These operations work with the spatial elements as they were entered in the data base. Information from database tables can be accessed directly through the map, or new maps can be created using information in the tabular database. Both graphic and tabular data must be stored in formats the computer can recognize and retrieve. Classification Classification is the procedure of identifying a set of features as belonging to a group and defining patterns. In a raster-based GIS, numerical values are often used to indicate classes.
Classification is important because it defines patterns.
One of the important functions of a GIS is to assist in recognizing new patterns. Classification is done using single data layers, as well as with multiple data layers as part of an overlay operation. Generalization , also called map dissolve , is the process of making a classification less detailed by combining classes. Generalization is often used to reduce the level of classification detail to make an underlying pattern more apparent. Verification Verification is a procedure for checking the values of attributes for all records in a database against their correct values.