Hyperspectral Data Processing

How to orthorectify Headwall Nano data collected by a Phoenix LiDAR System in Headwall's SpectralView software.

Phoenix LiDAR Systems store Headwall Nano data slightly differently than payloads from other integrators. This document explains the necessary workflow for utilizing PLS data in Headwall's software.

Input Data

• SBET format post-processed trajectory

  • This is required for georeferencing the Nano Hyperspectral imagery.

  • Utilize NavLab (Cloud or Embedded) or alternatively Novatel's InertialExplorer to produce an SBET .out file

• DEM

  • DEM files must have a geographic projection, such as WGS84 EPSG:4326, that matches the processed SBET datum

  • The best source for a digital elevation model is from co-acquired LiDAR data.

    • After achieving an accurate ground classified point cloud in SpatialExplorer, use the Create Maps tool to output a Geodetic Elevation raster .tif file.

  • Other DEM sources can also be used.

• Hyperspectral Imagery

  • It is highly recommended that users Reformat Headwall data in SpatialExplorer before proceeding to SpectralView

SpectralView

• Place a copy of your project DEM raster into the "dem" folder that is located in the Headwall software install directory

  • Similar to "C:\Headwall\dem"

• Place a copy of your SBET .out file in the same directory as your reformatted Headwall data

• Open a hyperspectral data cube in SpectraView.

Other steps, such as Radiance and Reflectance computation, may be taken prior to orthorectification in SpectralView

• Click the "Ortho R." tool and configure the orthorectification settings.

  • Enable "Advanced settings..."

    • Set "Time offset (ms)" to -18000 to account for GPS leap seconds

    • Check "Use post process file"

  • All other settings are sensor specific.

Example Ortho Rectification Settings

• Click "Start O.R" and ensure that the results displayed on the Preview tab look satisfactory.

• Select all of the wavelengths that you would like output on the Create tab and then press "Create Cube"