Geographic Information Systems (GIS) Cheat Sheet

The core ideas of Geographic Information Systems (GIS) distilled into a single, scannable reference — perfect for review or quick lookup.

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Quick Reference

Spatial Data Models (Vector and Raster)

The two fundamental approaches to representing geographic features in a GIS. Vector data uses discrete points, lines, and polygons with precise coordinate geometry, while raster data uses a continuous grid of cells (pixels) where each cell stores a value representing a phenomenon.

Coordinate Reference Systems (CRS)

Mathematical frameworks that define how the curved surface of the Earth is projected onto a flat map or referenced in three-dimensional space. A CRS includes a datum (a model of the Earth's shape), a projection method, and coordinate units.

Spatial Analysis

A set of techniques for examining the locations, attributes, and relationships of features in spatial data to extract meaningful patterns, detect clusters, measure distances, and model spatial processes.

Overlay Analysis

A GIS operation that combines two or more spatial datasets by stacking them and performing logical or arithmetic operations (union, intersect, erase) to create new datasets that reveal relationships between layers.

Geocoding and Georeferencing

Geocoding is the process of converting addresses or place names into geographic coordinates. Georeferencing is the process of aligning a non-spatial image (such as a scanned map) to a coordinate system so it can be used in a GIS.

Remote Sensing

The acquisition of information about the Earth's surface from sensors mounted on satellites, aircraft, or drones without direct physical contact. Remote sensing data, including multispectral and LiDAR, serves as a primary data source for GIS analysis.

Geostatistics and Interpolation

Statistical methods that exploit the spatial correlation between observations to predict values at unmeasured locations. Techniques such as kriging, inverse distance weighting (IDW), and spline interpolation generate continuous surfaces from point samples.

Network Analysis

A GIS capability that models connectivity and flow through linear features such as roads, pipelines, or rivers. It enables route optimization, service area analysis, and closest facility identification using graph theory principles.

Digital Elevation Models (DEM)

Raster datasets that represent the continuous surface elevation of terrain. DEMs are used for slope analysis, watershed delineation, viewshed analysis, and 3D visualization. Common types include Digital Surface Models (DSM) and Digital Terrain Models (DTM).

Web GIS and Spatial Data Infrastructure

The architecture and standards for publishing, discovering, and consuming geospatial data and maps over the internet. Web GIS uses standards like WMS, WFS, and REST APIs to serve interactive maps and spatial services to users through web browsers.

Key Terms at a Glance

Attribute Table:A tabular database associated with a set of geographic features, storing descriptive information (attributes) for each feature in rows and columns.

Buffer:A zone of a specified distance created around a point, line, or polygon feature, used for proximity analysis.

Cartography:The art and science of designing and producing maps, including decisions about symbolization, labeling, generalization, and layout.

Coordinate Reference System:A framework that defines how 2D or 3D coordinates relate to actual locations on the Earth, including a datum and projection.

Datum:A mathematical model of the Earth's shape used as a reference surface for calculating coordinates. Examples include WGS 84 and NAD 83.

Digital Elevation Model:A raster dataset representing the continuous elevation of the Earth's bare ground surface.

Digitizing:The process of converting analog geographic data (e.g., paper maps) into digital vector format by tracing features.

Feature Class:A collection of geographic features sharing the same geometry type (point, line, or polygon) and attribute schema, stored in a geodatabase.

Geocoding:The process of transforming textual location descriptions (addresses, place names) into geographic coordinates.

Geodatabase:Esri's native data storage format for GIS data, supporting feature classes, rasters, topology rules, and relationship classes in a relational database structure.

Georeferencing:Aligning a raster image or non-spatial dataset to a geographic coordinate system using ground control points.

Geostatistics:A branch of statistics dealing with spatially correlated data, using methods like kriging to model spatial variation and predict values at unmeasured locations.

GeoJSON:An open standard format for encoding simple geographic features and their attributes using JSON syntax.

Global Positioning System (GPS):A satellite-based navigation system providing precise location and time information to GPS receivers anywhere on Earth.

Interpolation:Estimating unknown values at unsampled locations based on known values at surrounding sample points.

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