=============================================================================== AVIRIS-NG Distribution Document =============================================================================== Michael Eastwood, meastwood@jpl.nasa.gov Robert O. Green, Robert.O.Green@jpl.nasa.gov Sarah R. Lundeen, Sarah.R.Lundeen@jpl.nasa.gov David R. Thompson, David.R.Thompson@jpl.nasa.gov This document describes the AVIRIS Next Generation (AVIRIS-NG) L1 and L2 data products. AVIRIS-NG is an imaging spectrometer that measures reflected radiance at 5nm intervals in the Visible/Short-Wave Infrared (VSWIR) spectral range from 380-2500nm. Additional information may be found on http://avirisng.jpl.nasa.gov ------------------------------------------------------------------------------- OVERVIEW ------------------------------------------------------------------------------- Each flightline uses a specific base filename prefix: angYYYYMMDDtHHNNSS YYYY: The year of the airborne flight run. MM: The month of the airborne flight run (i.e. 05 represents May). DD: The day of the airborne flight run (22 is the 22nd day of the month) HH: UTC hour at the start of acquisition NN: UTC minute at the start of acquisition SS: UTC second at the start of acquisition The AVIRIS-NG data products for a particular airborne flight run are organized in the following directory structure, labeled with a data type extension (rdn/rfl) and processing version marker VVV: /YYYYMMDDtHHNNSS_rdn_VVV | angYYYYMMDDtHHNNSS_obs_ort | angYYYYMMDDtHHNNSS_obs_ort.hdr | angYYYYMMDDtHHNNSS_ort_glt | angYYYYMMDDtHHNNSS_ort_glt.hdr | angYYYYMMDDtHHNNSS_ort_igm | angYYYYMMDDtHHNNSS_ort_igm.hdr | angYYYYMMDDtHHNNSS_rdn_VVV_img | angYYYYMMDDtHHNNSS_rdn_VVV_img.hdr | angYYYYMMDDtHHNNSS_rdn_VVV_README.txt | YYYYMMDD_ANG_Data_Products_Info.txt /YYYYMMDDtHHNNSS_rfl_VVV | angYYYYMMDDtHHNNSS_corr_VVV_img | angYYYYMMDDtHHNNSS_corr_VVV_img.hdr | angYYYYMMDDtHHNNSS_h2o_VVV | angYYYYMMDDtHHNNSS_h2o_VVV.hdr | angYYYYMMDDtHHNNSS_rdn_VVV_README.txt | YYYYMMDD_ANG_Data_Products_Info.txt The file product codes signify: *obs_ort parameters relating to the geometry of observation and illumination rendered using the *_ort_glt lookup table *obs_ort.hdr obs_ort image header file *ort_glt geometric look-up table *ort_glt.hdr GLT image header file *ort_igm input geometry file *ort_igm.hdr IGM image header file *rdn_VVV_img orthocorrected, scaled radiance image file *rdn_VVV_img.hdr RDN image header file *corr_VVV_img orthocorrected, scaled reflectance image file *corr_VVV_img.hdr CORR image header file *h2o_VVV orthocorrected water absorption data *h2o_VVV.hdr H2O header file *README.txt Overview of AVIRIS-NG data products *Info.txt This file ------------------------------------------------------------------------------ FILE DESCRIPTIONS ------------------------------------------------------------------------------ *ort_glt GEOMETRIC LOOKUP TABLE (GLT) Contents: Orthocorrected product with a fixed pixel size projected into a rotated UTM system that contains the information about which original pixel occupies which output pixel in the final product. Additionally, each pixel is sign-coded to indicate if it is real (indicated by a positive value) or a nearest-neighbor infill (indicated by negative values). The GLT file contains two parameters: 1) sample number 2) original line number File type: BINARY 16-bit, integer, IEEE. Format: Band interleaved by line ------------------------------------------------------------------------------ *ort_glt.hdr HEADER FILE FOR GEOMETRIC LOOKUP TABLE (GLT.HDR) DATA Contents: Format of each *ort_glt file. This file contains the number of lines, samples, channel, integer format, pixel size, scene elevation, UTM zone number and rotation angle information, etc. File type: ASCII ------------------------------------------------------------------------------- *ort_igm INPUT GEOMETRY FILE (IGM) Contents: Pixel location data for each radiance image cube. The IGM file data contain three parameters: 1) WGS-84 longitude (reported in decimal degrees) 2) WGS-84 latitude (reported in decimal degrees) 3) Estimated ground elevation at each pixel center (reported in meters) No map correction or resampling is applied to the radiance image cube; the IGM file only reports the surface location of the unadjusted pixel centers. File type: BINARY 64-bit double precision, floating point IEEE. Units: Band 1 - decimal degrees Band 2 - decimal degrees Band 3 - meters Format: Band interleaved by line ---------------------------------------------------------------------------- *ort_igm.hdr HEADER FILE FOR INPUT GEOMETRY FILE (IGM) DATA Contents: Format of each *ort_igm file. This file contains the number of lines, samples, channel, integer format, etc. File type: ASCII ---------------------------------------------------------------------------- *rdn_VVV_img CALIBRATED AVIRIS-NG RADIANCE (IMAGE) DATA Contents: AVIRIS-NG calibrated radiance File type: BINARY 32-bit little-endian floating point IEEE. Units: microwatts per centimeter_squared per nanometer per steradian Format: Band interleaved by line -------------------------------------------------------------------------------- *rdn_VVV_img.hdr HEADER FILE FOR CALIBRATED AVIRIS RADIANCE (IMAGE) DATA Contents: Format of each AVIRIS calibrated radiance scene. This file contains the number of lines, samples, channel, etc. It also records the spectral calibration (wavelength and full-width at half-maximum value) for every channel in the radiance data. File type: ASCII ---------------------------------------------------------------------------- *corr_VVV_img CALIBRATED AVIRIS-NG REFLECTANCE (IMAGE) DATA Contents: AVIRIS-NG calibrated reflectance File type: BINARY 32-bit little-endian floating point IEEE. Units: Apparent surface reflectance (Gao et al., 1993) Format: Band interleaved by line -------------------------------------------------------------------------------- *corr_VVV_img.hdr HEADER FILE FOR CALIBRATED AVIRIS REFLECTANCE (IMAGE) DATA Contents: Format of each AVIRIS calibrated radiance scene. This file contains the number of lines, samples, channel, etc. It also records the spectral calibration (wavelength and full-width at half-maximum values) for every channel in the radiance data. The "Smoothing factors" field contains a list of multiplicative coefficients applied to smooth the resulting reflectance spectrum. These coefficients were derived from Calibration measurements using spectrally-invariant surface targets. To remove this correction simply divide the apparent reflectance by these values. File type: ASCII ---------------------------------------------------------------------------- *h2o_VVV WATER ABSORPTION PATH (IMAGE) DATA Contents: Retrieved column water vapor and optical absorption paths for liquid H2O and ice File type: BINARY 32-bit little-endian floating point IEEE. Units: Band 1: Retrieved column H2O vapor in cm Band 2: Total liquid H2O absorption path in cm Band 3: Total ice absorption path in cm Format: Band interleaved by line -------------------------------------------------------------------------------- *h2o_VVV.hdr HEADER FILE FOR WATER ABSORPTION PATH (IMAGE) DATA Contents: Format of each AVIRIS-NG H2O cene. This file contains the number of lines, samples, channel, etc. File type: ASCII -------------------------------------------------------------------------------- REFERENCES -------------------------------------------------------------------------------- Gao, B.C., K. H. Heidebrecht, and A. F. H. Goetz, Derivation of scaled surface reflectances from AVIRIS data, Remote Sens. Env., 44, 165-178, 1993 -------------------------------------------------------------------------------- ACKNOWLEDGEMENTS -------------------------------------------------------------------------------- This research was performed at the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration (NASA). We are grateful for the help and assistance of colleagues including Bo-Cai Gao (NRL), Ian McCubbin (JPL), Dar Roberts (UCSB), Mark Helmlinger (JPL), Scott Nolte (JPL), Ernie Diaz (JPL), Daniel Nunes (JPL), Yasha Mouradi (JPL), and the rest of the AVIRIS-NG team. Copyright 2014 California Institute of Technology. All Rights Reserved. U.S. Government Support Acknowledged. -------------------------------------------------------------------------------- MODIFICATIONS -------------------------------------------------------------------------------- 09 Sep. 2014 (D. R. Thompson) - Initial document 10 Sep. 2014 (S. R. Lundeen) - Revisions to Overview section