Typify is one type of cartographic generalization operation in which a large, often cluttered set of similar features is replaced with a smaller set of those features.. It helps to create a simple and smooth view of the data represented on the map.
A common example of the typify operator is to use two or three line symbols to represent a river delta, rather than using numerous lines to represent all of the streams in the delta. Another example of typification could be representing buildings in a small-scale map. The buildings cannot all be represented individually, but the spatial extent of the buildings can be represented with fewer symbols in the same area. This is very common when map scales are decreased. Likewise with roads, especially roads such as interstates that have multiple elements that illustrate a single feature. At large scales, the interstate may be symbolized using multiple lines to indicate the direction of traffic. However, at smaller scales these should be replaced by a single line that represents the feature generally.
Related Generalization Operations
There are other types of operators that are used for cartographic generalization that differ from typification. The Eliminate operator, which simplifies the map by removing some of the original features in a group, by replacing them with a new arrangement of fewer features.
The Aggregation operator differs from the typify operator in that it is used to combine polygons within a certain distance of each other creating a bigger polygon that combines all the smaller ones and at the same time represents the boundary of the former small features. It is intended for simple scales.
The Combine or Merge operator differentiates from the typify operator because it is used to join polygons or raster data together while maintaining the area, as well as merges the metadata of each feature that was combined.
Typify does not combine multiple features into a single feature nor does it combine metadata, rather it replaces the graphical representation of multiple features with a smaller representation that simplifies the displayed objects and reduces the visual clutter. It reduces the number of equal features in an area to make the map look smooth and not crowded.