isValid

Returns true when the geometry is well-formed and valid in 2D according to the OGC rules. For geometries with 3 and 4 dimensions, the validity is still only tested in 2 dimensions.

Validity is defined for each Geometry type as follows:

• Point coordinates must be finite (not NaN or Infinity)
• MultiPoint points must all be valid
• LineString must have at least 2 unique points
• MultiLineString lines must all be valid
• LinearRing must have at lest 4 unique points, be closed (first and last point must be equal), be simple i.e. must not self-intersect except at endpoints
• Polygon interior must be connected (some hole cannot split interior into parts)
  • Shell (exterior ring) must be a valid LinearRing, not be self-touching (could be configured by options.isInvertedRingValid parameter), not be exverted ("bow-tie" configuration)
  • Holes (interior rings) each must be a valid LinearRing, be completely inside the shell, not be nested inside other holes, not self-touch to create disconnected interiors, not be "C-shaped" with self-touching that creates islands
• MultiPolygon polygons must all be valid, no polygon can be in the interior of another polygon, shells cannot partially overlap or touch along an edge
• GeometryCollection geometries must all be valid
• Empty geometries are valid

Parameters

Name	Type	Default	Description
geometry	Geometry		The geometry to check
options?	object		Optional options object
options.isInvertedRingValid?	boolean	false	Sets how to treat a polygon with self-touching rings. If set to true the following self-touching conditions are treated as being valid (ESRI SDE model): inverted shell - the shell ring self-touches to create a hole touching the shell exverted hole - a hole ring self-touches to create two holes touching at a point If set to false the above conditions, following the OGC SFS standard, are treated as not valid.

Returns

boolean

true when geometry is valid, false otherwise

Throws

• GEOSError on unsupported geometry types (curved)

See also

• isValidOrThrow throws an error when geometry is not valid
• makeValid repairs invalid geometries

Examples

const line = lineString([ [ 1, 1 ], [ 2, 2 ] ]);
const line_valid = isValid(line); // true

const poly = polygon([ // self-touching exterior ring forming hole
    [ [ 0, 0 ], [ 0, 10 ], [ 10, 0 ], [ 0, 0 ], [ 4, 2 ], [ 2, 4 ], [ 0, 0 ] ],
]);
const poly_valid1 = isValid(poly); // false
const poly_valid2 = isValid(poly, { isInvertedRingValid: true }); // true

const line = lineString([ [ 1, 1 ], [ 2, 2 ] ]); const line_valid = isValid(line); // true const poly = polygon([ // self-touching exterior ring forming hole [ [ 0, 0 ], [ 0, 10 ], [ 10, 0 ], [ 0, 0 ], [ 4, 2 ], [ 2, 4 ], [ 0, 0 ] ], ]); const poly_valid1 = isValid(poly); // false const poly_valid2 = isValid(poly, { isInvertedRingValid: true }); // true