=============================================================================== AVIRIS-NG Distribution Document =============================================================================== Sarah R. Lundeen, Sarah.R.Lundeen@jpl.nasa.gov David R. Thompson, David.R.Thompson@jpl.nasa.gov Robert O. Green, Robert.O.Green@jpl.nasa.gov Michael Eastwood, meastwood@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 the following file name definition: angYYYYMMDDtHHNNSS_LLL_vNN 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 LLL: The type of data product (i.e. rdn for radiance) vNN: The version number of the product. All downloaded files are in a tar.gz file. Windows Users: ============= Download the following gzip and tar tools into the same directory as the AVIRIS-NG gzip (*gz) file. Download the GZIP executable for Windows here - http://aviris.jpl.nasa.gov/alt_locator/gzip.exe Download 7-Zip to unpack tar files here - http://www.7-zip.org/ The following commands must be executed from a Windows Command Prompt window. - To decompress the AVIRIS tar file, type gzip -d "gzip file name (i.e. ang20150728t174323_rdn_v1e.tar.gz)" - To list files (table-of-contents), type tar tvf "tar file name (i.e. ang20150728t174323_rdn_v1e.tar)" - To extract files, in a command prompt window type tar xvf "tar file name" "extract file name (i.e. ang20150728t174323_rdn_v1e.tar)" Mac/UNIX/LINUX Users: ===================== The following commands must be executed from a Terminal Window. - To decompress the AVIRIS-NG tar file, type gzip -d "gzip file name (i.e. ang20150728t174323_rdn_v1e.tar.gz)" - To list files (table-of-contents), type tar tvf "tar file name (i.e. ang20150728t174323_rdn_v1e.tar)" - To extract files, in a command prompt window type tar xvf "tar file name" "extract file name (i.e. ang20150728t174323_rdn_v1e.tar)" ------------------------------------------------------------------------------- AVIRIS-NG DATA PRODUCT CONTENTS ------------------------------------------------------------------------------- The AVIRIS-NG data products for a particular airborne flight run are organized in the following directory structures for Level 1 (orthocorrected radiance) and Level 2 (orthocorrected and atmospherically corrected reflectance data), respectively. /YYYYMMDDtHHNNSS_rdn_vNN | angYYYYMMDDtHHNNSS_obs_ort | angYYYYMMDDtHHNNSS_obs_ort.hdr | angYYYYMMDDtHHNNSS_ort_glt | angYYYYMMDDtHHNNSS_ort_glt.hdr | angYYYYMMDDtHHNNSS_ort_igm | angYYYYMMDDtHHNNSS_ort_igm.hdr | angYYYYMMDDtHHNNSS_rdn_vNN_img | angYYYYMMDDtHHNNSS_rdn_vNN_img.hdr | angYYYYMMDDtHHNNSS_vNN_README.txt /YYYYMMDDtHHNNSS_refl_vNN | angYYYYMMDDtHHNNSS_corr_vNN_img | angYYYYMMDDtHHNNSS_corr_vNN_img.hdr | angYYYYMMDDtHHNNSS_h2o_vNN | angYYYYMMDDtHHNNSS_h2o_vNN.hdr | angYYYYMMDDtHHNNSS_vNN_README.txt The file extension definitions are: *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_vNN_img orthocorrected, scaled radiance image file *rdn_vNN_img.hdr RDN image header file *corr_vNN_img orthocorrected, scaled reflectance image file *corr_vNN_img.hdr CORR image header file *h2o_vNN orthocorrected water absorption data *h2o_vNN.hdr H2O header file *README.txt this file ------------------------------------------------------------------------------ FILE CONTENT DESCRIPTIONS ------------------------------------------------------------------------------ *obs_ort OBSERVATIONAL AND ILLUMINATION PARAMETERS (OBS) Contents: Orthocorrected product that has been rendered using the *ort_glt lookup table and matches the orthocorrected imagery. The OBS file has ten parameters: 1) path length (sensor-to-ground in meters) 2) to-sensor-azimuth (0 to 360 degrees clockwise from N) 3) to-sensor-zenith (0 to 90 degrees from zenith) 4) to-sun-azimuth 5) to-sun-zenith 6) phase (degrees between to-sensor and to-sun vectors in principal plane) 7) slope (local surface slope as derived from DEM in degrees) 8) aspect (local surface aspect 0 to 360 degrees clockwise from N) 9) cosine i (apparent local illumination factor based on DEM slope and aspect and to-sun vector, -1 to 1) 10) UTC time (decimal hours for mid-line pixels). ------------------------------------------------------------------------------ *obs_ort.hdr HEADER FILE FOR OBSERVATIONAL AND ILLUMINATION PARAMETERS (OBS.HDR) Contents: Format of each *obs_ort file. This file contains the number of lines, samples, channel, integer format, etc. File type: ASCII ------------------------------------------------------------------------------ *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_vNN_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_vNN_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_vNN_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_vNN_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_vNN 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_vNN.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), and the rest of the AVIRIS-NG team. Copyright 2014 California Institute of Technology. All Rights Reserved. U.S. Government Support Acknowledged. -------------------------------------------------------------------------------- MODIFICATIONS -------------------------------------------------------------------------------- 10 Sept. 2014 (D. R. Thompson) - Initial document 03 Aug. 2015 (S. R. Lundeen) - Added *obs_ort file details ------------------------------------------------------------------------------ VERSION-SPECIFIC PARAMTERS ------------------------------------------------------------------------------ Level 1 Version tag: v1f Radiometric calibration: ANGv5_rcc.txt Flat field: ang20150526_average_ff Bad detector mask: ANGv5_bad Wavelength calibration: ang20150521t002622_wavelength_fit.txt Point spread function: ANGv3_psf Level 2 Atmosphere model: Mid latitude summer Sensor altitude (km): 4.7197052 Aerosol model: Continental Visibility (km): 300 H2O estimation algorithm: Iterative log linear 760nm O2 scaling: 1.0 1140nm H2O scaling: 1.0