Terrain maps displaying hill-shading with curvature

Kennelly, Patrick

doi:10.1016/j.geomorph.2008.05.046

Cited by 73 publications

(61 citation statements)

References 15 publications

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“…In order to achieve the best visual interpretation it therefore makes sense to combine both techniques (e.g., with the use of a transparent overlay; Figure 9). A similar approach was already proposed by Kennelly [44] who combined relief hill-shading and curvature. As curvature considers only the closest pixels, our tests indicate that a combination of hill-shading and SVF based visualization is more effective.…”

Section: Figurementioning

confidence: 97%

Sky-View Factor as a Relief Visualization Technique

2011

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Abstract:Remote sensing has become the most important data source for the digital elevation model (DEM) generation. DEM analyses can be applied in various fields and many of them require appropriate DEM visualization support. Analytical hill-shading is the most frequently used relief visualization technique. Although widely accepted, this method has two major drawbacks: identifying details in deep shades and inability to properly represent linear features lying parallel to the light beam. Several authors have tried to overcome these limitations by changing the position of the light source or by filtering. This paper proposes a new relief visualization technique based on diffuse, rather than direct, illumination. It utilizes the sky-view factor-a parameter corresponding to the portion of visible sky limited by relief. Sky-view factor can be used as a general relief visualization technique to show relief characteristics. In particular, we show that this visualization is a very useful tool in archaeology as it improves the recognition of small scale features from high resolution DEMs.

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Section: Figurementioning

confidence: 97%

Sky-View Factor as a Relief Visualization Technique

2011

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“…Terrain surface critical points such as peaks, pits, and saddles are treated as gravity equilibria and key elements depicting the surface geometry in the large (Banchoff, 1967;Milnor, 1963); a further extension of the critical points on secondorder surface derivatives will describe a more fundamental terrain geometry shape (Jenny et al, 2011;Kennelly, 2008). When constructing a generalised DEM surface, these feature points are commonly used as a base set, and additional input points, or pre-extracted terrain structures, are embedded for further approximation (Guilbert et al, 2014;Zakšek and Podobnikar, 2005;Zhou and Chen, 2011).…”

Section: Curvature As Density Functionmentioning

confidence: 99%

“…For optimised spatial distribution of these sample points, we calculate a robust discrete mean curvature as a density function, which is based on the recognition of curvature's flexibility in capturing shape characteristics and capability in conducting shape evolution (Banchoff, 1967;Kennelly, 2008;Pan et al, 2012). Curvature's ability to flexibly describe terrain morphology has been appreciated by many researchers.…”

Section: Curvature As Density Functionmentioning

confidence: 99%

“…Curvature's ability to flexibly describe terrain morphology has been appreciated by many researchers. For example, Kennelly (2008) noted that, compared to the results of the flow accumulation model, curvature-based delineation of drainage networks is not limited to 1 pixel thickness and requires no depression filling. The robust discrete curvature calculation is referred to in Meyer et al (2003).…”

Section: Curvature As Density Functionmentioning

confidence: 99%

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A high-fidelity multiresolution digital elevation model for Earth systems

Duan¹,

Lin

Zhu³

et al. 2017

Geosci. Model Dev.

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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.

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“…Beside the simple version of the method there are its modifications. They are based on combining two types of the shading effect induced by different positions of the light source: oblique shading and slope shading (KENNELLY 2008), (PATTERSON and HERMANN 2004). In combined shading the principle of depicting slopes: ''the steeper, the darker'' is preserved together with the 3D effect property of oblique shading (IMHOF 1982).…”

Section: Introductionmentioning

confidence: 99%

Towards a More Realistic Depiction of the Earth’s Surface on Maps

Drachal

Dębowska

2013

Pure Appl. Geophys.

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Abstract-In 2000, the shuttle radar topography mission (SRTM) produced the most complete, highest resolution digital elevation model (DEM) of the Earth. These data were used to create global 3 00 DEM and to correct 30 00 DEM which are both available on the internet. After a careful survey in the Institute of Geodesy and Cartography, Poland, these elevation data were recognized as extremely valuable and worth developing a unique form of visualization. As a result, a new design of a physical map of Europe at scale of 1:10 million was developed. For depicting the shape of the terrain, an original modification of combined shaded relief was employed, to reveal all the nuances of elevation data. True colors of the Earth's surface represented on the map originated from MODIS satellite image. The combination of true colors and terrain features made a realistic map, showing the landscapes as if from a point above the Earth. The image of the terrain is extremely detailed as it is based on the abundance of data defining the elevation of each point of land.

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Terrain maps displaying hill-shading with curvature

Cited by 73 publications

References 15 publications

Sky-View Factor as a Relief Visualization Technique

Sky-View Factor as a Relief Visualization Technique

A high-fidelity multiresolution digital elevation model for Earth systems

Towards a More Realistic Depiction of the Earth’s Surface on Maps

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