GIS For Dummies

The most common form of raster surface model is called the Digital Elevation Model (DEM), which was developed by the United States Geological Survey (USGS) to store and eventually process topographical surface data.

One other factor both characterizes the complexity of a network and adds to the robustness of traffic modeling capabilities. That characteristic, called circuitry, is based on the idea of closed loops. Closed loops allow moving objects, fluids, and so forth to travel alternate routes when moving along a network

Raster generally provides visually less desirable output (especially with its coarser resolution) than vector.

Raster is faster (computationally) than vector.

This data structure, the Triangulated Irregular Network (TIN), represents surfaces and volumes as a collection of non-overlapping triangles, which is very similar to the way that computer games model 3-D objects.

Raster is compatible with much scanned and remotely sensed data.

Raster is more powerful for modeling than vector.

Raster data takes up more computer space than vector data.

One of the many possible coordinate systems that you may encounter in GIS is called the UTM system. UTM stands for Universal Transverse Mercator, which is the most commonly used system.