Using "Intensity Products"

This tool is meant to convert LiDAR point data into various raster intensity products.

Usage:

• Select the input LAS file(s). Input LAS file(s) must have intensity information stored for each points. Multiple files may be selected to combine into a single raster or separate rasters.
• Select whether to use the first return, last return, or both.
• Input the raster pixel resolution. The units of this parameter are the same as the horizontal coordinates of the data.
• Enter the value for pixels where no data exists.
• If the "Interpolate data?" box is checked, the tool will interpolate gaps within the raster. However, the tool does not extrapolate outside the edges of the data.
• If the "Use vector mask(s)?" box is checked, the tool will prompt the user to select one or more EVF files. Pixels within these areas will not be processed.
• If the "Mosaic multiple files?" box is checked, then multiple input files will be combined into a single raster. If this box is not checked, and multiple input files are selected, a raster will be created for each input file.
• If the "Ignore outliers?" box is checked, then lidar points whose elevation is five or more standard deviations from the median will be ignored.
• Set the desired geographic extents of the output raster. The default values are the overall extents of the selected input file(s).
• If necessary, set the projection associated with the data.
• Select which products to display. These include:
  • Minimum Intensity - The point with the minimum intensity value within each pixel
  • Maximum Intensity - The point with the maximum intensity value within each pixel
  • Mean Intensity - The mean intensity of all points within each pixel
  • St. Dev Intensity - The standard deviation of intensity value of all points within each pixel
• The following products require the LiDAR data to have been processed through the height filtering:
  • Minimum Vegetation Intensity - The vegetation point with the minimum intensity value within each pixel
  • Maximum Vegetation Intensity - The vegetation point with the maximum intensity value within each pixel
  • Mean Vegetation Intensity - The mean intensity of all vegetation points within each pixel
  • St. Dev. Vegetation Intensity - The standard deviation of intensity value of all vegetation points within each pixel
  • Minimum Bare-earth Intensity - The bare-earth point with the minimum intensity value within each pixel
  • Maximum Bare-earth Intensity - The bare-earth point with the maximum intensity value within each pixel
  • Mean Bare-earth Intensity - The mean intensity of all bare-earth points within each pixel
  • St. Dev. Bare-earth Intensity - The standard deviation of intensity value of all bare-earth points within each pixel
  • Mean AGC - The mean automatic gain correction (AGC) value of all points within each pixel. AGC value must be stored in 'User Data' field of the input LAS file(s).
• Click "OK"
• Select the output file, or save to memory. (If multiple files are selected and the "Mosaic multiple files?" box is unchecked, the user will be prompted for an output directory instead.)

Notes:

• This tool requires data that are in the LAS format.
• The raster products are saved as one or more ENVI data files, with each product as an individual band. If a single file is processed, or multiple files mosaicked, the output file is immediately opened in an ENVI display window.
• If multiple input files are selected, this tool may leave artifacts along the seams of the input files. This is due to processing the input files individually and the resulting lack of points near at the seams.
• Tip: If the input files overlap, then the output raster should be seamless. Use the buffering tool to create overlapping LAS files.
• This tool currently uses simple nearest neighbor-type interpolation, which may not be optimal in some cases.

images/IntensityProducts.jpg