The Lines of Communication (LOC) - Water and Trails workflow is identical to the Target Detection tool except that you provide signatures of the water or trails of interest, either from a spectral library or from the image. The Unsupervised Water Detection (UWD) method is available to find water without the use of signatures. UWD is identical in form to a normalized difference vegetation index (NDVI), except it uses bands centered at 450 nm and 2250 nm. THOR also uses other target detection methods as needed to search for LOCs. After you map the LOCs, the workflow will guide you through combining the rule images from each target detection algorithm into a single detection overlay for each LOC type.

  1. From the Toolbox, select THOR > THOR LOC - Water and Trails. The LOC - Water and Trails dialog appears.
  2. Select an input file.
  3. Perform atmospheric correction.
  4. Select target signatures.
  5. Select background signatures.
  6. Reduce dataset dimensionality and select bands.
  7. Perform signature matching.
  8. Perform rule thresholding.
  9. Perform spatial filtering.
  10. Export targets.