GIS Terminology
ArcGIS Online: a predefined, secure (password protected) server space hosted by Esri that allows for the collection, storage, display, and editing of spatial data accessible from anywhere that an internet signal is available. All Esri organizational accounts have access to this from the payment of maintenance fees for ArcGIS software.
Attribute: an attribute is a category of data attached to a feature that describes some aspect of that feature. An example of this is Ownership.
Cadastral: data showing the extent of land-based ownership and jurisdictions as informed by surveys, county assessors, and the State. Taxlots and urban growth boundaries are examples of cadastral data.
Cartography: the study, art, and science of making maps representing real geographic areas on a flat surface.
Coordinate Reference System (CRS): also called a geographic coordinate system (GCS) is a system of spatial definitions describing a location on Earth that includes a spheroidal geographic datum, an angular unit of measure, and a prime meridian. Coordinate systems and datums are highly detailed scientific topics that merit in-depth exploration and should be handled with great care in mapping.
Data field: a column in a data table.
Dataset: a dataset is group of GIS data tables that are generally related to the same system. An example is illustrated by the Storm dataset which includes manholes, lines, catch basins, detention basins, culverts, ditches, swales, and flow direction involved in stormwater runoff. Dataset is sometimes also used to describe the entirety of a data collection.
Derive/Develop: to devise a particular manner of achieving a goal or producing a product. An example of this might be to create and document a set of steps or instructions needed to collect field data.
Documentation: in GIS terms, documentation refers to the description of a feature class, dataset, database, and/or related processes. One example of this would be listing and defining feature attributes. Metadata is often referred to as documentation although metadata contains more extensive details about geodata.
Domain: with respect to geodatabases, a domain is a set list of possible values that a data field can take on. Feature classes can contain data fields that draw upon domains defined at the database level.
Embeddable: refers to conveniently concise html encoding that can be inserted into a web page where a map will then appear as a result of inserting the code. The map that appears on the web page draws the information from the server that hosts the mapped data.
Esri: Environmental Systems Research Institute, headquartered in Redlands, CA. Developer and supplier of ArcGIS software.
Feature: any system or cadastral component that is mapped. Examples include a sewer manhole, a tax lot, a street segment, etc.
Feature class: similar to a shapefile but is incorporated into a geodatabase giving it a more robust status with added functionality.
Field: locations outside of the office environment.
Field data: raw data collected in situ (in see'too) or 'at the site'; i.e., at its real location.
Geodatabase: a file management system specifically designed to store data about features including spatial reference system and coordinates, attributes, and behavioral rules for data. A geodatabase stores a variety of geographic data including points, lines, polygons, and rasters, and facilitates rapid retrieval, analysis, and manipulation of the data.
GIS: Geographic Information System.
GIS Plan: an existing document that describes the purpose for, and details of creating and using a geographic information system. This document includes a goal statement, detailed project plan with a timeline, needs assessment, design and acquisition details, an implementation plan, and intended future usage and direction.
Hyperlink: a clickable local computer or internet address (url) that facilitates rapid retrieval of information from the internet or a local computer filing system.
Layer: this term is often used interchangeably with shapefile or feature class because these are shown (drawn) as being stacked one atop another. The fundamental difference is that a Layer retains symbology definitions and draws upon the data in a shapefile or feature class. Shapefiles and feature classes contain the data that is used: (1) to inform users about feature details; and (2) to set up symbology for subtypes or layers.
Map element: map elements are visual objects that add contextual information to maps. An example of this is the inclusion of a North arrow to provide directional context.
Mapbook: a production mapping mechanism that facilitates creating multi-page books with each page depicting a distinct area with a map frame of the same size, scale, and page formatting. Mapbooks are generally specific to one aspect of the jurisdiction in question (like a storm system) but include other general reference information (context) like streets/roads, streams, taxlot lines, and imagery.
Metadata: data that contains the description of a feature class, dataset, or database which includes but is not limited to listing and defining feature attributes. Metadata also includes, at minimum, a summary, a longer description of what the data is used for, use and distribution restrictions, author name, organization name, date of creation or update, and datum/CRS/projection.
Model: in the most literal sense, a model is a picture, diagram, or set of instructions that describes some phenomenon or object in the real world. When we make maps we are modeling the real world. When we document how a database is to be set up, we are creating a data model that will help us depict objects in the real world.
Polygon: any multi-sided, two dimensional representation of a shape. Examples include: square, rectangle, triangle, hexagon, and irregular shapes representing the boundaries a finite area.
Projection: a set of parameters that describe the scientific transformation of real locations (based on a GCS or CRS) on the geoid known as Earth onto a two-dimensional (flat) surface. Projections also provide constant units of measure in terms of lengths, angles, and areas. All projections contain some form of distortion resulting from this transformation. Projections, coordinate systems, and datums are highly detailed scientific topics that merit in-depth exploration and should be handled with great care in mapping.
PubWorks: asset management software produced by Tracker Software Systems that facilitates tracking inventory and crew work hours where work tasks and service requests can be mapped to GIS features if spatial data exists. While asset management systems are largely based on tracking work by location, many asset management software systems exist and it is prudent to explore several of these before making purchase decisions.
Raw data: unprocessed field data. Processing describes an array of activities including, but not limited to: location verification, post processing of gps coordinates, data cleaning, and incorporation into a database or final acceptance of the data as being in acceptable condition in terms of spatial and content accuracy and general completeness.
Relates: relates are defined either within a map document (.mxd) or by a relationship class contained in a geodatabase. Relates and Relationship Classes provide explicit instructions on how one data table is related to another data table and are based on the contents of a key field. A relate that is based on location is called a Spatial Join.
Schema: In the most basic sense, a GIS schema is a a set of charts or tables containing details about: the symbology of a feature class (points/lines/polygons/raster/terrain); what feature attributes are to be stored; precision and accuracy required; predefined attribute values or ranges of values to preserve data accuracy and integrity; and the interrelated relationships of features. A schema used for data collection is often called a Data Dictionary.
Shapefile: a shapefile is a table of data that includes location information in the form of x,y coordinates recognizable by a GIS for depicting locations of features on a map.
Spatial analysis: refers to categorizing, calculating, depicting patterns, and otherwise summarizing and/or measuring spatial data in order to derive meaning from and/or to describe particular circumstances involving the data in question.
Stakeholder: any party having a vested interest in the outcome of a project, product, or investment.
Symbology: a term that refers to the manner in which an object is depicted. Examples include: using an array of colors to show subtle differences in continuous data; using a hydrant symbol to depict fire hydrant points; and using lines to indicate where streams are located.
Topology: a topology defines how a feature is connected to other features. One example of this occurs where park boundaries in a Parks feature class must align with taxlot boundaries because taxlots describe the official cadastral location and extent of the property boundaries. A proper topology ensures that the parks are always depicted within the boundaries of their associated taxlots. This kind of interrelatedness among feature classes enhances cartographic consistency, precision, and data integrity.
Web map: any form of digital map that can be viewed via an internet browser.
Attribute: an attribute is a category of data attached to a feature that describes some aspect of that feature. An example of this is Ownership.
Cadastral: data showing the extent of land-based ownership and jurisdictions as informed by surveys, county assessors, and the State. Taxlots and urban growth boundaries are examples of cadastral data.
Cartography: the study, art, and science of making maps representing real geographic areas on a flat surface.
Coordinate Reference System (CRS): also called a geographic coordinate system (GCS) is a system of spatial definitions describing a location on Earth that includes a spheroidal geographic datum, an angular unit of measure, and a prime meridian. Coordinate systems and datums are highly detailed scientific topics that merit in-depth exploration and should be handled with great care in mapping.
Data field: a column in a data table.
Dataset: a dataset is group of GIS data tables that are generally related to the same system. An example is illustrated by the Storm dataset which includes manholes, lines, catch basins, detention basins, culverts, ditches, swales, and flow direction involved in stormwater runoff. Dataset is sometimes also used to describe the entirety of a data collection.
Derive/Develop: to devise a particular manner of achieving a goal or producing a product. An example of this might be to create and document a set of steps or instructions needed to collect field data.
Documentation: in GIS terms, documentation refers to the description of a feature class, dataset, database, and/or related processes. One example of this would be listing and defining feature attributes. Metadata is often referred to as documentation although metadata contains more extensive details about geodata.
Domain: with respect to geodatabases, a domain is a set list of possible values that a data field can take on. Feature classes can contain data fields that draw upon domains defined at the database level.
Embeddable: refers to conveniently concise html encoding that can be inserted into a web page where a map will then appear as a result of inserting the code. The map that appears on the web page draws the information from the server that hosts the mapped data.
Esri: Environmental Systems Research Institute, headquartered in Redlands, CA. Developer and supplier of ArcGIS software.
Feature: any system or cadastral component that is mapped. Examples include a sewer manhole, a tax lot, a street segment, etc.
Feature class: similar to a shapefile but is incorporated into a geodatabase giving it a more robust status with added functionality.
Field: locations outside of the office environment.
Field data: raw data collected in situ (in see'too) or 'at the site'; i.e., at its real location.
Geodatabase: a file management system specifically designed to store data about features including spatial reference system and coordinates, attributes, and behavioral rules for data. A geodatabase stores a variety of geographic data including points, lines, polygons, and rasters, and facilitates rapid retrieval, analysis, and manipulation of the data.
GIS: Geographic Information System.
GIS Plan: an existing document that describes the purpose for, and details of creating and using a geographic information system. This document includes a goal statement, detailed project plan with a timeline, needs assessment, design and acquisition details, an implementation plan, and intended future usage and direction.
Hyperlink: a clickable local computer or internet address (url) that facilitates rapid retrieval of information from the internet or a local computer filing system.
Layer: this term is often used interchangeably with shapefile or feature class because these are shown (drawn) as being stacked one atop another. The fundamental difference is that a Layer retains symbology definitions and draws upon the data in a shapefile or feature class. Shapefiles and feature classes contain the data that is used: (1) to inform users about feature details; and (2) to set up symbology for subtypes or layers.
Map element: map elements are visual objects that add contextual information to maps. An example of this is the inclusion of a North arrow to provide directional context.
Mapbook: a production mapping mechanism that facilitates creating multi-page books with each page depicting a distinct area with a map frame of the same size, scale, and page formatting. Mapbooks are generally specific to one aspect of the jurisdiction in question (like a storm system) but include other general reference information (context) like streets/roads, streams, taxlot lines, and imagery.
Metadata: data that contains the description of a feature class, dataset, or database which includes but is not limited to listing and defining feature attributes. Metadata also includes, at minimum, a summary, a longer description of what the data is used for, use and distribution restrictions, author name, organization name, date of creation or update, and datum/CRS/projection.
Model: in the most literal sense, a model is a picture, diagram, or set of instructions that describes some phenomenon or object in the real world. When we make maps we are modeling the real world. When we document how a database is to be set up, we are creating a data model that will help us depict objects in the real world.
Polygon: any multi-sided, two dimensional representation of a shape. Examples include: square, rectangle, triangle, hexagon, and irregular shapes representing the boundaries a finite area.
Projection: a set of parameters that describe the scientific transformation of real locations (based on a GCS or CRS) on the geoid known as Earth onto a two-dimensional (flat) surface. Projections also provide constant units of measure in terms of lengths, angles, and areas. All projections contain some form of distortion resulting from this transformation. Projections, coordinate systems, and datums are highly detailed scientific topics that merit in-depth exploration and should be handled with great care in mapping.
PubWorks: asset management software produced by Tracker Software Systems that facilitates tracking inventory and crew work hours where work tasks and service requests can be mapped to GIS features if spatial data exists. While asset management systems are largely based on tracking work by location, many asset management software systems exist and it is prudent to explore several of these before making purchase decisions.
Raw data: unprocessed field data. Processing describes an array of activities including, but not limited to: location verification, post processing of gps coordinates, data cleaning, and incorporation into a database or final acceptance of the data as being in acceptable condition in terms of spatial and content accuracy and general completeness.
Relates: relates are defined either within a map document (.mxd) or by a relationship class contained in a geodatabase. Relates and Relationship Classes provide explicit instructions on how one data table is related to another data table and are based on the contents of a key field. A relate that is based on location is called a Spatial Join.
Schema: In the most basic sense, a GIS schema is a a set of charts or tables containing details about: the symbology of a feature class (points/lines/polygons/raster/terrain); what feature attributes are to be stored; precision and accuracy required; predefined attribute values or ranges of values to preserve data accuracy and integrity; and the interrelated relationships of features. A schema used for data collection is often called a Data Dictionary.
Shapefile: a shapefile is a table of data that includes location information in the form of x,y coordinates recognizable by a GIS for depicting locations of features on a map.
Spatial analysis: refers to categorizing, calculating, depicting patterns, and otherwise summarizing and/or measuring spatial data in order to derive meaning from and/or to describe particular circumstances involving the data in question.
Stakeholder: any party having a vested interest in the outcome of a project, product, or investment.
Symbology: a term that refers to the manner in which an object is depicted. Examples include: using an array of colors to show subtle differences in continuous data; using a hydrant symbol to depict fire hydrant points; and using lines to indicate where streams are located.
Topology: a topology defines how a feature is connected to other features. One example of this occurs where park boundaries in a Parks feature class must align with taxlot boundaries because taxlots describe the official cadastral location and extent of the property boundaries. A proper topology ensures that the parks are always depicted within the boundaries of their associated taxlots. This kind of interrelatedness among feature classes enhances cartographic consistency, precision, and data integrity.
Web map: any form of digital map that can be viewed via an internet browser.
