Skip to main content

Discrete Detectors and Scanning mirrors Across the track scanner Whisk broom scanner.

Multispectral Imaging Using Discrete Detectors and Scanning Mirrors (Across-Track Scanner or Whisk Broom Scanner)

Multispectral Imaging: This technique involves capturing images of the Earth's surface using multiple sensors that are sensitive to different wavelengths of electromagnetic radiation. This allows for the identification of various features and materials based on their spectral signatures.

Discrete Detectors: These are individual sensors that are arranged in a linear or array configuration. Each detector is responsible for measuring the radiation within a specific wavelength band.

Scanning Mirrors: These are optical components that are used to deflect the incoming radiation onto the discrete detectors. By moving the mirrors, the sensor can scan across the scene, capturing data from different points.

Across-Track Scanner or Whisk Broom Scanner: This refers to the scanning mechanism where the mirror moves perpendicular to the direction of flight. This allows for the collection of data along a swath, covering a wide area on the ground.

Remote Sensing Terminologies

A. Rotating Mirror

  • Definition: A mechanical component in some satellite-based remote sensing systems that rotates to scan the Earth's surface. It directs sunlight onto a sensor, enabling the collection of data over a wide area.
  • Purpose: To increase the coverage area of the sensor, allowing for rapid data acquisition.

B. Internal Detectors

  • Definition: Sensors within a remote sensing instrument that convert electromagnetic radiation into electrical signals. These signals are then processed to produce images or data.
  • Purpose: To capture and measure the intensity of radiation reflected or emitted from the Earth's surface.

C. Instantaneous Field of View (IFOV)

  • Definition: The smallest area on the ground that can be resolved by a remote sensing sensor at a given time.
  • Purpose: To determine the spatial resolution of the sensor, indicating the level of detail it can capture.

D. Ground Resolution Cell Viewed (GRCV)

  • Definition: The area on the ground corresponding to the IFOV of a sensor at a specific altitude.
  • Purpose: To measure the size of the smallest distinguishable feature on the Earth's surface.

E. Angular Field of View (AFOV)

  • Definition: The angle between the extreme rays of the field of view of a sensor.
  • Purpose: To determine the extent of the area that can be observed by the sensor at a given distance.

F. Swath

  • Definition: The width of the area on the ground that a sensor can cover in a single pass.
  • Purpose: To measure the lateral coverage of the sensor, indicating the efficiency of data collection.

How it works:

  1. Radiation Collection: The scanning mirror deflects incoming radiation from the Earth's surface onto the array of discrete detectors.
  2. Spectral Separation: Each detector measures the radiation within its specific wavelength band, capturing information about different materials and features.
  3. Scanning: The scanning mirror moves across the scene, allowing the sensor to collect data from multiple points.
  4. Data Processing: The collected data is processed to create multispectral images that can be analyzed to identify and classify features based on their spectral signatures.

Key advantages of this approach:

  • High spatial resolution: Can capture detailed images of the Earth's surface.
  • Wide swath coverage: Can cover a large area in a single pass.
  • Versatility: Can be used for various remote sensing applications, such as land use mapping, vegetation monitoring, and mineral exploration.
Warm regards.
..
Vineesh V
AISHE and UGC Nodal Officer
Assistant Professor of Geography,
Government College Chittur, Palakkad
https://g.page/vineeshvc

Comments

Post a Comment

Popular posts from this blog

History of Geography.

Chronological sequence and categorized by era and region. I. Introduction & Etymology •  Etymology : The term "Geography" derives from the Greek γεωγραφία (geographia) , meaning "Earth-writing" (description or writing about the Earth). •  First Use : Eratosthenes (276–194 BC) was the first person to use the word. •  Pre-Term Practices : Recognizable geographic practices like cartography (map-making) existed prior to the coining of the term. II. Antiquity & Ancient Civilizations 1. Ancient Egypt (Pre-Classical) •  Cosmology : Ancient Egyptians viewed the Nile as the center of the world, with existence based upon "the" river. •  Geographical Knowledge : •  Oases : Known to the east and west, considered locations of various gods (e.g., Siwa for the god Amon ). •  Kushitic Region : Lay to the south, known as far as the 4th cataract . •  Punt : A region located south a...
Post a Comment
Read more

Building Topology in GIS, Data Query in GIS, Geoprocessing and Automation in GIS

A Geographic Information System (GIS) is more than a digital mapping tool. It is a comprehensive system for capturing, storing, managing, analysing, querying, and visualising spatial (geographic) and non-spatial (attribute) data . To maintain accurate spatial data and perform advanced analyses, GIS relies on three important concepts: Building Topology Data Query Geoprocessing and Automation These concepts ensure data integrity, efficient data retrieval, and automated spatial analysis , making GIS an indispensable tool in geography, environmental science, urban planning, disaster management, transportation, agriculture, and resource management. 1. Building Topology in GIS Topology is the mathematical and logical framework that defines the spatial relationships between geographic features such as points, lines, and polygons. It ensures that spatial data maintain correct geometric relationships even after editing or analysis. Simple Definiti...
Post a Comment
Read more

Development of Health Geography

Health Geography (formerly Medical Geography ) is the branch of geography that studies the relationship between health, disease, environment, place, and healthcare systems . The discipline has evolved over more than 2,500 years through contributions from physicians, geographers, epidemiologists, microbiologists, and public health experts. The development of Health Geography can be divided into the following periods: Ancient Period Medieval Period Renaissance and Pre-Modern Period Nineteenth Century (Pre-World War Era) World War Period Post-World War Period Modern Health Geography 1. Ancient Period (5th Century BC – 500 AD) Characteristics Health closely linked with the natural environment. Diseases explained through climate, water, air, and seasons. No knowledge of microorganisms. Medical observations were descriptive. Major Concepts Environmental Determinism Disease Ecology Climate and Healt...
Post a Comment
Read more

Nature and Scope of Geography

Geography is the scientific study of the Earth's surface, its physical features, human populations, and the interactions between people and their environment. The word Geography is derived from the Greek words Geo (Earth) and Graphien (to describe or write), meaning "description of the Earth." Modern geography goes far beyond description; it seeks to explain where phenomena occur, why they occur there, how they are spatially distributed, and how they change over time. Geography is regarded as a spatial science , an environmental science , and an integrative discipline because it bridges natural sciences, social sciences, and geospatial technologies. Nature The nature of geography refers to the characteristics and fundamental features that define the discipline. 1. Geography as a Spatial Science Terminology: Spatial Science A discipline concerned with the location, distribution, arrangement, organization, and interaction of phenomena in ...
Post a Comment
Read more

geography as a science - place of geography in classification of sciences

Geography is the scientific study of the Earth , its physical features , human activities , and the relationships between people and the environment . It answers four basic questions: What is found? Where is it located? Why is it there? How does it interact with other places? Why is Geography Called a Science? Geography is a science because it: Observes natural and human phenomena. Collects and analyzes data. Uses scientific methods. Explains spatial patterns and relationships. Uses modern tools such as GIS , Remote Sensing , GPS , and Artificial Intelligence (AI) . Place of Geography in the Classification of Sciences Geography is unique because it belongs to more than one branch of science . Branch of Science Role of Geography Natural Science Studies landforms, climate, soils, water, vegetation, and ecosystems. ...
Post a Comment
Read more