Table 3. Viewshed analysis method

Researcher Viewshed analysis Definition Analysis method Note
A Reverse-viewshed frequency analysis Analyzes the viewshed of the surroundings from the target area, contrary to previous methods • Reverse the viewshed analysis • Select points with view concerns as LCPs • Improves accuracy of landscape impact assessment • Reduces unnecessary LCPs to be selected
B Viewshed frequency analysis An analysis presented as an arithmetic operation of the frequency analysis of multiple viewpoints Multiple LCP to viewshed analysis • Presents results of the viewshed frequency analysis from multi-layered multiple viewpoints as frequency using an arithmetic operation • Convenient to determine significance of the viewshed in a large apartment complex or a new town • As it is represented as frequency, it is possible to identify important observation locations
C Sight-surface analysis Analyzes the difference between line of sight and topographic heights difference analysis in height between the sight-surface and terrain • Analyzes the difference between topographic heights and line of sight from where a viewer observes the view target frequency analysis of multiple LCP to viewshed analysis • Line of sight: an imaginary line to project the sight of a viewer • Surface of sight: A surface consisting of a number of lines of sight
D Sequence sight-surface analysis Analyzes the difference between line of sight and topographic heights from a multi-viewpoint •Identifies criteria for views and multi-viewpoint • Sets minimum and maximum view lines within the view distance and identifies an angle where the two lines cross at the spot of equal height • Provides objective results of the plan for mountainous skylines • Used to regulate the height of buildings