Geographic Information Systems – Core Vocabulary

A comprehensive set of GIS vocabulary flashcards covering system definition, data models, spatial structures, databases, analysis techniques, and data acquisition methods for exam preparation.

Geographic Information System (GIS)

A system of hardware, software, data, and procedures for capturing, storing, manipulating, analyzing, and displaying spatially-referenced information.

Spatial Data

Information that describes the location and shape of geographic features and their spatial relationships.

Attribute (Non-Spatial) Data

Descriptive information about spatial features, detailing what, how much, or when something occurred at a location.

GIS Components

Inter-related parts including data capture, data input, manipulation, transformation, visualization, and analysis tools.

Vector Data Model

Represents geographic features with points, lines, and polygons defined by coordinate pairs.

Raster Data Model

Represents geographic space as a regular grid of cells (pixels) where each cell holds a single value.

Point Feature

A zero-dimensional vector object used for entities with no measurable area, e.g., wells or streetlights.

Line Feature

A one-dimensional vector object composed of ordered coordinate pairs, representing linear entities such as roads or rivers.

Polygon Feature

A two-dimensional vector object representing areas enclosed by lines, such as lakes or parcels.

Triangulated Irregular Network (TIN)

A vector data structure that models surfaces using connected, non-overlapping triangles.

Cell Size (Raster Resolution)

The ground dimensions of a raster cell; smaller cells capture finer detail but increase file size.

Map Layer

A thematic slice of geographic information, e.g., hydrology, land use, or elevation, that can be overlaid with others.

Topology

Rules and relationships describing how vector features share geometry (adjacency, connectivity, containment).

Arc-Node Topology

Vector structure where arcs (lines) are defined by start and end nodes, enabling reconstruction of polygons.

Quadtree

Hierarchical raster data structure that recursively subdivides homogeneous regions into quadrants, reducing storage.

Run-Length Encoding (RLE)

Raster compression technique storing sequences of identical cell values as single value-length pairs.

Cell-by-Cell Encoding

Simplest raster storage where every grid cell value is recorded individually by row and column.

Spatial Data Structure

Computer representation (raster or vector) that organizes geographic data for storage and processing.

Data Model Purpose

Digitally represent real-world geographic features in a database for mapping and problem solving.

Projection

Mathematical transformation of Earth’s curved surface to a flat map, defining coordinate relationships.

Scale

Ratio between map distance and real-world distance, indicating level of detail represented.

Accuracy (Positional)

Closeness of recorded coordinates to their true ground locations.

Resolution

Smallest measurable unit in spatial data; in raster, synonymous with cell size.

Geodatabase

An organized collection of spatial and attribute data stored within a database management system.

Database Management System (DBMS)

Software that stores, organizes, and manipulates collections of data, offering query and reporting tools.

Spatial Database (SDBMS)

A DBMS extended with spatial data types, indices, and query operations for efficient geographic data handling.

Oracle Spatial / ESRI SDE

Examples of spatial extensions (cartridges) that add GIS functionality to relational databases.

TIGER Files

Topologically Integrated Geographic Encoding and Referencing data format created by the U.S. Census Bureau.

Coverage Data Model

Topology-based vector format used by early ESRI software to store points, lines, and polygons.

Map Algebra

Set of cell-by-cell raster operations treating layers as variables in mathematical expressions.

Buffer Analysis

Spatial operation creating zones of specified distance around features to evaluate proximity.

Overlay Analysis

Combining two or more spatial layers to produce a new layer containing shared or combined information.

Network Analysis

GIS procedures that evaluate connectivity, shortest paths, and flow within linear networks.

Spatial Query

Question posed to a GIS using location criteria, e.g., "find all schools within 1 km of rivers."

Spatial Analysis

Techniques that study geographic entities through their topological, geometric, or statistical properties.

Descriptive Statistics (Spatial)

Numerical summaries like mean center or standard distance that characterize spatial distributions.

Optimization (Location)

Analytical process that identifies ideal placement of facilities based on predefined criteria.

Hypothesis Testing (Spatial)

Inferential statistical methods evaluating whether observed spatial patterns differ from random chance.

Surveying

Field technique measuring distances, angles, and elevations to map features accurately.

Photogrammetry

Deriving measurements and maps from aerial photographs using stereoscopic techniques.

Remote Sensing

Acquiring information about Earth’s surface via sensors on satellites, aircraft, or drones.

LiDAR

Light Detection and Ranging technology using laser pulses to generate high-resolution elevation data.

Digitizing

Converting analog maps into digital vector data by tracing features.

Scanning

Converting hard-copy maps into raster images for digital use.

Metadata

Documentation describing the content, quality, condition, and other characteristics of spatial data.

GIS Application Areas

Fields using GIS, such as urban planning, environmental science, health care, business, and civil engineering.

Spatial Resolution (Imagery)

Smallest area on the ground detectable by a sensor; finer resolution provides more detail.

Thematic Raster

Raster data representing discrete classes, such as land cover or soil type.

Spectral Raster

Raster dataset containing multiple spectral bands (e.g., satellite imagery) for analysis of surface materials.

Digital Elevation Model (DEM)

Raster representation of ground surface topography, storing elevation values per cell.

Spatial Index

Data structure (e.g., R-tree) that accelerates spatial searches and queries in a database.

Spatial Data Acquisition

Processes for collecting geographic information, including surveying, remote sensing, and digitization.

Topology Rules

Constraints enforcing spatial integrity, such as no gaps between polygons or no intersecting lines without nodes.

Raster Advantages

Efficient for continuous data, fast analysis, simple overlay, and compatible with image processing.

Raster Disadvantages

Can create large files, blocky appearance, limited attribute depth, and difficulties with linear features.

Vector Advantages

Precise representation of discrete features, compact storage, topology support, and high-quality cartography.

Vector Disadvantages

Complex data structures, intensive processing for topology building, and less suited for continuous surfaces.

Spatial Transformations

Operations converting or combining datasets, such as raster-to-vector, reprojection, or classification.

Map Registration

Aligning multiple spatial datasets to a common coordinate system for integration.

Data Capture

Initial collection of spatial information for entry into a GIS.

GIS Process Steps

Capture, store, register, interpret, process, and display spatial data results.