Shiny.Spatial

A dependency-free, cross-platform .NET geospatial database library. Uses SQLite R*Tree for spatial indexing with custom C# geometry algorithms for query refinement. No SpatiaLite, no NetTopologySuite — only SQLite via Microsoft.Data.Sqlite.

AOT compatible and trimmable.

Features

Two-pass spatial query pipeline (R*Tree bounding box filter + C# geometry refinement)
WGS84 (Haversine) and Cartesian (Euclidean) coordinate systems
Full geometry type support: Point, LineString, Polygon (with holes), Multi*, GeometryCollection
WKB (Well-Known Binary) serialization
Fluent query builder with property filtering, distance ordering, and paging
Bulk insert with transaction support
Works on iOS, Android, and all .NET platforms

Installation

<PackageReference Include="Shiny.Spatial" Version="1.0.0" />

Target Frameworks

Framework	Notes
`netstandard2.0`	Broad compatibility (Xamarin, .NET Framework, etc.)
`net10.0`	Modern .NET with AOT support

Dependencies

Microsoft.Data.Sqlite — brings SQLitePCLRaw.bundle_e_sqlite3 with R*Tree enabled
System.Memory — netstandard2.0 only (Span polyfill)

Quick Start

Create a Database and Table

using Shiny.Spatial.Database;
using Shiny.Spatial.Geometry;

using var db = new SpatialDatabase("mydata.db");  // or ":memory:"

var table = db.CreateTable("cities", CoordinateSystem.Wgs84,
    new PropertyDefinition("name", PropertyType.Text),
    new PropertyDefinition("population", PropertyType.Integer));

Insert Features

table.Insert(new SpatialFeature(new Point(-104.99, 39.74))
{
    Properties = { ["name"] = "Denver", ["population"] = 715000L }
});

table.Insert(new SpatialFeature(new Point(-104.82, 38.83))
{
    Properties = { ["name"] = "Colorado Springs", ["population"] = 478000L }
});

Bulk Insert

var features = new List<SpatialFeature>();
for (int i = 0; i < 100_000; i++)
    features.Add(new SpatialFeature(new Point(lon, lat)));

table.BulkInsert(features); // wrapped in a transaction

Distance Query

// Find all cities within 150 km of Denver
var nearby = table.FindWithinDistance(
    new Coordinate(-104.99, 39.74),
    distanceMeters: 150_000
);

Shape Containment Query

var colorado = 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)
});

var inState = table.FindIntersecting(colorado);

Fluent Query Builder

var center = new Coordinate(-104.99, 39.74);

var results = table.Query()
    .WithinDistance(center, 150_000)
    .WhereProperty("population", ">", 200000L)
    .OrderByDistance(center)
    .Limit(10)
    .ToList();

// Other terminal operations
int count = table.Query().InEnvelope(envelope).Count();
var first = table.Query().WithinDistance(center, 1000).FirstOrDefault();

Architecture

Two-Pass Query Pipeline

R*Tree bounding box filter (SQL, O(log n)) — eliminates most candidates using the SQLite R*Tree index
C# geometry refinement — exact Contains/Intersects/WithinDistance checks on survivors

SQLite Schema

Each spatial table creates a single R*Tree virtual table with auxiliary columns:

CREATE VIRTUAL TABLE {name}_rtree USING rtree(
    id, min_x, max_x, min_y, max_y,
    +geometry BLOB,              -- WKB-encoded geometry
    +prop_{name} {type}, ...     -- user-defined property columns
);

Metadata is tracked in __spatial_meta and __spatial_columns tables.

API Reference

Geometry Types

All geometry classes are immutable and sealed, extending the abstract Geometry base class.

Type	Description
`Coordinate`	Readonly struct with `X`/`Y` (aliased as `Longitude`/`Latitude`)
`Envelope`	Readonly struct — bounding box with `MinX`, `MaxX`, `MinY`, `MaxY`
`Point`	Single coordinate
`LineString`	Ordered sequence of coordinates (minimum 2)
`Polygon`	Exterior ring + optional interior rings (holes)
`MultiPoint`	Collection of Points
`MultiLineString`	Collection of LineStrings
`MultiPolygon`	Collection of Polygons
`GeometryCollection`	Collection of mixed Geometry types

Serialization

using Shiny.Spatial.Serialization;

byte[] wkb = WkbWriter.Write(geometry);
Geometry restored = WkbReader.Read(wkb);

Full roundtrip support for all geometry types using the WKB (Well-Known Binary) format.

Algorithms

using Shiny.Spatial.Algorithms;

Class	Method	Description
`DistanceCalculator`	`Haversine(a, b)`	Great-circle distance in meters (WGS84)
`DistanceCalculator`	`Euclidean(a, b)`	Cartesian distance
`DistanceCalculator`	`DistanceToSegment(p, a, b)`	Perpendicular distance from point to segment
`PointInPolygon`	`Contains(polygon, point)`	Ray-casting with hole support
`SegmentIntersection`	`Intersects(a1, a2, b1, b2)`	Cross-product segment intersection test
`SpatialPredicates`	`Intersects(a, b)`	Dispatch for all geometry type combinations
`SpatialPredicates`	`Contains(container, contained)`	Dispatch for all geometry type combinations
`EnvelopeExpander`	`ExpandByDistance(env, meters, cs)`	Expand envelope by distance (WGS84 or Cartesian)

Database

`SpatialDatabase` (IDisposable)

var db = new SpatialDatabase("path.db");    // file-backed
var db = new SpatialDatabase(":memory:");   // in-memory

SpatialTable table = db.CreateTable(name, coordinateSystem, properties...);
SpatialTable table = db.GetTable(name);
bool exists       = db.TableExists(name);
db.DropTable(name);
db.Dispose();

Validates R*Tree support on startup via PRAGMA compile_options.

`SpatialTable`

Method	Description
`Insert(feature)`	Insert a feature, returns its ID
`BulkInsert(features)`	Insert many features in a single transaction
`Update(feature)`	Update a feature by ID
`Delete(id)`	Delete a feature by ID
`GetById(id)`	Retrieve a single feature
`Count()`	Total feature count
`FindInEnvelope(envelope)`	R*Tree bounding box query
`FindIntersecting(geometry)`	Two-pass intersection query
`FindContainedBy(geometry)`	Two-pass containment query
`FindWithinDistance(center, meters)`	Two-pass distance query
`Query()`	Returns a fluent `SpatialQuery` builder

`SpatialQuery` (Fluent Builder)

Method	Type	Description
`InEnvelope(envelope)`	Filter	Bounding box filter
`Intersecting(geometry)`	Filter	Geometry intersection
`ContainedBy(geometry)`	Filter	Geometry containment
`WithinDistance(center, meters)`	Filter	Distance radius
`WhereProperty(name, op, value)`	Filter	Property comparison (`=`, `!=`, `<`, `<=`, `>`, `>=`, `LIKE`)
`OrderByDistance(center)`	Sort	Order by distance from coordinate
`Limit(count)`	Paging	Limit result count
`Offset(count)`	Paging	Skip first N results
`ToList()`	Terminal	Execute and return results
`Count()`	Terminal	Execute and return count
`FirstOrDefault()`	Terminal	Execute and return first or null

`SpatialFeature`

var feature = new SpatialFeature(new Point(-104.99, 39.74))
{
    Properties = { ["name"] = "Denver", ["population"] = 715000L }
};

long id = feature.Id;              // set after Insert
Geometry geom = feature.Geometry;
Dictionary<string, object?> props = feature.Properties;

`PropertyDefinition`

new PropertyDefinition("name", PropertyType.Text)
new PropertyDefinition("population", PropertyType.Integer)
new PropertyDefinition("area", PropertyType.Real)
new PropertyDefinition("data", PropertyType.Blob)

Pre-Built Databases

The databases/ folder contains ready-to-use spatial databases seeded with real geographic data.

Database Catalog

Database	Table	Geometry	Records	Properties
`us-states.db`	`states`	Polygon	51 (50 states + DC)	`name`, `abbreviation`, `population`
`us-cities.db`	`cities`	Point	100 (top 100 by pop.)	`name`, `state`, `population`
`ca-provinces.db`	`provinces`	Polygon	13 (all provinces/territories)	`name`, `abbreviation`, `population`
`ca-cities.db`	`cities`	Point	50 (top 50 by pop.)	`name`, `province`, `population`

All databases use the CoordinateSystem.Wgs84 coordinate system with WGS84 (longitude/latitude) coordinates.

Using a Pre-Built Database

using var db = new SpatialDatabase("databases/us-states.db");
var states = db.GetTable("states");

// Find which state Denver is in
var denver = new Point(-104.99, 39.74);
var results = states.FindIntersecting(denver);
// results[0].Properties["name"] == "Colorado"

// Find all states within 500km of Chicago
var nearby = states.FindWithinDistance(new Coordinate(-87.6298, 41.8781), 500_000);

using var db = new SpatialDatabase("databases/us-cities.db");
var cities = db.GetTable("cities");

// Find cities near San Francisco with population over 500K
var sf = new Coordinate(-122.4194, 37.7749);
var results = cities.Query()
    .WithinDistance(sf, 100_000)
    .WhereProperty("population", ">", 500000L)
    .OrderByDistance(sf)
    .ToList();

using var db = new SpatialDatabase("databases/ca-provinces.db");
var provinces = db.GetTable("provinces");

// Find which province Toronto is in
var toronto = new Point(-79.3832, 43.6532);
var results = provinces.FindIntersecting(toronto);
// results[0].Properties["name"] == "Ontario"

Regenerating Databases

The databases are generated by the Shiny.Spatial.DatabaseSeeder tool. To regenerate:

dotnet run --project tools/Shiny.Spatial.DatabaseSeeder -- ./databases

The seeder contains hardcoded geographic data with simplified polygon boundaries for states/provinces and point locations for cities, using census population figures.

Geofencing (`Shiny.Spatial.Geofencing`)

GPS-driven geofence monitoring for iOS and Android. Built on Shiny.Locations for background GPS and Shiny.Spatial for spatial queries.

The primary use case is monitoring preexisting spatial databases containing city and state/province polygons. Point the monitor at one or more spatial database tables and it detects region enter/exit automatically.

Installation

<PackageReference Include="Shiny.Spatial.Geofencing" Version="1.0.0" />

Setup

Add() requires a file path on disk. For databases bundled as MAUI raw assets (Resources/Raw), copy to AppDataDirectory first since SQLite cannot open files directly from the app package:

// In MauiProgram.cs
builder.Services.AddSpatialGps<MyGeofenceDelegate>(config =>
{
    config.MinimumDistance = Distance.FromMeters(300); // default
    config.MinimumTime = TimeSpan.FromMinutes(1);     // default
    config
        .Add(CopyAssetToAppData("us-states.db"), "states")
        .Add(CopyAssetToAppData("us-cities.db"), "cities");
});

// Helper to copy a MAUI raw asset to a writable location
static string CopyAssetToAppData(string assetFileName)
{
    var destPath = Path.Combine(FileSystem.AppDataDirectory, assetFileName);
    if (!File.Exists(destPath))
    {
        using var source = FileSystem.OpenAppPackageFileAsync(assetFileName).GetAwaiter().GetResult();
        using var dest = File.Create(destPath);
        source.CopyTo(dest);
    }
    return destPath;
}

Controlling the Monitor

Use ISpatialGeofenceManager to start/stop geofence monitoring and query the current region:

// Inject ISpatialGeofenceManager
await geofences.RequestAccess();
await geofences.Start();

// Check current regions at any time
var regions = await geofences.GetCurrent();
foreach (var r in regions)
{
    var name = r.Region?.Properties.GetValueOrDefault("name") ?? "None";
    Console.WriteLine($"{r.TableName}: {name}");
}

await geofences.Stop();

Handling Events

Implement ISpatialGeofenceDelegate to receive enter/exit events:

public class MyGeofenceDelegate(ILogger<MyGeofenceDelegate> logger) : ISpatialGeofenceDelegate
{
    public Task OnRegionChanged(SpatialRegionChange change)
    {
        var regionName = change.Region.Properties.GetValueOrDefault("name") ?? "Unknown";
        var action = change.Entered ? "Entered" : "Exited";
        logger.LogInformation("{Action} {Region} in {Table}", action, regionName, change.TableName);
        return Task.CompletedTask;
    }
}

Each SpatialRegionChange has:

TableName — the spatial table that was matched
Region — the SpatialFeature being entered or exited
Entered — true for entry, false for exit

When transitioning directly from Region A to Region B, two events fire: exit A, then enter B.

Project Structure

geospatialdb/
├── Shiny.Spatial.slnx
├── databases/                  Pre-built spatial databases
│   ├── us-states.db
│   ├── us-cities.db
│   ├── ca-provinces.db
│   └── ca-cities.db
├── src/Shiny.Spatial/
│   ├── Shiny.Spatial.csproj
│   ├── Geometry/               Coordinate, Envelope, Point, LineString, Polygon,
│   │                           MultiPoint, MultiLineString, MultiPolygon, GeometryCollection
│   ├── Serialization/          WkbReader, WkbWriter
│   ├── Algorithms/             DistanceCalculator, PointInPolygon, SegmentIntersection,
│   │                           SpatialPredicates, EnvelopeExpander
│   └── Database/               SpatialDatabase, SpatialTable, SpatialFeature, SpatialQuery
│       └── Internal/           ConnectionPool, SchemaManager, SqlBuilder
├── src/Shiny.Spatial.Geofencing/
│   ├── Shiny.Spatial.Geofencing.csproj
│   ├── ISpatialGeofenceDelegate.cs     Delegate interface for enter/exit events
│   ├── ISpatialGeofenceManager.cs      Manager interface (start/stop/get current)
│   ├── SpatialGpsDelegate.cs           GPS listener that detects region changes
│   ├── SpatialMonitorConfig.cs         Configuration (databases, tables, thresholds)
│   ├── SpatialRegionChange.cs          Event data (Region, Entered bool)
│   ├── ServiceCollectionExtensions.cs  DI registration (AddSpatialGps)
│   └── Infrastructure/
│       └── SpatialGeofenceManager.cs   Manager implementation
├── tests/Shiny.Spatial.Tests/
│   ├── GeometryTests.cs
│   ├── WkbTests.cs
│   ├── AlgorithmTests.cs
│   ├── DatabaseTests.cs
│   ├── QueryTests.cs
│   └── PerformanceTests.cs
├── tests/Shiny.Spatial.Geofencing.Tests/
│   ├── SpatialGpsDelegateTests.cs      GPS delegate enter/exit/transition tests
│   └── SpatialRegionChangeTests.cs     Record equality and deconstruction tests
├── tests/Shiny.Spatial.Benchmarks/
│   ├── InsertBenchmarks.cs
│   ├── SpatialQueryBenchmarks.cs
│   ├── QueryBuilderBenchmarks.cs
│   ├── AlgorithmBenchmarks.cs
│   └── SerializationBenchmarks.cs
├── samples/Sample.Maui/               MAUI sample app with geofencing
└── tools/Shiny.Spatial.DatabaseSeeder/
    ├── Shiny.Spatial.DatabaseSeeder.csproj
    ├── Program.cs
    └── Data/                   Hardcoded geographic seed data
        ├── UsStates.cs             51 US state/territory polygons
        ├── UsCities.cs             100 US city points
        ├── CanadianProvinces.cs    13 Canadian province/territory polygons
        └── CanadianCities.cs       50 Canadian city points

Benchmarks

Measured with BenchmarkDotNet on Apple M2, .NET 10.0.3, Arm64 RyuJIT AdvSIMD. All database benchmarks use in-memory SQLite (:memory:) to isolate CPU/algorithm cost from disk I/O.

# Run all benchmarks
dotnet run --project tests/Shiny.Spatial.Benchmarks -c Release

# Run a specific suite
dotnet run --project tests/Shiny.Spatial.Benchmarks -c Release -- --filter "*Algorithm*"

Insert Performance

Method	Count	Mean	Allocated
SingleInsert	1,000	14.27 ms	4.32 MB
BulkInsert	1,000	9.81 ms	3.15 MB
SingleInsert	10,000	120.51 ms	43.12 MB
BulkInsert	10,000	93.11 ms	31.37 MB
SingleInsert	100,000	1,204.32 ms	431.07 MB
BulkInsert	100,000	963.87 ms	313.59 MB

Spatial Queries (100K points)

Method	Mean	Allocated
FindInEnvelope_Small	1,815.44 us	693.47 KB
FindInEnvelope_Large	60,631.83 us	17,767.42 KB
FindIntersecting_Polygon	1,153.05 us	447.58 KB
FindWithinDistance	183.22 us	85.04 KB
FindContainedBy	986.73 us	447.58 KB
GetById	9.40 us	3.48 KB

Fluent Query Builder (100K points)

Method	Mean	Allocated
SpatialOnly	2,019.6 us	851.75 KB
SpatialPlusPropertyFilter	1,442.1 us	426.27 KB
DistanceWithOrderAndLimit	253.7 us	84.95 KB
PropertyFilterOnly	87,064.9 us	7,230.53 KB

Algorithms (pure computation, no DB)

Method	Mean	Allocated
Haversine	28.33 ns	-
Euclidean	0.15 ns	-
PointInPolygon_Simple (5 vertices)	23.63 ns	-
PointInPolygon_Complex (100 vertices)	252.58 ns	-
SegmentIntersection	2.72 ns	-
SpatialPredicates_PointInPolygon	25.70 ns	32 B
SpatialPredicates_PolygonIntersectsPolygon	41.86 ns	-

WKB Serialization

Method	Mean	Allocated
WritePoint	57.87 ns	432 B
ReadPoint	49.51 ns	248 B
WritePolygon (5 vertices)	115.96 ns	504 B
ReadPolygon (5 vertices)	135.63 ns	672 B
WriteComplexPolygon (100 vertices)	1,373.27 ns	5,696 B
ReadComplexPolygon (100 vertices)	2,207.57 ns	8,352 B
WriteLineString (50 coords)	705.30 ns	2,808 B
ReadLineString (50 coords)	827.24 ns	4,232 B

Running Tests

dotnet test

53 tests covering geometry types, WKB roundtrips, spatial algorithms, database CRUD, query pipeline, and a 100K point performance benchmark.

License

MIT

Name		Name	Last commit message	Last commit date
Latest commit History 26 Commits
.github		.github
SKILLS/shiny-spatial		SKILLS/shiny-spatial
databases		databases
samples/Sample.Maui		samples/Sample.Maui
src		src
tests		tests
tools/Shiny.Spatial.DatabaseSeeder		tools/Shiny.Spatial.DatabaseSeeder
.editorconfig		.editorconfig
.gitattributes		.gitattributes
.gitignore		.gitignore
Directory.build.props		Directory.build.props
Directory.packages.props		Directory.packages.props
LICENSE		LICENSE
README.md		README.md
Shiny.Spatial.slnx		Shiny.Spatial.slnx
build.slnf		build.slnf
global.json		global.json
nuget.config		nuget.config
nuget.png		nuget.png
nuget.txt		nuget.txt
version.json		version.json

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License

shinyorg/geospatialdb

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Shiny.Spatial

Features

Installation

Target Frameworks

Dependencies

Quick Start

Create a Database and Table

Insert Features

Bulk Insert

Distance Query

Shape Containment Query

Fluent Query Builder

Architecture

Two-Pass Query Pipeline

SQLite Schema

API Reference

Geometry Types

Serialization

Algorithms

Database

SpatialDatabase (IDisposable)

SpatialTable

SpatialQuery (Fluent Builder)

SpatialFeature

PropertyDefinition

Pre-Built Databases

Database Catalog

Using a Pre-Built Database

Regenerating Databases

Geofencing (Shiny.Spatial.Geofencing)

Installation

Setup

Controlling the Monitor

Handling Events

Project Structure

Benchmarks

Insert Performance

Spatial Queries (100K points)

Fluent Query Builder (100K points)

Algorithms (pure computation, no DB)

WKB Serialization

Running Tests

License

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`SpatialDatabase` (IDisposable)

`SpatialTable`

`SpatialQuery` (Fluent Builder)

`SpatialFeature`

`PropertyDefinition`

Geofencing (`Shiny.Spatial.Geofencing`)