What is the difference between optical and SAR (radar) satellite imagery?
- Anvita Shrivastava
- Apr 18
- 2 min read
Satellite imagery is essential across various industries, including agriculture, environmental monitoring, defence, and disaster management. Two primary types of satellite imaging technologies are optical imagery and radar imagery. But what are the key differences between them?
What is Optical or Visible Satellite Imagery?
Optical satellite imagery captures images using reflected sunlight, much like a traditional camera. These images are collected across visible, near-infrared, and short-wave infrared bands of the electromagnetic spectrum.
Key Features of Optical Imagery:
Visual Interpretation: Optical imagery looks like a photograph and is easier to interpret for the human eye.
Colour Bands: Offers true-colour and false-colour images for different applications (e.g., vegetation analysis).
Cloud-Dependent: Cannot capture data through clouds, smoke, or during nighttime.
High Spatial Resolution: Excellent for land use, urban planning, and vegetation monitoring.
What is Radar Satellite Imagery?
Radar satellite imagery, known as Synthetic Aperture Radar (SAR), utilises microwave signals to generate images. It transmits radar pulses toward the Earth and measures the signals that are reflected from the satellite.
Key Features of Radar Imagery:
All-Weather Capability: Works through clouds, smoke, and in total darkness.
Penetration: Can detect surface roughness, moisture, and sometimes even underground features.
Textural Detail: Ideal for structural analysis and topography.
Different Look: Images appear grainy and monochrome but contain rich information not visible in optical data.
Optical vs Radar Satellite Imagery: A Side-by-Side Comparison
Feature | Optical Imagery | Radar Imagery |
Source of Signal | Sunlight | Active radar pulses |
Day/Night Imaging | Day only | Day and night |
Weather Dependence | Affected by clouds/smoke | All-weather capability |
Image Appearance | Photo-like | Textural, grayscale |
Ideal For | Vegetation, urban areas | Topography, water, and soil moisture |
Examples | Landsat, Sentinel-2, WorldView | Sentinel-1, RADARSAT, TerraSAR-X |
Major Providers of Optical and Radar Satellite Imagery
Optical Satellite Imagery providers
Here is a list of notable optical satellite imagery providers, including both commercial companies and government organisations.
Radar Satellite Imagery providers
Here's a list of notable radar satellite imagery providers (companies and organizations offering Synthetic Aperture Radar, or SAR, imagery):
Capella Space (USA)
ICEYE (Finland)
Umbra (USA)
Synspective (Japan)
PredaSAR (USA, part of Terran Orbital)
iQPS (Institute for Q-shu Pioneers of Space) (Japan)
When to Use Optical vs Radar Satellite Imagery
Use Optical Imagery when you need clear, natural-looking visuals for vegetation health, land use planning, or disaster damage assessment in cloud-free conditions.
Use Radar Imagery when monitoring during night or cloudy weather, especially for flood mapping, soil moisture analysis, or infrastructure movement detection.
Understanding the difference between optical and radar satellite imagery is key to selecting the right data source for your project. Each has its strengths—optical imagery excels in clear, colourful visual analysis, while radar imagery is unbeatable in harsh weather or low-light conditions.
Whether you're in precision agriculture, environmental science, or infrastructure monitoring, leveraging the right type of satellite imagery can significantly enhance decision-making and insight.
If you want to learn more about our satellite imagery or need help using it, please feel free to contact us.
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