A Uniform Sky Illumination Model to Enhance Shading of Terrain and Urban Areas

@article{Kennelly2006AUS,
  title={A Uniform Sky Illumination Model to Enhance Shading of Terrain and Urban Areas},
  author={Peter J. Kennelly and A. James Stewart},
  journal={Cartography and Geographic Information Science},
  year={2006},
  volume={33},
  pages={21 - 36}
}
Users of geographic information systems (GIS) usually render terrain using a point light source defined by an illumination vector. A terrain shaded from a single point provides good perceptual cues to surface orientation. This type of hill shading, however, does not include any visual cues to the relative height of surface elements. We propose shading the terrain under uniform diffuse illumination, where light arrives equally from all directions of a theoretical sky surrounding the terrain… 
HILL-SHADING TECHNIQUES TO ENHANCE TERRAIN MAPS
Maps shading terrain as if illuminated by a point light source (i.e. hill-shading) are commonly used in cartographic displays. These hill-shaded maps are especially important for representing
HILL-SHADING BASED ON ANISOTROPIC DIFFUSE ILLUMINATION
TLDR
This contribution explores alternative terrain visualization techniques based on diffuse, rather than direct, illumination and shows that such a visualization improves the recognition of local scale features on high resolution DEMs, which is very important in different applications: visual inspection of DEM, recognition of archaeological features, etc.
General sky models for illuminating terrains
TLDR
It is argued that this process of creating hill-shaded visualizations of terrain with sky models shows parallels to other geo-simulations, and that basing such work on standards from the computer graphics industry shows potential for its use in VGE.
1 TEXTURE SHADING : A NEW TECHNIQUE FOR DEPICTING TERRAIN RELIEF
While conventional relief shading based on hillslope and illumination models has a long and successful history for visualization of mountainous topography, it also suffers certain limitations. Among
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TLDR
The aim of this work is to evaluate analytical hillshading methods against a set of landforms within an online survey and revealed that the clear sky model performs best applied to most of the landforms included in the survey, in particular all the mountain and valley types.
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TLDR
This research indicates that when the method of fusing the processed SRM with the IHS color system is used, the optimum index factor (OIF) and entropy of the generated map are much greater than for the results of the traditional method, which can greatly enhance the terrain effect.
A novel method for determining sky view factor for isotropic diffuse radiations for a collector in obstacles-free or urban sites
A novel method for computing sky view factor for isotropic diffuse radiations on tilted collectors located in obstacle free and urban sites has been introduced in this paper. The proposed method
Improving the representation of major landforms in analytical relief shading
TLDR
An automated digital method is introduced that produces shaded relief with locally adjusted illumination directions to simulate the techniques and cartographic principles of manual relief shading and best highlights major landforms in terrain characterized by sharp, clearly defined ridges and valleys.
Automated Reduction of Visual Complexity in Small-Scale Relief Shading
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A new method of generalizing digital elevation models for deriving small-scale shaded relief that resembles the manual style is proposed, which consists of the following raster operations.
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