Terminology. Remote Sensing

Absorptance : The ratio of the radiant energy absorbed by a substance to the energy

it receives.

Band : The specific wavelength interval in the electromagnetic spectrum.

Digital image : An array of digital numbers (DN) arranged in rows and columns,

having the property of an intensity value and their locations.

Digital Number : An intensity value of a pixel in a digital image.

Digital Image Processing : The numerical manipulation of DN values for the purpose

of extracting information about the phenomena of the surface they represent.

Electromagnetic Radiation (EMR) : The Energy propagated through a space or a

medium at a speed of light.

Electromagnetic Spectrum : The continuum of EMR that ranges from short wave

high frequency cosmic radiations to long wavelength low frequency radio waves.

False Colour Composite (FCC) : An artificially generated colour image in which

blue, green and red colours are assigned to the wavelength regions to which they do

not belong in nature. For example, in standard a False Colour Composite blue is

assigned to green radiations (0.5 to 0.6 µm), green is assigned to red radiations (0.6

to 0.7 µm and red is assigned to Near Infrared radiation (0.7 to 0.8 µm).

Gray scale : A medium to calibrate the variations in the brightness of an image that

ranges from black to white with intermediate grey values.

Image : The permanent record of a scene comprising of natural and man-made

features and activities, produced by photographic and non–photographic means.

Scene : The ground area covered by an image or a photograph.

Sensor : Any imaging or non–imaging device that receives EMR and converts it into

a signal that can be recorded and displayed as photographic or digital image.

Reflectance : The ratio of the radiant energy reflected by a substance to the energy

it receives.

Spectral Band : The range of the wavelengths in the continuous spectrum such as

the green band ranges from 0.5 to .6 µ and the range of NIR band 0.7 to 1.1 µ.

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Energy Interaction with Atmosphere and Earth Surface

In Remote Sensing , satellites record electromagnetic radiation (EMR) that is reflected or emitted from the Earth. Before reaching the sensor, radiation interacts with: The Atmosphere The Earth's Surface These interactions control how satellite images look and how we interpret them. I. Interaction of EMR with the Atmosphere When solar radiation travels from the Sun to the Earth, four main processes occur: 1. Absorption Definition: Absorption occurs when atmospheric gases absorb radiation at specific wavelengths and convert it into heat. Main absorbing gases: Ozone (O₃) → absorbs Ultraviolet (UV) Carbon dioxide (CO₂) → absorbs Thermal Infrared Water vapour (H₂O) → absorbs Infrared Concept: Atmospheric Windows These are wavelength regions where absorption is very low, allowing radiation to pass through the atmosphere. Remote sensing depends on these windows. For example, satellites like Landsat 8 use visible, near-infrared, and thermal bands located in atmospheric windows. 2. Trans...

Types of Remote Sensing

Remote Sensing means collecting information about the Earth's surface without touching it , usually using satellites, aircraft, or drones . There are different types of remote sensing based on the energy source and the wavelength region used. 🛰️ 1. Active Remote Sensing 📘 Concept: In active remote sensing , the sensor sends out its own energy (like a signal or pulse) to the Earth's surface. The sensor then records the reflected or backscattered energy that comes back from the surface. ⚙️ Key Terminology: Transmitter: sends energy (like a radar pulse or laser beam). Receiver: detects the energy that bounces back. Backscatter: energy that is reflected back to the sensor. 📊 Examples of Active Sensors: RADAR (Radio Detection and Ranging): Uses microwave signals to detect surface roughness, soil moisture, or ocean waves. LiDAR (Light Detection and Ranging): Uses laser light (near-infrared) to measure elevation, vegetation...

Platforms in Remote Sensing

In remote sensing, a platform is the physical structure or vehicle that carries a sensor (camera, scanner, radar, etc.) to observe and collect information about the Earth's surface. Platforms are classified mainly by their altitude and mobility : Ground-Based Platforms Definition : Sensors mounted on the Earth's surface or very close to it. Examples : Tripods, towers, ground vehicles, handheld instruments. Applications : Calibration and validation of satellite data Detailed local studies (e.g., soil properties, vegetation health, air quality) Strength : High spatial detail but limited coverage. Airborne Platforms Definition : Sensors carried by aircraft, balloons, or drones (UAVs). Altitude : A few hundred meters to ~20 km. Examples : Airplanes with multispectral scanners UAVs with high-resolution cameras or LiDAR High-altitude balloons (stratospheric platforms) Applications : Local-to-regional mapping ...

Government of Kerala Initiatives for Water Management

Kerala, with its abundant rainfall and network of rivers, faces a dual challenge of water scarcity and excess —seasonal droughts and monsoon floods. The state government has implemented various policies and programs to address these challenges through sustainable water conservation, management, and distribution practices . Below is a detailed breakdown of the major water management initiatives in Kerala. 1. Jal Jeevan Mission (JJM) – Kerala Implementation Objective: To provide functional household tap connections (FHTC) to all rural households by 2024. Focuses on source sustainability and community-led water resource management. Key Features: Water Quality Monitoring & Surveillance: Ensures supply of safe drinking water through real-time monitoring. Decentralized Approach: Implementation through gram panchayats and local self-governments (LSGs) . Recharge & Conservation Measures: Rainwater harvesting, groundwater recharge, and watershed development inte...

The Leopold Matrix and environmental impact assessment (EIA)

"Leopold Matrix" or more commonly known as the "Leopold Matrix" or "Leopold's Matrix." The Leopold Matrix is a decision-making tool used in environmental impact assessment (EIA) and land-use planning processes. It helps evaluate and compare the potential environmental consequences of different land management alternatives. The matrix was developed by Aldo Leopold, an influential American conservationist and author, in the mid-20th century. Leopold recognized the need for a systematic approach to assess the ecological impacts of human activities and proposed the matrix as a practical framework. The Leopold Matrix consists of a grid or table with two main dimensions: actions and environmental factors. Actions refer to specific land management or development options being considered, such as building a road, constructing a dam, or clearing a forest. Environmental factors encompass various ecological aspects affected by these actions, including soil, wate...

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