scholarly journals Suitability of Unmanned Aerial Vehicles for Cadastral Surveys

2019 ◽  
Vol 19 (1) ◽  
pp. 1-8
Author(s):  
S. Mantey
Keyword(s):  
High Resolution ◽  
Unmanned Aerial Vehicles ◽  
Global Navigation Satellite Systems ◽  
Satellite Systems ◽  
Aerial Vehicles ◽  
High Resolution Images ◽  
The Difference ◽  
Cadastral Surveying ◽  
Difficult Terrain ◽  
Global Navigation Satellite

Cadastral surveys in Ghana often employ well known surveying equipment such as Total Station andGNSSreceivers or a combination of both. These survey techniques are well-established and widely accepted. However, there are limitations in certain areas. In situations where difficult terrain and inaccessible areas and dense vegetation are encountered or when surveyor’s life may be at risk, Unmanned Aerial Vehicles (UAVs) could be used to overcome the limitations of these well-established survey instruments. This research used high resolution images from UAV (DJI Phantom 4) to survey plots within the University of Mines and Technology land area. Coordinates of the boundary points were extracted using Agisoft Photoscan.GNSSreceivers were also used to survey the land and the same boundary point coordinates obtained and compared. This enabled the establishment of accurate ground control points for georeferencing. The coordinates obtained from both UAV andGNSSSurveys were used to prepare cadastral plans and compared. The difference in Northings and Eastings from UAV andGNSSsurveys were +0.380 cmand +0.351 cmrespectively. These differences are well within tolerance of +/-0.9114 m(+/-3 ft) set by the Survey and Mapping Division (SMD) of the Lands Commission for cadastral plans production. This research therefore concludes that high resolution images from UAVs are suitable for cadastral surveying. Keywords: Unmanned Aerial Vehicles, Drones, Global Navigation Satellite Systems, Cadastral Surveys

Global Navigation Satellite Systems

2011 ◽  
pp. 348-352 ◽  
Author(s):  
Phillip Olla
Keyword(s):  
Global Navigation Satellite Systems ◽  
Global Network ◽  
Navigation Satellite ◽  
Satellite Systems ◽  
Mobile Phone Technology ◽  
Sensing Applications ◽  
Radio Signals ◽  
High Resolution Images ◽  
Global Navigation ◽  
Global Navigation Satellite

There is a need to determine precise ground locations for use in a variety of innovative and emerging applications such as earth observation, mobile-phone technology, and rescue applications. Location information is pertinent to a large number of remote sensing applications, some of which support strategic tasks such as disaster management, earth monitoring, protecting the environment, management of natural resources, and food production. With the availability of high-resolution images, some applications will require a location precision down to 1 m (Kline, 2004). The global navigation satellite systems (GNSSs) provide signals that can serve this purpose; these signals can be incorporated into a large range of innovative applications with immense benefits for the users (Hollansworth, 1999). Satellite navigation is achieved by using a global network of satellites that transmit radio signals from approximately 11,000 miles in high earth orbit. The technology is accurate enough to pinpoint locations anywhere in the world, 24 hours a day. Positions are provided in latitude, longitude, and altitude. This article provides an overview of the GNSSs in operation along with their uses.

scholarly journals A New High-Resolution GPS Multipath Mitigation Technique Using Fast Orthogonal Search

2016 ◽  
Vol 69 (4) ◽  
pp. 794-814 ◽  
Author(s):  
Mohamed Tamazin ◽  
Aboelmagd Noureldin ◽  
Michael J. Korenberg ◽  
Ahmed M. Kamel
Keyword(s):  
High Resolution ◽  
Global Navigation Satellite Systems ◽  
Multipath Mitigation ◽  
Gps Receivers ◽  
Satellite Systems ◽  
Delay Locked Loop ◽  
Orthogonal Search ◽  
Fast Orthogonal Search ◽  
Global Navigation Satellite ◽  
Mitigation Technique

The Delay Locked Loop (DLL) tracking algorithm is one of the most widely used in GPS receivers. It uses different correlators such as the Early-Late Slope (ELS) correlator and High-Resolution Correlator (HRC) to mitigate code phase multipath. These techniques are effective for weak multipath environments but they may not be suitable for challenging multipath environments. The Multipath Estimating Delay Lock Loop (MEDLL) shows better performance than the classical methods. However, MEDLL still has limited capabilities in severe multipath environments. This paper introduces a robust multipath mitigation technique based on fast orthogonal search to obtain better delay estimation for GPS receivers. This research utilised a SPIRENT Global Navigation Satellite Systems (GNSS) simulator to compare the performance of the proposed method with other multipath mitigation techniques. Experimental results demonstrated that the performance of the proposed algorithm was better than the classical and advanced techniques under the multipath scenarios tested.

scholarly journals Potential Use of GPS Technology For Cadastral Surveys in Nepal

2013 ◽  
Vol 12 ◽  
pp. 33-40
Author(s):  
Rabindra Man Tamrakar
Keyword(s):  
Conventional Technique ◽  
Global Navigation Satellite Systems ◽  
Land Reforms ◽  
Administrative Services ◽  
Satellite Systems ◽  
Gps Technology ◽  
Rtk Gps ◽  
Cadastral Surveying ◽  
Land Information System ◽  
Global Navigation Satellite

Global Positional Systems (GPS) now is competing with traditional surveying techniques in almost all fields of geodesy and cadastral surveying after the availability of highly productive new systems such as Real Time Kinematic (RTK) systems along with the use of Global Navigation Satellite Systems (GNSS). Although the cadastral mapping of the entire Nepal was completed in 1996 using graphical survey with plane table technique, derived information from the existing maps now are outdated and do not fulfil the needs of the general public. Updating cadastral maps is not only necessary but vital in Nepal. Survey Department under the Ministry of Land Reforms & Management, Government of Nepal now has to adopt an appropriate innovative approach for cadastral mapping in the country in order to meet the growing public demands on reliable land information system, to provide speedy land administrative services as well as for overall development of the country. With continual research and development into GPS, the techniques and systems developed have become more reliable, cheaper and more productive, making GPS more attractive for a range of surveying solutions including cadastral mapping. Though high resources may be initially required for the RTK GPS technology for cadastral surveys in Nepal when compared to presently available optical surveying techniques, it would be justifiable in investing in GPS surveys. This technology, however, will not replace the existing survey techniques but it will provide another means in carrying out cadastral surveys especially in the area where the conventional technique is not economically and temporally viable. Nepalese Journal on Geoinformatics -12, 2070 (2013AD): 33-40

scholarly journals Survey Of GNSS Coordinates Systems

2016 ◽  
Vol 12 (24) ◽  
pp. 33
Author(s):  
Martina Szabova ◽  
Frantisek Duchon
Keyword(s):  
Coordinate System ◽  
Reference Frame ◽  
Local Coordinate System ◽  
Local Area ◽  
Global Navigation Satellite Systems ◽  
Positioning Systems ◽  
Satellite Systems ◽  
Satellite Positioning ◽  
Cadastral Surveying ◽  
Global Navigation Satellite

The use of satellite positioning systems to determine position in reference frame can introduce serious practical difficulties. The problem can be in the fields of navigation, map revision or cadastral surveying. It arises because in local area the local coordinate system were used. The problem can be solved by transformation between coordinates frame. Global navigation satellite systems (GNSS) don’t use same reference frame and it is important to know transformation between this systems. This paper works with information of many international organizations and their documents. It contains information about reference coordinate system of GNSS, information about local coordinates system used in North America, UK, and Europe.

scholarly journals QUICK 3D WITH UAV AND TOF CAMERA FOR GEOMORPHOMETRIC ASSESSMENT

2020 ◽  
Vol XLIII-B1-2020 ◽  
pp. 259-264
Author(s):  
A. Masiero ◽  
G. Sofia ◽  
P. Tarolli
Keyword(s):  
High Resolution ◽  
Real Time ◽  
Low Cost ◽  
Wide Band ◽  
Global Navigation Satellite Systems ◽  
3D Reconstructions ◽  
Satellite Systems ◽  
Close Range ◽  
Tof Camera ◽  
Global Navigation Satellite

Abstract. Most of the high resolution topographic models are currently obtained either by means of Light Detection and Ranging (LiDAR) or photogrammetry: the former is usually preferred for producing very accurate models, whereas the latter is much more frequently used in low cost applications. In particular, the availability of more affordable Unmanned Aerial Vehicles (UAVs) equipped with high resolution cameras led to a dramatic worldwide increase of UAV photogrammetry-based 3D reconstructions. Nevertheless, accurate high resolution photogrammetric reconstructions typically require quite long data processing procedures, which make them less suitable for real-time applications.This work aims at investigating the use of a low cost Time of Flight (ToF) camera, combined with an Ultra-Wide Band (UWB) positioning system, mounted on a drone, in order to enable quasi real time 3D reconstructions of small to mid-size areas, even in locations where Global Navigation Satellite Systems (GNSSs) are not available.The proposed system, tested on a small area on the Italian Alps, provided high resolution mapping results, with an error of few centimeters with respect to a terrestrial close-range photogrammetry survey conducted on the same day.

scholarly journals INTERFEROMETRIC PATH MODELS FOR GNSS GROUND-BASED PHASE ALTIMETRY

2019 ◽  
Vol XLII-4/W18 ◽  
pp. 597-603
Author(s):  
S. Khajeh ◽  
A. A. Ardalan ◽  
H. Schuh
Keyword(s):  
Ray Tracing ◽  
Phase Retrieval ◽  
Mapping Function ◽  
Global Navigation Satellite Systems ◽  
Total Delay ◽  
Satellite Systems ◽  
Planar Model ◽  
Model Based ◽  
The Difference ◽  
Global Navigation Satellite

Abstract. Altimetry by using GNSS (Global Navigation Satellite Systems) reflectometry is regarded as a new promising technique. One important step to utilize this technique is modeling the interferometric path (the difference between the direct and the reflected signal paths). This paper evaluates three models: the planar model, the planar model with tropospheric correction and a model based on ray-tracing. If decimeter level accuracy for water surface fluctuation is required, the planar model cannot be used when a receiver is at an altitude of a few hundred meters and observations are taken at low elevation angles. On the other hand, depending on the mapping function and zenith total delay in the tropospheric correction, the planar model with tropospheric correction can provide decimeter level accuracy for low altitude stations. If simulated observations with a 1 cm accuracy have been employed to estimate Sea Surface Height (SSH) by the model based on ray-tracing the numerical results present 1 cm as RMSE for phase retrieval and 5 cm for Doppler retrieval. The planar model with tropospheric correction does not yield RMSE better than some decimeters for the same condition.

scholarly journals Research on the eLoran Differential Timing Method

Sensors ◽  
2020 ◽  
Vol 20 (22) ◽  
pp. 6518
Author(s):  
Yun Li ◽  
Yu Hua ◽  
Baorong Yan ◽  
Wei Guo
Keyword(s):  
Differential Method ◽  
Global Navigation Satellite Systems ◽  
Signal Delay ◽  
Timing Accuracy ◽  
Satellite Systems ◽  
System A ◽  
Timing Precision ◽  
The Difference ◽  
Global Navigation Satellite ◽  
Differential Timing

An enhanced long-range navigation (eLoran) system was selected as the backup of Global Navigation Satellite Systems (GNSS), and experts and scholars are committed to improving the accuracy of the eLoran system such that its accuracy is close to the GNSS system. A differential method called eLoran differential timing technology is applied to the eLoran system, which has been used in maritime applications of eLoran. In this study, an application of eLoran differential timing technology in a terrestrial medium is carried out. Based on the eLoran timing service error, the correlation of the timing service error is analyzed in theory quantitatively to obtain the range of the difference station in the ground. The results show that to satisfy the timing accuracy of 100 ns, the action range of eLoran difference station on the land needs to be less than 55 km. Therefore, the eLoran differential method is proposed, and in the difference station, the theoretical calculation is combined with the measurement of the signal delay to obtain the difference information, which is sent to the users to adjust the prediction delay and improve the eLoran timing precision. The experiment was carried out in the Guan Zhong Plain, and the timing error of the user decreased from 394.7287 ns (pre-difference) to 19.5890 ns (post-difference). The proposed method is found to effectively enhance the timing precision of the eLoran system within the scope of action.

scholarly journals Homogenized Time Series of the Atmospheric Water Vapor Content Obtained from the GNSS Reprocessed Data

2016 ◽  
Vol 29 (7) ◽  
pp. 2443-2456 ◽  
Author(s):  
T. Ning ◽  
J. Wickert ◽  
Z. Deng ◽  
S. Heise ◽  
G. Dick ◽  
...  
Keyword(s):  
Time Series ◽  
Water Vapor ◽  
Global Scale ◽  
Global Navigation Satellite Systems ◽  
Radiosonde Data ◽  
Gps Data ◽  
Satellite Systems ◽  
Weather Forecasts ◽  
The Difference ◽  
Global Navigation Satellite

Abstract The potential temporal shifts in the integrated water vapor (IWV) time series obtained from reprocessed data acquired from global navigation satellite systems (GNSS) were comprehensively investigated. A statistical test, the penalized maximal t test modified to account for first-order autoregressive noise in time series (PMTred), was used to identify the possible mean shifts (changepoints) in the time series of the difference between the GPS IWV and the IWV obtained from the European Centre for Medium-Range Weather Forecasts (ECMWF) interim reanalysis (ERA-Interim) data. The approach allows for identification of the changepoints not only in the GPS IWV time series but also in ERA-Interim. The IWV difference time series formed for 101 GPS sites were tested, where 47 of them were found to contain in total 62 changepoints. The results indicate that 45 detected changepoints were due to the inconsistencies in the GPS IWV time series, and 16 were related to ERA-Interim, while one point was left unverified. After the correction of the mean shifts for the GPS data, an improved consistency in the IWV trends is evident between nearby sites, while a better agreement is seen between the trends from the GPS and ERA-Interim data on a global scale. In addition, the IWV trends estimated for 47 GPS sites were compared to the corresponding IWV trends obtained from nearby homogenized radiosonde data. The correlation coefficient of the trends increases significantly by 38% after using the homogenized GPS data.

scholarly journals Logging Mats and Logging Residue as Ground Protection during Forwarder Traffic along Till Hillslopes

2021 ◽  
Vol 42 (3) ◽  
Author(s):  
Eva Ring ◽  
Mikael Andersson ◽  
Linnea Hansson ◽  
Gunnar Jansson ◽  
Lars Högbom
Keyword(s):  
Mineral Soil ◽  
Soil Surface ◽  
Soil Disturbance ◽  
Global Navigation Satellite Systems ◽  
Soil Conditions ◽  
Satellite Systems ◽  
Ground Conditions ◽  
Logging Residue ◽  
The Difference ◽  
Global Navigation Satellite

Forest soils in Northern Europe are generally trafficked by forest machinery on several occasions during a forest rotation. This may create ruts (wheel tracks), which could increase sediment transport to nearby surface water, reduce recreational value, and affect tree growth. It is therefore important to reduce soil disturbance during off-road forest transportation. In this study, rut depth was measured following forwarder traffic on study plots located along four harvested till hillslopes in Northern Sweden with drier soil conditions uphill and wet conditions downhill. The treatments included driving 1) using no ground protection, 2) on logging residue (on average, 38–50 kg m–2) and 3) on logging mats measuring 5×1×0.2 m. The hillslopes contain areas with a high content of boulders, stones, and gravel as well as areas with a significant content of silt. Six passes with a laden forwarder with four bogie tracks were performed. On the plots with ground protection, the application of logging residue and the application and removal of logging mats necessitated additional passes. Rut depth was measured using two methods: 1) as the difference in elevation between the interpolated original soil surface and the surface of the rut using GNSS positioning (Global Navigation Satellite Systems), and 2) manually with a folding rule from an aluminium profile, placed across the rut, to the bottom of the rut. The two methods generally gave similar results. Driving without ground protection in the upper part of the hillslopes generated ruts with depths <0.2 m. Here, the rut depth was probably modified by the high content of boulders and stones in the upper soil and drier soil conditions. In the lower part of the hillslopes, the mean rut depth ranged from 0.21 to 0.34 m. With a few exceptions, driving on logging residue or logging mats prevented exposure of mineral soil along the entire hillslope. Soil disturbance can thus be reduced by acknowledging the onsite variability in ground conditions and considering the need for ground protection when planning forest operations.

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