Sensors
A sensor is a device used in remote sensing to gather electromagnetic radiation, convert it into a signal, and present it in a suitable form for obtaining information about objects. Sensors are classified into photographic (analogue) and non-photographic (digital) sensors based on the form of data output.
Photographic sensors, like cameras, capture images of objects at an instance of exposure. Non-photographic sensors, known as scanners, obtain images in a bit-by-bit form. Multispectral Scanners (MSS) are commonly used as sensors in satellite remote sensing.
MSS sensors are designed to sweep across the field of view while obtaining images of objects. They consist of a reception system with a mirror and detectors. The scanning sensor constructs the scene by recording a series of scan lines, with the motor device oscillating the scanning mirror through the angular field of view, known as swath. The received energy is converted into electrical signals and then into numerical values called Digital Number (DN Values) for recording.
MSS sensors are further divided into two types:
- Whiskbroom Scanners
- Pushbroom Scanners
Whiskbroom Scanners use a rotating mirror and a single detector to sweep across the field of view and obtain images in narrow spectral bands. The mirror completes a rotation, allowing the detector to sweep across the field of view between 90° and 120°.
Pushbroom Scanners consist of multiple detectors arranged linearly. Each detector collects energy reflected by ground cells (pixels) at nadir’s view. The number of detectors is determined by dividing the swath of the sensor by the size of the spatial resolution.
Chapter 6: Introduction to Remote Sensing| Class 11 Geography Practical Work
Class 11 Geography Ch 6 Introduction to Remote Sensing Notes: Introduction to Remote Sensing is the sixth chapter in CBSE Class 11 Geography, which discusses the concept of Remote Sensing and its various forms. The chapter explains how this technique works, its different methods, and how it’s used in various fields like geography, agriculture, and environmental science.
Students learn about the sensors used to collect data, like cameras and scanners, and how they create images and information about the Earth. They also learn how to analyze this data to understand changes in things like land use, vegetation, and the environment. Overall, the chapter helps students understand how remote sensing helps us learn more about our planet from afar.
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