S2 Geometry

S2 Geometry is an open-source library developed by Google for performing geometric operationsGeometric OperationsGeometric operations are spatial transformations applied to vector geometries, including union, intersection, differe... and spatial indexingSpatial IndexingSpatial indexing organizes geospatial data into efficient data structures that dramatically accelerate location-based... directly on the surface of a sphere. Unlike planar geometry libraries that project Earth's curved surface onto a flat plane (introducing distortions), S2 operates natively in spherical coordinates, providing accurate results for global-scale applications without projection-related artifacts. S2 partitions the sphere into a hierarchy of cells using a Hilbert space-filling curve mapped onto the six faces of a cube projected onto the sphere. Each cell receives a 64-bit identifier that preserves spatial locality, meaning nearby cells on the sphere have numerically similar IDs. This property enables efficient range queries and spatial indexing in databases. S2 supports point, polyline, and polygon operations including containment tests, intersection, buffering, distance computation, and region covering (approximating arbitrary shapes with collections of S2 cells). S2 Geometry is the spatial backbone of numerous Google products including Google Maps, Google Earth, and BigQuery GISGISGeographic Information Systems (GIS) enable users to analyze and visualize spatial data to uncover patterns, relation.... It is also used in MongoDB's geospatial indexes, DynamoDB, and other systems requiring planetary-scale spatial operations. The library is available in C++, Java, Go, and Python, and its cell-based indexing approach has influenced the design of other spatial indexing systems. S2 is particularly suited for applications involving global datasets, cross-hemisphere queries, and polar regions where traditional map projections struggle.