MAIN GIS CONCEPTS

Add Field- Add or remove fields from a table or feature class. The add field option is usually used to personally manage datasets.

Algorithm- A mathematical procedure used to solve problems with a series of steps.

ArcGIS-A collection of Geographic Information System’s (GIS) software used for spatial analysis, data management, and mapping.

ArcMap-A GIS application that is used to create and edit datasets, as well as, create maps that represent geographic information using a collection of layers.

ArcCatalog-A GIS application that allows for the organization and management of datasets by means of geodatabases and file based workspaces.

ArcToolbox-A GIS application used for accessing, organizing, and managing an assortment of geoprocessing tools.

Attribute table-A tabular file that contains information associated with a set of geographic features.

Coordinate system-A means of spatial reference that uses lines and points in conjunction with a set of rules.  The rules provide spatial recognition associated with each line or point.

Clip-Extracts input features that overlay the input features.

Dataset- Any collection of related data, usually grouped or stored together.

DEM-A Digital Elevation Model is raster data of the shape of the Earth’s surface used as input to quantify the characteristics of the Earth’s surface.

Feature class-A data source that is composed of geographic features with similar geometry (i.e. point, polygon, and line), similar attributes, and the same spatial reference within a geodatabase.

Feature dataset-A collection of feature classes grouped together that share the same spatial reference within a geodatabase.

Geodatabase- A database or file structure used primarily to store, query, and manipulate spatial data.  Feature classes and feature datasets are located within a geodatabase.

Geoprocessing- A GIS operation used to manipulate GIS data.  Geoprocessing allows for definition, management, and analysis of information used to form decisions.

Layer-The visual representation of a geographic dataset in any digital map environment.

Overlay Analysis-Laying maps of varying geographic information over one another in order to provide analysis.  Typically used for raster datasets.

Polygon- A closed shape defined by a connected sequence of x,y coordinate pairs, where the first and last coordinate pair are the same and all other pairs are unique.

Projection-The method used to portray the 3-dimensional surface of the earth on a 2-dimensional planar surface.

Raster-A dataset that represents geographic features which are portrayed as square or rectangular grid cells.  Each grid cell corresponds with an associated value representing unique characteristics.

Reclassify- Changes the values in a raster.

Shapefile-A vector data storage format for storing the location, shape, and attribute of geographic features.

Union-Computes the geometric intersection of two polygon coverages.

UTM-Universal Transverse Mercator is a projected coordinate system that splits the earth up into zones.

Vector-Geographic data that is represented as points, lines, and polygons.

 

SPATIAL ANALYST CONCEPTS

Spatial Analyst-An ArcGIS tool that allows for spatial modeling and analysis.

Analysis mask- Identifies those cells within the analysis extent that will be considered when performing an operation or a function. Setting an analysis mask means that processing will only occur on selected locations and that all other locations will be assigned values of NoData.

Cell Size- The dimensions on the ground of a single cell in a raster, measured in map units. Cell size is often used synonymously with pixel size.

Extent-The minimum bounding rectangle (xmin, ymin and xmax, ymax) defined by coordinate pairs of a data source. All coordinates for the data source fall within this boundary.

Raster Calculator-A spatial analyst tool used to perform mathematical calculations and queries.

 

HYDROLOGY CONCEPTS

Hydrology-Tool used in ArcToolbox for the study of water, its behavior, and its movements across and below the surface of the earth, and through the atmosphere.

Delineate Watershed-Tool used to determine the boundaries of a desired watershed.

Fill Sinks-An extension from the hydrology tool used to fill sinks and depressions within a DEM to establish a depressionless DEM.

Flow Accumulation- Creates a raster of accumulated flow to each cell.

Flow Direction- Creates a raster of flow direction from each cell to its steepest downslope neighbor.

 

*The above concepts and definitions were composed using the ESRI Support Center GIS Dictionary, and the ArcCatalog Version 9.2 help menu.