FC-18 - Adjacency and connectivity
- List different ways connectivity can be determined in a raster and in a polygon dataset
- Explain the nine-intersection model for spatial relationships
- Demonstrate how adjacency and connectivity can be recorded in matrices
- Calculate various measures of adjacency in a polygon dataset
- Create a matrix describing the pattern of adjacency in a set of planar enforced polygons
- Describe real world applications where adjacency and connectivity are a critical component of analysis
FC-14 - Directional Operations
In the same manner as distance, direction plays an equally important role in GIS. This article first summarizes different ways of measuring direction, either quantitatively or qualitatively. Formulas and examples are provided. In the following discussion, fundamental differences between distance and direction in describing spatial relations is examined; properties of angles are emphasized in the context of GIS; and the classification of both cardinal and projective direction is illustrated. With a focus on quantitative operations, various directional operations are categorized and elaborated based on factors such as the underlying data model (vector or raster) and whether direction effect is explicitly or implicitly embedded in the data.