a general data model that's modified to address the specific data and query needs for a given application is called a schema.

When you establish a relational join, all the information in the first table is shared with all the information in the second table, which is much easier than trying to make a huge, complex, comprehensive table from scratch. It's much easier to design small, individual, focused tables (that can be related to other small ones) than to create large,

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

shapefile) stores the geometry of each feature as a shape that contains the coordinates and links to the attributes. GIS software packages widely use this data model today because of its relatively low processing overhead, low storage requirements, fast drawing speeds, and its ability to handle overlaps and non-contiguous features. You can also, wi

ESRI and its software users have created an ever-increasing array of industry-specific schemas that they refer to as geodatabase models. ESRI intended not only to share these schemas, but also to use them as examples for other industries when developing their own schemas.

TIGER files are readily available both from the U.S. Bureau of the Census and third-party vendors who often repackage the files. TIGER files are compatible with a vast array of other data types, possess lots of data already in this format, and constitute an elegant implementation of the topological data model, so they're likely to be around for a w

When you treat networks as corridors, the movement of fluids, objects, animals, and/or vehicles is your primary concern. For any movement, the nature of the network as a corridor has an impact on how fast things move and in some cases, even whether they move at all. The resistance to movement is called impedance and can be a function of the size of

You can measure connectivity in a network by comparing the number of actual node-to-node links that exist in a given network to the maximum number of nodes that are possible. This measure of connectivity is called the gamma index. Usually, the index ranges from a value of 0 (which indicates no connected links at all) to 1 (where all possible links

If you want GIS to be useful for finding solutions to geographic problems, it needs to be appropriate (to the degree possible) in the following ways: Scale or resolution: How much detail do you need for your study? Measurement level: Do you need interval data, or are categories enough? Accuracy: How well can your measurement tool capture your data?