scholarly journals Hierarchical Sea-Land Segmentation for Panchromatic Remote Sensing Imagery

2017 ◽  
Vol 2017 ◽  
pp. 1-8 ◽  
Author(s):  
Long Ma ◽  
Nouman Q. Soomro ◽  
Jinjing Shen ◽  
Liang Chen ◽  
Zhihong Mai ◽  
...  
Keyword(s):  
State Of The Art ◽  
Temporal Variations ◽  
Memory Storage ◽  
Computationally Efficient ◽  
High Resolution Data ◽  
Digital Elevation ◽  
Segmentation Approach ◽  
Fully Automatic ◽  
Elevation Model ◽  
Coarse To Fine

Automatic sea-land segmentation is an essential and challenging field for the practical use of panchromatic satellite imagery. Owing to the temporal variations as well as the complex and inconsistent intensity contrast in both land and sea areas, it is difficult to generate an accurate segmentation result by using the conventional thresholding methods. Additionally, the freely available digital elevation model (DEM) also difficultly meets the requirements of high-resolution data for practical usage, because of the low precision and high memory storage costs for the processing systems. In this case, we proposed a fully automatic sea-land segmentation approach for practical use with a hierarchical coarse-to-fine procedure. We compared our method with other state-of-the-art methods with real images under complex backgrounds and conducted quantitative comparisons. The experimental results show that our method outperforms all other methods and proved being computationally efficient.

scholarly journals Measuring Decadal Vertical Land-level Changes from SRTM-C (2000) and TanDEM-X (~ 2015) in the South-Central Andes

2018 ◽  
Author(s):  
Benjamin Purinton ◽  
Bodo Bookhagen
Keyword(s):  
Central Andes ◽  
Control Surface ◽  
The South ◽  
High Resolution Data ◽  
Gravel Bed ◽  
South Central ◽  
Digital Elevation ◽  
Mountain Belts ◽  
Elevation Model ◽  
Limit Detection

Abstract. Vertical change is often measured in the cryosphere via digital elevation model (DEM) differencing to assess glacier and ice-sheet mass balances. This requires the signal of change to outweigh the noise associated with the datasets. On the ice-free earth, land-level change is much smaller in magnitude and thus requires more accurate DEMs for differencing and identification of change. Previously, this has required high-resolution data at small scales. For the first time we measure land-level changes at the scale of entire mountain belts in the south-central Andes using the SRTM-C (collected in 2000) and the TanDEM-X (collected from 2010–2015), both spaceborne radar DEMs. Long-standing errors in the SRTM-C are corrected using the TanDEM-X as a control surface and applying cosine-fit co-registration to remove ~ 1/10 pixel (~ 3 m) shifts, Fast Fourier Transform and filtering to remove SRTM-C short- and long-wavelength stripes, and blocked shifting to remove remaining complex biases. The datasets are then differenced and outlier pixels are identified as potential signal for the case of gravel-bed channels and hillslopes. We are able to identify signals of incision and aggradation (with magnitudes down to ~ 3 m in best case) in two > 100 km river reaches, with increased geomorphic activity downstream of knickpoints. Anthropogenic gravel excavation and piling is prominently measured, with magnitudes exceeding ±5 m (up to > 10 m for large piles). These values correspond to conservative rates of 0.2 to > 0.5 m/yr for vertical changes in gravel-bed rivers. For hillslopes, since we require stricter cutoffs for noise, we are only able to identify one major landslide with a deposit volume of 16 ± 0.15 × 106 m3. Additional signals of change can be garnered from TanDEM-X auxiliary layers, however, these are more difficult to quantify. The methods presented can be extended to any region of the world with SRTM-C and TanDEM-X coverage where vertical land-level changes are of interest, with the caveat that remaining vertical uncertainties in primarily the SRTM-C limit detection in steep and complex topography.

scholarly journals A computationally efficient depression-filling algorithm for digital elevation models applied to proglacial lake drainage

2016 ◽  
Author(s):  
Constantijn J. Berends ◽  
Roderik S. W. van de Wal
Keyword(s):  
Geographical Area ◽  
Computation Time ◽  
Equation Model ◽  
Limiting Factor ◽  
Computationally Efficient ◽  
Digital Elevation ◽  
Lake Drainage ◽  
Elevation Model ◽  
Flood Fill

Abstract. We present and evaluate several optimizations to a standard flood-fill algorithm in terms of computational efficiency. As an example, we determine the land/ocean-mask for a 1 km resolution digital elevation model (DEM) of North America and Greenland, a geographical area of roughly 7000 by 5000 km (roughly 35 million elements), about half of which is covered by ocean. Determining the land/ocean-mask with our improved flood-fill algorithm reduces computation time by 90 % relative to using a standard stack-based flood-fill algorithm. In another experiment, we use the bedrock elevation, ice thickness and geoid perturbation fields from the output of a coupled ice-sheet–sea-level equation model at 30,000 years before present and determine the extent of Lake Agassiz, using both the standard and improved versions of the flood-fill algorithm. We show that several optimizations to the flood-fill algorithm used for filling a depression up to a water level, that is not defined at forehand, decrease the computation time by up to 99 %. The resulting reduction in computation time allows determination of the extent and volume of depressions in a DEM over large geographical grids or repeatedly over long periods of time, where computation time might otherwise be a limiting factor.

scholarly journals Estimating spatial and temporal variations in solar radiation within Bordeaux winegrowing region using remotely sensed data

OENO One ◽  
2008 ◽  
Vol 42 (1) ◽  
pp. 15 ◽  
Author(s):  
Benjamin Bois ◽  
Lucien Wald ◽  
Philippe Pieri ◽  
Cornelis Van Leeuwen ◽  
Loïc Commagnac ◽  
...  
Keyword(s):  
Solar Radiation ◽  
Temporal Variations ◽  
Spatial And Temporal Variations ◽  
Remotely Sensed Data ◽  
High Solar Radiation ◽  
Daily Data ◽  
Digital Elevation ◽  
Terrain Effect ◽  
Resolution Mapping ◽  
Elevation Model

<p style="text-align: justify;"><strong>Aims</strong>: This paper presents a study of spatial and temporal variations in solar radiation for the Bordeaux winegrowing region, over a 20 year period (1986-2005).</p><p style="text-align: justify;"><strong>Methods and results</strong>: Solar radiation data was retrieved from the HelioClim-1 database, elaborated from Meteosat satellite images, using the Heliosat-2 algorithm. Daily data was interpolated using ordinary kriging to produce horizontal solar radiation maps at a 500 m resolution. Then using a digital elevation model, 50 m resolution daily solar radiation maps with terrain integration were produced for the period 2001-2005. The long term (20 year) analysis of solar radiation at low spatial resolution (500 m) showed a west to east decreasing gradient within the Bordeaux winegrowing region. Mean August-to-September daily irradiation values, on horizontal surface, were used to classify the Bordeaux winegrowing region into three zones: low, medium, and high solar radiation areas. This initial zoning was downscaled to 50 m resolution, applying a local correction ratio, based on 2001-2005 solar radiation from the inclined surface analysis. Grapevine development and maturation potential of the different zones of appellation of origin of Bordeaux winegrowing regions are discussed in relation with this zoning.</p><p style="text-align: justify;"><strong>Conclusion</strong>: Solar radiation variability within the Bordeaux winegrowing region is mainly governed by terrain slopes and orientations, which induce considerable variations within the eastern part of Bordeaux vineyards. Significance and impact of study: Solar radiation has a major impact on vineyard water balance, grapevine development and berry ripening. However, irradiation data is seldom available in weather stations records. This paper highlights the need for high resolution mapping of solar radiation that uses remote sensing and terrain effect integration for agroclimatic studies in viticulture.</p>

scholarly journals A Fully Automatic Algorithm for Editing the TanDEM-X Global DEM

2020 ◽  
Vol 12 (23) ◽  
pp. 3961
Author(s):  
Carolina González ◽  
Markus Bachmann ◽  
José-Luis Bueso-Bello ◽  
Paola Rizzoli ◽  
Manfred Zink
Keyword(s):  
Scientific Community ◽  
Gap Filling ◽  
Bistatic Sar ◽  
Digital Elevation ◽  
X Band ◽  
Fully Automatic ◽  
Elevation Model ◽  
Interferometric Sar ◽  
Sar Processing ◽  
Automatic Algorithm

The spaceborne mission TanDEM-X successfully acquired and processed a global Digital Elevation Model (DEM) from interferometric bistatic SAR data at X band. The product has been delivered in 2016 and is characterized by an unprecedented vertical accuracy. It is provided at 12 m, 30 m, and 90 m sampling and can be accessed by the scientific community via a standard announcement of opportunity process and the submission of a scientific proposal. The 90 m version is freely available for scientific purposes. The DEM is unedited, which means that it is the pure result of the interferometric SAR processing and subsequent mosaicking. Residual gaps, resulting, e.g., from unprocessable data, are still present and water surfaces appear noisy. This paper reports on the algorithms developed at DLR’s Microwaves and Radar Institute for a fully automatic editing of the global TanDEM-X DEM comprising gap filling and water editing. The result is a new global gap-free DEM product at 30 m sampling, which can be used for a large variety of scientific applications. It also serves as a reference for processing the upcoming TanDEM-X Change DEM layer.

scholarly journals Statistics and Possible Sources of Aviation Turbulence over South Korea

2011 ◽  
Vol 50 (2) ◽  
pp. 311-324 ◽  
Author(s):  
Jung-Hoon Kim ◽  
Hye-Yeong Chun
Keyword(s):  
South Korea ◽  
Analysis Data ◽  
Temporal Variations ◽  
Lightning Flash ◽  
Air Turbulence ◽  
Digital Elevation ◽  
Annual Total ◽  
Elevation Model ◽  
Generation Mechanisms ◽  
Wave Induced

Abstract The characteristics of aviation turbulence over South Korea during the recent five years (2003–08, excluding 2005) are investigated using pilot reports (PIREPs) accumulated by the Korea Aviation Meteorological Agency (KAMA). Among the total of 8449 PIREPs, 4607 (54.53%), 1646 (19.48%), 248 (2.94%), 7 (0.08%), and 1941 (22.97%) correspond to the turbulence categories of null, light, moderate, severe, and missing, respectively. In terms of temporal variations, the annual total number of turbulence events increased from 2003 to 2008, and the seasonal frequency is the highest in the spring. With regard to spatial distributions, reported turbulence encounters are dominant along the prevailing flight routes, but are locally higher over the west coast, Jeju Island, and the Sobaek and Taebaek mountains. The turbulence events in these regions vary by season. To examine the regional differences and possible sources of the observed turbulence, lightning flash data, Regional Data Assimilation and Prediction System (RDAPS) analysis data with a 30-km horizontal grid spacing provided by the Korean Meteorological Administration (KMA), and a digital elevation model (DEM) dataset with a 30-s resolution, are additionally used. Convectively induced turbulence (CIT) and clear-air turbulence (CAT) events comprised 11% and 89% of the total 255 moderate or greater (MOG)-level turbulence events, respectively. CAT events are classified as tropopause/jet stream–induced CAT (TJCAT) and mountain-wave-induced CAT (MWCAT) events. The MOG-level TJCAT and MWCAT events are responsible for 41.2% and 19.6% of the total MOG-level turbulence events, respectively. The CIT events in summer and the TRCAT and MWCAT events in spring occur most frequently over the previously mentioned regions of South Korea, associated with specific generation mechanisms.

scholarly journals TanDEM-X PolarDEM 90 m of Antarctica: generation and error characterization

2021 ◽  
Vol 15 (11) ◽  
pp. 5241-5260
Author(s):  
Birgit Wessel ◽  
Martin Huber ◽  
Christian Wohlfart ◽  
Adina Bertram ◽  
Nicole Osterkamp ◽  
...  
Keyword(s):  
Data Set ◽  
High Resolution Data ◽  
Ice Cloud ◽  
Amplitude Data ◽  
Open Sea ◽  
Digital Elevation ◽  
Error Characterization ◽  
Antarctic Continent ◽  
Set Up ◽  
Elevation Model

Abstract. We present the generation and validation of an updated version of the TanDEM-X digital elevation model (DEM) of Antarctica: the TanDEM-X PolarDEM 90 m of Antarctica. Improvements compared to the global TanDEM-X DEM version comprise filling gaps with newer bistatic synthetic aperture radar (SAR) acquisitions of the TerraSAR-X and TanDEM-X satellites, interpolation of smaller voids, smoothing of noisy areas, and replacement of frozen or open sea areas with geoid undulations. For the latter, a new semi-automatic editing approach allowed for the delineation of the coastline from DEM and amplitude data. Finally, the DEM was transformed into the cartographic Antarctic Polar Stereographic projection with a homogeneous metric spacing in northing and easting of 90 m. As X-band SAR penetrates the snow and ice pack by several meters, a new concept for absolute height adjustment was set up that relies on areas with stable penetration conditions and on ICESat (Ice, Cloud, and land Elevation Satellite) elevations. After DEM generation and editing, a sophisticated height error characterization of the whole Antarctic continent with ICESat data was carried out, and a validation over blue ice achieved a mean vertical height error of just −0.3 m ± 2.5 m standard deviation. The filled and edited Antarctic TanDEM-X PolarDEM 90 m is outstanding due to its accuracy, homogeneity, and coverage completeness. It is freely available for scientific purposes and provides a high-resolution data set as basis for polar research, such as ice velocity, mass balance estimation, or orthorectification.

scholarly journals Space-time high-resolution data of the potential insolation and solar duration for Montenegro

Spatium ◽  
2020 ◽  
pp. 45-52
Author(s):  
Branislav Bajat ◽  
Ognjen Antonijevic ◽  
Milan Kilibarda ◽  
Aleksandar Sekulic ◽  
Jelena Lukovic ◽  
...  
Keyword(s):  
High Resolution ◽  
Spatial Resolution ◽  
Power Plants ◽  
Solar Panels ◽  
Renewable Energy Resources ◽  
High Resolution Data ◽  
Digital Elevation ◽  
Solar Power Plants ◽  
Environment Agency ◽  
Elevation Model

The assessment of the potential use of renewable energy resources requires reliable and precise data inputs for sustainable energy planning on a regional, national and local scale. In this study, we examine high spatial resolution grids of potential insolation and solar duration in order to determine the location of potential solar power plants in Montenegro. Grids with a 25-m spatial resolution of potential solar radiation and duration were produced based on observational records and publicly available high-resolution digital elevation model provided by the European Environment Agency. These results could be further used for the estimation and selection of a specific location for solar panels. With an average annual potential insolation of 1800 kWh/m? and solar duration of over 2000 h per year for most of its territory, Montenegro is one of the European countries with the highest potential for the development, production, and consumption of solar energy.

scholarly journals A METHOD TO GENERATE FLOOD MAPS IN 3D USING DEM AND DEEP LEARNING

2020 ◽  
Vol XLIV-M-2-2020 ◽  
pp. 25-28
Author(s):  
A. Gebrehiwot ◽  
L. Hashemi-Beni
Keyword(s):  
Deep Learning ◽  
High Resolution ◽  
Image Classification ◽  
Three Dimensional ◽  
Integrated Approach ◽  
High Resolution Data ◽  
Water Index ◽  
Digital Elevation ◽  
Inundation Map ◽  
Elevation Model

Abstract. High-resolution remote sensing imagery has been increasingly used for flood applications. Different methods have been proposed for flood extent mapping from creating water index to image classification from high-resolution data. Among these methods, deep learning methods have shown promising results for flood extent extraction; however, these two-dimensional (2D) image classification methods cannot directly provide water level measurements. This paper presents an integrated approach to extract the flood extent in three-dimensional (3D) from UAV data by integrating 2D deep learning-based flood map and 3D cloud point extracted from a Structure from Motion (SFM) method. We fine-tuned a pretrained Visual Geometry Group 16 (VGG-16) based fully convolutional model to create a 2D inundation map. The 2D classified map was overlaid on the SfM-based 3D point cloud to create a 3D flood map. The floodwater depth was estimated by subtracting a pre-flood Digital Elevation Model (DEM) from the SfM-based DEM. The results show that the proposed method is efficient in creating a 3D flood extent map to support emergency response and recovery activates during a flood event.

scholarly journals River Bathymetry Model Based on Floodplain Topography

Water ◽  
2019 ◽  
Vol 11 (6) ◽  
pp. 1287
Author(s):  
Ludek Bures ◽  
Petra Sychova ◽  
Petr Maca ◽  
Radek Roub ◽  
Stepan Marval
Keyword(s):  
Hydrodynamic Model ◽  
State Of The Art ◽  
Model Parameters ◽  
Hydrodynamic Modelling ◽  
The Czech Republic ◽  
Bed Topography ◽  
Digital Elevation ◽  
Proposed Model ◽  
Elevation Model

An appropriate digital elevation model (DEM) is required for purposes of hydrodynamic modelling of floods. Such a DEM describes a river’s bathymetry (bed topography) as well as its surrounding area. Extensive measurements for creating accurate bathymetry are time-consuming and expensive. Mathematical modelling can provide an alternative way for representing river bathymetry. This study explores new possibilities in mathematical depiction of river bathymetry. A new bathymetric model (Bathy-supp) is proposed, and the model’s ability to represent actual bathymetry is assessed. Three statistical methods for the determination of model parameters were evaluated. The best results were achieved by the random forest (RF) method. A two-dimensional (2D) hydrodynamic model was used to evaluate the influence of the Bathy-supp model on the hydrodynamic modelling results. Also presented is a comparison of the proposed model with another state-of-the-art bathymetric model. The study was carried out on a reach of the Otava River in the Czech Republic. The results show that the proposed model’s ability to represent river bathymetry exceeds that of his current competitor. Use of the bathymetric model may have a significant impact on improving the hydrodynamic model results.

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