arcgis-geometry-operations

SKILL.md

ArcGIS Geometry Operations

Use this skill for creating geometries and performing spatial operations with the modern geometry operators module.

Important: The geometryEngine and geometryEngineAsync modules are deprecated as of version 4.29. Use the geometry operators module instead. See the Deprecation Notice section for migration guidance.

Geometry Classes Overview

Class Use Case
Point Single location (x, y, z, m)
Polyline Lines and paths
Polygon Areas with rings
Multipoint Collection of points
Extent Bounding box
Circle Circular geometry
Mesh 3D mesh with vertices and faces

Creating Geometries

Point

const point = {
  type: "point",
  longitude: -118.80657,
  latitude: 34.02749,
  z: 1000,           // Optional elevation
  m: 0,              // Optional measure
  spatialReference: { wkid: 4326 }
};

// Or using x, y coordinates
const point = {
  type: "point",
  x: -13044706,
  y: 4036320,
  spatialReference: { wkid: 102100 } // Web Mercator
};

Polyline

const polyline = {
  type: "polyline",
  paths: [
    [[-118.821527, 34.0139576], [-118.814893, 34.0137161]],  // First path
    [[-118.8148893, 34.0215816], [-118.813120, 34.0215816]]  // Second path
  ],
  spatialReference: { wkid: 4326 }
};

// Single path
const line = {
  type: "polyline",
  paths: [
    [-118.821527, 34.0139576],
    [-118.814893, 34.0137161],
    [-118.808878, 34.0102256]
  ]
};

Polygon

const polygon = {
  type: "polygon",
  rings: [
    // Outer ring (clockwise)
    [[-118.818984, 34.01991], [-118.806796, 34.01991],
     [-118.806796, 34.02937], [-118.818984, 34.02937],
     [-118.818984, 34.01991]],
    // Inner ring/hole (counter-clockwise) - optional
    [[-118.815, 34.022], [-118.810, 34.022],
     [-118.810, 34.026], [-118.815, 34.026],
     [-118.815, 34.022]]
  ],
  spatialReference: { wkid: 4326 }
};

Extent

const extent = {
  type: "extent",
  xmin: -118.82,
  ymin: 34.01,
  xmax: -118.80,
  ymax: 34.03,
  spatialReference: { wkid: 4326 }
};

Circle

import Circle from "@arcgis/core/geometry/Circle.js";

const circle = new Circle({
  center: [-118.80657, 34.02749],
  radius: 1000,
  radiusUnit: "meters",  // feet, kilometers, miles, nautical-miles, yards
  geodesic: true,
  spatialReference: { wkid: 4326 }
});

Multipoint

const multipoint = {
  type: "multipoint",
  points: [
    [-118.821527, 34.0139576],
    [-118.814893, 34.0137161],
    [-118.808878, 34.0102256]
  ],
  spatialReference: { wkid: 4326 }
};

Geometry Operators (Modern API)

The geometry operators module is the modern, recommended approach for geometry operations. Each operator is imported individually for better tree-shaking and performance.

Importing Operators

// Import specific operators as needed
import bufferOperator from "@arcgis/core/geometry/operators/bufferOperator.js";
import unionOperator from "@arcgis/core/geometry/operators/unionOperator.js";
import intersectsOperator from "@arcgis/core/geometry/operators/intersectsOperator.js";

// Or import multiple at once
import bufferOperator from "@arcgis/core/geometry/operators/bufferOperator.js";
import unionOperator from "@arcgis/core/geometry/operators/unionOperator.js";
import containsOperator from "@arcgis/core/geometry/operators/containsOperator.js";
import differenceOperator from "@arcgis/core/geometry/operators/differenceOperator.js";

Important: Some operators require loading before use. Call await operator.load() before calling .execute(). For example: await bufferOperator.load(); before bufferOperator.execute(...). Check operator documentation for specific requirements.

Buffer Operations

import bufferOperator from "@arcgis/core/geometry/operators/bufferOperator.js";

await bufferOperator.load();

// Simple buffer (distance in meters by default)
const buffered = bufferOperator.execute(point, 1000);

// Buffer with unit option (distance is a separate parameter)
const buffered = bufferOperator.execute(point, 500, {
  unit: "meters"  // feet, kilometers, miles, nautical-miles, yards
});

// Buffer multiple geometries
const buffered = bufferOperator.execute([point1, point2, point3], 1000);

// Geodesic buffer (for geographic coordinates)
import geodesicBufferOperator from "@arcgis/core/geometry/operators/geodesicBufferOperator.js";

await geodesicBufferOperator.load();
const geoBuffered = geodesicBufferOperator.execute(point, 1000, {
  unit: "meters"
});

Spatial Relationships

// Contains - geometry1 completely contains geometry2
import containsOperator from "@arcgis/core/geometry/operators/containsOperator.js";
const result = containsOperator.execute(polygon, point);  // returns boolean

// Within - geometry1 is completely within geometry2
import withinOperator from "@arcgis/core/geometry/operators/withinOperator.js";
const result = withinOperator.execute(point, polygon);  // returns boolean

// Intersects - geometries share any space
import intersectsOperator from "@arcgis/core/geometry/operators/intersectsOperator.js";
const result = intersectsOperator.execute(polygon1, polygon2);  // returns boolean

// Crosses - geometries cross each other
import crossesOperator from "@arcgis/core/geometry/operators/crossesOperator.js";
const result = crossesOperator.execute(line, polygon);  // returns boolean

// Overlaps - geometries share some but not all space
import overlapsOperator from "@arcgis/core/geometry/operators/overlapsOperator.js";
const result = overlapsOperator.execute(polygon1, polygon2);  // returns boolean

// Touches - geometries share boundary but not interior
import touchesOperator from "@arcgis/core/geometry/operators/touchesOperator.js";
const result = touchesOperator.execute(polygon1, polygon2);  // returns boolean

// Disjoint - geometries don't share any space
import disjointOperator from "@arcgis/core/geometry/operators/disjointOperator.js";
const result = disjointOperator.execute(polygon1, polygon2);  // returns boolean

// Equals - geometries are identical
import equalsOperator from "@arcgis/core/geometry/operators/equalsOperator.js";
const result = equalsOperator.execute(geom1, geom2);  // returns boolean

Set Operations

// Union - combine geometries
import unionOperator from "@arcgis/core/geometry/operators/unionOperator.js";
const combined = unionOperator.execute([polygon1, polygon2, polygon3]);

// Intersection - common area between geometries
import intersectionOperator from "@arcgis/core/geometry/operators/intersectionOperator.js";
const common = intersectionOperator.execute(polygon1, polygon2);

// Difference - subtract geometry2 from geometry1
import differenceOperator from "@arcgis/core/geometry/operators/differenceOperator.js";
const diff = differenceOperator.execute(polygon1, polygon2);

// Symmetric Difference - areas in either but not both
import symmetricDifferenceOperator from "@arcgis/core/geometry/operators/symmetricDifferenceOperator.js";
const symDiff = symmetricDifferenceOperator.execute(polygon1, polygon2);

// Clip - clip geometry by envelope
import clipOperator from "@arcgis/core/geometry/operators/clipOperator.js";
const clipped = clipOperator.execute(polygon, extent);

Measurements

// Area (for polygons)
import areaOperator from "@arcgis/core/geometry/operators/areaOperator.js";
const areaValue = areaOperator.execute(polygon);  // square meters

import geodeticAreaOperator from "@arcgis/core/geometry/operators/geodeticAreaOperator.js";
const geoArea = geodeticAreaOperator.execute(polygon, { unit: "square-kilometers" });

// Length (for polylines)
import lengthOperator from "@arcgis/core/geometry/operators/lengthOperator.js";
const lengthValue = lengthOperator.execute(polyline);  // meters

import geodeticLengthOperator from "@arcgis/core/geometry/operators/geodeticLengthOperator.js";
const geoLength = geodeticLengthOperator.execute(polyline, { unit: "kilometers" });

// Distance between geometries
import distanceOperator from "@arcgis/core/geometry/operators/distanceOperator.js";
const dist = distanceOperator.execute(point1, point2);  // meters

Geometry Manipulation

// Simplify - remove self-intersections
import simplifyOperator from "@arcgis/core/geometry/operators/simplifyOperator.js";
const simplified = simplifyOperator.execute(polygon);

// Generalize - reduce vertices
import generalizeOperator from "@arcgis/core/geometry/operators/generalizeOperator.js";
const generalized = generalizeOperator.execute(polyline, {
  maxDeviation: 100,
  unit: "meters"
});

// Densify - add vertices
import densifyOperator from "@arcgis/core/geometry/operators/densifyOperator.js";
const densified = densifyOperator.execute(polyline, {
  maxSegmentLength: 100,
  unit: "meters"
});

// Offset - create parallel geometry
import offsetOperator from "@arcgis/core/geometry/operators/offsetOperator.js";
const offsetGeom = offsetOperator.execute(polyline, {
  distance: 50,
  unit: "meters",
  joinType: "round"  // round, bevel, miter
});

// Convex Hull
import convexHullOperator from "@arcgis/core/geometry/operators/convexHullOperator.js";
const hull = convexHullOperator.execute(polygon);
const multiHull = convexHullOperator.execute([point1, point2, point3]);

// Centroid
import centroidOperator from "@arcgis/core/geometry/operators/centroidOperator.js";
const center = centroidOperator.execute(polygon);

// Label Point (guaranteed inside polygon)
import labelPointOperator from "@arcgis/core/geometry/operators/labelPointOperator.js";
const label = labelPointOperator.execute(polygon);

Available Operators

Category Operators
Relationship containsOperator, crossesOperator, disjointOperator, equalsOperator, intersectsOperator, overlapsOperator, relateOperator, touchesOperator, withinOperator
Set Operations clipOperator, cutOperator, differenceOperator, intersectionOperator, symmetricDifferenceOperator, unionOperator
Buffer bufferOperator, geodesicBufferOperator
Shape autoCompleteOperator, boundaryOperator, convexHullOperator, simplifyOperator
Measurement areaOperator, geodeticAreaOperator, lengthOperator, geodeticLengthOperator, distanceOperator
Transform densifyOperator, generalizeOperator, offsetOperator, projectOperator
Analysis centroidOperator, labelPointOperator

Projection (projectOperator)

import projectOperator from "@arcgis/core/geometry/operators/projectOperator.js";

// Load projection engine (required before projecting)
await projectOperator.load();

// Project geometry to new spatial reference (spatial reference is a separate parameter)
const projected = projectOperator.execute(geometry, { wkid: 4326 });

// Project with geographic transformation
const projectedWithTransform = projectOperator.execute(geometry, { wkid: 4326 }, {
  geographicTransformation: {
    steps: [{ wkid: 108190 }]  // NAD_1983_To_WGS_1984_5
  }
});

Note: To get available geographic transformations, use the geographicTransformationUtils module, not projectOperator.

Note: The legacy projection module is deprecated since 4.32. Use projectOperator instead.

Web Mercator Utilities

import webMercatorUtils from "@arcgis/core/geometry/support/webMercatorUtils.js";

// Convert to Web Mercator
const webMercatorGeom = webMercatorUtils.geographicToWebMercator(geographicPoint);

// Convert to Geographic
const geoGeom = webMercatorUtils.webMercatorToGeographic(webMercatorPoint);

// Check if can project
const canProject = webMercatorUtils.canProject(geom1.spatialReference, geom2.spatialReference);

Mesh (3D Geometry)

Mesh is used for complex 3D surfaces with vertices and faces.

import Mesh from "@arcgis/core/geometry/Mesh.js";

// Create mesh from primitives
const box = Mesh.createBox(location, {
  size: { width: 100, height: 100, depth: 50 },
  material: { color: "red" }
});

const sphere = Mesh.createSphere(location, {
  size: 50,
  densificationFactor: 2,
  material: { color: "blue" }
});

const cylinder = Mesh.createCylinder(location, {
  size: { width: 50, height: 100 },
  material: { color: "green" }
});

// Load from glTF/GLB (URL is a separate parameter)
const mesh = await Mesh.createFromGLTF(location, "model.glb");

JSON Utilities

import jsonUtils from "@arcgis/core/geometry/support/jsonUtils.js";

// Create geometry from JSON
const geometry = jsonUtils.fromJSON({
  rings: [[[-118.8, 34.0], [-118.7, 34.0], [-118.7, 34.1], [-118.8, 34.1], [-118.8, 34.0]]],
  spatialReference: { wkid: 4326 }
});

// Get JSON from geometry
const json = geometry.toJSON();

Common Patterns

Check if Point is in Polygon

import containsOperator from "@arcgis/core/geometry/operators/containsOperator.js";

function isPointInPolygon(point, polygon) {
  return containsOperator.execute(polygon, point);
}

Create Buffer and Query

import geodesicBufferOperator from "@arcgis/core/geometry/operators/geodesicBufferOperator.js";

async function queryWithinDistance(point, distance, layer) {
  await geodesicBufferOperator.load();
  const bufferGeom = geodesicBufferOperator.execute(point, distance, { unit: "meters" });
  const query = layer.createQuery();
  query.geometry = bufferGeom;
  query.spatialRelationship = "contains";
  return await layer.queryFeatures(query);
}

Calculate Total Area

import unionOperator from "@arcgis/core/geometry/operators/unionOperator.js";
import geodeticAreaOperator from "@arcgis/core/geometry/operators/geodeticAreaOperator.js";

function calculateTotalArea(polygons) {
  const combined = unionOperator.execute(polygons);
  return geodeticAreaOperator.execute(combined, { unit: "square-kilometers" });
}

Reference Samples

  • geometry-operator-centroid - Computing geometry centroids
  • geometry-operator-offset-visualizer - Visualizing geometry offsets
  • geometry-operator-proximity - Proximity analysis with geometry operators
  • geometry-operator-worker - Running geometry operations in a web worker
  • ge-geodesicbuffer - Geodesic buffer operations

Common Pitfalls

  1. Spatial Reference Mismatch: Always ensure geometries are in the same spatial reference before operations

    // Project if needed
    import projectOperator from "@arcgis/core/geometry/operators/projectOperator.js";
    await projectOperator.load();
    if (!geom1.spatialReference.equals(geom2.spatialReference)) {
      geom2 = projectOperator.execute(geom2, geom1.spatialReference);
    }
    
  2. Geodesic vs Planar: Use geodesic operators for geographic coordinates (WGS84)

    // Use geodesicBufferOperator for lat/lon, bufferOperator for projected coordinates
    import geodesicBufferOperator from "@arcgis/core/geometry/operators/geodesicBufferOperator.js";
    import bufferOperator from "@arcgis/core/geometry/operators/bufferOperator.js";
    const bufferOp = geometry.spatialReference.isGeographic ? geodesicBufferOperator : bufferOperator;
    
  3. Ring Orientation: Outer rings clockwise, holes counter-clockwise

  4. Self-intersecting Polygons: Use simplifyOperator before operations on user-drawn polygons

  5. Load Operators: Call await operator.load() before using operators that require it (e.g., await projectOperator.load() before projectOperator.execute())


Deprecated: geometryEngine

DEPRECATED: The geometryEngine and geometryEngineAsync modules are deprecated as of version 4.29. Use the geometry operators module (shown above) instead.

The following is kept for reference when maintaining legacy code. Do not use for new development.

Migration Guide

Deprecated (geometryEngine) Modern (operators)
geometryEngine.buffer(geom, dist, unit) bufferOperator.execute(geom, dist, { unit })
geometryEngine.geodesicBuffer(geom, dist, unit) geodesicBufferOperator.execute(geom, dist, { unit })
geometryEngine.union([geoms]) unionOperator.execute([geoms])
geometryEngine.intersect(g1, g2) intersectionOperator.execute(g1, g2)
geometryEngine.contains(g1, g2) containsOperator.execute(g1, g2)
geometryEngine.within(g1, g2) withinOperator.execute(g1, g2)
geometryEngine.distance(g1, g2, unit) distanceOperator.execute(g1, g2)
geometryEngine.planarArea(geom, unit) areaOperator.execute(geom)
geometryEngine.geodesicArea(geom, unit) geodeticAreaOperator.execute(geom, { unit })
geometryEngine.simplify(geom) simplifyOperator.execute(geom)
geometryEngine.convexHull(geom) convexHullOperator.execute(geom)

Legacy geometryEngine (Deprecated)

// DEPRECATED - Do not use for new development
import geometryEngine from "@arcgis/core/geometry/geometryEngine.js";

// These methods still work but will be removed in a future release
const buffer = geometryEngine.buffer(point, 1000, "meters");
const intersects = geometryEngine.intersects(polygon1, polygon2);
const union = geometryEngine.union([polygon1, polygon2]);
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