15.4.10.1. Remote Sensing

Remote Sensing according to Campbell(1987) is the science of deriving information about the earth’s land water areas from images acquired at a distance. It relies upon measurement of electromagnetic energy reflected or emitted from the features of interest.

Remote sensing is a scientific method that allows us to gather information about the Earth's surface from a distance, without the need to be in direct contact with the area being studied. This is achieved through imaging technology that detects and measures electromagnetic energy. This means that tools like satellites or aircraft can capture images of land, water, and other features, helping scientists and researchers learn about the environment.

Think of remote sensing like using a camera to take pictures of a landscape from a high mountain. Just as a photographer captures a scene without stepping into it, remote sensing captures images of the Earth without needing to physically be at the location.

The Electro-magnetic spectrum (EMS) is the physical basis for Remote Sensing. It is an abstract idea and diagram of forms of electromagnetic energy for illuminating earth surface features.

The electromagnetic spectrum includes all types of light waves, ranging from radio waves to gamma rays. In remote sensing, different wavelengths of this spectrum are used to illuminate and gather information about the Earth's surface. For example, visible light is what we see, but infrared light can provide additional data about the health of vegetation or the temperature of the land.

Imagine different colors of light in a rainbow. Each color represents a different energy type in the spectrum. Just like how a painter uses different colors to depict a scene, scientists use various wavelengths of electromagnetic energy to understand and analyze the Earth better.

The process of Remote Sensing involves 1) Making observation using sensors (camera, scanners, radiometers, radar, and lasers) mounted on platforms (ground, aircraft, satellites, balloons) which may be at considerable height from the earth surface. 2) Then, recording the observations on a suitable medium (photographic films and magnetic tapes) or transmitting/down linking the data to a ground receiving station where the data are corrected for geometric and radiometric distortions.

Remote sensing consists of two main steps. First, sensors gather data from above the Earth's surface using various technologies like cameras or lasers mounted on different platforms. This data is then recorded on mediums like films or transmitted electronically to receiving stations. Once the data reaches the ground, it is corrected for any distortions that may have occurred during collection, ensuring accuracy.

Picture a friend using a drone to take aerial photos of a park. The drone's camera (the sensor) captures images, which are then sent back to your friend’s smartphone (the ground receiving station). Just like your friend needs to edit and enhance the images for clarity, scientists correct their data to ensure it is accurate for analysis.

Remote sensing serves as a tool for environmental resources (biotic, abiotic and cultural) assessment and monitoring. Remote sensing has some fundamental advantages that make it a veritable tool in environmental monitoring and management and impact studies.

Remote sensing is a vital tool for assessing and monitoring various environmental resources, including biological (trees, animals), abiotic (water, minerals), and cultural resources (sites of human activity). Its key advantages include the ability to cover large areas quickly and provide valuable data for managing and protecting the environment, as well as conducting environmental impact studies.

Think of remote sensing like a health check-up for the planet. Just as a doctor uses various tests to assess a person’s health, scientists use remote sensing to gather information about the Earth’s health by monitoring changes in land use, deforestation, or pollution levels, helping us understand and protect our environment.

--