Buffer

Draft: written, not yet checked by a person Operation · buffer

Polygons covering everything within a given distance of the input features.

Pitfall. A planar buffer of data in a geographic CRS is in degrees unless the engine switches to geodesic.

About this operation
Also called	buffer zone, proximity zone, offset polygon, Pairwise Buffer
Group	`vector/proximity`
Checks	`crs.measure, geometry.valid`
Pitfalls	1 listed above
Columbus tool	`vector_op · buffer`
Notes	Not stated
Status	active
Broader	Not stated
Narrower	Not stated
Related	Not stated

Parameters

Name	Type	Required	Default	Values	Note
`distance`	length	yes	Not stated	Not stated	Not stated
`unit`	enum	yes	Not stated	`m, ft, us-ft, km, mi`	Not stated
`dissolve`	boolean	no	`no`	Not stated	Merge all buffers into one shape.
`segments`	integer	no	`8`	Not stated	Segments per quarter circle; more is smoother.

Inputs and outputs

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

In each engine

Engine	Tool	Parameters	Differences
`apache-sedona`	`sedona.sql.ST_Buffer`	`distance` → `buffer` `unit` always crs-units. CRS units; with useSpheroid = true on longitude/latitude data, metres. `dissolve` always no. Aggregate with ST_Union_Aggr. `segments` quad_segs=N in the parameters text. `layer` → `geometry`	A Spark SQL function: arguments are columns or column names, run over a Spark DataFrame.
`gdal`	`gdal vector buffer`	`distance` → `distance` `unit` always crs-units. Distance is in the layer's CRS units; convert it first. `dissolve` always no. No dissolve; union the output afterwards. `segments` → `quadrant-segments` `layer` → `input` `output` → `output`	Distance is in the layer's CRS units, so data in a geographic CRS is buffered in degrees.
`geopandas`	`geopandas.GeoSeries.buffer`	`distance` → `distance` `unit` always crs-units. Distance is in the series' CRS units; convert it first. `dissolve` always no. Call union_all or dissolve on the result. `segments` → `quad_segs`	Called on the GeoSeries itself; returns a GeoSeries without the other columns. Warns but still buffers in degrees when the CRS is geographic.
`grass`	`v.buffer`	`distance` → `distance` `unit` always crs-units. Distance is in the map units of the GRASS project. `layer` → `input` `output` → `output`	None noted
`postgis`	`st_buffer`	`distance` → `radius` `unit` always crs-units. On geometry, CRS units; on geography, metres. `dissolve` always no. Aggregate with ST_Union. `segments` → `quadsegs` `layer` → `geom`	On a geometry column the distance is in CRS units (degrees for EPSG:4326); cast to geography for metres. Caps and joins go in the options text ('endcap=flat join=mitre').
`qgis`	`native:buffer`	`distance` → `DISTANCE` `unit` always crs-units. Distance is in the layer's CRS units; convert it first. `dissolve` → `DISSOLVE` `segments` → `SEGMENTS` `layer` → `INPUT` `output` → `OUTPUT`	Distance is in the layer's CRS units, so data in a geographic CRS is buffered in degrees. Defaults to 5 segments per quarter circle (Columbus uses 8).
`sf`	`sf::st_buffer`	`distance` → `dist` `unit` always crs-units. Projected data: CRS units. Longitude/latitude data with sf_use_s2() on (the default): metres, through S2. `dissolve` always no. Call st_union on the result. `segments` → `nQuadSegs` `layer` → `x`	Default nQuadSegs is 30 segments per quarter circle (Columbus 8). On longitude/latitude data with S2 the buffer is built from S2 cells, so its outline differs from a GEOS buffer; nQuadSegs, end caps and joins only apply with GEOS.
`shapely`	`shapely.buffer`	`distance` → `distance` `unit` always crs-units. Shapely has no CRS; distance is in the coordinates' units. `dissolve` always no. Union the results with shapely.union_all. `segments` → `quad_segs` `layer` → `geometry`	Works on geometries, not layers, and knows no CRS.
`terra`	`terra::buffer`	`distance` → `width` `unit` always crs-units. Projected data: CRS units. Longitude/latitude data: metres. `dissolve` always no. Call aggregate on the result. `segments` → `quadsegs` `layer` → `x`	Default quadsegs is 10 (Columbus 8); quadsegs, cap and join styles are ignored for longitude/latitude data. On a SpatRaster, buffer marks the cells within the distance of non-NA cells instead.
`turf-js`	`turf.buffer`	`distance` → `radius` `unit` → `options.units` : m = meters; ft = feet; km = kilometers; mi = miles. not supported: us-ft `dissolve` always no. Call turf.dissolve or turf.union on the result. `segments` → `options.steps` `layer` → `geojson`	units defaults to kilometers. Each feature is buffered in an azimuthal equidistant projection centred on it, so distances are true ground distances near the feature. Turf works on GeoJSON in longitude/latitude (WGS 84); data in another CRS must be reprojected first.

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