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LIDAR_CLASSIFY_GRAPH

Updated

LIDAR_CLASSIFY_GRAPH

The LIDAR_CLASSIFY_GRAPH command allows for automatically identifying and classifying building/high vegetation points from Lidar point clouds using a segmentation method. The following parameters are supported by the command:

  • FILENAME - filename or description of loaded layer(s) to classify Lidar points in. This parameter can be listed more than once to specify multiple input files, like FILENAME="FILENAME_1" FILENAME="FILENAME_2".
  • TYPE - specifies what type(s) of points to classify. If you don't provide a TYPE parameter only ground points will be classified. To classify multiple types, provide a comma-separated list, like TYPE="BUILDIN, HIGH_VEG". The following values are valid:
    • BUILDING - Classify building points
    • HIGH_VEG - Classify high vegetation points
  • GRID_BIN_SIZE -specifies the gating distance for the local neighborhood used in principal component analysis. For example a value of GRID_BIN_SIZE="3.0" would make each local neighborhood 3 times the calculated native spacing of the point data. This is the same as the 'Neighborhood Range' setting within the dialog of the classification tool. If you want to specify a spacing in meters rather than as a multiple of the native spacing for the point cloud, use a negative value (-). For example, to get a spacing of 0.6 meters, use GRID_BIN_SIZE="-0.6".
  • LIDAR_RESET_NON_GROUND - specifies that any points that are already marked as one of the types being classified should be reset to unclassified at the start of the operation. Add LIDAR_RESET_NONGROUND=YES to reset the points.
  • LIDAR_MIN_HEIGHT - specifies the minimum height above ground that a point has to be in order to consider it as a possible building or high vegetation point.
  • LIDAR_MAX_NUM_NEIGHBORS - Maximum number of neighbors used in principal component analysis. Allows for reduction in computational cost in the case that points are densely packed.
  • LIDAR_MAX_STD_DEV - Point-to-point associations used for clustering are limited to those that are within a specified statistical distance. This threshold reduces processing requirements and maintains the purity of clusters in the sense that it inhibits associations with points that have very different local neighborhood characteristics. A good value for this is generally around 3-4 with larger values required for data that is noisy, striped or has other measurement related problems. If this parameter is too small, then little or no clustering will happen and there will be a low probability of detection. If this parameter is too large, then clustering may be overly permissive and there will be a high probability of false alarm.
  • LIDAR_MIN_CLUSTER_SIZE - The minimum number of points required in a cluster based on similar principal component analysis statistics for the cluster to be classified.
  • Specify Bounding Box for Operation
    • GLOBAL_BOUNDS - specifies the combine bounds in units of the current global projection. There should be 4 values in a comma-delimited list following the parameter name. The values should be in order of minimum x, minimum y, maximum x, maximum y.
    • GLOBAL_BOUNDS_SIZE - specifies the combine bounds in units of the current global projection. There should be 4 values in a comma-delimited list following the parameter name. The values should be in order of minimum x, minimum y, width in x, width in y.
    • LAT_LON_BOUNDS - specifies the combine bounds in latitude/longitude degrees. There should be 4 values in a comma-delimited list following the parameter name. The values should be in order of west-most longitude, southern-most latitude, eastern-most longitude, northern-most latitude.
    • LAYER_BOUNDS - specifies that the operation should use the bounds of the loaded layer(s) with the given filename. For example, to export to the bounds of the file "c:\test.tif", you would use LAYER_BOUNDS="c:\test.tif". Keep in mind that the file must be currently loaded.
    • LAYER_BOUNDS_EXPAND - specifies that the operation should expand the used LAYER_BOUNDS bounding box by some amount. The amount to expand the bounding rectangle by should be specified in the current global projection. For example, if you have a UTM/meters projection active and want to expand the bounds retrieved from the LAYER_BOUNDS parameter by 100 meters on the left and right, and 50 meters on the top and bottom, you could use LAYER_BOUNDS_EXPAND="100.0,50.0". You can also specify a single value to apply to all 4 sides, or supply 4 separate values in the order left,top,right,bottom.
    • SNAP_BOUNDS_TO_MULTIPLE - specifies that the top-left corner of the bounding box for the operation should be snapped to a multiple of the given value. For example, using SNAP_BOUNDS_TO_MULTIPLE=1 will snap the top-left corner to the nearest whole number. The values will always go smaller for X/easting/longitude and larger to Y/northing/latitude so you always get at least what is requested.
    • SNAP_BOUNDS_TO_SPACING - specifies that the top-left corner of the bounding box for the operation should be snapped to a multiple of the resolution of the operation. For example, if you are exporting at 5 meter spacing, the top left corner will be snapped to the nearest multiple of 5. Use SNAP_BOUNDS_TO_SPACING=YES to enable or SNAP_BOUNDS_TO_SPACING=NO to disable. If not provided, the global setting for snapping exports to the nearest sample spacing boundary from the Advanced section of the General tab of the Configuration dialog will be used.
    • USE_EXACT_BOUNDS - specifies that the exact bounds that were defined in the command should be used. Generally, when the bounds specified in a command are not the same as the data bounds, the command uses the intersection between the two. When USE_EXACT_BOUNDS=YES is specified, the command will use the bounds as specified, instead of the intersection.
  • Lidar Advanced Filter Parameters

    See also Lidar Advanced Filter Options

    • LIDAR_ELEV_RANGE - specifies the range of elevations to include in the grid in meters. By default all elevations are gridded, but if you want to restrict values to say 50m - 150m, you could add LIDAR_ELEV_RANGE="50,150".
    • LIDAR_HEIGHT_RANGE - specifies the range of heights above ground to keep in meters. By default all heights are used, but if you want to restrict values to say 0m - 2m above ground, you could add LIDAR_HEIGHT_RANGE="0,2".
    • LIDAR_SCAN_ANGLE_RANGE - specifies the range of scan angles to include in the grid in degrees. By default all scan angles are gridded, but if you want to restrict the grid to only those points with scan angles between 0 and 30 degrees, you could add LIDAR_SCAN_ANGLE_RANGE="0,30".
    • LIDAR_FILTER - specifies a comma-separated list of Lidar class numbers to export. 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 Return
      • 5 - First of Many Returns
      • 6 - Second of Many Returns
      • 7 - Third of Many Returns
      • 8 - Last of Many Returns
    • LIDAR_COLOR_FILTER - specifies a color to include in the grid. If no value is provided then all colors are gridded. Otherwise, you can provide multiple LIDAR_COLOR_FILTER parameters of the format LIDAR_COLOR_FILTER="RGB(red,green,blue)" to specify colors to keep. The LIDAR_COLOR_DIST parameter specifies how far from an exact match to a specified color that a point color can be to be kept.
    • LIDAR_DENSITY_RANGE - specifies the range of point densities in points per square meter to include. Any Lidar points in regions with densities outside the range are ignored. If you use two values then everything between the values is used. If only one value is specified then all points in areas >= to the specified value are used. For example, LIDAR_DENSITY_RANGE="1.0" means that all points in areas with densities of 1.0 points per square meter or higher are used.
    • LIDAR_SOURCE_ID_LIST - specifies a comma-separated list of point source IDs to keep. If no list is provided all points are kept. For example, to keep just points with a source ID of 5 or 6, use LIDAR_SOURCE_ID_LIST="5,6".
    • LIDAR_INTENSITY_RANGE - filter to only the specified intensity values. The value is a pair of integers representing the range of intensity values to be included. Example: LIDAR_INTENSITY_RANGE=100,15. If only the first value is provided, it will be considered the minimum intensity value, so all values greater than that value will be included.

SAMPLE

GLOBAL_MAPPER_SCRIPT VERSION=1.00
UNLOAD_ALL
LOG_MESSAGE Script <%SCRIPT_FILENAME%> started at %DATE% %TIME%
DEFINE_VAR NAME="LASFILE" VALUE="Augusta_LiDAR.laz"
DEFINE_VAR NAME="DATA_DIR" VALUE="C:\Users\ChrisSmith\src\GMTrunk\geoStats\test\data\"
SET_LOG_FILE FILENAME=".%LASFILE%.log" APPEND_TO_FILE=NO

IMPORT FILENAME="%DATA_DIR%%LASFILE%"

LIDAR_CLASSIFY FILENAME="%LASFILE%"\
TYPE=GROUND\
GRID_BIN_SIZE=3.0\
LIDAR_RESET_GROUND=YES\
LIDAR_CURVATURE=0.3\
LIDAR_MAX_HEIGHT_DELTA=50.0\
LIDAR_SLOPE=2.0
LIDAR_CLASSIFY_GRAPH FILENAME="%LASFILE%"\
GRID_BIN_SIZE=4.0\
TYPE=BUILDING,HIGH_VEG\
LIDAR_RESET_NON_GROUND=YES\
LIDAR_MIN_HEIGHT=2.0\
LIDAR_MIN_NUM_NEIGHBORS=3\
LIDAR_MAX_NUM_NEIGHBORS=64\
LIDAR_MAX_STD_DEV=3

LIDAR_EXTRACT FILENAME="%LASFILE%"\
GRID_BIN_SIZE=4.0\
TYPE=BUILDING\
LIDAR_MIN_POINTS_IN_PLANE=20\
LIDAR_MAX_DISTANCE_TO_PLANE=0.5\
LIDAR_MIN_FOOTPRINT_AREA_SQM=20\
LIDAR_PSEUDOMEASUREMENTS_AT_PLANAR_INTERSECTIONS=YES\
LIDAR_SIMPLIFICATION_EPSILON=1\
LIDAR_CREATE_FOOTPRINTS=YES\
LIDAR_CREATE_SIDEWALLS=YES\
LIDAR_CREATE_SEPERATE_ROOF_PLANES=YES\
LIDAR_CREATE_BUILDINGS_AS_MESH=YES\
LIDAR_COLOR_VERTICES=NO

SAVE_WORKSPACE FILENAME=".%LASFILE%.gmw"