Least Cost Path Analysis in Global Mapper Pro finds the best route between specified locations across a terrain layer based on minimized terrain slope angle. Avoid problematic or undesirable areas by using slope, elevation, or area feature constraints. The resulting path is generated as a line layer in the workspace. Locations can be specified by importing a previously loaded point layer, or by choosing points on the map from within the tool.
POINT_ORDER - specifies how to order the points in the generated path(s). The supported values are:
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FIRST_TO_LAST - create a path through the points in order from the first point to the last
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FIRST_TO_EACH - create a separate path from the first point to each additional point
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MOST_EFFICIENT - find the most efficient path starting at the first point that passes through every other point
LAYER_DESC - - specifies the name to assign to this layer. If no layer description is provided, the default name of "LEAST COST PATH" will be used.
ELEV_FILENAME - specifies the name of a loaded terrain layer to find the path(s) in. You can include multiple ELEV_FILENAME parameters to specify multiple input layers. If no ELEV_FILENAME is provided, all loaded terrain layers will be considered for input.
POINT_FILENAME - specifies the name of a loaded point layer to add route points from. You can include POINT_FILENAME parameters to specify multiple layers. You can also use the POINT_DEF parameter add points to the route.
POINT_DEF - specifies a point location to add to the route. Enter the coordinates delineated with a semicolon, e.g. “<x/easting/longitude>;<y/northing/latitude>[;<name>[;<projection_name_or_epsg_code>]]”. At a minimum, x and y coordinates need to be provided. By default, the coordinates will be in the current projection, but if a projection field is provided, you can specify the coordinates in a different projection. For example, to specify a latitude/longitude WGS84 coordinate: POINT_DEF=”94.5W,32.3N,Test Point Name,EPSG:4326”. Specify a POINT_DEF field for each point needed in the analysis.
SIMPLIFICATION - specifies the simplification threshold to apply to the generated path lines. If not specified, no simplification is done. The simplification threshold is in meters. The slope (in degrees) can also be simplified by providing a space-delimited value. For example, to simplify the paths to 2 meters and up to 2.5 degrees of slope, use SIMPLIFICATION=”2 2.5”.
SMOOTH_FEATURES - specifies whether or not the generated path features should be smoothed. Use SMOOTH_FEATURES=YES to enable.This option will modify the position of the vertices to smooth the appearance.
CREATE_SINGLE_LINE - specifies that the generated path through the points should be made a single line feature rather than a separate line feature for each sub-path. Use CREATE_SINGLE_LINE=YES to enable.
SPATIAL_RES - specifies spatial resolution to sample the terrain layer(s) at. Defaults to the minimum spatial resolution of the layers if not specified. Should be formatted as x_resolution,y_resolution. The units are the units of the current global projection. For example, if UTM was the current global projection and you wanted to export at 30 meter spacing, the parameter/value pair would look like SPATIAL_RES=30.0,30.0.
You can also specify resolution as a percentage of the default; to get half the detail, double the spatial resolution value: SPATIAL_RES="200%,200%".
SPATIAL_RES_METERS - specifies spatial resolution to use in meters. The value in meters will automatically be converted to the curent 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 meters in X by 1.5 meters in Y, use SPATIAL_RES_METERS="1.0,1.5".
SAMPLING_METHOD - specifies the sampling method to use when resampling the terrain layer(s) layer. The following values are supported:
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DEFAULT - Use either automatic resampling based on export or layer resampling, depending on setting of global flag about whether to resample on export
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AUTO - Automatically select a resampling method based on how the export resolution and bounds compare to the original layout for a layer. For example if you export to a lower resolution a box averager of appropriate size may be used automatically
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LAYER - Use the sampling method set for each layer
The list of SAMPLING_METHOD values from the IMPORT command can also be specified to use a particular sampling method for all layers being exported.
Avoid Settings (parameters for limiting the path):
MIN_ELEV - minimum elevation in meters to allow a path to travel at. If not specified, no minimum elevation limit is applied.
MAX_ELEV - maximum elevation in meters to allow a path to travel at. If not specified, no maximum elevation limit is applied.
MIN_SLOPE - minimum slope in degrees to allow a path to travel at. If not specified, no minimum slope limit is applied.
MAX_SLOPE - maximum slope in degrees to allow a path to travel at. If not specified, no maximum slope limit is applied.
AVOID_FILENAME - specifies the name of a loaded area layer to avoid area features from. You can specify multiple AVOID_FILENAME parameters to avoid areas from multiple layers. Use AVOID_FILENAME=”*” to avoid all loaded area features.
Cost Settings
SLOPE_COST_MULT - multiplier to apply to the slope-based cost along a segment. Larger values will cause steeper slopes to be more costly and thus avoided more. The default value is SLOPE_COST_MULT=”10”.
SLOPE_CHANGE_COST_MULT - multiplier to apply to the change in slope between two segments. Larger values will cause larger changes in slope to be more costly and thus avoided more. The default value is SLOPE_CHANGE_COST_MULT=”5”.