GPS and GNSS in GIS are foundational technologies used to collect, manage, and analyze location-based data. Here’s a clear explanation of how GPS (Global Positioning System) and GNSS (Global Navigation Satellite Systems) are used in GIS (Geographic Information Systems):
🔍 What is GPS?
GPS (Global Positioning System) is a U.S.-owned satellite navigation system that allows users to determine their exact location (latitude, longitude, and altitude) anywhere on Earth using signals from a constellation of at least 24 satellites.
What is GNSS?
GNSS (Global Navigation Satellite System) is a broader term that includes GPS and other global or regional satellite navigation systems:
- GPS (USA)
- GLONASS (Russia)
- Galileo (EU)
- BeiDou (China)
- NavIC (India)
- QZSS (Japan)
GNSS-enabled devices can use satellites from multiple systems, providing higher accuracy and reliability than GPS alone.
Role of GPS/GNSS in GIS
GIS is a system used to capture, store, analyze, and present spatial or geographic data. GPS/GNSS play a crucial role in data acquisition and fieldwork for GIS.
1. Data Collection
- Field surveyors use GPS/GNSS receivers to collect accurate geographic coordinates for features like roads, utilities, land parcels, or natural features.
- Used in mobile GIS apps (e.g., ArcGIS Field Maps, QField).
2. Real-Time Positioning
- In applications like asset tracking, navigation, or precision agriculture, GNSS provides real-time positioning data to GIS systems.
3. Georeferencing
- Satellite imagery, drone data, or field-collected data can be aligned to real-world locations using GPS/GNSS-based coordinates.
4. Mapping and Visualization
- Accurate location data from GNSS improves the accuracy of maps and spatial analysis in GIS.
Benefits of Using GNSS in GIS
- Improved accuracy: Especially when using GNSS with correction services (e.g., RTK, SBAS).
- Global coverage
- Real-time data availability
- Efficient field data collection
Common Applications
- Environmental monitoring
- Urban planning
- Disaster management
- Infrastructure mapping
- Agriculture
- Transportation and logistics
Comparison Table: GPS vs GNSS vs GIS
| Feature / Aspect | GPS | GNSS | GIS |
|---|---|---|---|
| Full Form | Global Positioning System | Global Navigation Satellite System | Geographic Information System |
| Type | Satellite navigation system | Collective term for all satellite navigation systems | Information system for geographic data |
| Purpose | Determine location and time | Provide accurate global location and timing | Capture, store, analyze, and visualize spatial data |
| Components | U.S. satellite constellation | Multiple satellite systems (GPS, GLONASS, etc.) | Hardware, software, data, and users |
| Accuracy | 5–10 meters (consumer); sub-meter (survey-grade) | Higher than GPS when using multiple constellations | Depends on data input (can use GPS/GNSS data) |
| Usage Scope | Global | Global | Local to global |
| Real-time Capability | Yes (with receiver) | Yes (often more reliable) | Yes, if integrated with GNSS |
| Main Use | Location and navigation | Precise global positioning | Spatial data management and decision-making |
| Example Device/App | Handheld GPS unit, smartphone | GNSS receiver (e.g., Trimble, Emlid) | ArcGIS, QGIS, Google Earth |
Example Project: Integrating GPS/GNSS with GIS
Project Title: Mapping Urban Tree Canopy for a Smart City Initiative
Objective
To create a spatial database of urban trees with accurate geolocation and attributes for environmental planning and public awareness.
Step-by-Step Integration:
| Step | Technology Used | Description |
|---|---|---|
| 1. Field Data Collection | GNSS receiver or GPS-equipped smartphone | Technicians collect location of each tree using GNSS for high accuracy (±30 cm with RTK). |
| 2. Attribute Input | Mobile GIS app (e.g., ArcGIS Field Maps) | Input species, height, health status, canopy width while in the field. |
| 3. Data Upload | Cloud Sync / GIS Database | Data is synced to a central GIS system in real time or via batch upload. |
| 4. GIS Analysis | GIS software (e.g., ArcGIS Pro, QGIS) | Analyze tree density, health distribution, and canopy coverage. |
| 5. Visualization | Web map / Dashboard | Interactive maps show tree locations, species diversity, and potential shade zones. |
| 6. Decision Making | Urban planners and city officials | Use GIS insights to plan tree planting, manage maintenance, and communicate with the public. |
