GIS CH. 11 Vector Data Analysis Terms

Line-in-polygon overlay

A GIS operation in which a line layer is dissected by the polygon boundaries on the overlay layer, and each line segment on the output combines attributes from the line layer and the polygon within which it falls

Point-in-polygon overlay

A GIS operation in which each point of a layer is assigned attribute data of the polygon within which it falls.

Polgon-onpolygon

A GIS operation in which the output combines the polygon boundaries from he inputs to crate a new set o polygons, each carrying attributes from the inputs.

Overlay

A GIS operation that combines the geometries and attributes of the input layers to create the output.

Append

A GIS operation that creates a new layer by piecing together two or more layers

Eliminate

A GIS operation that creates a new layer by removing features that meet a user defined logical expression from the input layer

Clip

A GIS operation that creates a new layer including only those features of the input layer that fall within the area extend of the clip layer

Buffering

A GIS operation that creates zones consisting of areas within a specified distance of selected features.

Split

A GIS operation that divides the input layer into two or more layers

Dissolve

A GIS operation that removes boundaries between polygons that have the same attribute value(s)

Erase

A GIS operation that removes from the input layer those features that fall within the area extent of the erase layer

Update

A GIS operation that replaces the input layer with the update layer and its features

Select

A GIS operation that uses a logical expression to select features from the input layer for the output layer

Cluster tolerance

A distance tolerance that forces points and lines to be snapped together if they fall within the specified distance.

Unon

A polygon-on-polygon overlay method that preserves all features from the input layers

Areal interpolation

A process of transferring known data from one set of polygons to another

Ripley's K function

A spatial statistic that determines whether a point pattern is random, regular, or clustered over a range of distances

Spatial autocorrelation

A spatial statistic that determines whether a point pattern is random, regular, or clustered over a range of distances.

G-statisic

A spatial statistic that measures the clustering of high and low values in a data set. The G-statistic can be either general or local

Nearest neighbor analysis

A spatial statitic that detmines if apoin paern is randon, regular, or clustered

Symmetrical Difference

An overlay method that preserves features falling within the area that is common to only one of the input layers

Identity

An overlay method that preserves only featurre that fall within the are extent defined by the identity layer

Intersect

An overlay method that preserves only those features falling within the area extent common to the input layers

Error propagation

The generation of errors in the overlay output that are due to inaccuracies of the input layers

Local Indicators of Spatial Association (LISA)

The local version of Moran's I

Minimum mapping unit

The smallest are unit that is managed b a government agency or an organization

Slivers

Very small polygons found along the shared boundary of the two input layers in overlay