scholarly journals Determining the Variability of the Territorial Sea Baseline on the Example of Waterbody Adjacent to the Municipal Beach in Gdynia

2019 ◽  
Vol 9 (18) ◽  
pp. 3867 ◽  
Author(s):  
Specht ◽  
Specht ◽  
Wąż ◽  
Dąbrowski ◽  
Skóra ◽  
...  
Keyword(s):  
Temporal Variability ◽  
Satellite System ◽  
Spatial And Temporal Variability ◽  
Position Change ◽  
Digital Terrain ◽  
Terrain Models ◽  
Sea Bottom ◽  
Surface Models ◽  
Global Navigation Satellite ◽  
Sand Bottom

The purpose of this publication is to analyze the spatial and temporal variability of the territorial sea baseline in sand bottom waterbodies, which were determined twice, in 2016 and 2018, by the Real Time Kinematic (RTK) method. This involves direct measurement of sea bottom coordinates on planned hydrographic sounding profiles using a Global Navigation Satellite System (GNSS) receiver mounted on a pole. The data were the basis for creating Digital Terrain Models (DTM), which were then used to determine the baseline for both measurement campaigns. Subsequently, terrain surface models were compared to determine bathymetry changes in the area under analysis, and an assessment was made of the baseline spatial position change over the previous two years. The measurements have shown considerable spatial and temporal variability of the baseline course along a short section of sandy beach. The territorial sea baseline was very unstable; in some places, it moved by even 20–25 m, landwards and seawards. Therefore, one can suppose that these changes are periodic, and one can conclude that the reliability of the baseline measurements can decrease quite quickly.

scholarly journals Photogrammetric 3D Model via Smartphone GNSS Sensor: Workflow, Error Estimate, and Best Practices

2020 ◽  
Vol 12 (21) ◽  
pp. 3616
Author(s):  
Stefano Tavani ◽  
Antonio Pignalosa ◽  
Amerigo Corradetti ◽  
Marco Mercuri ◽  
Luca Smeraglia ◽  
...  
Keyword(s):  
3D Model ◽  
Model Building ◽  
Satellite System ◽  
Test Case ◽  
Digital Terrain ◽  
Ground Control Points ◽  
Terrain Models ◽  
Aerial Vehicle ◽  
Global Navigation Satellite ◽  
The Impact

Geotagged smartphone photos can be employed to build digital terrain models using structure from motion-multiview stereo (SfM-MVS) photogrammetry. Accelerometer, magnetometer, and gyroscope sensors integrated within consumer-grade smartphones can be used to record the orientation of images, which can be combined with location information provided by inbuilt global navigation satellite system (GNSS) sensors to geo-register the SfM-MVS model. The accuracy of these sensors is, however, highly variable. In this work, we use a 200 m-wide natural rocky cliff as a test case to evaluate the impact of consumer-grade smartphone GNSS sensor accuracy on the registration of SfM-MVS models. We built a high-resolution 3D model of the cliff, using an unmanned aerial vehicle (UAV) for image acquisition and ground control points (GCPs) located using a differential GNSS survey for georeferencing. This 3D model provides the benchmark against which terrestrial SfM-MVS photogrammetry models, built using smartphone images and registered using built-in accelerometer/gyroscope and GNSS sensors, are compared. Results show that satisfactory post-processing registrations of the smartphone models can be attained, requiring: (1) wide acquisition areas (scaling with GNSS error) and (2) the progressive removal of misaligned images, via an iterative process of model building and error estimation.

scholarly journals ASSESSING FLOOD IMPACTS IN RURAL COASTAL COMMUNITIES USING LIDAR

2016 ◽  
Vol XLI-B8 ◽  
pp. 1135-1139
Author(s):  
E. S. Johnson
Keyword(s):  
Storm Surges ◽  
Coastal Communities ◽  
Lidar Data ◽  
Storm Events ◽  
Flood Events ◽  
Flood Impacts ◽  
Digital Terrain ◽  
Terrain Models ◽  
Surface Models ◽  
Coastal Residents

Coastal communities are vulnerable to floods from storm events which are further exacerbated by storm surges. Additionally, coastal towns provide specific challenges during flood events as many coastal communities are peninsular and vulnerable to inundation of road access points. Publicly available lidar data has been used to model areas of inundation and resulting flood impacts on road networks. However, these models may overestimate areas that are inaccessible as they rely on publicly available Digital Terrain Models. Through incorporation of Digital Surface Models to estimate bridge height, a more accurate model of flood impacts on rural coastal residents can be estimated.

scholarly journals Utilizing Airborne LiDAR and UAV Photogrammetry Techniques in Local Geoid Model Determination and Validation

2020 ◽  
Vol 9 (9) ◽  
pp. 528 ◽  
Author(s):  
Serdar Erol ◽  
Emrah Özögel ◽  
Ramazan Alper Kuçak ◽  
Bihter Erol
Keyword(s):  
Point Clouds ◽  
Satellite System ◽  
Airborne Lidar ◽  
Geoid Model ◽  
Digital Terrain ◽  
Novel Approach ◽  
Aerial Vehicle ◽  
Global Navigation Satellite ◽  
Regional Gravimetric Geoid ◽  
Local Geoid

This investigation evaluates the performance of digital terrain models (DTMs) generated in different vertical datums by aerial LiDAR and unmanned aerial vehicle (UAV) photogrammetry techniques, for the determination and validation of local geoid models. Many engineering projects require the point heights referring to a physical surface, i.e., geoid, rather than an ellipsoid. When a high-accuracy local geoid model is available in the study area, the physical heights are practically obtained with the transformation of global navigation satellite system (GNSS) ellipsoidal heights of the points. Besides the commonly used geodetic methods, this study introduces a novel approach for the determination and validation of the local geoid surface models using photogrammetry. The numeric tests were carried out in the Bergama region, in the west of Turkey. Using direct georeferenced airborne LiDAR and indirect georeferenced UAV photogrammetry-derived point clouds, DTMs were generated in ellipsoidal and geoidal vertical datums, respectively. After this, the local geoid models were calculated as differences between the generated DTMs. Generated local geoid models in the grid and pointwise formats were tested and compared with the regional gravimetric geoid model (TG03) and a high-resolution global geoid model (EIGEN6C4), respectively. In conclusion, the applied approach provided sufficient performance for modeling and validating the geoid heights with centimeter-level accuracy.

scholarly journals Ice front change of marine-terminating outlet glaciers in northwest and southeast Greenland during the 21st century

2018 ◽  
Vol 64 (246) ◽  
pp. 523-535 ◽  
Author(s):  
CHARLIE BUNCE ◽  
J. RACHEL CARR ◽  
PETER W. NIENOW ◽  
NEIL ROSS ◽  
REBECCA KILLICK
Keyword(s):  
Temporal Variability ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Spatial And Temporal Variability ◽  
Spatial And Temporal Patterns ◽  
Negative Mass ◽  
Position Change ◽  
Specific Factors ◽  
Enhanced Surface

ABSTRACTThe increasingly negative mass balance of the Greenland ice sheet (GrIS) over the last ~25 years has been associated with enhanced surface melt and increased ice loss from marine-terminating outlet glaciers. Accelerated retreat during 2000–2010 was concentrated in the southeast and northwest sectors of the ice sheet; however, there was considerable spatial and temporal variability in the timing and magnitude of retreat both within and between these regions. This behaviour has yet to be quantified and compared for all glaciers in both regions. Furthermore, it is unclear whether retreat has continued after 2010 in the northwest, and whether the documented slowdown in the southeast post-2005 has been sustained. Here, we compare spatial and temporal patterns of frontal change in the northwest and southeast GrIS, for the period 2000–2015. Our results show near-ubiquitous retreat of outlet glaciers across both regions for the study period; however, the timing and magnitude of inter-annual frontal position change is largely asynchronous. We also find that since 2010, there is continued terminus retreat in the northwest, which contrasts with considerable inter-annual variability in the southeast. Analysis of the role of glacier-specific factors demonstrates that fjord and bed geometry are important controls on the timing and magnitude of glacier retreat.

scholarly journals Unmanned Aerial Vehicle Surveying For Monitoring Road Construction Earthworks

2019 ◽  
Vol 14 (1) ◽  
pp. 1-17 ◽  
Author(s):  
Kalev Julge ◽  
Artu Ellmann ◽  
Romet Köök
Keyword(s):  
Unmanned Aerial Vehicle ◽  
Road Construction ◽  
Point Clouds ◽  
Satellite System ◽  
Ground Control Points ◽  
Surface Models ◽  
Aerial Vehicle ◽  
Global Navigation Satellite ◽  
Sand And Gravel ◽  
The Impact

Unmanned aerial vehicle photogrammetry is a surveying technique that enables generating point clouds, 3D surface models and orthophoto mosaics. These are based on photos captured with a camera placed on an unmanned aerial vehicle. Within the framework of this research, unmanned aerial vehicle photogrammetry surveys were carried out over a sand and gravel embankment with the aim of assessing the vertical accuracy of the derived surface models. Flight altitudes, ground control points and cameras were varied, and the impact of various factors on the results was monitored. In addition, the traditional real-time-kinematic Global Navigation Satellite System surveys were conducted for verifications. Surface models acquired by different methods were used to calculate volumes and compare the results with requirements set by Estonian Road Administration. It was found that with proper measuring techniques an accuracy of 5.7 cm for the heights were achieved.

scholarly journals IWV retrieval from ground GNSS receivers during NAWDEX

2021 ◽  
Vol 55 ◽  
pp. 13-22
Author(s):  
Pierre Bosser ◽  
Olivier Bock
Keyword(s):  
Water Vapor ◽  
North Atlantic ◽  
Regional Scale ◽  
Satellite System ◽  
Tropospheric Delay ◽  
Spatial And Temporal Variability ◽  
Data Set ◽  
The North ◽  
The North Atlantic ◽  
Global Navigation Satellite

Abstract. A ground-based network of more than 1200 Global Navigation Satellite System (GNSS) Continuously Operating Reference Stations (CORS) was analysed using GIPSY-OASIS II software package for the documentation of time and space variations of water vapor in atmosphere during the North Atlantic Waveguide and Downstream impact EXperiment (NAWDEX) during fall 2016. The network extends throughout the North Atlantic, from the Caribbeans to Morocco through Greenland. This paper presents the methodology used for GNSS data processing, screening, and conversion of Zenith Tropospheric Delay (ZTD) estimates to Integrated Water Vapor content (IWV) using surface parameters from reanalysis. The retrieved IWV are used to evaluate the European Centre for Medium-Range Weather Forecasts (ECMWF) reanalyses ERAI and ERA5. ERA5 shows an overall improvement over ERAI in representing the spatial and temporal variability of IWV over the study area. The mean bias is decreased from 0.31±0.63 to 0.19±0.56 kg m−2 (mean ±1σ over all stations) and the standard deviation reduced from 2.17±0.67 to 1.64±0.53 kg m−2 combined with a slight improvement in correlation coefficient from 0.95 to 0.97. At regional scale, both reanalyses show a general wet bias at mid and northern latitudes but a dry bias in the Caribbeans. We hypothesize this results from the different nature of data being assimilated over the tropical oceans. This GNSS IWV data set is intended to be used for a better description of the high impact weather events that occurred during the NAWDEX experiment.

scholarly journals Evaluation of the accuracy of volume calculation obtained by UAV

2020 ◽  
Vol 14 ◽  
Author(s):  
Fernanda Helena Oliveira da Silva ◽  
Éder Ramon Feitoza Lêdo ◽  
Caike Silva Candido Damasceno ◽  
José Adriano Da Silva ◽  
Iderlan Medeiros De Brito Alves
Keyword(s):  
High Reliability ◽  
Satellite System ◽  
Aerial Images ◽  
Volume Data ◽  
Volume Calculation ◽  
Gnss Receiver ◽  
Stabilization Pond ◽  
Digital Terrain ◽  
Waste Stabilization ◽  
Global Navigation Satellite

The emergence of increasingly accurate, fast, and inexpensive tools in the acquisition of data for the management base suitable for each type of environment is fundamental in the development of sustainable engineering. Based on this, the evaluation of the accuracy of the volume calculation performed using Digital Terrain Models (DTM’s), generated by images of Unmanned Aerial Vehicle (UAV) was carried out. The study was conducted in the area of the new landfill in the municipality of Fortaleza, state of Ceará, in a waste stabilization pond. Two DTM’s were generated and evaluated. The first was generated by collecting points from a Global Navigation Satellite System (GNSS) receiver, using 445 points, whereas the second was generated by aerial images obtained through a multirotor UAV, with 17 checkpoints and 10 Ground Control Points (GCP’s). With the two DTM’s of the GNSS Receiver and the UAV, the volume of the stabilization pond was calculated using the TopoEVN and Pix4D software, respectively. The estimated pond volume obtained through the Global Positioning System (GPS) data was 48548,33 m³, while by the UAV DTM, it was 48504,9 m³. The accuracy of the volume data obtained by DTM generated by UAV, even with considerable flight height (120 m), presented a result with variation less than 1% compared to those arising from conventional topography, thus indicating high reliability and data accuracy.

scholarly journals POTENTIAL OF MULTITEMPORAL TANDEM-X DERIVED CROP SURFACE MODELS FOR MAIZE GROWTH MONITORING

2016 ◽  
Vol XLI-B7 ◽  
pp. 803-808
Author(s):  
C. Hütt ◽  
N. Tilly ◽  
H. Schiedung ◽  
G. Bareth
Keyword(s):  
Laser Scanning ◽  
General Trend ◽  
Growth Monitoring ◽  
Data Sets ◽  
Bare Ground ◽  
Digital Terrain ◽  
Area Of Interest ◽  
Terrain Models ◽  
Surface Models ◽  
First Results

In this study, first results of retrieving plant heights of maize fields from multitemporal TanDEM-X images are shown. Three TanDEM-X dual polarization spotlight acquisitions were taken over a rural area in Germany in the growing season 2014. By interferometric processing, digital terrain models (DTM) were derived for each date with 5m resolution. From the data of the first acquisition (June 1st) taken before planting, a DTM of the bare ground is generated. The data of the following acquisition dates (July 15th, July 26th) are used to establish crop surface models (CSM). A CSM represents the crop surface of a whole field in a high resolution. By subtracting the DTM of the ground from each CSM, the actual plant height is calculated. Within these data sets 30 maize fields in the area of interest could be detected and verified by external land use data. Besides the spaceborne measurements, one of the maize fields was intensively investigated using terrestrial laser scanning (TLS), which was carried out at the same dates as the predicted TanDEM-X acquisitions. Visual inspection of the derived plant heights, and accordance of the individually processed polarisations over the maize fields, demonstrate the feasibility of the proposed method. Unfortunately, the infield variability of the intensively monitored field could not be successfully captured in the TanDEM-X derived plant heights and merely the general trend is visible. Nevertheless, the study shows the potential of the TanDEM-X constellation for maize height monitoring on field level.

scholarly journals Estimated Land and Building Tax using Aerial Photography (Case Study: Tingkir District, Salatiga City)

2020 ◽  
Vol 4 (2) ◽  
pp. 372-378
Author(s):  
Josef Allen ◽  
Frederik Samuel Papilaya
Keyword(s):  
Aerial Photographs ◽  
Digital Terrain Models ◽  
Raster Calculator ◽  
Digital Terrain ◽  
Terrain Models ◽  
Surface Models ◽  
Building Area ◽  
The City ◽  
Area Data

Salatiga, a city that borders directly and is surrounded by Semarang Regency. It has an area of ​​56.78 km2, with four sub-districts including, Sidorejo Regency, Argomulyo Regency, Tingkir Regency, and Sidomukti Regency, which covers 23 villages. The city of Salatiga has a fairly high population density with a proportion of more than 3300 inhabitants / km2. In this study took place in the Central Tingkir and Tingkir Lor areas by taking several points that are considered as housing as a case study. This study aims to estimate the price of land and building tax on an object of land and building tax. The process of this research uses aerial photo processing, where aerial photographs will be processed using professional software Agisoft photoscan to become an orthophoto, digital surface models and digital terrain models to obtain building area and land area data, then digital surface models and digital terrain models are processed . with ArcGIS 10.6 software using a raster calculator to get the height of the object to be used as the height of the building. The data obtained will be used to perform land and building tax calculations. The results of this study estimate the estimated land and building tax prices of at least IDR 37,313.00 and a maximum value of IDR 3,809,763.00.  

scholarly journals POTENTIAL OF MULTITEMPORAL TANDEM-X DERIVED CROP SURFACE MODELS FOR MAIZE GROWTH MONITORING

2016 ◽  
Vol XLI-B7 ◽  
pp. 803-808 ◽  
Author(s):  
C. Hütt ◽  
N. Tilly ◽  
H. Schiedung ◽  
G. Bareth
Keyword(s):  
Laser Scanning ◽  
General Trend ◽  
Growth Monitoring ◽  
Data Sets ◽  
Bare Ground ◽  
Digital Terrain ◽  
Area Of Interest ◽  
Terrain Models ◽  
Surface Models ◽  
First Results

In this study, first results of retrieving plant heights of maize fields from multitemporal TanDEM-X images are shown. Three TanDEM-X dual polarization spotlight acquisitions were taken over a rural area in Germany in the growing season 2014. By interferometric processing, digital terrain models (DTM) were derived for each date with 5m resolution. From the data of the first acquisition (June 1st) taken before planting, a DTM of the bare ground is generated. The data of the following acquisition dates (July 15th, July 26th) are used to establish crop surface models (CSM). A CSM represents the crop surface of a whole field in a high resolution. By subtracting the DTM of the ground from each CSM, the actual plant height is calculated. Within these data sets 30 maize fields in the area of interest could be detected and verified by external land use data. Besides the spaceborne measurements, one of the maize fields was intensively investigated using terrestrial laser scanning (TLS), which was carried out at the same dates as the predicted TanDEM-X acquisitions. Visual inspection of the derived plant heights, and accordance of the individually processed polarisations over the maize fields, demonstrate the feasibility of the proposed method. Unfortunately, the infield variability of the intensively monitored field could not be successfully captured in the TanDEM-X derived plant heights and merely the general trend is visible. Nevertheless, the study shows the potential of the TanDEM-X constellation for maize height monitoring on field level.

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