Topology
Definition
In GIS, topology describes the spatial relationships among features—connectivity, adjacency, containment—independent of exact coordinates. A topological data model stores nodes, edges, and faces so that editing preserves relationships and analytic operations rely on logical structure rather than raw geometry alone. Topology enables routing, network tracing, parcel fabrics, and reliable polygon overlays.
Application
Transportation networks, utility circuits, administrative boundaries, and ecological patches all benefit from topological integrity for accurate analytics and maintenance.
FAQ
How does a topological model differ from spaghetti geometry?
Spaghetti stores independent shapes; topology shares boundaries and nodes, preventing slivers and ensuring consistent adjacency and connectivity.
What performance tradeoffs come with strict topology?
Edits incur validation costs and complexity, but the payoff is fewer downstream errors and simpler analytics once rules are enforced.
How is topology represented for rasters?
Neighborhood relationships are implicit in cell adjacency; graph-based methods can be built on rasters for flow or connectivity analyses.
When is soft topology acceptable?
For visualization layers where perfect adjacency is unnecessary; for authoritative datasets used in analysis, strict topology is recommended.
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