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.
Highlights
Relief characteristics have always been of great importance for the perception of the landscape.Surveyors were excited to learn about the development of aerial photogrammetry a century ago
In an attempt to overcome the limitations, we propose a new visualization method based on a relief parameter called sky-view factor
We argue that sky-view factor is not just an effective visualization method and a powerful spatial analysis method that can be used in numerous applications
Summary
Relief characteristics have always been of great importance for the perception of the landscape. The focus of interest has moved towards automated image matching, the interferometric synthetic aperture radar (InSAR), and airborne laser scanning (ALS) All these techniques allow very fast and dense relief sampling. Digital elevation models (DEMs) [2] are a typical result of relief acquisition. Hill-shading gained importance in the 19th century with the “Swiss Style” maps. In an attempt to overcome the limitations, we propose a new visualization method based on a relief parameter called sky-view factor. Sky-view factor can be used as a proxy for diffuse illumination of relief which makes it a good alternative to the standard analytical hill-shading. We argue that sky-view factor is not just an effective visualization method and a powerful spatial analysis method that can be used in numerous applications
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