CesiumJS Spatial Math

---
name: cesiumjs-spatial-math
description: "CesiumJS spatial math - Cartesian3, Cartographic, Matrix4, Quaternion, Transforms, Ellipsoid, BoundingSphere, projections, coordinate conversions. Use when converting between coordinate systems, computing positions on the ellipsoid, performing spatial intersection tests, building model matrices, or working with geographic projections."
---
# CesiumJS Spatial Math & Transforms

Version baseline: CesiumJS v1.142 (2026-06-01)

Mathematical foundation for every CesiumJS application: coordinate types, unit conversions, ellipsoid geometry, reference frame transforms, bounding volumes, intersection tests, and projections.

## Core Concepts

CesiumJS uses a right-handed Earth-Centered Earth-Fixed (ECEF) coordinate system:

- **Cartesian3** -- ECEF (x, y, z) in meters. Internal representation for all 3D positions.
- **Cartographic** -- (longitude, latitude, height). Angles are **radians**, height in meters above ellipsoid.

All angular values in core math are radians. Use `Math.toRadians()` / `Math.toDegrees()`. Math types use a **static-method-with-result** pattern: pass a `result` parameter to reuse allocations.

## Cartesian3 -- Positions and Vectors

```js
import { Cartesian3, Math as CesiumMath } from "cesium";

// From lon/lat degrees -- most common entry point