@turf/idw

@turf/idw

idw

Takes a FeatureCollection of points with known value, a power parameter, a cell depth, a unit of measurement and returns a FeatureCollection of polygons in a square-grid with an interpolated value property "IDW" for each grid cell. It finds application when in need of creating a continuous surface (i.e. rainfall, temperature, chemical dispersion surface...) from a set of spatially scattered points.

Parameters

• controlPoints FeatureCollection<Point> Sampled points with known value
• valueField string GeoJSON field containing the known value to interpolate on
• b number Exponent regulating the distance-decay weighting
• cellWidth number The distance across each cell
• units [string] used in calculating cellSize, can be degrees, radians, miles, or kilometers (optional, default kilometers)

Returns FeatureCollection<Polygon> grid A grid of polygons with a property field "IDW"

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This module is part of the Turfjs project, an open source module collection dedicated to geographic algorithms. It is maintained in the Turfjs/turf repository, where you can create PRs and issues.

Installation

Install this module individually:

$ npm install @turf/idw

Or install the Turf module that includes it as a function:

$ npm install @turf/turf

Changelog

4.4.0

🚀 New Modules

• @turf/line-offset Adds a new lineOffset module as per this issue. Basically takes an input line and returns a new line offset by the distance. (PR https://github.com/Turfjs/turf/pull/729 - Author @rowanwins)
• @turf/polygonize Polygonizes (Multi)LineString(s) into Polygons. Implementation of GEOSPolygonize function (geos::operation::polygonize::Polygonizer). (PR https://github.com/Turfjs/turf/pull/767 - Author @NickCis)
• @turf/transform-rotate Rotates any geojson Feature or Geometry of a specified angle, around its centroid or a given pivot point; all rotations follow the right-hand rule. (Issue https://github.com/Turfjs/turf/issues/747 - Author @stebogit)
• @turf/transform-translate Moves any geojson Feature or Geometry of a specified distance along a Rhumb Line on the provided direction angle. (Issue https://github.com/Turfjs/turf/issues/747 - Author @stebogit)
• @turf/transform-scale Scale a GeoJSON from a given point by a factor of scaling (ex: factor=2 would make the GeoJSON 200% larger). If a FeatureCollection is provided, the origin point will be calculated based on each individual Feature. (Issue https://github.com/Turfjs/turf/issues/747 - Author @stebogit)

🏅 New Features

• Support z-coordinate as input for @turf/turf-tin (PR https://github.com/Turfjs/turf/pull/772)
• Adds properties parameter to @turf/centroid and @turf/center (PR https://github.com/Turfjs/turf/pull/769)
• Include Yarn.lock for all modules & Lerna uses Yarn (Issue https://github.com/Turfjs/turf/issues/704, https://github.com/Turfjs/turf/issues/765, PR https://github.com/Turfjs/turf/pull/766)
• Use Tap at root which enables code coverage reports (Issue https://github.com/Turfjs/turf/issues/328 & PR https://github.com/Turfjs/turf/pull/762)
• Support z-coordinate as input for @turf/pointplane (PR https://github.com/Turfjs/turf/pull/754)
• Add core tests - file management & package.json rules (PR https://github.com/Turfjs/turf/pull/749 & https://github.com/Turfjs/turf/pull/756)

🐛 Bug Fixes

• Website http://turfjs.org is back up and running (Issue https://github.com/Turfjs/turf/issues/777)
• @turf/rhumb-destination issue at 180th meridian (Issue https://github.com/Turfjs/turf/issues/770 & PR https://github.com/Turfjs/turf/pull/771)
• Getting too large numbers for Longitude (Issue https://github.com/Turfjs/turf/issues/758 & PR https://github.com/Turfjs/turf/pull/763)
• Throw error if FeatureCollection not array #751 (PR https://github.com/Turfjs/turf/pull/760)
• Change default param coordinates to 3 @turf/truncate (PR https://github.com/Turfjs/turf/pull/757)
• along returns a point that is not found by @turf/point-on-line (Issue https://github.com/Turfjs/turf/issues/691)
• Fix location of intersect point for @turf/point-on-line. (PR https://github.com/Turfjs/turf/pull/750)
• Handle empty geometries as undefined @turf/buffer (PR https://github.com/Turfjs/turf/pull/746)