Remote Sensing
Definition:
Remote sensing is a process that involves the collection of information about an object or phenomenon without physical contact, done from a distance often using satellite or aerial platforms.
Key Components:
1. Sensor: Device or instrument used to collect data, eg cameras, spectrometers, radar systems etc.
2. Platform: Which vehicle carries the sensor for example satellites, aircrafts, drones etc.
3. Data Transmission: The movements of collected data from the sensor to the ground stations for further analysis.
Types of Remote Sensing:
1. Passive Remote Sensing:
This relies on external sources of radiation such as sunlight and measures reflected or emitted energy (eg optical sensors capturing visible light).
2. Active Remote Sensing:
It uses its own energy source like radar and measures the reflected signal (useful in cloudy conditions and for mapping topography).
Electromagnetic Spectrum:
One must understand the electromagnetic spectrum to study remote sensing. It includes various forms of energy like radio waves, microwaves, infrared, visible light, ultraviolet rays, x-rays and gamma rays.
Applications:
- Environmental Monitoring: Tracking deforestation; land use changes; monitoring ecosystems.
- Agriculture: To access crop health; monitor irrigation; predict yields.
- Urban Planning: Analyzing urban growth; infrastructure development; land-use planning.
- Disaster Management: Assessing impact of natural disasters e.g earthquakes; floods; wildfires.
Image Interpretation:
1. Resolution:
- Spatial: Level of detail in the image.
- Spectral: Number and size of spectral bands in the sensor.
- Temporal: time interval between image acquisitions
2. Enhancement Techniques:
- Image enhancement improves visualization e.g contrast stretching or histogram equalization
Challenges:
1. Cloud Cover:
It limits visibility in optical sensors
Radar and microwave sensors are less affected
2. Cost:
Some applications may be prohibitive due to satellite and sensor costs
3. Data Interpretation:
It requires expertise in image analysis and interpretation