Densify

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

Adds vertices along lines and polygon outlines so that no segment is longer than a given distance.

Pitfall. In a geographic CRS the distance is in degrees unless the engine densifies along the geodesic.

Pitfall. Engines differ on whether new vertices split each segment into equal parts or sit at the exact distance from its start, leaving a shorter last piece.

About this operation
Also called	segmentize, add vertices, Densify by interval, Densify (Editing)
Group	`vector/geometry`
Checks	`crs.measure`
Pitfalls	2 listed above
Columbus tool	Not stated
Notes	Not stated
Status	active
Broader	Not stated
Narrower	Not stated
Related	`simplify`

Parameters

Name	Type	Required	Default	Values	Note
`distance`	length	yes	Not stated	Not stated	Longest segment allowed.
`unit`	enum	yes	Not stated	`m, ft, us-ft, km, mi`	Not stated

Inputs and outputs

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

In each engine

Engine	Tool	Parameters	Differences
`apache-sedona`	`sedona.sql.ST_Segmentize`	`distance` → `maxSegmentLength` `unit` always crs-units `layer` → `geometry`	A Spark SQL function: arguments are columns or column names, run over a Spark DataFrame.
`gdal`	`gdal vector segmentize`	`distance` → `max-length` `unit` always crs-units `layer` → `input` `output` → `output`	None noted
`geopandas`	`geopandas.GeoSeries.segmentize`	`distance` → `max_segment_length` `unit` always crs-units	Splits each segment into equal parts no longer than the distance.
`grass`	`v.split`	`distance` → `length` `unit` → `units` : m = meters; ft = feet; us-ft = surveyfeet; km = kilometers; mi = miles `layer` → `input` `output` → `output`	v.split cuts lines into pieces; this mapping sets flag n, which adds the vertices without cutting. Flag f instead makes the pieces exactly the given length, except the last. vertices instead sets the most vertices a segment may have. Preset: `{"flag_n":true}`
`postgis`	`st_segmentize`	`distance` → `#2` `unit` always crs-units. CRS units on geometry; metres on geography, along the geodesic. `layer` → `#1`	Splits each segment into equal parts no longer than the distance.
`qgis`	`native:densifygeometriesgivenaninterval`	`distance` → `INTERVAL` `unit` always crs-units `layer` → `INPUT` `output` → `OUTPUT`	Splits each segment into one more piece than needed when its length is an exact multiple of the interval (a 100 m segment at 10 m gets 11 pieces of 9.09 m). native:densifygeometries adds a fixed number of vertices to every segment instead.
`sf`	`sf::st_segmentize`	`distance` → `dfMaxLength` `unit` always crs-units. Longitude/latitude data is densified along great circles with the distance in metres. `layer` → `x`	None noted
`shapely`	`shapely.segmentize`	`distance` → `max_segment_length` `unit` always crs-units `layer` → `geometry`	Splits each segment into equal parts no longer than the distance.
`terra`	`terra::densify`	`distance` → `interval` `unit` always crs-units. Longitude/latitude data is densified along the geodesic with the interval in metres. `layer` → `x`	equalize (on by default) spaces the new vertices evenly.