Important GIS Vocabulary

Important GIS Vocabulary

Part 1

Reclassification

• using one set of values to derive a second set more directly useful to the problem at hand

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Dissolve

• remove boundaries between polygons of the same designation



Query

• extracts polygons and places them in a new layer by themselves



Buffers

• polygons created within a certain distance of a feature (usually outside)



Union

• combines layers



Project-Oriented GIS

• scale and frame of the project is well defined and project life is finite



Enterprise GIS

• designed for long-term support of critical functions within an organization



Attributes

• each feature from a vector file containing information linked to a storage table with a feature identification code (FID)

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Feature classes • features grouped into data sets, can

only contain one type of geometry that share attributes – data set can have only points, or only

lines, or only polygons – data set can not share rivers and

highways because they have different attributes




Feature datasets

• contain multiple feature classes that are in some way related to each other




Features

• points, lines or polygons




FID

• feature identification code links the feature with it’s attributes




Georeferenced

• the information is tied to a specific location on the earth’s surface




Node/nodes

• end points of a line




Shapefile

• contain only one feature class, spatial data model developed for and used by ArcView3 and later versions




Spaghetti model • a model which stores spatial features

as a series of xy coordinates as independent objects unrelated to each other and does not store topological relationships between features




Thematic mapping

• displaying the features of a spatial data layer based on values in its attribute table




Topological model

• a data model which stores spatial relationships between features in addition to their xy coordinates




Two basic vector models

• topological models and spaghetti models



Vector model

• a spatial data storage method in which features are represented by one or more pairs of x,y coordinate values forming points, lines or polygons




Vertex/vertices

• intermediate points along the line



Raster model

• a spatial data storage method in which spatial data are represented by a series of small squares called cells or pixels

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Two styles of raster storage

• continuous rasters • discrete rasters


Continuous raster

• data that take on a variety of different values and that change rapidly across a data set (elevation, for example)


Discrete raster

• data which take on a relatively small number of distinct values


Each pixel

• has a numeric code indicating the land use, and the raster is stored as an array of numbers


Raster data set

• is laid out as a series of rows and columns which provide the address for a pixel


Resolution

• ground area represented by one cell value in a raster


SOURCE

All this vocabulary comes from:• Price, Maribeth. Mastering ArcGIS.

McGraw-Hill; 3 edition. 2007.

Important GIS Vocabulary

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