Nsdi vision and metadata

The National Geospatial Policy (NGP) is a strategic framework introduced by the Government of India to regulate, promote, and facilitate the development and utilization of geospatial data and services. The policy is designed to strengthen India's geospatial infrastructure, support decision-making, and drive economic growth, environmental management, and disaster response through the use of advanced geospatial technologies.

Key Components of the National Geospatial Ecosystem

1. Department of Science and Technology (DST) & National Spatial Data Infrastructure (NSDI)

Department of Science and Technology (DST) is the nodal agency responsible for coordinating geospatial activities in India. DST oversees the implementation of the National Spatial Data Infrastructure (NSDI).
National Spatial Data Infrastructure (NSDI) is a framework designed to facilitate the collection, sharing, and management of spatial data at different administrative levels, ensuring data interoperability and accessibility.

2. National Data Registry (NDR)

The National Data Registry (NDR) serves as a central repository where metadata about geospatial datasets is cataloged. It ensures that data users can locate, evaluate, and access the necessary geospatial information efficiently. NDR supports:

Metadata indexing: Providing essential details about available datasets.
Data discovery: Enabling users to search for relevant geospatial data.
Interoperability: Ensuring compatibility with different geospatial standards.

NSDI Vision and Metadata Standards

The NSDI Vision aims to ensure that geospatial data is:

Accurate and up-to-date: Reliable datasets that reflect real-world conditions.
Well-organized and accessible: Structured and standardized for seamless usage.
Available at multiple levels: From national to village level, to support development planning.

NSDI Metadata Standards

The NSDI Metadata Standards are based on international metadata frameworks such as:

ISO 19115 (Geographic Information – Metadata) – Defines standards for geospatial metadata.
FGDC (Federal Geographic Data Committee, USA) – Establishes geospatial metadata guidelines.
ANZLIC (Australia-New Zealand Land Information Council) – Defines best practices for spatial data sharing.
Dublin Core – Provides a general-purpose metadata standard.
CSDGM (Content Standard for Digital Geospatial Metadata, USA) – Defines metadata elements for spatial data.

Key Metadata Elements Defined in NSDI Standards

Metadata Category	Description
Availability	Specifies whether the geospatial data is publicly available or restricted.
Compliance	Ensures the dataset meets regulatory and technical standards.
Access	Defines how users can obtain the data (download, request, licensing, etc.).
Quality	Describes the accuracy, resolution, and reliability of the dataset.
Features	Lists the attributes and spatial properties of the data (e.g., roads, rivers, land use).
Lineage	Tracks the source, history, and transformation of the dataset over time.
Temporality	Indicates whether the dataset is static, periodic, or real-time.
Reference Systems	Specifies the coordinate reference system (CRS) used (e.g., WGS 84, EPSG codes).
Extent	Defines the geographic coverage of the dataset (regional, national, global).

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Platforms in Remote Sensing

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Optical Sensors in Remote Sensing

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Types of Remote Sensing

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Resolution of Sensors in Remote Sensing

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Radar Sensors in Remote Sensing

Radar sensors are active remote sensing instruments that use microwave radiation to detect and measure Earth's surface features. They transmit their own energy (radio waves) toward the Earth and record the backscattered signal that returns to the sensor. Since they do not depend on sunlight, radar systems can collect data: day or night through clouds, fog, smoke, and rain in all weather conditions This makes radar extremely useful for Earth observation. 1. Active Sensor A radar sensor produces and transmits its own microwaves. This is different from optical and thermal sensors, which depend on sunlight or emitted heat. 2. Microwave Region Radar operates in the microwave region of the electromagnetic spectrum , typically from 1 mm to 1 m wavelength. Common radar frequency bands: P-band (70 cm) L-band (23 cm) S-band (9 cm) C-band (5.6 cm) X-band (3 cm) Each band penetrates and interacts with surfaces differently: Lo...

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