globalmapper.SpatialConcaveHull
===============================

.. currentmodule:: globalmapper
.. py:function:: SpatialConcaveHull (GM_LayerHandle_t32 aLayer, GM_SpatialOps_Params_t aParams, float aSmoothing, GM_FeatureGrouping_t8 aGrouping, str aStr) -> GM_Error_t32

	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 :doc:`SpatialConvexHull <globalmapper.SpatialConvexHull>`.

	:param GM_LayerHandle_t32 aLayer: Input layer
	:param GM_SpatialOps_Params_t aParams: Parameters
	:param float aSmoothing: Smoothing value from 1 to 10000
	:param GM_FeatureGrouping_t8 aGrouping: Grouping type
	:param str aStr: The attribute list string; may be an empty string
	:returns: Error Code
	:rtype: GM_Error_t32