"The spectral signature of an object is a function of the incidental EM wavelength and material interaction with that section of the electromagnetic spectrum."
The unique spectral reflectance characteristics of different features on the Earth's surface that can be used to identify and distinguish them using remote sensing data.
Electromagnetic spectrum: Understanding the different wavelengths of electromagnetic energy and how they interact with objects on Earth.
Spectral bands: Understanding the types and characteristics of the satellite sensors and bands used for remote sensing.
Reflectance: Understanding how different surfaces reflect and absorb electromagnetic energy in the form of reflectance spectra.
Radiance and irradiance: Understanding the basic definitions of radiance and irradiance and their relationship to spectral signatures.
Atmospheric interactions: Understanding how the atmosphere interacts with electromagnetic energy, including absorption and scattering.
Vegetation indices: Understanding the different indices used to study vegetation, such as NDVI and EVI.
Image processing: Understanding how to process and analyze remote sensing data using various software and algorithms.
Spectral signature analysis: Developing the skills to interpret and analyze spectral signatures and what they can tell us about the physical properties of different surfaces.
Remote sensing platforms: Understanding the different types of remote sensing platforms and the advantages of each type.
Applications of spectral signatures: Understanding the different applications of spectral signatures in Earth Science, including land cover classification, crop management, and mineral exploration.
Reflectance Spectral Signature: Reflectance is the measure of the amount of light reflected by different objects, such as vegetation, water, soil, and rocks, across different electromagnetic wavelengths. The reflectance spectral signature helps to identify the features and properties of the Earth's surface.
Absorption Spectral Signature: Absorption refers to the amount of light absorbed by different objects at different wavelengths. The absorption spectral signature helps identify the presence of minerals, trace elements, and other chemical compounds in the Earth's surface.
Emission Spectral Signature: Emission is the amount of radiation that is emitted by an object, such as plants or rocks, due to their temperature or chemical composition. The emission spectral signature helps to identify the temperature and chemical properties of different objects.
Scattering Spectral Signature: Scattering occurs when light reflects off different objects at different angles. Scattering affects the intensity, direction, and polarization of light. The scattering spectral signature is used to identify the presence of aerosols, clouds, and other atmospheric phenomena.
Fluorescence Spectral Signature: Fluorescence is the process by which a material absorbs radiation and emits it at a lower energy (often visible) wavelength. The fluorescence spectral signature can be used to detect chlorophyll and other bio-products in plants.
Raman Spectral Signature: Raman scattering is the inelastic scattering of light due to vibrations of molecules. The Raman spectral signature is used to identify the chemical structure and properties of different minerals, rocks, and other materials.
Thermal Infrared Spectral Signature: The thermal infrared spectral signature is used to measure the emitted radiation from the Earth's surface due to its temperature. It is used to identify the thermal properties of different objects, as well as to detect fires and volcanic eruptions.
Microwave Spectral Signature: The microwave spectral signature is used to measure the interactions of microwaves with different materials such as snow and ice, vegetation, and soil. It is used to study the moisture content and structural properties of different objects.
X-Ray Spectral Signature: X-ray spectra are produced when X-ray radiation interacts with materials, causing ionization and resulting in the release of photons. The X-ray spectral signature is used to study the elemental composition of different objects and materials.
Gamma Ray Spectral Signature: Gamma rays are emitted from the nucleus of an atom and can penetrate materials much deeper than X-rays. The gamma ray spectral signature is used to study the elemental composition and structure of different materials.
"The measurements can be made with various instruments, including a task-specific spectrometer, although the most common method is separation of the red, green, blue, and near-infrared portion of the EM spectrum as acquired by digital cameras."
"Calibrating spectral signatures under specific illumination are collected in order to apply a correction to airborne or satellite imagery digital images."
"The spectral signature of stars indicates the composition of the stellar atmosphere."
"The user sees specific lines of color falling on a graduated scale."
"Each substance will have its own unique pattern of spectral lines."
"Most remote sensing applications process digital images to extract spectral signatures at each pixel and use them to divide the image into groups of similar pixels (segmentation) using different approaches."
"Depending on pixel resolution, a pixel can represent many spectral signature 'mixed' together - that is why much remote sensing analysis is done to 'unmix mixtures'."
"Ultimately correct matching of spectral signature recorded by image pixel with spectral signature of existing elements leads to accurate classification in remote sensing."
"The variation of reflectance or emittance of a material with respect to wavelengths."