With access to Radiant.Earth, you have access to images from around the globe and from a variety of times. In this article, you can learn about the imagery we have available for your use.

To see how to view the breakdown of each datasource by band, see Managing Datasources.

In order to understand the data sources available, you need to know about the four resolutions of imagery:

  • Spatial Resolution: The size of the area that each pixel in an image represents.
  • Temporal Resolution: How often an image is taken of the same area.
  • Spectral Resolution: What frequencies of light are captured--usually captured in different bands. The most common are visible light bands (broken into the colors red, green, and blue) and near infrared (which is often used to highlight differences in vegetation).
  • Radiometric Resolution: The sensitivity of the sensor to light, given in how many bits of data are recorded (for example, 8 bit data allows for a spectrum of 256 different values of brightness).

Each of these resolutions will affect what kind of imagery you want to use. If you're looking at the scar of a forest fire, you probably would use relatively low spatial resolution since you are looking at a large area, temporal resolution that will allow you to see change over on a week or so, spectral resolution that includes visual and near-infrared bands so that you can find dead vegetation, and a high enough radiometric resolution to differentiate areas.

With that information, you'll be able to choose what imagery best suits your needs, from the list below:

Landsat (4, 5, 7, and 8)

The Landsat program, controlled by USGS, includes of a chain of data stretching back to 1972, meant to cover the entire globe in medium-high resolution in multiple bands every 16 days. Landsat 4 (operational July 1982–December 1993) and 5 (March 1984–June 2013) used the Thematic Mapper (TM) sensor, Landsat 7 (April 1999– ) uses the Enhanced Thematic Mapper + (ETM+) sensor, and Landsat 8 (March 2013– ) uses the Operational Land Imager (OLI) sensor. (Landsat 6 was destroyed during launch.)

Landsat 7 and Landsat 8 are currently orbiting. Landsat 7 imagery has had an error since May 2003 due to the Scan Line Corrector failing, resulting in about 20% of every scene missing data.

Landsat 8 is available through the Raster Foundry repository.
Landsat 4, 5, and 7 are available through the NASA CMR repository.

  • Spatial Resolution: 30 meter in most bands, except for panchromatic (15 m) and thermal (120 m on Landsat 4/5, 60 m on Landsat 7, 100 m on Landsat 8). Each scene has an extent of approximately 170 km by 185 km (106 mi by 115 mi).
  • Temporal Resolution: 16 days for each sensor.
  • Spectral Resolution:
    -
    Landsat 8 has 11 bands, including visual/RGB, Near Infrared (NIR), Shortwave Infrared (SWIR), Panchromatic, Cirrus, Coastal/Aerosal/Ultrablue, and Thermal Infrared.
    - Landsat 7 has 8 bands, including RGB, NIR, SWIR, and Panchromatic.
    - Landsat 4 and 5 each have 7 bands, including RGB, NIR, and SWIR.
  • Radiometric Resolution:
    - Landsat 8 has 12-bit quantization.
    - Landsat 4, 5, and 7 have 8-bit quantization.

Sentinel 2 (A and B)

Sentinel 2 is a multi-spectral medium-resolution system controlled by the European Space Agency (ESA). Sentinel 2 uses two satellites to increase temporal resolution. Sentinel 2A began collecting imagery in June 2015, and Sentinel 2B began collecting imagery in June 2017.
Radiant.Earth currently uses data that provides slivers rather than rectangular tiles, which may have variable cloud coverage.

  • Spatial Resolution: 10 meter to 60 meter. 10 meter for RGB and NIR, 20 meter for vegetation red edge, narrow NIR and SWIR, and 60 meter for coastal aerosol and water vapor. 
  • Temporal Resolution: 5 days, once Sentinel 2B was launched. (2A was launched in June of 2015, 2B was launched March 2017)
  • Spectral Resolution: 13 bands, including visual/RGB, NIR, three bands of Vegetation Red Edge, a narrow-NIR sub-band, Coastal Aerosol, Water Vapor, Cirrus/SWIR, and two additional SWIR bands.
  • Radiometric Resolution: 12-bit.

ISERV

The ISS SERVIR Environmental Research and Visualization System (ISERV) was a telescope-mounted camera based on the International Space Station to collect imagery for research into remote sensing. It used out-of-the-box technology, including a standard DSLR camera, to help with pan-sharpening Landsat 8 imagery. Lots of additional imagery was captured and made available to the global community.

  • Spatial Resolution: Approximately 3.5 m, 19 km by 11 km.
  • Temporal Resolution: Variable based on the orbit of the ISS and chosen operational times. May 2012 - September 2015.
  • Spectral Resolution: Only included the visible spectrum, Red, Green, and Blue.
  • Radiometric Resolution: 14-bit.

MODIS

NASA's MODerate resolution Imaging Spectroradiometer program uses two satellites (Terra and Aqua) to gather multispectral imagery of the entire Earth every one to two days. This imagery is designed to give insights into global dynamics and environmental changes on a global scale. MODIS's primary benefits come in the data products provided by NASA, which include atmospheric conditions, landcover, fire tracking, and more.

Currently available MODIS data includes the 8-day Aqua Surface Reflectance 500m product, based on a selection of imagery from an 8 day period with the lowest amount of disturbance and cloud cover.

MODIS data is available in the NASA CMR repository.

  • Spatial Resolution: Approximately 500 m, 1200 km by 1200 km.
  • Temporal Resolution: Eight day composite from daily imagery.
  • Spectral Resolution: Seven surface reflectance bands including RGB, NIR, and three SWIR bands. Other bands are included: band quality control flags, state flags, solar zenith angle, view zenith angle, relative azimuth angle, and day of the year, for each pixel.
  • Radiometric Resolution: 16-bit for all bands except quality control flags, which has 32-bit resolution.
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