Lecture 4

The Topology
1. DESCRIBE Connectivity to toplology IS BETWEEN Spatial Features, Which IS A Collection of the rules of that Coupled with A SET Editing Tools and Techniques, the geodatabase to the Enables More Accurately Model The Geometric Relationships provide a well-defined way to automatically clear the data input and verify data errors
2. topology need data validation (verification) + Spatial Analysis
3. Digitizing Typical Procedure
a) Digitize All Lines
B) Build Topology
C) Polygons label
D) Clean up Slivers, Dangles, and under- and overshoots
E ) Build Topology Again, repeating the Clean and Build Phases AS MANY AS Times Necessary
Topological Model
1. feature geometry defined by spatial objects, their relationships, and wherein a boundary
2. Two views:
a) features (Points, Lines, and Polygons)
b) topological elements (nodes, edges, faces, and their relationships)
3. 使用功能
a) features are defined by their coordinates(坐标)
b) features are represented as an ordered graph of their topological elements
Topology rules
1. 定义了features之间允许的空间关系
2. The rules you define control the relationships between features within a feature class, between features in different feature classes, or between subtypes of features
Spatial relationships
1. Spatial relationships express specifically how features share coincident geometry along with the rules for the behavior of their spatial representations

 

2. Draw a line from the point to infinity in any direction, and count the number of intersections between this line and each polygon’s boundary. The polygon with an odd number of intersections is the containing polygon: all other polygons have an even number of intersections
# You cannot create network datasets or perform topology rules on rasters