairs images for topographic mapping was investigated for the mountainous relief in the Serra dos Carajás, Pará. The quality of information derived from these optical images was evaluated regarding field altimetric measurements. Precise topographic field information acquired from Global Positioning System (GPS) was used as Ground Control Points (GCPs) for the modeling of the stereoscopic Digital Elevation Models (DEMs) and as Independent Check Points (ICPs) for the calculation of elevation accuracies. The analysis was performed following two approaches: (1) the use of Root Mean Square Error (RMSE) and (2) calculations of trend analysis and accuracy. The investigation has shown that the altimetric accuracy from ASTER fulfilled the Brazilian Map Accuracy Standards elevation requirements for 1:100,000 A Class. In addition, ASTER can provide up-dated planimetric information that is also necessary for cartographic production. Thus, when the environment condition allows the acquisition of stereo-pairs, the use of ASTER can be considered an alternative for semi-detailed topographic mapping in similar environments of the Brazilian Amazon.
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Zhang, Guo, Kai Xu, Peng Jia, Xiaoyun Hao, and Deren Li. "Integrating Stereo Images and Laser Altimeter Data of the ZY3-02 Satellite for Improved Earth Topographic Modeling." Remote Sensing 11, no. 20 (October 22, 2019): 2453. http://dx.doi.org/10.3390/rs11202453.
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The positioning accuracy is critical for satellite-based topographic modeling in cases of exterior orientation parameters with high uncertainty and scarce ground control data. The integration of multi-sensor data can help to ensure precision topographical modeling in such situations. Presently, research on the combined processing of optical camera images and laser altimeter data has focused on planetary observations, especially on the Moon and Mars. This study presents an endeavor to establish a combined adjustment model with one constraint in image space for integration of ZY3-02 stereo images and laser altimeter data for improved Earth topographic modeling. The geometric models for stereo images and laser altimeter data were built first, and then, the laser ranging information was introduced to construct a combined adjustment model on the basis of the block adjustment model. One constraint that minimized the back-projection discrepancies in image space was incorporated into the combined adjustment. Datasets in several areas were collected as experimental data for the validation work. Experimental results demonstrated that the inconsistencies between stereo images and laser altimeter data for the ZY3-02 satellite can be reduced, and the elevation accuracy of stereo images can be significantly improved after applying the proposed combined adjustment. Experiments further proved that the improved height accuracy is insensitive to the number and relative position of laser altimeter points (LAPs) in stereo images. Moreover, additional plane control points (PCPs) were incorporated to achieve better planimetric accuracy. Experimental results in the Dengfeng area showed that the adjustment results derived by using LAPs and additional four PCPs were only slightly lower than those for the block adjustment with four ground control points (GCPs). Generally, the proposed approach can effectively improve the quality of Earth topographic model.
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Vieira, Gonçalo Teles, Miguel Ramos, and Jorge Gárate. "Detailed geomorphological mapping with Kinematic GPS. Examples from Livingston Island, Antarctic." Estudos do Quaternário / Quaternary Studies, no. 4 (December 26, 2001): 35–42. http://dx.doi.org/10.30893/eq.v0i4.35.
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The detailed geomorphological mapping of landforms and deposits is widespread in Quaternary geomorphology studies. It consists on the precise representation of the spatial position of geomorphological information and their characterization (e.g. topography, hydrology, morphometry, morphography, morphogenesis,morphochronology and morphodynamics) in large-scale maps (usually 1:5,000 to 1:25,000).The data is collectcd using both remote sensing (aerial photo interpretation, satellite images, etc.) and detailed field surveys. However, in areas without topographic maps, or where the scale of the existing is too small, it becomes very difficult, or even impossible to make a detailed geomorphological survey. But even in areas with good topographic data, the precise location of small or very irregular landforms and deposits is frequently difficult. The recent development of high precision GPS (Global Positioning System) allows the cartographic produclion with an accuracy that could only be achieved using traditional geodetic surveys. The main advantage is the much raster working procedure and direct data storage in a digital format. The later can easily be integrated in a Geographical lnlormation System. The installation of a Kynematic GPS in the Spanish Antartic Station (Livingston Island, South Shetlands) in the Austral summer of 1999-2000, made its use possible in the framework of the geomorphological survey that was being conducted at lhe time. ln this paper the application of the Kynematic GPS system is explained and two examples of detailed geomorphological maps at the scale 1:5,000 produced using this technique are presented.
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Lu, Y. H., and J. Y. Han. "GNSS SATELLITE VISIBILITY ANALYSIS BASED ON 3D SPATIAL INFORMATION IN URBAN AREAS." ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLIII-B4-2020 (August 24, 2020): 123–28. http://dx.doi.org/10.5194/isprs-archives-xliii-b4-2020-123-2020.
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Abstract. Global Navigation Satellite System (GNSS) is a matured modern technique for spatial data acquisition. Its performance has a great correlation with GNSS receiver position. However, high-density building in urban areas causes signal obstructions and thus hinders GNSS’s serviceability. Consequently, GNSS positioning is weakened in urban areas, so deriving proper improvement resolutions is a necessity. Because topographic effects are considered the main factor that directly block signal transmission between satellites and receivers, this study integrated aerial borne LiDAR point clouds and a 2D building boundary map to provide reliable 3D spatial information to analyze topographic effects. Using such vector data not only reflected high-quality GNSS satellite visibility calculations, but also significantly reduced data amount and processing time. A signal obstruction analysis technique and optimized computational algorithm were also introduced. In conclusion, this paper proposes using superimposed column method to analyze GNSS receivers’ surrounding environments and thus improve GNSS satellite visibility predictions in an efficient and reliable manner.
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Zuo, C., X. Xiao, Q. Hou, and B. Li. "BLOCK ADJUSTMENT AND IMAGE MATCHING OF WORLDVIEW-3 STEREO PAIRS AND ACCURACY EVALUATION." ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLII-3 (May 2, 2018): 2473–77. http://dx.doi.org/10.5194/isprs-archives-xlii-3-2473-2018.
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WorldView-3, as a high-resolution commercial earth observation satellite, which is launched by Digital Global, provides panchromatic imagery of 0.31&thinsp;m resolution. The positioning accuracy is less than 3.5 meter CE90 without ground control, which can use for large scale topographic mapping. This paper presented the block adjustment for WorldView-3 based on RPC model and achieved the accuracy of 1&thinsp;:&thinsp;2000 scale topographic mapping with few control points. On the base of stereo orientation result, this paper applied two kinds of image matching algorithm for DSM extraction: LQM and SGM. Finally, this paper compared the accuracy of the point cloud generated by the two image matching methods with the reference data which was acquired by an airborne laser scanner.<br> The results showed that the RPC adjustment model of WorldView-3 image with small number of GCPs could satisfy the requirement of Chinese Surveying and Mapping regulations for 1&thinsp;:&thinsp;2000 scale topographic maps. And the point cloud result obtained through WorldView-3 stereo image matching had higher elevation accuracy, the RMS error of elevation for bare ground area is 0.45&thinsp;m, while for buildings the accuracy can almost reach 1 meter.
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Sarti, Jefferson Kran, Priscilla Rayanne e. Silva Noll, Daise Fernanda Santos Souza Escobar, Sheila Oliveira Feitosa, Dhecyeny Alves Ferreira, and Matias Noll. "Repeatability and reproducibility of a topographic system to evaluate the spine." Research, Society and Development 10, no. 11 (September 7, 2021): e494101119356. http://dx.doi.org/10.33448/rsd-v10i11.19356.
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Objective: This study aimed to determine the repeatability and reproducibility of a topographic system for evaluating the spine in students. Methods: Thirty-seven students participated in this study. Participants were positioned with their backs facing the system, in orthostatic posture, with bare backs. The spinous processes of the seventh cervical vertebra (C7) and second sacral vertebra (S2), and the right and left posterior superior iliac spine (PSIS) were marked. Each student was evaluated five times, once on the first day and four times on the second day. The following variables were used for evaluation: kyphosis angle, lordosis angle, trunk length, and anterior and lateral perturbations. SPSS 17.0 (IBM, Armont, NY, USA) was used for performing statistical analyses, which included descriptive analysis, Intraclass Correlation Coefficient (ICC), and one-way ANOVA, with a significance level of 0.05. Results: topographic system showed excellent values, and a positive correlation was observed with reference to the ICC of reproducibility and repeatability for all analyzed variables. Conclusion: These results show that this system can be used to diagnose postural changes, and to estimate thoracic kyphosis and lumbar lordosis angles. It can also be used for providing additional information on the positioning of the surface of the back.
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Wang, De Bao, Jun Feng Qu, Xue Ling Fang, and Mei Lan Yu. "Key Technology Discussion on Surveying and Mapping 1:1000 Photogrammetric Digital Topographic Map of Laicheng Industrial Zone in Laiwu City." Advanced Materials Research 846-847 (November 2013): 1166–70. http://dx.doi.org/10.4028/www.scientific.net/amr.846-847.1166.
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Taking use of VirtuoZos digital photogrametric workstations of Supresoft Inc., employing full digital aerophotogrammetric mapping method, according to existing aerial photographic image database, at the foundation of basic control survey, we carry out aerial photographic control survey, surveying and mapping with pile point method, digital aerotriangulation and full digital stereocompilation. When taking 1:1000 topographic map obtained by indoor edition to field work for compration, supplement and regulation, we mainly aim at the following purposes: determining the nature and quantity as well as filling vacancy for ground and land features obtained by indoor stereocompilation; positioning for habitation, wall and railing, incompletely surveyed, drop shadow-covered and trees-obstructed ground features, as well as newly-added planimetric features after aerial photogrammetry; especially measuring the solid width of a house to centimeter and making eaves correction after measuring the length of a house when needed; correcting the geomatric positioning relationand of ground features according to their solid shape and fairly drawing them in the map; afterwards, we carry out graphic edition again during indoor work. Only in this way can we guarantee the horizontal and vertical accuracy of large scale photogrammetric mapping.
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Kuznetsov, A. A., A. M. Porshakov, A. N. Matrosov, E. V. Kuklev, V. B. Korotkov, V. M. Mezentsev, N. V. Popov, V. P. Toporkov, A. V. Toporkov, and V. V. Kutyrev. "Prospects of GIS-Passportization of Natural Plague Foci in the Territory of the Russian Federation." Problems of Particularly Dangerous Infections, no. 1(111) (February 20, 2012): 48–53. http://dx.doi.org/10.21055/0370-1069-2012-1(111)-48-53.
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Characterized in brief are the results of natural plague foci passportization carried out in the late XX century. Evaluation of the principle of formalized spatial differentiation between enzootic territories is made. The principle can guarantee high degree of data ordering, obtained in the process of epizootiological surveillance. Therefore, prospects of a new stage of plague foci passportization based on GIS-technologies are viewed, the strategy is determined, and methodological approaches for its realization are put forward. Large-scale implementation of digital topographic maps and global positioning system into the work of plague control organizations is accentuated.
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Le Corre, Mathieu, Jonathan Gula, and Anne-Marie Tréguier. "Barotropic vorticity balance of the North Atlantic subpolar gyre in an eddy-resolving model." Ocean Science 16, no. 2 (April 20, 2020): 451–68. http://dx.doi.org/10.5194/os-16-451-2020.
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Abstract. The circulation in the North Atlantic subpolar gyre is complex and strongly influenced by the topography. The gyre dynamics are traditionally understood as the result of a topographic Sverdrup balance, which corresponds to a first-order balance between the planetary vorticity advection, the bottom pressure torque, and the wind stress curl. However, these dynamics have been studied mostly with non-eddy-resolving models and a crude representation of the bottom topography. Here we revisit the barotropic vorticity balance of the North Atlantic subpolar gyre using a new eddy-resolving simulation (with a grid space of ≈2 km) with topography-following vertical coordinates to better represent the mesoscale turbulence and flow–topography interactions. Our findings highlight that, locally, there is a first-order balance between the bottom pressure torque and the nonlinear terms, albeit with a high degree of cancellation between them. However, balances integrated over different regions of the gyre – shelf, slope, and interior – still highlight the important role played by nonlinearities and bottom drag curls. In particular, the Sverdrup balance cannot describe the dynamics in the interior of the gyre. The main sources of cyclonic vorticity are nonlinear terms due to eddies generated along eastern boundary currents and time-mean nonlinear terms in the northwest corner. Our results suggest that a good representation of the mesoscale activity and a good positioning of mean currents are two important conditions for a better representation of the circulation in the North Atlantic subpolar gyre.
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Pruitt, Russell F., Ronald F. Sing, C. W. Austin, and W. Joseph Messick. "57. Feasibility of the Global Positioning Satellite System for Rural Aeromedical Transport." Prehospital and Disaster Medicine 11, S2 (September 1996): S44. http://dx.doi.org/10.1017/s1049023x00045945.
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Aeromedical navigation to the scene of an accident using navigational assistance computer mapping software (NACM) can be difficult in rural areas due to the lack of topographic landmarks. In these instances, navigation is made easier using the Global Positioning Satellite (GPS) system to determine latitude and longitude.Purpose: To determine the reliability and feasibility of portable GPS receivers compared with our current system of NACM (MAP EXPERT®) in the navigation of aeromedical transport flights.Design: A non-randomized prospective trial comparing flights using either GPS or NACM. Setting: Flight program at a Level I trauma center.Methods: GPS receivers (for transmitting location) were carried by half the helicopters and ground EMS units. The NACM system was used to transmit the location of the accident to the other flights. Data on flight time, distance, and accident location were collected. Pilots and EMS personnel using the portable GPS system completed a questionnaire regarding accuracy, reliability, and ease of use.Results: This study included 51 flights; GPS (n = 26) and NACM (n = 25). There was no difference in the miles flown per minute in the NACM group (1.69 miles/minute) compared with the GPS group (1.70 miles/minute). Pilots and EMS personnel rated the GPS reliable, accurate, and easy to use for navigation.
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Garrido, Ma Selmira, Elena Gimenez, Ma Clara de Lacy, and Antonio J. Gil. "Quality Analysis of NRTK Positioning on Boundary Regions and Under Unfavorable Topographic Conditions in the Southern Iberian Peninsula." IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing 6, no. 6 (December 2013): 2364–74. http://dx.doi.org/10.1109/jstars.2013.2251865.
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Hoque, Ashabul, Dipankar Kumar, Anip Kumar Paul, Masudar Rahman, Gour Chandra Paul, and Shin Ichi Aoki. "Sedimentation in Dune Forests, Mangrove Forests and CC Block System and Associated Topographic Changes." Journal of Bangladesh Academy of Sciences 43, no. 1 (July 16, 2019): 67–78. http://dx.doi.org/10.3329/jbas.v43i1.42235.
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This paper is concerned with the deposition of sediment due to dune forests (Nakatajima dune, Japan) and CC block system on a riverbank (Padma, Bangladesh). Measurements of sediment deposition were carried out at Nakatajima dune, Japan and at Padma riverbank, Rajshahi, Bangladesh using Global Positioning System (GPS). 2442 m3 sediment migrates each year to the East side of Nakatajima dune by wind and the edge of the dune develops about 6-7 m/year due to the existence of forests. Sedimentation rate is also greater in shallower mangrove areas. The trapped sediment height varies from 8.0 to 10.0 cm in the mangrove-lined bank. Mangrove forests help to trap 25% more sedimentation at low tide than at high tide. On the other hand, only for setting up the CC block and groynes along the bank, the sedimentation rate is observed almost twice than that of the previous year. An analysis shows that there is a similarity of sedimentation among dune, beach forests, mangrove forests and CC blocks.
Journal of Bangladesh Academy of Sciences, Vol. 43, No. 1, 67-78, 2019
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Varfolomeev, A. F., E. A. Kovalenko, V. F. Manukhov, and O. V. Syromyatnikova. "Design works at creating geodetic control grids using GIS-technologies." Geodesy and Cartography 945, no. 3 (April 20, 2019): 20–25. http://dx.doi.org/10.22389/0016-7126-2019-945-3-20-25.
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During the last decades Geodesy and other Earth Sciences have undergone revolutionary changes concerning the use of Global Positioning Systems. Currently, traditional geodetic and topographic technologies are giving way to high-precision, productive and all-weather space systems. In 1995 the Federal Service of Geodesy and Cartography approved “the Concept of transiting topographic and geodetic production to autonomous methods of satellite coordinate definitions”. The transition to new technologies entails restructuring not only the methods of determining the coordinates, but also the stages of pre-design and design work. Currently, there has been intensive penetration of geoinformation technologies into sciences related to the analysis and processing spatially coordinated data, and geodetic data in particular. Specialized software products are developed but they are quite expensive and difficult for mastering. The authors describe the opportunities of using standard geographic information systems (for example, GIS ArcView V. 3.1) in the view of their spatial orientation for the analysis and optimal selection of the points of the initial geodetic framework and effective implementation of the complex of geodetic works, in order to accurately determine the coordinates of the points of the created geodetic reference network.
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Pourghasemi, Hamid, Amiya Gayen, Sungjae Park, Chang-Wook Lee, and Saro Lee. "Assessment of Landslide-Prone Areas and Their Zonation Using Logistic Regression, LogitBoost, and NaïveBayes Machine-Learning Algorithms." Sustainability 10, no. 10 (October 15, 2018): 3697. http://dx.doi.org/10.3390/su10103697.
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The occurrence of landslide in the hilly region of South Korea is a matter of serious concern. This study tries to produce landslide susceptibility maps for Jumunjin Country in South Korea. Three machine learning algorithms, namely Logistic Regression (LR), LogitBoost (LB), and NaïveBayes (NB) are used, and their final model outcomes are compared to each other. Firstly, a landslide inventory map and the associated input data layers of the landslide conditioning factors were developed based on field verification, historical records, and high-resolution remote-sensing data in the geographic information system (GIS) environment. Seventeen landslide conditioning factors were prepared, including aspect, slope, altitude, maximum curvature, profile curvature, topographic wetness index (TWI), topographic positioning index (TPI), distance from fault, convexity, forest type, forest diameter, forest density, land use/land cover, lithology, soil, flow accumulation, and mid slope position. The result showed that the area under the curve (AUC) values of LR, LB, and NB models were 84.2%, 70.7%, and 85.2%, respectively. The results revealed that the LR and LB models produced reasonable accuracy than respect to NB model in landslide susceptibility assessment. The final susceptibility maps would be useful for preliminary land-use planning and hazard mitigation purpose.
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Capra, A., R. Cefalo, S. Gandolfi, G. Manzoni, I. E. Tabacco, and L. Vittuari. "Surface topography of Dome Concordia (Antarctica) from kinematic interferential GPS and bedrock topography." Annals of Glaciology 30 (2000): 42–46. http://dx.doi.org/10.3189/172756400781820606.
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AbstractA new plano-altimetric map of the Dome Concordia (Dome C) area was drawn up from 1995/96 kinematic double-frequency global-positioning-system (GPS) data of two different projects, as well as static GPS data from a geodetic net for deformation analysis and ice-flow velocity measurements covering an area of about 2000 km2.The GPS surveys were carried out for EPICA during the 10th and 11th Italian Expeditions to choose the optimal location for deep ice-core drilling at Dome C. The accuracy of the kinematic survey was tested by analysing the height-value differences at intersections between different profiles; values ranged from 50–150 mm.The new map was compared with the 1993 kinematic interferential GPS data and residuals between the 1993 and 1995 data were calculated. The surface topographic values were used to calculate the elevation of the Dome C area bedrock, obtained from the reference ground-based and airborne radio-echo-sounding surveys.
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Prather, Timothy S., and Robert H. Callihan. "Weed Eradication Using Geographic Information Systems." Weed Technology 7, no. 1 (March 1993): 265–69. http://dx.doi.org/10.1017/s0890037x00037246.
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A Geographic Information System (GIS) was developed to evaluate its utility in an eradication program of common crupina. Infested areas were recorded in the GIS along with information normally found on United States Geological Survey topographic maps. Infested areas were separated into management areas according to possible treatment method and special environmental or health requirements such as proximity to streams or inhabited buildings. The location, size, and type of each management area were recorded in the database. The database was constructed to maintain treatment and efficacy data for tracking the process of eradication for each infestation. Areas were identified for detection surveying, including coordinates for navigating with a global positioning system (GPS).
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Sevruk, B., and M. Nevenic. "The geography and topography effects on the areal pattern of precipitation in a small prealpine basin." Water Science and Technology 37, no. 11 (June 1, 1998): 168–70. http://dx.doi.org/10.2166/wst.1998.0460.
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Analysis of altitudinal dependency of corrected summer season, June-September, precipitation data from 61 gauges shows that precipitation in the valley and on the leeward slopes of a small, rugged prealpine basin, 13 km2 in area, is greater than that on windward slopes. This indicates that (i) the redistribution of precipitation by wind can play a significant role in the spatial distribution of precipitation in mountainous areas, (ii) the use of exclusive valley positioning of gauges which is the common practice in the mountains can overestimate the precipitation on slopes and (iii) the results of studies of effects of geographic and topographic variables on the precipitation in the mountain are biased and rather network specific than physically based, and considerably depend on the general strategy of the network design including the gauge type and positioning of gauge sites. The corrections of wind-induced error were based on comparisons of precipitation from paired ground level gauges and elevated gauges. Such pairs have been situated under different exposure conditions. The corrections included also wetting and evaporation error, and amounted from 5 to 15% depending on the gauge type and site altitude, exposure and insulation.
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Gucevic, Jelena, Vukan Ogrizovic, Olivera Vasovic, and Sinisa Delcev. "Staking-out projected boundaries of natural property Vrsac Mountains using the RTK GPS/glonass method." Glasnik Srpskog geografskog drustva 92, no. 4 (2012): 79–98. http://dx.doi.org/10.2298/gsgd1204079g.
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The existing topographic and cadastral maps of the former Yugoslav republics are in Gauss-Kr?ger projection on Bessel ellipsoid. For the collected GPS data to comply with the existing cartographic material, it is necessary to provide the transformation parameters from WGS84 to Bessel ellipsoid and according to the principles of cartographic mapping, to make mappings in the plane of the State Coordinate System (SCS). The aim of this research is to present the surveying activities necessary for the establishment and maintenance of digital cartographic basis, which is shown in the test area of ?VRSAC MOUNTAINS?, a Serbian region with outstanding characteristics. In order to establish a connection between the collected data, it is necessary to primarily calculate the parameters of transformation from WGS84 into the SCS. After the vectorisation of projected boundaries from bases made in the SCS, the transformation of vectorised boundary lines from SCS into the WGS84 is carried out, followed by staking the boundaries. To understand the fundamental differences in the methodology of using GPS receivers, it is important to emphasise that the concept of GPS determination of the coordinates is generally divided into absolute and relative positioning. If the correct procedure of GPS positioning, applied to certain environmental conditions, is not followed, the error up to 200 m could be expected. Conclusions are drawn about the selection of staking methods, related to the applied instruments and specific field conditions. The stakeout procedures are given in accordance with the principles of geodetic positioning.
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Pälli, Anja, John C. Moore, Jacek Jania, and Piotr Glowacki. "Glacier changes in southern Spitsbergen, Svalbard,1901–2000." Annals of Glaciology 37 (2003): 219–25. http://dx.doi.org/10.3189/172756403781815573.
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AbstractHigh-resolution ground-penetrating radar surveys at 50 MHz on the polythermal glaciers Hornbreen, Hambergbreen and several surrounding glaciers in southern Spitsbergen, Svalbard, are presented and interpreted. Accurate positioning was obtained using differential global positioning system (DGPS). Digital elevation models (DEMs) of the bedrock and surface were constructed. Comparison of DGPS data and surface DEMs with data from the topographic mappings from 1936 oblique stereoscopic aerial photographs and from Mission Russe in 1899–1901 shows that the Hornbreen and Hambergbreen surfaces are about 60–100 m thinner today in the upper part than at the beginning of the 20th century. Hornbreen has retreated by 13.5 km from the central part of the front, and Hambergbreen by 16 km. All the fronts of the nearby east-coast glaciers in this area have retreated. The bedrock DEM shows that the Hornbreen and Hambergbreen beds lie at –25 to 25 m a.s.l. The combination of sub-sea-level fronts and increasing steepness of the glaciers suggests that the low-lying glaciated valley filled by Hornbreen and Hambergbreen may become a partially inundated ice-free isthmus within perhaps 100 years.
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Mahmood, Sajid, Zulkepli bin Majid, Khairulnizam bin M. Idris, and Muhammad Hamid Chaudhry. "Influence of incident angle and laser footprint on precision and level of detail in terrestrial laser scanner measurements." Geodetski vestnik 65, no. 02 (2021): 260–81. http://dx.doi.org/10.15292/geodetski-vestnik.2022.01.260-281.
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Terrestrial laser scanners (TLS) are used for a variety of applications, e.g., surveying, forestry, cultural heritage preservation, mining, topographic mapping, urban planning, forensics etc. This technology has made a huge shift in 3D spatial data collection due to much faster speed compared to other techniques. In the absence of guiding principles for positioning TLS relative to an object, surveyors collect data at maximum arrangements of scanning geometry elements due to fear of incomplete data of TLS. In 3D spatial data acquisition, positional accuracy and Level of Detail (LOD) are major considerations and are dependent on laser incident angle, footprint size, range and resolution. Mathematical models have been developed relating range, incident angle and laser footprint size for different surface configurations. These models can be used to position TLS to collect data at required positional accuracy and LOD. Models have been verified by deriving one model from other surface models by changing parameters. Effects of incident angle and footprint size have been studied mathematically and experimentally on a natural sloping surface. From the results, surveyors can plan the positioning of the scanner so that data is collected at the required accuracy and LOD.
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Phillips, Helen A., Ian Allison, R. Coleman, G. Hyland, Peter J. Morgan, and N. W. Young. "Comparison of ERS satellite radar altimeter heights with GPS-derived heights on the Amery Ice Shelf, East Antarctica." Annals of Glaciology 27 (1998): 19–24. http://dx.doi.org/10.3189/1998aog27-1-19-24.
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In the spring of 1995 an extensive global positioning system (GPS) survey was carried out on the Amery Ice Shelf, East Antarctica, providing ground-truth ellipsoidal height measurements for the European remote-sensing satellite (ERS) radar altimeters. GPS- and altimeter-derived surface heights have been compared at the intersecting points of the ERS ground tracks and the GPS survey. The mean and rms height difference for all ERS-1 geodetic-phase tracks across the survey region is 0.0 + 0.1 m and 1.7 m, respectively. The spatial distribution of the height differences is highly correlated with surface topographic variations. Comparisons of GPS-derived surface-elevation profiles along ERS ground tracks show that the ERS altimeters can closely follow the GPS representation of the actual surface.
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Ndomba, Preksedis M. "Accuracy of Dem-Based Topographic Data in Flood Inundation Modelling: A Case of Wami River, Tanzania." Tanzania Journal of Engineering and Technology 35, no. 1 (June 30, 2014): 15–35. http://dx.doi.org/10.52339/tjet.v35i1.466.
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The objective of this paper is to evaluate and further comment on the accuracy of the DEM-based topographic data as input in flood modelling. Recent studies have indicated thathydraulic parameters of the modified cross sections based on high resolution DEM aregeometrically and hydraulically similar to the measured ones. In the current study hydraulicmodelling was intended to guide a development project whereby a floodplain protectionembankment is contemplated. Therefore, accuracy in terms of positioning/alignment of naturalfeatures such as river banks and heights/elevations was imperative to attain. In order to achievethese, accuracy of various topographic data sources were qualitatively and/or quantitativelyanalysed before and after hydraulic modelling. As the study river reach is ungauged, thehydraulic model was verified and validated with field observations, readily availableinformation and professional judgement. Based on error analysis, it was found thatuncalibrated 90-m resolution STRM DEM-based topographic data are biased, i.e., 80% of theerror mass is negative. The error increases with elevation. The final input to the hydraulicmodel was a composite/hybrid DEM derived after merging geometric data from fourrepresentative field-measured cross sections, a 2-m interval contour map covering part of theriver valley, and calibrated 90-m resolution DEM. Although, calibration improves the data, itdoes not remove completely the inherent bias. Further to DEM calibration, it was thereforerecommended to include an elevation uncertainty value of -0.5 m, as derived from topographicanalysis, into simulated water surface profiles elevations. The hydraulic model satisfactorilysimulated flood inundation extent after considering the elevation uncertainty. In order toimprove the findings further studies should use adequate measured cross sections and DEM ofhigher resolutions.
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Oliveira, F. R., F. R. Lima, M. J. Silvino, L. F. Pereira, and F. G. G. Dias. "Topography and syntopy of abdominopelvic viscera of the giant anteater (Myrmecophage tridactyla - Linnaeus, 1758)." Arquivo Brasileiro de Medicina Veterinária e Zootecnia 71, no. 6 (December 2019): 1961–67. http://dx.doi.org/10.1590/1678-4162-11124.
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ABSTRACT In view of the scarcity of data about the topography and syntopy of abdominopelvic viscera of the giant anteater (Myrmecophage tridactyla - Linnaeus, 1758), the present study aimed to elucidate these characteristics and to compare them with the other animal species, especially the domestic ones. Three specimens, two males and one female, were donated by the Environmental Military Police of Franca to the Anatomy Veterinary Laboratory of the University of Franca, after death by road killings. The animals were fixed and maintained in aqueous 10% formaldehyde solution, followed by conventional dissection of the abdominopelvic cavities for subsequent direct inspection and topographic description of the viscera, aiming at comparative analyzes with other species, whose positioning and particularities are already established in the literature. It was observed that most of the viscera of these cavities have similar location and syntopy to domestic animals, except for the kidneys and testicles. In view of the established methodology and the results obtained, it is accepted that more specimens of anteater, both genera, should be evaluated and registered scientifically to confirm the data of the current research and anatomical preconization of the abdominopelvic cavity, inasmuch anatomical individual variation are possible between animals of the same species.
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Butler, Andrew R., Kristy L. S. Bly, Heather Harris, Robert M. Inman, Axel Moehrenschlager, Donelle Schwalm, and David S. Jachowski. "Winter movement behavior by swift foxes (Vulpes velox) at the northern edge of their range." Canadian Journal of Zoology 97, no. 10 (October 2019): 922–30. http://dx.doi.org/10.1139/cjz-2018-0272.
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Winter can be a limiting time of year for many temperate species, who must access depressed prey resources to meet energetic demands. The swift fox (Vulpes velox (Say, 1823)) was extirpated from Canada and Montana (USA) by 1969, but was reintroduced in the 1980s to Canada, and subsequently spread into northern Montana. Swift foxes in this region are at the current northern range edge where winter conditions are harsher and persist longer than in their southern range (i.e., Colorado (USA) to Texas (USA)). We collected fine-scale locational data from swift foxes fitted with global positioning system collars to examine movement and resource-use patterns during winter of 2016–2017 in northeastern Montana. Our results suggest that swift foxes displayed three distinct movement patterns (i.e., resting, foraging, and travelling) during the winter. Distance to road decreased relative probability of use by 39%–46% per kilometre across all movement states and individuals, whereas the influence of topographic roughness and distance to crop field varied among movement states and individuals. Overall, while our findings are based on data from three individuals, our study suggests that across movement states during the critical winter season, swift foxes are likely using topography and areas near roads to increase their ability to detect predators.
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Goodwin, A. H., and D. G. Vaughan. "A topographic origin for double-ridge features in visible imagery of ice divides in Antarctica." Journal of Glaciology 41, no. 139 (1995): 483–89. http://dx.doi.org/10.1017/s0022143000034821.
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AbstractThe appearance of double-ridge features on visible imagery of the ice divides of Antarctic ice rises has often been noted but, largely due to a lack of adequate ground truth, their origins have remained enigmatic. We present several examples of ice rises and other isolated ice-flow centres that apparently show double ridges. We investigate one of these in particular: Fletcher Promontory, Antarctica. A digtal-elevation model (DEM) of the summit region is derived from surface profiles obtained using the Global Positioning System (GPS) and this is correlated with Landsat MSS satellite imagery. Precise registration is achieved by correlating image-brightness values with surface slope calculated along the direction of the Sun azimuth in the image. Using a simple bi-directional relation, the DEM data are used to model the Landsat image. We therefore demonstrate that the double ridge is a product of a subtle concavity parallel to the ridge and is unlikely to be dependent on other factors. This concavity is not predicted by steady-state models of ice divides and so we suggest that the ridge may not be in a steady-state but responding to changes in the glaciological boundary conditions. We speculate that this may be an indication of ongoing migration of the ice divide.
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Goodwin, A. H., and D. G. Vaughan. "A topographic origin for double-ridge features in visible imagery of ice divides in Antarctica." Journal of Glaciology 41, no. 139 (1995): 483–89. http://dx.doi.org/10.3189/s0022143000034821.
Full textAbstract:
AbstractThe appearance of double-ridge features on visible imagery of the ice divides of Antarctic ice rises has often been noted but, largely due to a lack of adequate ground truth, their origins have remained enigmatic. We present several examples of ice rises and other isolated ice-flow centres that apparently show double ridges. We investigate one of these in particular: Fletcher Promontory, Antarctica. A digtal-elevation model (DEM) of the summit region is derived from surface profiles obtained using the Global Positioning System (GPS) and this is correlated with Landsat MSS satellite imagery. Precise registration is achieved by correlating image-brightness values with surface slope calculated along the direction of the Sun azimuth in the image. Using a simple bi-directional relation, the DEM data are used to model the Landsat image. We therefore demonstrate that the double ridge is a product of a subtle concavity parallel to the ridge and is unlikely to be dependent on other factors. This concavity is not predicted by steady-state models of ice divides and so we suggest that the ridge may not be in a steady-state but responding to changes in the glaciological boundary conditions. We speculate that this may be an indication of ongoing migration of the ice divide.
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Lowe, Meagan K., Farrah Anis Fazliatul Adnan, Sarah M. Hamylton, Rafael C. Carvalho, and Colin D. Woodroffe. "Assessing Reef-Island Shoreline Change Using UAV-Derived Orthomosaics and Digital Surface Models." Drones 3, no. 2 (May 14, 2019): 44. http://dx.doi.org/10.3390/drones3020044.
Full textAbstract:
This study presents an analysis of shoreline change on reef islands using unmanned aerial vehicle (UAV)-derived orthomosaics and digital surface models (DSMs) collected on Sipadan Island, Sabah, Malaysia, and Sasahura Ite Island, Isabel Province, Solomon Islands. The high resolution of UAV-derived orthomosaics enabled changes in the position of the base of beach to be detected with confidence. The accuracy of the UAV-derived DSMs was assessed against equivalent topographic profiles via root-mean-square error, and found to be <0.21 m in all but one case; this demonstrates the potential for using UAV-derived DSMs to interpret three-dimensional island beach morphology and detect patterns of geomorphic change. The correlation between planimetric and volumetric change along selected beach transects was also investigated and found to be variable, indicating that a multifaceted approach including both planimetric (two-dimensional) and volumetric (three-dimensional) metrics is of value when analysing reef-island change. However, interpretations of UAV-derived data must carefully consider errors associated with global positioning system (GPS) positioning, the distribution of ground control points, the chosen UAV flight parameters, and the data processing methodology. Further application of this technology has the potential to expand our understanding of reef-island morphodynamics and their vulnerability to sea-level rise and other stressors.
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El-Rabbany, Ahmed. "Assessment of Hydrographic Data Uncertainty for Seamless Reference Surface." Journal of Navigation 59, no. 2 (April 6, 2006): 213–20. http://dx.doi.org/10.1017/s0373463306003729.
Full textAbstract:
The development of a seamless vertical reference surface is accompanied by a number of challenges pertinent to the availability, volume and uncertainty of bathymetric and topographic data. Data uncertainty, which is by far the most difficult to deal with, is attributed to various sources of errors including those of geodetic and hydrographic origin. The uncertainties in the geodetic measurements originate mainly from the limitations in the geodetic technique employed, i.e. terrestrial or space. Old nautical charts and topographic maps were based on terrestrial techniques, which are far less accurate than modern space techniques. In addition, the distribution of the positioning uncertainty is not expected to follow a consistent pattern across the chart (map). This is mainly due to the inconsistent datum distortion as well as the discrepancies in the measuring techniques in the subsequent chart (map) versions. The existing paper (and digitized) charts in many areas of the world were also based on old hydrographic surveying methods, for example the lead-line, which are far less accurate than modern techniques such as multibeam echo-sounding surveys. This creates inconsistent depth uncertainty across the chart. As uncertainties are propagated into the estimated transformation parameters, estimated positions and their covariance matrix, it is of utmost importance that they are properly modelled. This paper addresses the issue of uncertainty in hydrographic data and suggests ways to account for it.
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Merkle, Dominik, Carsten Frey, and Alexander Reiterer. "Fusion of ground penetrating radar and laser scanning for infrastructure mapping." Journal of Applied Geodesy 15, no. 1 (January 27, 2021): 31–45. http://dx.doi.org/10.1515/jag-2020-0004.
Full textAbstract:
AbstractMobile mapping vehicles, equipped with cameras, laser scanners (in this paper referred to as light detection and ranging, LiDAR), and positioning systems are limited to acquiring surface data. However, in this paper, a method to fuse both LiDAR and 3D ground penetrating radar (GPR) data into consistent georeferenced point clouds is presented, allowing imaging both the surface and subsurface. Objects such as pipes, cables, and wall structures are made visible as point clouds by thresholding the GPR signal’s Hilbert envelope. The results are verified with existing utility maps. Varying soil conditions, clutter, and noise complicate a fully automatized approach. Topographic correction of the GPR data, by using the LiDAR data, ensures a consistent ground height. Moreover, this work shows that the LiDAR point cloud, as a reference, increases the interpretability of GPR data and allows measuring distances between above ground and subsurface structures.
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Saravanamuthu, J., A. M. Seifalian, W. M. Reid, and A. B. Maclean. "A new technique to map vulva microcirculation using laser Doppler perfusion imager." International Journal of Gynecologic Cancer 13, no. 6 (2003): 812–18. http://dx.doi.org/10.1136/ijgc-00009577-200311000-00012.
Full textAbstract:
The location of the vulva has had limited technologic progress in the assessment of the skin microcirculation and its application to clinical practice. Our group previously demonstrated increased perfusion in vulvar cancer compared to adjacent uninvolved skin with the laser Doppler flowmetry (LDF). The LDF is severely limited by its low spatial resolution (∼1 mm2) and pressure involved in positioning of the probe, which may affect value of the underlying tissue perfusion. Topographic perfusion mapping of the whole vulvar skin using LDF is also time consuming and is not clinically practical. We describe for the first time the application of the novel laser Doppler perfusion imager (LDPI) to map vulvar skin blood flow and give example in two cases with well-defined vulvar pathology—psoriasis and lichen sclerosus with invasive neoplasia—and discuss the potential of LDPI to study vulvar skin blood flow.