Arcwhere

Arcwhere is a term used in geospatial analysis to describe a collection of methods, models, and tools designed to work with arc-based geometries in geographic information systems. It emphasizes representing curved features as arcs rather than solely as sequences of straight segments, enabling more faithful modeling of real-world phenomena such as road curves, river bends, and flight paths.

Data within arcwhere are organized around a core arc-centric data model. An Arc represents a curved segment defined by endpoints and either a center/radius or parametric representation, while Nodes or Points denote endpoints and junctions. Attributes such as curvature, radius, central angle, and direction help describe the geometry and its geometric/topological behavior. Additional primitives may include Polygonal envelopes or Buffers that follow arc contours.

Core operations include constructing arcs from endpoints and center information, converting polylines to arc sequences, computing arc length and curvature, projecting points onto an arc, measuring distances to an arc, and determining intersections between arcs. Arc subdivision, simplification, and matching against spatial indices are supported to enable scalable querying. Arc-centric spatial indexing accelerates operations like nearest-arc search, intersection tests, and range queries.

Implementation and usage typically involve libraries in multiple languages (e.g., Python, C++, JavaScript) that integrate with existing GIS ecosystems. Arcwhere components support standard spatial formats such as GeoJSON, Well-Known Text, and Well-Known Binary, and are designed to interoperate with map rendering and spatial databases.

Applications span transportation network modeling, utility and power-line analysis, environmental routing, and any domain where curved geometries provide a more accurate representation than piecewise linear approximations.

See also geometry, curved geometries, GIS, spatial indexing.