Introducing Geographic Information Systems with ArcGIS: A Workbook Approach to Learning GIS, 3rd Edition

TIN-Based Geographic Data Sets—Layout in the Computer

If you look at a TIN in terms of folders and files, you find a single folder, residing within a work space, with a bunch of files within it. As with all spatial data sets, if you want to copy it, move it around, or rename it, you must do so with ArcCatalog, not the operating system.

The primary apparent difference between a TIN data set and other GIS data sets is that there is no attribute table. You can, however, use the Identify tool with TINs. It provides the elevation, slope, and aspect, as well as some additional information tags that the user may add. How does it do this? By calculating information on the fly when you click on a point in the TIN.

For particular problems such as surface analysis, surface display, and hydrological analysis, TINs can be quite useful. You will see more of them in future chapters.

Terrains

An Esri Terrain dataset is a TIN-based surface that may be viewed at several levels of resolution derived from measurements stored in one or more feature classes in a geodatabase. An Esri Terrain is not actually stored in its entirety but is calculated as needed, because of the great size of the datasets that underlie it and the fact that only smaller portions of those datasets are needed at any one time. The principle is sort of similar to a handheld calculator approach to providing functions such as square root or sine. Rather than storing the values in a table they are calculated from a formula as needed. ...