GENERATE_SSI

This command generates a Swath Separation Image (SSI) from load lidar point cloud data which has overlapping flight lines. The output image will be a rendered intensity image of the data, with the height differences in the overlap area shaded using an elevation shader and 50% blended with the underlying intensity image.

  • OUTPUT_FILENAME - the name of the image to create as output. The image format is determined by the extension.
  • FILENAME - the filename or description of a loaded Lidar point cloud layer to use as input. You can include multiple FILENAME parameters to specify multiple input layers. Wildcards are also supported. If no FILENAME is provided, all loaded Lidar point clouds inside the specified bounds will be used as input.
  • FLIGHT_LINES - specifies where the flight line information comes from. One of the following values is supported:

    • POINT_SOURCE_ID - (default) each unique Point Source ID is treated as a separate flight line

    • LAYER - each point cloud layer is treated as a separate flight line

  • LOAD_OUTPUT - This is enabled by default and will automatically import the generated swath separation image from the saved OUTPUT_FILENAME location. Use LOAD_OUTPUT=NO to disable.
  • GEN_PRJ_FILE - enabled by default to generated a projection file saved with the Swath Separation Image. Use GEN_PRJ_FILE=NO to disable.
  • GEN_WORLD_FILE - enabled by default. Use GEN_WORLD_FILE=NO to disable.
  • SHADER_NAME - specifies the name of the elevation shader to use when coloring the overlap elevation differences. If nothing is provided, the default 'Swath Separation Overlap Difference (QL1 / QL2)' shader will be used.

  • LIDAR_FILTER - specifies a comma-separated list of lidar class numbers to enable or disable. Provide a minus sign to remove the type from the filter rather than add it. The filter starts off with nothing in it if you provide a LIDAR_FILTER string, but you can add ALL to enable everything or NONE to clear the filter, then add or remove stuff after that. For example, to specify a class filter with only types 2 and 3 enabled, use LIDAR_FILTER="NONE,2,3". To get one with everything but classes 2 and 3, use LIDAR_FILTER="ALL,-2,-3". If no LIDAR_FILTER is provided then all types currently enabled in the shared global Lidar filter are used.

  • LIDAR_RETURN_FILTER - specifies a comma-separated list of lidar return types to enable or disable. Provide a minus sign to remove the type from the filter rather than add it. The filter starts off with the current filter settings, but you can add ALL to enable everything or NONE to clear the filter, then add or remove stuff after that. For example, to specify a return filter with only unknown and first returns, use LIDAR_RETURN_FILTER="NONE,0,1". To get one with everything but the first return, use LIDAR_RETURN_FILTER="ALL,-1". The numeric values have the following meanings:

    • 0 - Unknown Returns
    • 1 - First Return
    • 2 - Second Return
    • 3 - Last Return
    • 4 - Single Returns
    • 5 - First of Many Returns
    • 6 - Second of Many Returns
    • 7 - Third of Many Returns
    • 8 - Last of Many Returns
  • GRID_ALG - specifies gridding algorithm to use

    • TIN - (default) triangulates 3D data and grid it. This is the default.

    • BIN_MIN - uses the minimum value within a bin of size GRID_BIN_SIZE.

    • BIN_AVG - uses the average value within a bin of size GRID_BIN_SIZE.

    • BIN_MAX - uses the maximum value within a bin of size GRID_BIN_SIZE.

  • Overlap Grid

    • SAVE_OVERLAP_GRID - specifies whether the elevation grid with the difference in elevation in overlap areas should be saved as a separate layer. Use SAVE_OVERLAP_GRID=YES to enable

    • OVERLAP_GRID_DESC - specifies the description to use for the overlap difference elevation grid (if SAVE_OVERLAP_GRID is specified). If not specified, a default value will be used.

  • SPATIAL_RES_METERS - specifies spatial resolution to use in meters. The value in meters will automatically be converted to the current view/ export projection units. For example, to do an export at 2.0 meter spacing (or as close as you can get to that in the current units), use SPATIAL_RES_METERS=2.0, or to do an export at 1.0 meter in X by 1.5 meters in Y, use SPATIAL_RES_METERS="1.0,1.5".
  • GRID_BIN_SIZE - specifies how many native spacings in size to make each bin. For example a value of GRID_BIN_SIZE="3.0" would make each square bin 3 times the calculated native spacing of the point data. You can specify a bin size in meters by using the SPATIAL_RES_METERS parameter or a negative GRID_BIN_SIZE (like GRID_BIN_SIZE="-0.5", or SPATIAL_RES_METERS=0.5 for 0.5 meter spacing. If not specified, a default of GRID_BIN_SIZE="2.0" will be used.

SAMPLE

This script will create and load a Swath Separation Image for all the loaded lidar data:

GENERATE_SSI OUTPUT_FILENAME="%SCRIPT_FOLDER%ssi_script_out.tif" \
FLIGHT_LINES="POINT_SOURCE_ID" GEN_PRJ_FILE="NO" GEN_WORLD_FILE="NO" LOAD_OUTPUT="YES" \
SHADER_NAME="Swath Separation Overlap Difference (QL0)" LIDAR_RETURN_FILTER="ALL" \
GRID_ALG="BIN_AVG"