Geometry Types

Shiny.Spatial provides a complete set of immutable geometry types following the OGC Simple Features specification. All types are sealed and thread-safe.

Coordinate

A 2D coordinate pair representing a point in space. This is a value type (struct).

var coord = new Coordinate(x: -104.99, y: 39.74);

// Aliases for geographic coordinates
double lon = coord.Longitude; // same as coord.X
double lat = coord.Latitude;  // same as coord.Y

Property	Type	Description
X	double	X coordinate (aliased as Longitude)
Y	double	Y coordinate (aliased as Latitude)

Supports equality comparison and ToString().

Envelope

A bounding box (minimum bounding rectangle) defined by min/max coordinates. This is a value type (struct).

var envelope = new Envelope(minX: -109.05, maxX: -102.05, minY: 37.0, maxY: 41.0);

bool inside = envelope.Contains(new Coordinate(-104.99, 39.74)); // true
bool overlaps = envelope.Intersects(otherEnvelope);
var expanded = envelope.ExpandToInclude(new Coordinate(-110.0, 42.0));

Property	Type	Description
MinX	double	Minimum X value
MaxX	double	Maximum X value
MinY	double	Minimum Y value
MaxY	double	Maximum Y value
Width	double	MaxX - MinX
Height	double	MaxY - MinY
Center	Coordinate	Center point of the envelope

Method	Returns	Description
Contains(Coordinate)	bool	Whether the coordinate is inside the envelope
Intersects(Envelope)	bool	Whether two envelopes overlap
ExpandToInclude(Coordinate)	Envelope	Returns a new envelope expanded to include the coordinate

The static Envelope.Empty property returns an empty envelope.

Geometry Base Class

All geometry types extend the abstract Geometry class.

Property/Method	Type	Description
Type	GeometryType	The geometry type enum value
IsEmpty	bool	Whether the geometry contains no coordinates
GetEnvelope()	Envelope	Computes the minimum bounding rectangle

GeometryType Enum

public enum GeometryType
{
    Point = 1,
    LineString = 2,
    Polygon = 3,
    MultiPoint = 4,
    MultiLineString = 5,
    MultiPolygon = 6,
    GeometryCollection = 7
}

Point

A single coordinate in space.

var point = new Point(-104.99, 39.74);

double x = point.X;         // -104.99
double y = point.Y;         // 39.74
var coord = point.Coordinate;

Property	Type	Description
Coordinate	Coordinate	The point’s coordinate
X	double	X value
Y	double	Y value

LineString

An ordered sequence of two or more coordinates forming a line.

var line = new LineString(new[]
{
    new Coordinate(0, 0),
    new Coordinate(1, 1),
    new Coordinate(2, 0)
});

bool closed = line.IsClosed; // false (first != last coordinate)

Property	Type	Description
Coordinates	IReadOnlyList<Coordinate>	Ordered list of coordinates
IsClosed	bool	Whether first and last coordinates are equal

Note

A LineString requires at least 2 coordinates. The constructor will throw if fewer are provided.

Polygon

A closed shape defined by an exterior ring and optional interior rings (holes).

// Simple polygon (no holes)
var polygon = new Polygon(new[]
{
    new Coordinate(-109.05, 37.0),
    new Coordinate(-102.05, 37.0),
    new Coordinate(-102.05, 41.0),
    new Coordinate(-109.05, 41.0),
    new Coordinate(-109.05, 37.0) // must close the ring
});

// Polygon with a hole
var withHole = new Polygon(
    exteriorRing: new[]
    {
        new Coordinate(0, 0), new Coordinate(10, 0),
        new Coordinate(10, 10), new Coordinate(0, 10),
        new Coordinate(0, 0)
    },
    interiorRings: new[]
    {
        new[]
        {
            new Coordinate(2, 2), new Coordinate(8, 2),
            new Coordinate(8, 8), new Coordinate(2, 8),
            new Coordinate(2, 2)
        }
    }
);

Property	Type	Description
ExteriorRing	IReadOnlyList<Coordinate>	The outer boundary coordinates
InteriorRings	IReadOnlyList<IReadOnlyList<Coordinate>>	Hole boundaries (may be empty)

Note

Polygon rings must have at least 4 coordinates, and the first and last coordinate must be identical (closed ring).

MultiPoint

A collection of Point geometries.

var multiPoint = new MultiPoint(new[]
{
    new Point(0, 0),
    new Point(1, 1),
    new Point(2, 2)
});

Property	Type	Description
Points	IReadOnlyList<Point>	The collection of points

MultiLineString

A collection of LineString geometries.

var multi = new MultiLineString(new[]
{
    new LineString(new[] { new Coordinate(0, 0), new Coordinate(1, 1) }),
    new LineString(new[] { new Coordinate(2, 2), new Coordinate(3, 3) })
});

Property	Type	Description
LineStrings	IReadOnlyList<LineString>	The collection of line strings

MultiPolygon

A collection of Polygon geometries.

var multi = new MultiPolygon(new[] { polygon1, polygon2 });

Property	Type	Description
Polygons	IReadOnlyList<Polygon>	The collection of polygons

GeometryCollection

A heterogeneous collection of any geometry types.

var collection = new GeometryCollection(new Geometry[]
{
    new Point(0, 0),
    new LineString(new[] { new Coordinate(1, 1), new Coordinate(2, 2) }),
    polygon
});

Property	Type	Description
Geometries	IReadOnlyList<Geometry>	The collection of mixed geometries