Geographic Information System (GIS)
Overview
A Geographic Information System (GIS) is an integrated framework of hardware, software, data, and personnel designed to capture, store, manage, analyze, and visualize geographically referenced (spatial) information. GIS enables users to understand spatial relationships, patterns, and trends by linking location data with descriptive attributes.
Key Concepts
Spatial data represents features with a known location on Earth, expressed as coordinates (latitude/longitude, projected coordinates, or addresses). Vector data represents discrete features using points, lines, and polygons (e.g., buildings, roads, parcels). Raster data represents continuous phenomena as a grid of cells/pixels (e.g., satellite imagery, elevation models, land cover). Attributes are non-spatial descriptive information associated with spatial features (e.g., parcel owner, road name, population). Coordinate Reference System (CRS) defines how coordinates relate to real-world locations; includes geographic (lat/long) and projected (planar) systems. Geoprocessing refers to operations that manipulate spatial data (buffering, overlay, intersection, union, dissolve). Geocoding is the process of converting addresses or place names into geographic coordinates. Spatial analysis involves techniques for examining spatial relationships, patterns, and processes (proximity, clustering, interpolation).
Core Components
- Hardware: Computers, GPS devices, servers, mobile devices for data collection and processing.
- Software: Desktop GIS (QGIS, ArcGIS), web GIS (Leaflet, OpenLayers), spatial databases (PostGIS, SQL Server Spatial).
- Data: Base maps, imagery, administrative boundaries, infrastructure layers, thematic datasets.
- Methods: Spatial analysis techniques, cartographic principles, data management workflows.
- People: Analysts, developers, cartographers, data managers, decision-makers.
Common Data Formats
| Format | Type | Description |
|---|---|---|
| Shapefile (.shp) | Vector | Legacy Esri format; widely supported but limited |
| GeoJSON | Vector | JSON-based; web-friendly and human-readable |
| GeoPackage (.gpkg) | Both | SQLite-based; modern, portable, single-file format |
| GeoTIFF | Raster | Tagged Image File Format with geospatial metadata |
| KML/KMZ | Both | Google Earth format; XML-based |
| WKT/WKB | Vector | Well-Known Text/Binary for geometry representation |
Applications
- Urban planning and zoning: Land use analysis, site selection, infrastructure planning.
- Real estate: Property valuation, market analysis, parcel management.
- Environmental science: Habitat modeling, watershed analysis, climate change mapping.
- Transportation: Route optimization, traffic analysis, logistics planning.
- Public health: Disease mapping, accessibility analysis, resource allocation.
- Utilities: Network management, asset tracking, outage analysis.
- Emergency management: Hazard mapping, evacuation planning, response coordination.
Appendix
Created: 2025-12-04 | Modified: 2025-12-13
See Also
- Topologically Integrated Geographic Encoding and Referencing (TIGER)
- Multi-Criteria Decision Analysis (MCDA)
- GIS Data Sources
- PostGIS
- Coordinate Reference System (CRS)