Remote Sensing of the Environment
Definition and Purpose
- Remote Sensing: Collecting information about the Earth from a distance without direct contact.
- Methods: Includes aerial photography and increasingly, satellite imaging.
Advantages of Satellite Imaging
- Global Coverage: No political barriers or fly zones in space.
- Imaging Techniques: Originally images captured on photographic film; later digital imaging.
Transition from Film to Digital
- Historical Methods: Early Russian satellites used film capsules retrieved by fighter planes.
- Shift to Digital: Digital imaging offers convenience, allowing for electronic transmission.
Benefits of Digital Imaging
- Transmission: Real-time data transfer via radio waves from space to Earth.
- Data Types: Ability to capture a wider range of electromagnetic radiation beyond visible light.
Electromagnetic Spectrum in Remote Sensing
- Photographic Film: Captures visible light, UV, shortwave infrared.
- Digital Scanners: Capture wide range, including thermal and radar wavelengths.
Key Wavelengths Used
- Near-Infrared (NIR): Reflects well from chlorophyll, useful for vegetation analysis.
- Thermal Infrared: (Discussed in next video)
- Radar: Captures surface roughness, elevation.
- Multi-Spectral Scanning: Captures multiple wavelength bands.
Applications of Near-Infrared (NIR)
- Vegetation Analysis: Enhanced imaging of plants; healthy vegetation appears bright red.
- Agricultural Use: Monitor crop health and growth.
- Military Applications: Identify camouflage, as fake vegetation appears differently in NIR.
Visual Examples
- Diagrams: Comparison of visible light and near-infrared images (e.g., Florida Keys).
- Colorizing NIR Images: Often colorized in shades of red for better visualization.
The lecture concludes with references to textbook figures for visual understanding and a mention of thermal infrared to be covered in the next session.