Remote sensing relies on satellite and airborne sensors that capture images of the Earth across multiple wavelengths of light. By analyzing how different materials absorb and reflect energy at these wavelengths, researchers can identify and classify features on the Earth’s surface and in the atmosphere.
Features such as healthy vegetation, dry vegetation, water, soil, and buildings each reflect and absorb light differently. These unique patterns create what is known as a spectral signature.
Spectral signatures are often displayed as graphs called spectral profiles, which show how a material reflects or emits energy across different portions of the electromagnetic spectrum, from visible light to infrared wavelengths and beyond.
What is the Spectral Characteristics Viewer?
The U.S. Geological Survey (USGS) developed the Spectral Characteristics Viewer, an online tool that helps users explore how different Earth observation sensors capture information across the electromagnetic spectrum.
The viewer allows users to compare the Relative Spectral Response (RSR) of satellite sensors with the spectral signatures of various materials and land cover types. RSR describes how sensitive a sensor is to different wavelengths of light and helps determine which sensors and bands are best suited for a particular remote sensing application.
Choosing the appropriate sensor is an important step in remote sensing analysis. A researcher interested in mapping vegetation, identifying minerals, monitoring water quality, or detecting burned areas may need different combinations of spectral bands to distinguish those features effectively.
The tool was updated through the USGS EROS EROS CalVal Center of Excellence (ECCOE) project. Updates include a cleaner interface, interactive highlighting, improved display controls, and zoom tools for examining specific parts of the spectrum.
What satellite bands are available for comparison?
The Spectral Characteristics Viewer includes response curves for a variety of Earth observation instruments, including:
- Landsat 8 OLI
- Landsat 8 TIRS
- Landsat 7 ETM+
- Landsat 5 TM
- Landsat 4 TM
- Landsat 5 MSS
- Landsat 4 MSS
- Earth Observing-1 (EO-1) Advanced Land Imager (ALI)
- Terra Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER)
- Terra Moderate Resolution Imaging Spectroradiometer (MODIS)
- Sentinel-2A
The tool helps researchers, students, and GIS professionals better understand how different sensors observe the Earth and which spectral bands are most appropriate for specific remote sensing applications.
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This article was originally written on March 27, 2019 and has since been updated.
