Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
Results
Showing 1 to 20 of 80 for “"DEMs"”.
-
On the development of a digital elevation model over South Africa using ground and satellite data
… represents the bare land surface of the Earth. DEMs are used in a wide range of applications, including geological studies, geomorphology, water resources and hydrology, evaluation of natural hazards, and vegetation surveys. In recent years, DEMs have increasingly been used in geographic …
-
Suitability of Aster and SRTM dems, and satellite imagery in detailed geomorphological mapping in Dzanani Area of Makhado Local Municipality, Limpopo Province, Republic of South Africa
… is to assess the suitability of ASTER and SRTM DEMs, and satellite imagery in detailed geomorphological mapping. Field survey and aerial photo interpretation were used to prepare a reference geomorphological map for comparisons. A similar approach of demarcating landform boundaries from aerial …
-
Digital terrain analysis to predict soil spatial patterns at the Hubbard Brook Experimental Forest
… analysis using digital elevation models (DEMs) has become commonplace in soil and hydrologic modeling and analysis and there has been considerable assessment of the effects of grid resolution on topographic metrics using DEMs of 10 m resolution or coarser. However, examining fine-scale …
-
Analysis and visualisation of digital elevation data for catchment management
… of water and sediment. Digital Elevation Models (DEMs) are widely used to simulate overland water paths in hydrological models. However, all DEMs are approximations to some degree and it is widely recognised that their characteristics can vary according to attributes such as spatial resolution and …
-
Use of the fractal dimension in characterization of terrestrial surfaces
… by decreasing the grid sampling interval of the DEMs in a systematic manner. The three DEMs examined were of a homogeneous character and were sampled on a 3 arc second latitude and longitude grid interval. The DEMs represented three distinct terrain types, subjectively described as smooth, …
-
Global Digital Elevation Model Accuracy Assessment in the Himalaya, Nepal
<p>Digital Elevation Models (DEMs) are digital representations of surface topography or terrain. Collection of DEM data can be done directly through surveying and taking ground control point (GCP) data in the field or indirectly with remote sensing using a variety of techniques. The accuracies of …
-
Comparison of Two Algorithms for Removing Depressions and Delineating Flow Networks From Grid Digital Elevation Models
Digital elevation models (DEMs) and their derivatives such as slope, flow direction and flow accumulation maps, are used frequently as inputs to hydrologic and nonpoint source modeling. The depressions which are frequently present in DEMs may represent the actual topography, but are often the …
-
Enhancement of digital elevation models using tree-based ensemble machine learning algorithms
… revision. Thus, global digital elevation models (DEMs) have gained worldwide prominence due to their free availability; a prime advantage when compared to prohibitively expensive airborne topographic surveys. However, the accuracies of global DEMs are affected by several anomalies that diminish …
-
Analysis of microtopography, vegetation, and active-layer thickness using terrestrial LIDAR and kite photography, Barrow, AK
… four 10 cm resolution digital elevation models (DEMs). Elevation data, collected using differential global positioning system (DGPS) to assess heave and subsidence, has been gathered annually since 2004 and was used to assess the accuracy of the DEMs generated for August 2010. Higher-resolution …
-
Analysis of microtopography, vegetation, and active-layer thickness using terrestrial LIDAR and kite photography, Barrow, AK
… four 10 cm resolution digital elevation models (DEMs). Elevation data, collected using differential global positioning system (DGPS) to assess heave and subsidence, has been gathered annually since 2004 and was used to assess the accuracy of the DEMs generated for August 2010. Higher-resolution …
-
ARRAY PROCESSING TECHNIQUES FOR ESTIMATION AND TRACKING OF AN ICE-SHEET BOTTOM
… in 2014, and produce digital elevation models (DEMs) for 102 data frames. We perform crossover analysis to self-assess the generated DEMs, where flight paths cross over each other and two measurements are made at the same location. Also, the tracked results are compared before and after manual …
-
Small-volume monogenetic igneous landforms and edifices statistics (SMILES) of Earth and Mars: one morphometric framework to classify them all
… of terrestrial Digital Elevation Models (DEMs) derived from uncrewed aerial system (UAS) photogrammetry was evaluated by an iterative approach and by comparing these DEM to LiDAR datasets. UAS DEMs are reasonably accurate and reproducible for morphometric analysis. These results reinforce …
-
Analysis of Viewshed Accuracy with Variable Resolution LIDAR Digital Surface Models and Photogrammetrically-Derived Digital Elevation Models
… using "bare-earth" Digital Elevation Models (DEMs) derived from the process of photogrammetry. More detailed models, known as Digital Surface Models (DSMs), are often generated using Light Detection and Ranging (LIDAR) which uses an airborne laser to scan the terrain. In addition to having …
-
Enhanced Soil Moisture and Streamflow Estimation in Ungauged or Data-Scarce Watersheds
… showed that low-resolution LiDAR and USGS DEMs outperformed high-resolution LiDAR DEMs, with equal-interval classification yielding the best performance. The result showed resampling to a lower resolution improved the performance of LiDAR DEMs, while TICs derived from publicly available …
-
Locality of Topographic Ground Truth Data for Salt Marsh Lidar DEM Elevation Bias Mitigation Using Machine Learning
… and ranging (lidar) digital elevation models (DEMs) are crucial for modeling coastal salt marsh systems, simulating the coastal dynamics of sea level rise (SLR), and predicting storm surge inundation depth and duration. Improvements in lidar acquisition technology and data processing over the …
-
Analysis of landslide volume, structures, and kinematics from satellite imagery of the 2016 Lamplugh rock avalanche, Glacier Bay National Park and Preserve, Alaska, An
… high-resolution (2m) Digital Elevation Models (DEMs). Differenced DEMs were used to calculate both source and deposit volumes and examine variations in deposit thickness. DEMs were also used in conjunction with high-resolution (~0.5m) optical imagery to map landslide structures and surficial …
-
Multi-Scale detection, mapping, and modelling geomorphic change in gravel-bed rivers with UAV remote sensing
… case study, four series of very high resolution DEMs (digital elevation model) and orthomosaic imagery are produced for a 2km reach of quasi-wandering gravel-bed river. Comparative analyses of DEMs between 2016 and 2018 reveals widening of the incised margin and significant geomorphic evolution …
-
Investigation of oxidation in nonaqueous lithium-air batteries
… differential electrochemical mass spectrometer (DEMS) designed and built over the course of this thesis, we showed that Ru-containing electrodes produce oxygen throughout the oxidation of Li₂O₂, while Pt generated both carbon dioxide and oxygen, indicative of electrolyte decomposition. These …
-
In-situ investigation and mitigation of carbon support corrosion of cathode catalyst in PEM fuel cells
… differential electrochemical mass spectrometry (DEMS) spectra of cathode exhaust gases, CO₂, H₂ and O₂, from a PEMFC fed with humidified H₂ and He to the anode and cathode respectively. Furthermore, the catalytic effects on CSC from different oxidation states of Pt were indicated. To determine …
Page 1 of 4