This paper brings forward a Digital Earth-based DEM server model – TON (Terrain On the INTERNET). TON takes client/server architecture and closely integrates with WWW server. The server side of TON builds multiresolution terrain database in a quadtree structure, which offers an effective method to retrieve terrain data. The client side of TON integrates with WWW browser as a component, which su...

To solve the problem of three-dimensional terrain simplification in large-scale based on digital elevation model data, a terrain simplified method based on the theory of spatial autocorrelation was proposed. According to principle of regional similarities in geomorphology, a cluster analysis was performed on the terrain data to get the thresholds distinguish terrain features. On the basis, the ...

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...

The geographical distribution of growing degree-days (GDDs) within Iran was studied using GIS-based maps. GDDs were calculated using daily thermal parameters (daily maximum and minimum air temperature). Based on the purpose of the study and climatic conditions of Iran, the average value of 5?C was chosen for GDD calculation. The calculations were carried out using daily weather data of 113 mete...

The problem of real-time photorealistic imaging of digital terrain is discussed. New technique for specifying digital terrain by scalar perturbation functions without its approximation by polygons is considered. A recursive algorithm for object space subdivision with masking of invisible surfaces and an effective technique of projective transformation for perspective imaging are proposed. The p...

Building a digital terrain model (DTM) from LiDAR data can successfully be performed using a few techniques, but the quality of the resulted model and the way the terrain information is handled during the processing phase remain a challenge. A new framework for creating a DTM from LiDAR data within ArcGIS ® utilizes the new ESRI data structure known as Terrain Data Set (TDS). This article prese...