On the Number of Views of Polyhedral Terrains

Experimental Verification of a Realistic Input Model for Polyhedral Terrains

A realistic input model for polyhedral terrains was introduced in [16]. With this model, improved upper and lower bounds on the combinatorial complexity of visibility and distance structures on these terrains were obtained. In this paper, we perform experiments with realworld data to determine how realistic the assumptions of that input model are, by examining what the values of the model param...

F G Representing the Visibility Structure of a Polyhedral Terrain through a Horizon Map : Digital Terrain Models, Visibility, Data Structures, Horizons : a Horizon-based Visibility Map for Terrains

horizon map Representing the Visibility Structure of a Polyhedral Terrain through a Horizon Map We present a model for describing the visibility of a polyhedral terrain from a xed viewpoint, based on a collection of nested horizons. We brie y introduce the concepts of mathematical and digital terrain models, and some background notions for visibility problems on terrains. Then, we de ne horizon...

Algorithms for Triangulated Terrains

Digital elevation models can represent many types of geographic data. One of the common digital elevation models is the triangulated irregular network (also called TIN, or polyhedral terrain, or triangulated terrain). We discuss ways to represent a TIN in a data structure, and give some of the basic algorithms that work on TINs. These include retrieving contour lines, computing perspective view...

Optimization of polyhedral terrains

Guarding Polyhedral Terrains

We prove that [n/2J vertex guards are always sufficient and sometimes necessary to guard the surface of an n-vertex polyhedral terrain. We also show that l(4n 4)/13J edge guards are sometimes necessary to guard the surface of an n-vertex polyhedral terrain. The upper bound on the number of edge guards is ln/3J (Everett and Rivera-Campo, 1994). Since both upper bounds are based on the four color...