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Generate Pedestal Height Images

Generate Pedestal Height Images

Use Pedestal Height Image to generate a pedestal height image for AIRSAR or SIR-C data as a means to measure the amount of multiple scatter of the radar wave for every pixel (higher pedestal heights mean more multiple scattering). The pedestal height is the height of a polarization signature above 0 and the value is calculated by averaging the following four polarization combinations: orientation 0 degrees, ellipticity -45 degrees; orientation 90 degrees, ellipticity -45 degrees; orientation 0 degrees, ellipticity 45 degrees; orientation 90 degrees, ellipticity 45 degrees.

The pedestal height of a polarization signature plot is a characteristic of the plot that provides information about the degree of polarization of the return signal. The pedestal height is the lowest z-axis value in the polarization signature. A larger pedestal height indicates low polarization purity. Low polarization purity (that is, a high degree of depolarization) may be due to multiple scattering, differences in scattering characteristics among pixels in a ROI, or noise in the image. It could also be due to movement of the surface at the time of measurement (foe example, ocean waves or vegetation in wind).

See References for more information about pedestal height.

  1. From the Toolbox, select one of the following options:
    • Radar > AIRSAR > AIRSAR Pedestal Height Image: The Input Stokes Matrix Files dialog appears.
    • Radar > SIR-C > SIR-C Pedestal Height Image: The Input Data Products dialog appears.
  2. Select the input compressed data file.
  3. Click OK. The Pedestal Height Image Parameters dialog appears.
  4. Select the check boxes to select the bands to use for the pedestal height image generation.
  5. Perform optional spatial subsetting by clicking Spatial Subset.
  6. Select output to File or Memory.
  7. Click OK. ENVI adds the resulting output to the Layer Manager.

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