Centroid
Overview
Centroid is the geometric center of a spatial feature, often used to represent the location of polygons or other complex shapes in GIS analysis. The centroid provides a single point that represents the average position of all points making up a shape.
Key Concepts
Geometric centroid is the mathematical center of mass of a shape (may fall outside the shape for concave polygons). Point on surface is a point guaranteed to be inside the polygon boundary. Representative point is a practical location within a feature for labeling or analysis. Weighted centroid incorporates attribute values to shift the center point.
Calculation
For a polygon with vertices:
- X-centroid = average of all vertex X coordinates
- Y-centroid = average of all vertex Y coordinates
Use Cases
- Labeling polygon features on maps
- Calculating distances between polygon features
- Point-based analysis of area features
- Spatial joins between polygons and points
Appendix
Created: 2025-12-13 | Modified: 2025-12-13