Convex Hull

Draft: written, not yet checked by a person Operation · convex-hull

The smallest convex polygon that contains each feature.

Pitfall. Engines differ on whether they hull each feature or the whole layer; for one hull around everything, dissolve first.

Pitfall. The hull of a single point or of collinear points is a point or a line, not a polygon.

About this operation
Also called	Minimum Bounding Geometry (convex hull), convex polygon, hull
Group	`vector/geometry`
Checks	`geometry.valid`
Pitfalls	2 listed above
Columbus tool	Not stated
Notes	Not stated
Status	active
Broader	Not stated
Narrower	Not stated
Related	`centroid` `dissolve`

Parameters

Not stated

Direction	Name	Type	Geometry	Note
Input	`layer`	vector	Not stated	Not stated
Output	`output`	vector	polygon	Not stated

Engine	Tool	Parameters	Differences
`apache-sedona`	`sedona.sql.ST_ConvexHull`	`layer` → `geometry`	A Spark SQL function: arguments are columns or column names, run over a Spark DataFrame.
`gdal`	`gdal vector convex-hull`	`layer` → `input` `output` → `output`	None noted
`geopandas`	`geopandas.GeoSeries.convex_hull`	Not stated	A property of the GeoSeries, not a method; returns a GeoSeries without the other columns.
`postgis`	`st_convexhull`	`layer` → `#1`	None noted
`qgis`	`native:convexhull`	`layer` → `INPUT` `output` → `OUTPUT`	None noted
`sf`	`sf::st_convex_hull`	`layer` → `x`	None noted
`shapely`	`shapely.convex_hull`	`layer` → `geometry`	None noted
`terra`	`terra::hull`	`layer` → `x`	One hull around all geometries unless by names a field to group on; type also gives rectangles, circles and concave hulls.
`whiteboxtools`	`MinimumConvexHull`	`layer` → `input` `output` → `output`	features = false gives one hull around the whole layer. Preset: `{"features":true}`