scholarly journals Characterization of a human brain cortical surface mesh using discrete curvature classification and digital elevation model

2012 ◽  
Vol 05 (03) ◽  
pp. 133-140 ◽  
Author(s):  
Kamel Aloui ◽  
Amine Naït-Ali ◽  
Mohamed Saber Naceur
Keyword(s):  
Human Brain ◽  
Digital Elevation Model ◽  
Cortical Surface ◽  
Surface Mesh ◽  
Discrete Curvature ◽  
Digital Elevation ◽  
Elevation Model

scholarly journals A high-fidelity multiresolution digital elevation model for Earth systems

2017 ◽  
Vol 10 (1) ◽  
pp. 239-253 ◽  
Author(s):  
Xinqiao Duan ◽  
Lin Li ◽  
Haihong Zhu ◽  
Shen Ying
Keyword(s):  
Digital Elevation Model ◽  
Voronoi Tessellation ◽  
High Fidelity ◽  
Discrete Curvature ◽  
Earth Systems ◽  
Digital Elevation ◽  
Elevation Model ◽  
Curvature Distribution ◽  
Input Uncertainties ◽  
The Impact

Abstract. The impact of topography on Earth systems variability is well recognised. As numerical simulations evolved to incorporate broader scales and finer processes, accurately assimilating or transforming the topography to produce more exact land–atmosphere–ocean interactions, has proven to be quite challenging. Numerical schemes of Earth systems often use empirical parameterisation at sub-grid scale with downscaling to express topographic endogenous processes, or rely on insecure point interpolation to induce topographic forcing, which creates bias and input uncertainties. Digital elevation model (DEM) generalisation provides more sophisticated systematic topographic transformation, but existing methods are often difficult to be incorporated because of unwarranted grid quality. Meanwhile, approaches over discrete sets often employ heuristic approximation, which are generally not best performed. Based on DEM generalisation, this article proposes a high-fidelity multiresolution DEM with guaranteed grid quality for Earth systems. The generalised DEM surface is initially approximated as a triangulated irregular network (TIN) via selected feature points and possible input features. The TIN surface is then optimised through an energy-minimised centroidal Voronoi tessellation (CVT). By devising a robust discrete curvature as density function and exact geometry clipping as energy reference, the developed curvature CVT (cCVT) converges, the generalised surface evolves to a further approximation to the original DEM surface, and the points with the dual triangles become spatially equalised with the curvature distribution, exhibiting a quasi-uniform high-quality and adaptive variable resolution. The cCVT model was then evaluated on real lidar-derived DEM datasets and compared to the classical heuristic model. The experimental results show that the cCVT multiresolution model outperforms classical heuristic DEM generalisations in terms of both surface approximation precision and surface morphology retention.

Micro-Surface Construction and Characterization From Digital Elevation Model Using Thin Plate Splines in Matlab Environment

2006 ◽  
Author(s):  
Mohammad Mayyas ◽  
Panos S. Shiakolas
Keyword(s):  
Digital Elevation Model ◽  
Thin Plate ◽  
Real Surface ◽  
Thin Plate Splines ◽  
Digital Elevation ◽  
Surface Irregularities ◽  
Elevation Model ◽  
Energy Surfaces ◽  
Surface Construction

The Thin Plate Splines (TPS) theory is modified and employed in the reconstruction of 2D 1/2 unfolded micro-topographical surfaces. The modified TPS allows the reconstruction of MEMS structures based on sampled digital elevation model (DEM). The developed algorithms are implemented in MATLAB and applied to restore bad samples, enhance surface reconstruction, and compensate for surface irregularities for micromachining purposes. In addition, the restored surface reveals the scale components of the real surface (roughness, waviness and form). The irregularity of meso, micro and nano surfaces is then characterized into slope, curvature, strike, dip, azimuth and energy surfaces. It is concluded that the simplicity, differentiability of TPS and roughness components relaxation make the proposed theory advantageous on reconstruction and characterization of micro surfaces for a variety of applications.

STUDY OF THE LANDSLIDE MORPHOLOGY BASED ON GNSS DATA AND AIRBORNE SOUNDING (ON THE EXAMPLE OF A SECTION OF THE PROTVA RIVER VALLEY)

2018 ◽  
Vol 12 (5-6) ◽  
pp. 50-57 ◽  
Author(s):  
I. S. Voskresensky ◽  
A. A. Suchilin ◽  
L. A. Ushakova ◽  
V. M. Shaforostov ◽  
A. L. Entin ◽  
...  
Keyword(s):  
Digital Elevation Model ◽  
Geodetic Network ◽  
Aerial Survey ◽  
River Valley ◽  
Ease Of Use ◽  
Digital Elevation ◽  
Loose Deposits ◽  
Positioning Method ◽  
Landslide Body ◽  
Elevation Model

To use unmanned aerial vehicles (UAVs) for obtaining digital elevation models (DEM) and digital terrain models (DTM) is currently actively practiced in scientific and practical purposes. This technology has many advantages: efficiency, ease of use, and the possibility of application on relatively small area. This allows us to perform qualitative and quantitative studies of the progress of dangerous relief-forming processes and to assess their consequences quickly. In this paper, we describe the process of obtaining a digital elevation model (DEM) of the relief of the slope located on the bank of the Protva River (Satino training site of the Faculty of Geography, Lomonosov Moscow State University). To obtain the digital elevation model, we created a temporary geodetic network. The coordinates of the points were measured by the satellite positioning method using a highprecision mobile complex. The aerial survey was carried out using an unmanned aerial vehicle from a low altitude (about 40–45 m). The processing of survey materials was performed via automatic photogrammetry (Structure-from-Motion method), and the digital elevation model of the landslide surface on the Protva River valley section was created. Remote sensing was supplemented by studying archival materials of aerial photography, as well as field survey conducted immediately after the landslide. The total amount of research results made it possible to establish the causes and character of the landslide process on the study site. According to the geomorphological conditions of formation, the landslide refers to a variety of landslideslides, which are formed when water is saturated with loose deposits. The landslide body was formed with the "collapse" of the blocks of turf and deluvial loams and their "destruction" as they shifted and accumulated at the foot of the slope.

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