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Semester 6: Core Course REMOTE SENSING AND GNSS
Remote Sensing Definition and Types- History of Remote Sensing in India Remote Sensing Processes Electromagnetic Spectrum, Atmospheric Window Plat Forms and its types
Remote Sensing
Definition of Remote Sensing
Remote sensing is the process of acquiring information about an object or area from a distance, typically using satellite or aerial sensors. It involves capturing data without making physical contact.
Types of Remote Sensing
Remote sensing can be classified into two main types: active remote sensing, where sensors emit signals and measure the reflected response; and passive remote sensing, which relies on natural energy, such as sunlight, to measure the reflected radiation.
History of Remote Sensing in India
India's journey in remote sensing began in the 1960s with the launch of the first Indian satellite, Aryabhata. ISRO has since developed various satellite systems, which have been used for agriculture, forestry, and disaster management.
Remote Sensing Processes
The remote sensing process consists of several steps including data acquisition, pre-processing, image interpretation, and application. Each step is crucial for ensuring high-quality data is obtained and analyzed.
Electromagnetic Spectrum
The electromagnetic spectrum encompasses all wavelengths of electromagnetic radiation. Remote sensing primarily uses visible, infrared, and microwave regions of the spectrum to capture data.
Atmospheric Window
An atmospheric window refers to the specific wavelengths of electromagnetic radiation that can pass through the Earth's atmosphere with minimal absorption or scattering. These windows are important for remote sensing as they determine which wavelengths can be effectively used for data acquisition.
Platforms and Types
Remote sensing platforms can be classified into satellite-based, aerial-based, and ground-based systems. Satellites provide global coverage, aerial platforms like drones offer high-resolution localized data, and ground-based systems are often used for calibration and validation.
Fundamentals of Aerial and Satellite Remote Sensing- Aerial Photography and Scale of Aerial Photographs and its Types Types of Satellites
Fundamentals of Aerial and Satellite Remote Sensing
Aerial Photography
Aerial photography involves capturing images of the ground from an elevated position using aircraft, drones, or other platforms. It is utilized in various fields, including geography, urban planning, and environmental monitoring. Aerial photographs can provide a comprehensive view of landscapes and help in habitat assessment, land-use mapping, and disaster management.
Scale of Aerial Photographs
The scale of aerial photographs is the ratio between a distance on the photograph and the corresponding distance on the ground. It affects the level of detail visible in the images. Larger scales (e.g., 1:1,000) provide more detail, while smaller scales (e.g., 1:100,000) cover larger areas but with less detail. Understanding scale is crucial for accurate measurements and analyses in remote sensing.
Types of Aerial Photographs
There are several types of aerial photographs: 1. Vertical: Taken directly overhead, useful for mapping and surveying. 2. Oblique: Taken at an angle, providing more perspective and context of the landscape. 3. Panoramic: Covers a wider horizontal field of view, useful for showcasing large areas.
Types of Satellites
Satellites used in remote sensing can be classified into different categories: 1. Earth Observation Satellites: Specifically designed to monitor and collect data about the Earth's surface and atmosphere (e.g., Landsat, Sentinel). 2. Communication Satellites: Positioned for telecommunications, they can also support remote sensing capabilities. 3. Weather Satellites: Used for meteorological purposes, collecting data related to weather patterns and climate.
Role of Remote Sensing in Geography
Remote sensing plays a significant role in the field of geography by providing valuable information about landforms, vegetation, and urban development. It supports geographical research, environmental monitoring, and spatial analysis, enabling better decision-making for land management and conservation efforts.
Resolution Spectral, Spatial, Radiometric and Temporal- Marginal Information of Aerial Photographs and Satellite Images
Resolution Spectral, Spatial, Radiometric and Temporal - Marginal Information of Aerial Photographs and Satellite Images
Spectral Resolution
Spectral resolution refers to the ability of a sensor to differentiate between different wavelengths of light. A higher spectral resolution allows for the identification of specific materials based on their spectral signatures. Multispectral and hyperspectral sensors capture data across various wavelength bands, enhancing material discrimination and providing detailed information about surface properties.
Spatial Resolution
Spatial resolution denotes the smallest distinguishable feature in an image. For example, higher spatial resolution means that the sensor can capture more detail. Aerial photographs generally have higher spatial resolution than satellite images, allowing for better identification of small features. Spatial resolution is crucial for applications like urban planning, agricultural monitoring, and environmental studies.
Radiometric Resolution
Radiometric resolution refers to the sensor's ability to detect and represent the intensity of light reflected from surfaces. It is typically measured in bits, with higher bit depth providing finer gradations of intensity. This influences the ability to capture subtle differences in surface properties and colors, which is pivotal in applications such as land cover classification and change detection.
Temporal Resolution
Temporal resolution indicates how frequently a sensor can collect data for the same area over time. High temporal resolution is essential for monitoring dynamic changes in the environment, such as vegetation growth, urbanization, or disaster recovery. Understanding temporal resolution is crucial for time-sensitive applications like weather forecasting and environmental monitoring.
Application of Remote Sensing Land use Land cover Urban Sprawl Agriculture and Environment
Application of Remote Sensing in Land Use, Land Cover, Urban Sprawl, Agriculture, and Environment
Introduction to Remote Sensing
Remote sensing involves the acquisition of data about an object or phenomenon without making physical contact. It uses satellite or aerial imagery to collect information on land use, land cover, urban sprawl, and environmental changes.
Land Use and Land Cover Mapping
Remote sensing is essential for mapping land use and land cover types. It allows for the analysis of spatial patterns and changes over time, helping in planning and management efforts.
Urban Sprawl Monitoring
Remote sensing provides tools to monitor urban sprawl by analyzing satellite images. It reveals changes in urban extents, identifying patterns of expansion and the impact on surrounding areas.
Agricultural Applications
Remote sensing aids in precision agriculture by providing data on crop health, soil moisture, and yield estimations. It helps farmers make informed decisions to optimize production.
Environmental Monitoring
Remote sensing is crucial for monitoring environmental changes, including deforestation, wetland loss, water quality, and natural disasters. It helps in assessing the impact of human activities on ecosystems.
Challenges in Remote Sensing Applications
Challenges include data interpretation, the resolution of images, and the need for ground-truth validation. Additionally, access to up-to-date data can be limited in some regions.
Global Navigation Satellite System Segments Space Segment - GPS Satellite Systems New Programmes IRNSS - Control Segment - Satellite tracking - User Segment Modern Survey Instruments - DGPS - GNSS Applications
Global Navigation Satellite System Segments
Space Segment
The space segment consists of satellites that are positioned in orbits around the Earth. These satellites transmit signals to users on the ground, allowing for accurate positioning and timing. Key satellite systems include the Global Positioning System (GPS), which is widely used for navigation, and the Indian Regional Navigation Satellite System (IRNSS), which provides regional coverage.
Control Segment
The control segment is responsible for managing the satellite system. This includes monitoring satellite health, maintaining orbital parameters, and updating satellite data. Control centers track the satellites' positions and ensure that the signals transmitted are accurate and reliable.
User Segment
The user segment comprises the end-users who utilize GNSS technology. This includes individuals and organizations that use GPS devices for navigation, as well as more advanced applications like surveying and mapping. Modern survey instruments often integrate GNSS technology for enhanced accuracy.
Modern Survey Instruments - DGPS
Differential Global Positioning System (DGPS) is an enhancement to the standard GPS system that provides improved accuracy. By using fixed ground reference stations to transmit correction signals, DGPS can achieve accuracies within a few centimeters, making it essential for precise surveying and mapping tasks.
GNSS Applications
GNSS applications span a wide range of fields including transportation, agriculture, disaster management, and urban planning. In transportation, GNSS is used for navigation systems in vehicles. In agriculture, it aids in precision farming. Disaster management benefits from GNSS for real-time tracking and coordination. Urban planning uses GNSS for mapping and spatial analysis.
