The DESIS hyperspectral imager produces Analysis Ready Data (ARD) processed to several different product levels. Acquired data is processed to Level1A, which consists of raw, quality screened image and calibration data, and stored in the archive. Higher level processing is applied when data sets are ordered by end users. The table below lists the DESIS data products:
Additional information about DESIS data product and the processing applied for each product may be found in the following documents:
- DESIS Product Specifications
- DESIS Processing Chain and Technical Guide ATBD
- DESIS Glossary and Abbreviations
L2A Additional Information
The DESIS L2A Surface Reflectance product is scaled by a factor of 10,000 and stored as a 16-bit integer. To convert the data to reflectance, multiply the image data by 0.0001.
Performance of the L2A Surface Reflectance product will depend on the radiometric calibration of DESIS, which may be periodically updated, as well as the presence of dark, vegetated, land pixels within the scene. Scenes that contain all desert or water may produce a reduced quality surface reflectance product.
A rugged terrain model is used when converting the data from TOA Radiance (L1C) to Surface Reflectance (L2A) if more than 1% of the pixels in the image have slope values greater than 6° in the corresponding Digital Elevation Model (DEM). The Shuttle Radar Topography Mission C-Band Digital Elevation Model is the default DEM used for generating L2A Surface Reflectance products.
When the rugged terrain model is applied to data sets with low solar zenith angles (SZA), the image quality may be reduced. At SZA > 45°, processing artifacts may be visible over extremely uniform features. SZA > 55° produces a reduced quality L2A product; SZA > 65° produces low quality L2A product; and SZA > 70° not processible to L2A.
The DESIS Processing Chain and Technical Guide ATBD contains a full description of the algorithm used to generate the L2A Surface Reflectance Product.
For US government-affiliated researchers, spectral binning may be selected when ordering data. The full 2.55 nm resolution data may be requested without binning, or spectrally binned to 5.1 nm, 7.65 nm, or 10.2 nm. Commercial or non-US government-affiliated end users may only request 10.2 nm binned product.
If you have questions concerning commercial, academic, or NGO site access, please contact our Geospatial Solutions Manager Heath Lester at firstname.lastname@example.org.
For DESIS technical information and calibration assistance, please contact Kara Burch at email@example.com.
Image from California Central Valley Atmospherically resistant index on the left and true color image on the right. You can see that Spectral enhancements allow one to see areas of stress more clearly (red areas in the image on the right).