globalmapper.SpatialConcaveHull(GM_LayerHandle_t32 aLayer, GM_SpatialOps_Params_t aParams, float aSmoothing, GM_FeatureGrouping_t8 aGrouping, str aStr) GM_Error_t32[source]

The Concave Hull operation creates a new layer with a polygon that encloses a set of points, lines, and/or areas. The polygon will be a tight concave shape that contains the specified features, with the level of tightness defined by the aSmoothing parameter. A concave fit is usually compared to shrink wrapping the data, with a lower aSmoothing value meaning a tighter wrap.

The aGrouping parameter controls how many polygons are created: with GM_GroupingNone, a polygon is created for each individual feature; with GM_GroupingPartition, one polygon will be created for each attribute group; and with GM_GroupingAll, all the features on the layer will be enclosed by one polygon.

For a hull with a looser fit to the features, see SpatialConvexHull.

  • aLayer (GM_LayerHandle_t32) – Input layer

  • aParams (GM_SpatialOps_Params_t) – Parameters

  • aSmoothing (float) – Smoothing value from 1 to 10000

  • aGrouping (GM_FeatureGrouping_t8) – Grouping type

  • aStr (str) – The attribute list string; may be an empty string


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