Structures for Storing Geographic Data - Introducing Geographic Information Systems with ArcGIS - page 277

The idea is that the Water_Lines (called laterals) are supposed to connect to the Fire_Hydrants. You will
use the topology capabilities in geodatabases to see if they do, or if they don't, but are close enough, to
move the water lines.
It is rare that two sets of coordinates meant to refer to the same point in space will be identical if the
coordinates of the points are created in different ways. (Think back to the previous exercise regarding
problems with computer computation.) So, it is wise to ask if two represented points are sufficiently close
together to be considered in the same place. You, the user, can indicate what is “sufficiently close” by
specifying a “cluster distance” when you develop topology for a feature dataset. You may have noticed this
option in several other places, but now instead of ignoring it we will utilize it.
Creating a New Topology
4. Highlight Hydrants (the feature dataset, not the feature class Fire Hydrants). Select File > New >
Topology. Read the New Topology window. Next. Accept the default name Hydrants_Topology.
Enter a cluster tolerance of 5.0 Feet. See Figure 4-23. Click Next.
FIGURE 4-23
5. Put checks in the boxes of Fire_Hydrants and Water_Lines, so they will participate in the
topology. Click Next.
Specifying Which Feature Moves When Features
Are Adjusted: Rank
The process of generating and validating topology in geodatabases may result in moving some features.
You have control over which features move. Each feature class is given a rank. The highest rank is 1; 2
would be a lower rank. When a feature must move to correct a topological error, the feature that moves is
the one whose feature class has been assigned the lower rank. Let's presume that the locations of the