Model / geo · All operations

Draw an area around each shape

A variant of Work with geography

Grow or shrink each geometry by a distance or drive time to make a buffer or trade area.

Status

In arcform

Not built yet

arcform does not do this yet. Its place on the roadmap

What other tools call it

Meridian's classification; an independent blind rating agreed on 95.7% of 324 rows (variant, version 3).

Alteryx Designer (3)
  • Bufferread 2026-09-27

    Expand or contract a polygon or polyline by a set distance

  • Non Overlap Drivetimeread 2026-09-27

    Create drive-time trade areas for a point file that do not overlap

  • Trade Arearead 2026-09-27

    Create regions around points by radius or drive time

Duckle (1)
  • Spatial Bufferread 2026-09-25

    buffered geometry around each row with ST_Buffer

Ibis (1)
  • GeoBufferread 2026-09-27

    Grow a geometry outward by a radius

Background

In a geographic information system (GIS), buffer analysis finds the zone around a feature that contains the locations within a specified distance of it.[1] A buffer is likely the most commonly used tool among the methods of proximity analysis.[1] In Alteryx Designer, the Trade Area tool creates regions around points in one of two ways: by a radius around each point or by a drive time.[2]

When to use it

In DuckDB's spatial extension, ST_Buffer takes its distance in the same units as the input geometry, and is a planar operation that does not take the curvature of the earth into account.[3] Reproject longitude and latitude into a projected system in metres before buffering with a planar function, so that the distance means what you intend. (Meridian's view) A buffer computed on a map projection is not identical to one drawn on the Earth's surface: at a local scale the difference is negligible, but at larger scales the error can be significant.[1]

In PostGIS, a negative distance shrinks a geometry in ST_Buffer, may shrink a polygon completely to POLYGON EMPTY, and always gives an empty result for points and lines.[4] In PostGIS, buffering is sometimes used to perform a within-distance search, a task for which ST_DWithin is more efficient.[4] To ask which rows lie within a distance of a place, test the distance directly rather than drawing a buffer and testing containment. (Meridian's view)

The method

The basic buffer method draws a circle of radius r around a point, and around a polyline draws a circle at each vertex and a rectangle along each segment, then merges them into one polygon.[1] In mathematics, a GIS buffer is a Minkowski sum, or difference, of a geometry and a disk.[1] The buffer operation has been a core part of GIS functionality since the integrated GIS packages of the late 1970s and early 1980s, such as ARC/INFO, Odyssey and MOSS.[1]

In PostGIS, the accuracy of a buffer's circular arcs is set by the number of line segments used to approximate a quarter circle, which is 8 by default.[4] In GIS software that offers the option, the end caps of a line's buffer are rounded by default but may be squared off or cut at the final vertex.[1] For the geography type, PostGIS computes a buffer in a planar spatial reference system that best fits the object's bounding box, then transforms the result back.[4]

Sources

  1. [1]Buffer analysis - Wikipediasecondary source
  2. [2]Trade Area Tooldocumentation
  3. [3]Spatial Functions – DuckDBdocumentation
  4. [4]ST_Bufferdocumentation