地理信息系统导论chap13.ppt

Raster vs. TIN As inputs to terrain mapping and analysis, rasters and TINs differ in data flexibility and computational efficiency. A main advantage of using a TIN lies in the flexibility with input data sources Computational efficiency is the main advantage of using rasters for terrain analysis. * Chapter 13. TERRAIN MAPPING AND ANALYSIS 13.1 Data for Terrain Mapping and Analysis 13.1.1 DEM Box 13.1 An Application Example of LIDAR DEM 13.1.2 TIN 13.2 Terrain Mapping 13.2.1 Contouring 13.2.2 Vertical Profiling 13.2.3 Hill Shading Box 13.2 The Pseudoscopic Effect Box 13.3 A Worked Example of Computing Relative Radiance 13.2.4 Hypsometric Tinting 13.2.5 Perspective View 13.3 Slope and Aspect 13.3.1 Computing Algorithms for Slope and Aspect Using Raster Box 13.4 Conversion of D to Aspect Box 13.5 A Worked Example of Computing Slope and Aspect Using Raster 13.3.2 Computing Algorithms for Slope and Aspect Using TIN Box 13.6 A Worked Example of Computing Slope and Aspect Using TIN 13.3.3 Factors Influencing Slope and Aspect Measures 13.4 Surface Curvature Box 13.7 A Worked Example of Computing Surface Curvature 13.5 Raster Versus TIN Key Concepts and Terms Review Questions Applications: Terrain Mapping and Analysis Task 1: Use DEM for Terrain Mapping Task 2: Derive Slope, Aspect, and Curvature from DEM Task 3: Build and Display a TIN Challenge Task References Data for Terrain Mapping and Analysis DEM (digital elevation model) and TIN (triangulated irregular network) are two common types of input data for terrain mapping and analysis. A DEM represents a regular array of elevation points. It can be converted to an elevation raster by placing each elevation point at the center of a cell. The USGS offers DEMs in three spatial resolutions: 1 arc-second (30 m), 1/3 arc-second (10 m), and 1/9 arc-second (3 m). Additionally, LIDAR data are increasingly being used for studies that require detailed topographic data. A TIN approximates the land surface with a series of nonoverlap